pulsed nd:yag lasers user’s manual -...

Quanta-Ray Lab-SeriesPulsed Nd:YAG Lasers

User’s Manual

1335 Terra Bella AvenueMountain View, CA 94043

Part Number 0000-311A, Rev. AJune 2003

iii

Preface

This manual contains information you need in order to safely install, align,operate, maintain and service your Quanta-Ray Lab-Series pulsed Nd:YAGlaser on a day-to-day basis. Also described is the installation and operationof the HG harmonic generator and IHS internal harmonic separator. Thesystem comprises three main elements: the Lab-Series laser head, thepower supply and a table-top controller. (The system can also be controlledremotely via the front panel RS-232 serial port.) An optional Model WA-1heat exchanger may also be present.

The “Introduction” contains a brief description of these three componentsand is followed by an important chapter on laser safety. The Lab-Series is aClass IV laser and, as such, emits laser radiation which can permanentlydamage eyes and skin, ignite fires and vaporize substances. Moreover,focused back-reflections of even a small percentage of its output energycan destroy expensive internal optical components. This section containsinformation about these hazards and offers suggestions on how to safe-guard against them. To minimize the risk of injury or expensive repairs, besure to read this chapter—then carefully follow these instructions. Thischapter also contains information regarding system compliance to CDRHand CE regulations.

“Laser Description” contains a short section on laser theory regarding theNd:YAG crystal rods that are used in the Lab-Series laser. Also included isa discussion of the second, third and fourth harmonic laser output gener-ated by the system. Following this is a more detailed description of theLab-Series laser system, concluding with system specifications and outlinedrawings.

The next few chapters describe the Lab-Series controls and interconnects,and guide you through its installation, alignment and operation. The lastpart of the manual covers maintenance and service and includes a replace-ment parts list and a list of world-wide Spectra-Physics service centers youcan call if you need help. Appendix A is a Programming Reference Guidefor those who wish to operate the laser system automatically.

Whereas the “Maintenance” section contains information you need to keepyour laser clean and operational on a day-to-day basis, “Service andRepair” is intended to help you guide your Spectra-Physics field serviceengineer to the source of any problems. Do not attempt repairs yourselfwhile the unit is still under warranty; instead, report all problems to Spectra-Physics for warranty repair.

Quanta-Ray Lab-Series Pulsed Nd:YAG Laser System

iv

This product has been tested and found to conform to “Directive 89/336/EEC for electromagnetic Compatibility.” Class A compliance was demon-strated for “EN 50081-2:1993 Emissions” and “EN 50082-1:1992 Immu-nity” as listed in the official Journal of the European Communities. It alsomeets the intent of “Directive 73/23/EEC for Low Voltage.” Class A com-pliance was demonstrated for “EN 61010-1:1993 Safety Requirements forElectrical Equipment for Measurement, Control and Laboratory use” and“EN 60825-1:2001 Radiation Safety for Laser Products.” Refer to the “CEDeclaration of Conformity” statements in Chapter 2.

Should you experience any problems with any equipment purchased fromSpectra-Physics, or you are in need of technical information or support,please contact Spectra-Physics as described in “Customer Service.” Thischapter contains a list of world-wide Spectra-Physics service centers youcan call if you need help.

Every effort has been made to ensure that the information in this manual isaccurate. All information in this document is subject to change withoutnotice. Spectra-Physics makes no representation or warranty, either expressor implied, with respect to this document. In no event will Spectra-Physicsbe liable for any direct, indirect, special, incidental or consequential dam-ages resulting from any defects in this documentation.

Finally, if you encounter any difficulty with the content or style of thismanual, or encounter problems with the laser itself, please let us know. Thelast page of this manual is a form to aid in bringing such problems to ourattention.

Thank you for your purchase of Quanta-Ray Spectra-Physics instruments.

v

CE Environmental Specifications

CE Electrical Equipment Requirements

For information regarding the equipment needed to provide the electricalservice listed under “Service Requirements” at the end of Chapter 3, pleaserefer to specification EN-309, “Plug, Outlet and Socket Couplers for Indus-trial Uses,” listed in the official Journal of the European Communities.

Environmental Specifications

The environmental conditions under which the laser system will functionare listed below:

Indoor useAltitude: up to 2000 mTemperatures: 10° C to 40° CMaximum relative humidity: 80% non-condensing for temperatures up to

31° C.Mains supply voltage: do not exceed ±10% of the nominal voltageInsulation category: IIPollution degree: 2

vii

Table of Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

CE Environmental Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vCE Electrical Equipment Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vEnvironmental Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Warning Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii

Standard Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

Unpacking and Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviiUnpacking Your Laser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviiSystem Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviiAccessory Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii

Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1The Quanta-Ray Lab-Series Pulsed Nd:YAG Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

The Laser Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1The Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2The Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

The Lab-Series Advantage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3Patents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

Chapter 2: Laser Safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1Precautions For The Safe Operation Of Class IV High Power Lasers . . . . . . . . . . . . . . . . . . . . . . . . . 2-1Safety Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Emission Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3MONITOR: PoWeR ON Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3MONITOR: INTERLOCK Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4REMOTE INTERLOCK Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4Cover Safety Interlocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4POWER Keyswitch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5POWER Circuit Breaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5Focused Back-Reflection Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

Maintenance Necessary to Keep this Laser Product in Compliance with Center for Devices and Radiological Health (CDRH) Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

CE/CDRH Radiation Control Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7Label Translations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8

CE Declaration of Conformity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9Sources for Additional Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10

Laser Safety Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10Equipment and Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11


viii

Chapter 3: Laser Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1A Brief Review of Ion Laser Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1

Emission and Absorption of Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1Population Inversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2Nd:YAG as an Excitation Medium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4

Q-switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5Resonant Optical Cavity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-6

Longitudinal Modes and Linewidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-7Producing Other Wavelengths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-8Resonator Structural Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-9

Pulse Triggering Sequence and Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-9General Note on Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-11Laser Output Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-12Outline Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-14

Chapter 4: Controls, Indicators and Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1The Laser Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1

End Connector Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3The Marx Bank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4The Seeder Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4The Emission Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5

The Power Supply Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6The Power Supply Rear Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-8The Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-9The GUI Software Menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-11

Main Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-11Setting Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-13Information Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-14

Chapter 5: Installation and Alignment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1Installing the Laser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1

Connecting the Electrical Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1Connecting the Power Supply and Laser Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-3Connecting the Harmonic Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-3

Filling the Cooling System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-4Installing the Lab-Series GUI Software for Remote Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-5Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-6

Chapter 6: Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1Operation Using the Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1

Quick Start/Stop Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-2Standard Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-2

Operation Using the GUI Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-5Quick Start/Stop Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-5Standard Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-6

Moving the Laser System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-8

Chapter 7: Harmonic Generator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1Harmonic Generator Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-1Harmonic Generator Temperature Controller Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-3Installing the Harmonic Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-3

Table of Contents

ix

Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5Type I and II Crystals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5

Second Harmonic (types I and II), and Third and Fourth Harmonic Generation . . . . . . . . . . . . . . 7-5

Chapter 8: Internal Harmonic Separator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1Dichroics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1IHS System Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1System Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2

Removing the Beam Dump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3Installing the IHS Mirror Mounts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3Replacing the Dichroic Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5Operating the IHS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6Removing/Replacing the Beam Dump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6

Chapter 9: Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1Cleaning Laser Optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1

Equipment Required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2Cleaning Prisms, Mirrors and Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3

Maintaining the Cooling System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3Maintaining the Harmonic Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4Replacing the Deionizing Water Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4

Tools needed: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-5

Replacing the Particulate Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-6Tools needed: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-6Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-6

Replacing the Air Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-7Tools needed: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-7Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-7

Replacing the Flash Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-8Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-8

Chapter 10: Service and Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1General Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1

Enabling Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1Analog Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1Local/Remote Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-2Q-switch Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-2Q-switch Advanced Sync Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-2Mode Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3Q-switch Drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3Single-Shot Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3LAMP ON Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3STOP/ENABLE buttons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4Interlock Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4Pulse-Forming Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4Flash Lamp Simmer Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-5

Shipping the Laser and Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-5Draining the Cooling System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-5

Replacement Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-7


x

Chapter 11: Customer Service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-1Customer Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-1

Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-1Return of the Instrument for Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-2

Service Centers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-3

Appendix A: Status/Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

Appendix B: Programming Reference Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

Notes

Report Form for Problems and Solutions

List of FiguresFigure 1-1: The Lab-Series Laser Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1Figure 1-2: The Lab-Series Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2Figure 1-3: The Lab-Series Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2Figure 2-1: This CE standard safety warning labels would be appropriate for use as an

entry warning sign (EN 60825-1, ANSI 4.3.10.1). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2Figure 2-2: Optical Beam Dump, Model BD-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2Figure 2-3: Laser Head Emission Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-3Figure 2-4: The Lab-Series Power supply Control Panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-3Figure 2-5: The Lab-Series Power supply Rear Panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4Figure 2-6: Interlock Switches, Laser Head. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4Figure 2-7:Interlock Switch, Power Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5Figure 2-8: CE/CDRH Radiation Control Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-7Figure 3-1: Electrons occupy distinct orbitals that are defined by the probability of finding

an electron at a given position, the shape of the orbital being determined by the radial and angular dependence of the probability. Shown is an “s” orbital on the left, a “p” type on the right. 3-2

Figure 3-2: A Typical Four-level Transition Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3Figure 3-3: Energy Level Scheme for the Nd:YAG Laser Source . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4Figure 3-4: The Q-switch comprises a polarizer, a quarter-wave polarization rotator, and a

Pockels cell. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5Figure 3-5: Stable and Unstable Resonator Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-6Figure 3-6: Frequency distribution of longitudinal modes for a single line . . . . . . . . . . . . . . . . . . . . . .3-7Figure 3-7: Simplified Block Diagram of the Lab-Series electronics. . . . . . . . . . . . . . . . . . . . . . . . . . .3-10Figure 3-8: Lab-Series Timing Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-11Figure 3-9: Outline Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-14Figure 4-1: An isometric view of the internal components of the Lab-series laser head. . . . . . . . . . . .4-1Figure 4-2: Laser Head Rear Panel Controls and Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3Figure 4-3: The Laser Head Side Panel Injection Seeder Controls . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4Figure 4-4: Laser Head Emission Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5Figure 4-5: The Power Supply Front Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6Figure 4-6: The 9-Pin SERIAL COM Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-7Figure 4-7: The Power Supply Rear Connector Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-8Figure 4-8: The Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-9Figure 4-9: The Main Menu Showing all Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-11Figure 4-10: The Setup Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-13Figure 4-11: The Information Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-14Figure 5-1: The location of the autotransformer in the power supply. Taps shown for

operating voltages ranging from 190 to 260 Vac. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-2Figure 5-2: Location of system fuses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-2

Table of Contents

xi

Figure 5-3: The Lab-series laser head showing connections for the umbilical. . . . . . . . . . . . . . . . . . . 5-3Figure 5-4: Cooling System Component Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4Figure 6-1: The Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1Figure 6-2: Burn Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3Figure 6-3: The Main Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5Figure 6-4: Burn Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7Figure 7-1: HG and Temperature Controller Component Identification. The controller is

located inside the laser head near the HG. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1Figure 7-2: Controller shown behind the HG. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2Figure 8-1: The various mounting and output options for the Lab-Series laser. . . . . . . . . . . . . . . . . . 8-2Figure 8-2: Single wavelength: second, third or fourth harmonic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2Figure 8-3: Dual wavelength: Second, third or forth harmonic plus the fundamental. . . . . . . . . . . . . . 8-3Figure 8-4: The IHS dichroic mirrors shown in the “normal” position. . . . . . . . . . . . . . . . . . . . . . . . . . 8-4Figure 8-5: The IHS Mirror Holder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5Figure 8-6: Model BD-6 water-cooled beam dump showing mounting screws. . . . . . . . . . . . . . . . . . . 8-6Figure 9-1: Lens Tissue Folded for Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2Figure 9-2: Cooling system component identification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3Figure 9-3: Short together posts A and B to prevent shock when servicing the flash lamps. . . . . . . . 9-8Figure 10-1: Cooling system component identification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-6Figure 10-2: Laser head showing coolant connections on the left. . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-6

List of TablesTable 2-1 : Label Translations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8Table 3-1 : Power Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12Table 3-2 : Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12Table 3-3 : Mode and Pulse Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13Table 3-4: Beam Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13Table 3-5: Service Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13Table 4-1: The SERIAL COM Port Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7Table 7-1: Controller Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4Table 7-2: Summary of Translation Arm Positions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6Table 7-3: Summary of HG Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7Table 10-1: Replacement Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-7Table A-1: Status/Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1


xii

xiii

Warning Conventions

The following warnings are used throughout this manual to draw yourattention to situations or procedures that require extra attention. They warnof hazards to your health, damage to equipment, sensitive procedures, andexceptional circumstances. All messages are set apart by a thin line aboveand below the text as shown here.

Warning!ESD

Laser radiation is present.

Condition or action may present a hazard to personal safety.

Condition or action may cause damage to equipment.

Condition or action may cause poor performance or error.

Text describes exceptional circumstances or makes a special refer-ence.

Do not touch.

Appropriate laser safety eyewear should be worn during this opera-tion.

Danger!

Warning!

Don'tTouch!

EyewearRequired

Note

Condition or action may present an electrical hazard to personalsafety.

Refer to the manual before operating or using this device.

Action may cause electrostatic discharge and cause damage to equip-ment.

Danger!Laser Radiation

Caution!

Danger!

xv

Standard Units

The following units, abbreviations, and prefixes are used in this Spectra-Physics manual:

Quantity Unit Abbreviation

mass kilogram kg

length meter m

time second s

frequency hertz Hz

force newton N

energy joule J

power watt W

electric current ampere A

electric charge coulomb C

electric potential volt V

resistance ohm Ωinductance henry H

magnetic flux weber Wb

magnetic flux density tesla T

luminous intensity candela cd

temperature celcius C

pressure pascal Pa

capacitance farad F

angle radian rad

Prefixes

tera (1012) T deci (10-1) d nano (10-9) n

giga (109) G centi (10-2) c pico (10-12) p

mega (106) M mill (10-3) m femto (10-15) f

kilo (103) k micro (10-6) µ atto (10-18) a

xvii

Unpacking and Inspection

Unpacking Your Laser

Your Quanta-Ray Lab-Series pulsed Nd:YAG laser was packed with greatcare, and its container was inspected prior to shipment—it left Spectra-Physics in good condition. Upon receiving your system, immediatelyinspect the outside of the shipping containers. If there is any major damage(holes in the containers, crushing, etc.), insist that a representative of thecarrier be present when you unpack the contents.

Carefully inspect your laser system as you unpack it. If any damage is evi-dent, such as dents or scratches on the covers or broken knobs, etc., imme-diately notify the carrier and your Spectra-Physics sales representative.

Keep the shipping containers. If you file a damage claim, you may needthem to demonstrate that the damage occurred as a result of shipping. Ifyou need to return the system for service at a later date, the speciallydesigned container assures adequate protection.

System Components

The following components comprise the Lab-Series pulsed Nd:YAG lasersystem:

• Nd:YAG laser head• Power supply• ControllerVerify all three components are present. Each component is shipped in aseparate container.

Accessory Kit

Included with the laser system is this manual, a packing slip listing all theparts shipped, and an accessory kit containing the following items:

• US or European (German) power cord for the controller, 2 m• table clamp kit: 4 clamps and hardware• a Bondhus SAE Allen wrench set• a 5/32 in. ball driver• 0–1 SCFH air flow gauge for nitrogen purge• purge hose adaptor couplings• garden hose couplings with ½ in. barbs• spare fuses


xviii

• alignment pinhole• Infrared card• CD-ROM with GUI software for remote operation from a Windows-

based PC.

1-1

Chapter 1 Introduction

The Quanta-Ray Lab-Series Pulsed Nd:YAG Lasers

The Quanta-Ray Lab-Series Nd:YAG laser comprises the laser head (Fig-ure 1-1 with the cover removed), a table-top controller (Figure 1-2) and apower supply (Figure 1-3). The system is controlled locally using the smallcontroller that is provided with the system, or remotely via a computer con-nected to the RS-232 serial port located on the front of the power supply.Provided on the side of the laser head are controls for operating theoptional injection seeder. Chapter 3 explains how the laser works. Chapter4 explains the functions of all the various system parts and controls. Thefollowing is a brief description of the system.

The Laser Head

The Lab-Series Nd:YAG laser is a pulsed, oscillator-only system config-ured with either two pump chamber assemblies with one flash lamp each(for high power), or a single pump chamber assembly with two flash lamps(for high rep. rate). The 1064 nm oscillator is typically followed by theoptional harmonic generation (HG) stage that can be set to generate 532,355 or 266 nm output wavelengths. The HG is followed by a pair of dich-roic mirrors that reflect the desired harmonic as laser output, while trans-mitting the undesired wavelengths into a beam dump.

Figure 1-1: The Lab-Series Laser Head


1-2

The Controller

Figure 1-2: The Lab-Series Controller

The easy-to-use controller employs conventional knobs and switches forsetting and controlling the various system parameters. It provides controlfrom virtually any point in the laboratory via an 8-foot cable that plugs intothe REMOTE connector on the front of the power supply. For remote controlfrom a computer or terminal, an RS-232C serial port is provided on thefront of the power supply. In addition, an IEEE-488 interface can beoptionally installed for system control.

The Power Supply

Figure 1-3: The Lab-Series Power Supply

The power supply houses the ac/dc power supplies, the PFN simmer powersupply (which stores the power required to flash the lamps at a given rate)and the flash lamp power supplies (which provides the energy in the firstplace). An RS-232C serial port is provided on the front panel for remotecontrol of the system. An optional IEEE-488 parallel interface is also avail-able for remote control.

Introduction

1-3

The power supply is water cooled and requires an external source of cleancooling water. (The optional Model WA-1 water-to-air heat exchanger canbe used for this purpose when plentiful clean water is not available.) Forelectrical power, 190–250 Vac, 35 A is required for 10 Hz systems, 40 Afor 30 Hz system and 55 A for 50 Hz systems.

The Lab-Series Advantage

• Easy-to-use controller• Dichroic mirror mounts that provide excellent beam pointing perfor-

mance (±50 µrad)• Diffused gold reflectors for optimum mode control over time• Sealed dust tubes with nitrogen purge to improve system cleanliness• Highest damage threshold optics in the industry• Single-rod oscillator design for high rep-rate operation• Dual-rod oscillator design for high power models• Ventilated cover design for system stability

Patents

The Quanta-Ray Lab-Series laser systems are manufactured under one ormore of the following U. S. patents:

4,156,209 4,232,2764,197,513 4.955,7254,936,932 4,232,2724,310,808 4,342,1134,360,925 5,001,716


1-4

2-1

Chapter 2 Laser Safety

Precautions For The Safe OperationOf Class IV High Power Lasers

• Wear protective eyewear at all times; selection depends on the wave-length and intensity of the radiation, the conditions of use and thevisual function required. Protective eyewear is available from supplierslisted in the Laser Focus World, Lasers and Optronics, and PhotonicsSpectra buyer’s guides. Consult the ANSI and ACGIH standards listedat the end of this section for guidance.

• To avoid unnecessary radiation exposure, keep the protective cover onthe laser head at all times.

• Avoid looking at the output beam; even diffuse reflections are hazard-ous.

• Avoid blocking the output beam or its reflections with any part of thebody.

• Avoid wearing reflective jewelry while using the laser.• Use an infrared detector or energy detector to verify the laser beam is

off before working in front of the laser.• Operate the laser at the lowest beam intensity possible, given the

requirements of the application.• Operate in the “long pulse” mode whenever possible, especially during

alignment of the experiment.• Expand the beam whenever possible to reduce beam intensity.• Establish a controlled access area for laser operation. Limit access to

those trained in the principles of laser safety.• Set up experiments so the laser beam is either above or below eye

level.

This Spectra-Physics Quanta-Ray Lab-Series Laser is a Class IV–HighPower Laser whose beam is, by definition, a safety and fire hazard. Takeprecautions to prevent accidental exposure to both direct and reflectedbeams. Diffuse as well as specular beam reflections can cause severeeye or skin damage. Because the 1064 nm output beam and some of its harmonics are invisi-ble, they are especially dangerous. Infrared radiation passes easilythrough the cornea, which, when focussed on the retina, can causeinstantaneous permanent damage.


EyewearRequired


2-2

• Provide enclosures for beam paths whenever possible.• Maintain a high ambient light level in the laser operation area so the

eye’s pupil remains constricted, reducing the possibility of damage.• Set up shields to prevent any unnecessary specular reflections.• Post prominent warning signs near the laser operating area (Figure 2-1).• Set up an energy absorbing beam trap to capture the laser beam and

prevent accidental exposure to unnecessary reflections or scattering(Figure 2-2).

Figure 2-1: This CE standard safety warning labels would be appropri-ate for use as an entry warning sign (EN 60825-1, ANSI 4.3.10.1).

Figure 2-2: Optical Beam Dump, Model BD-5

Operating this laser without due regard for these precautions or in a mannerthat does not comply with recommended procedures may be dangerous. Atall times during installation, maintenance or service of your laser, avoidunnecessary exposure to laser or collateral radiation* that exceeds theaccessible emission limits listed in “Performance Standards for Laser Prod-ucts,” United States Code of Federal Regulations, 21CFR1040.10(d).

Follow the instructions contained in this manual to ensure proper installa-tion and safe operation of your laser.

* Any electronic product radiation, except laser radiation, emitted by a laser product as aresult of or necessary for the operation of a laser incorporated into that product.

VISIBLE AND/OR INVISIBLE*LASER RADIATION

AVOID EYE OR SKIN EXPOSURE TODIRECT OR SCATTERED RADIATION

CLASS 4 LASER PRODUCTNd: YAG/1.5J/8ns

0451-8090*SEE MANUAL

Spectra-Physics

Use of controls or adjustments, or performance of procedures other thanthose specified herein may result in hazardous radiation exposure.

Caution!

Laser Safety

2-3

Safety Devices

Emission Indicator

When on, the amber lamp on the laser head (Figure 2-3) indicates thatpower is being supplied to the laser head and that emission is present orimminent.

Figure 2-3: Laser Head Emission Indicator

MONITOR: PoWeR ON Indicator

When on, this green LED in the upper left corner of the power supply (Fig-ure 2-4) indicates that ac power is applied to the system. However, the sys-tem will not turn on until the interlock keyswitch is also turned on.

©

Figure 2-4: The Lab-Series Power supply Control Panel.

OUTPUT REMOTEINPUTMONITOR

SHOTS X100

PWRON

INTERLOCKFAULT

LOWWATER

LASERID

Q-SWTRIG

LAMPTRIG

ANALOGSTROBE

Q-SWSYNC

LAMPSYNC

Q-SWADV SYNC

COMPUTERRS232C

POWER

I

0


2-4

Figure 2-5: The Lab-Series Power supply Rear Panel.

MONITOR: INTERLOCK Indicator

When on, this LED indicates there is a system interlock fault. Once thefault is corrected, this light turns off.

REMOTE INTERLOCK Connector

This safety interlock connector on the power supply rear panel (Figure 2-5)provides a means to include an external normally closed safety switch inthe interlock loop that turns off the laser in the event the safety switch isopened. To use this interlock, remove the jumper plug from the INTERLOCKconnector, and either remove the jumper inside or use a similar connectorwithout a jumper to wire to a perimeter safety switch. The switch can beattached to an access door or to other auxiliary safety equipment. Wire theswitch as “normally closed” so that when the door or safety device isopened and the switch opens, the power to the laser is immediately turnedoff, thus preventing unaware personnel from getting hurt.

The power supply is shipped with a 2-pin shorting jumper plug installedthat defeats (closes) this interlock when it is not used. This jumpered con-nector or an external safety switch wired to it must be in place in order forthe laser to operate.

Cover Safety Interlocks

Figure 2-6: Interlock Switches, Laser Head.

SPECTRA-PHYSICS LASERSP.O. BOX 7013

MT. VIEW, CALIFORNIA 94039-7013

MANUFACTURING DATE:

MODEL

S/N

THIS LASER PRODUCT COMPLIESWITH 21 CFR 1040 AS APPLICABLE

MADE IN U.S.A.

REMOTEINTERLOCK

WATER IN

WATER OUT

NORMALOPERATING

RANGE

Umbilical Connector

Power Cord

Power Requirement Label

Reservoir LevelIndicator Remote Interlock

System WATER IN Connector

System WATER OUT Connector

Laser Safety

2-5

Figure 2-7:Interlock Switch, Power Supply.

The LASER HEAD connector is also part of the interlock loop: if the laserhead cable is disconnected, the diode pump laser in the power supply isturned off.

The laser head and power supply covers are interlocked. Therefore, thelaser shuts off whenever either cover is removed. For troubleshooting, abypass is built into each switch so that the service engineer can pull up onthe switch to close the interlock with the cover off. For safety, replacing thecover will activate the switch again and turn off the laser.

POWER Keyswitch

Located in the lower right-hand corner of the power supply control panel(Figure 2-4), the POWER keyswitch provides interlock safety to preventunauthorized personnel from using the Lab-Series system when the key isturned to the “off” position and is removed from the switch. Turning thekey to the “on” position closes the interlock and allows the system to beenergized if all the other interlocks are closed and the circuit breaker switchis on. If the keyswitch is set to off but the circuit breaker is on, power is stillsupplied to the harmonic generator ovens to keep the crystals warm.

POWER Circuit Breaker

Provides ac power to the system and to the harmonic generator ovens. Thepower keyswitch must also be on in order for the system to operate. Turn-ing off the power circuit breaker removes all ac power from the system andturns off the harmonic generator ovens.

Collateral radiation! While the laser head cover is removed, beextremely careful to avoid exposure to laser or collateral radiation.



2-6

Focused Back-Reflection Safety

Focused back-reflections of even a small percentage of the output energy ofany Lab-Series laser can destroy its optical components. To illustrate, con-sider an uncoated convex lens, which reflects about 4% of the energy inci-dent on each of its surfaces. While the reflection off the first surfacediverges harmlessly, the reflection off the second surface focuses, and thepower density at the point of focus is high enough to destroy the Q-switch,Nd:YAG rod and the output coupler of the laser. Even anti-reflection coatedoptics can reflect enough energy to damage laser optical components.

To avoid laser damage, minimize back-reflections of its output beam and,where they are unavoidable, direct them away from the optical axis.

Maintenance Necessary to Keep this Laser Productin Compliance with Center for Devices and Radiological Health (CDRH) Regulations

This laser product complies with Title 21 of the United States Code of Fed-eral Regulations, chapter 1, subchapter J, parts 1040.10 and 1040.11, asapplicable. To maintain compliance with these regulations, once a year, orwhenever the product has been subjected to adverse environmental condi-tions (e.g., fire, flood, mechanical shock, spilled solvent, etc.), check to seethat all features of the product identified below function properly. Also,make sure that all warning labels remain firmly attached (refer to theCDRH/CE drawing later in this chapter).

1. Verify removing the AUXILIARY INTERLOCK plug on the power supplyprevents laser operation.

2. Verify the laser will only operate with the key switch in the ON posi-tion, and that the key can only be removed when the switch is in theOFF position.

3. Verify the emission indicator on the laser head works properly; that is,it emits a visible signal whenever the laser is on.

4. Verify the time delay between turn-on of the emission indicator andstarting of the laser gives enough warning to allow action to avoidexposure to laser radiation.

5. Verify that removing the laser head or power supply cover shuts off thelaser.

6. Verify that when the laser head cover interlock is defeated, the defeatmechanism is clearly visible and prevents installation of the cover untilit is removed.

Your Quanta-Ray warranty does not cover damage caused by focusedback-reflections.

Warning!

Laser Safety

2-7

CE/CDRH Radiation Control Drawing

Figure 2-8: CE/CDRH Radiation Control Drawing

CE Danger Label(4)


AVOID EYE OR SKIN EXPOSURE TO DIRECT ORSCATTERED RADIATION

CLASS 4 LASER PRODUCTNd: YAG/1.5J/8ns

0451-8090*SEE MANUAL

CE ApertureLabel (2)

CDRH ApertureLabel (1)

CE CertificationLabel (3)

Controller



MANUFACTURING DATE:

MODEL

S/N


MADE IN U.S.A.

V I S I B L E A N D I N V I S I B L EHAZARDOUS ELECTROMAGNETICR A D I A T I O N W H E N O P E N A N D

I N T E R L O C K D E F E A T E D *

* S E E M A N U A L

C A U T I O NC A U T I O N V I S I B L E A N D I N V I S I B L E

L A S E R R A D I A T I O N W H E N O P E N A N D I N T E R L O C K D E F E A T E D . A V O I D E Y E O R S K I N E X P O S U R E T O D I R E C T O R S C A T T E R E D R A D I A T I O N . *

* S E E M A N U A L

D A N G E RD A N G E R

STBY ON RESET Q-SW PIEZO FREQ

OFFSETVOLTBLD UP TIMEDSBLMNLAUTO

ON



MANUFACTURING DATE:

MODEL

S/N


MADE IN U.S.A. WA-1INTERFACE

REMOTEINTERLOCK

WATER IN

WATER OUT

NORMALOPERATING

RANGE

Laser Head, Output End Power Supply, Water Supply End Power Supply, Control Panel

Laser Head, Side View

CDRH Caution LabelInterlock Defeated EMI (5)

Patent Label (12)Serial Number LabelCDRH (11)

CDRH Danger LabelInterlock Defeated (6)

Input VoltageLabels (10)

V I S I B L E A N D I N V I S I B L E * L A S E R R A D I A T I O N W H E N O P E N - A V O I D S K I N O R E Y E E X P O S U R E T O D I R E C T O R S C A T T E R E D R A D I A T I O N

* S E E M A N U A L

D A N G E RD A N G E R

CDRH Danger LabelNon-Interlocked (7)

1 2

RemoteInterlock

InterlockSwitch

11

8

3

InterlockSwitch

4 3 11 5 6

7 2

7EmissionIndicator

Power OnLED

Power BreakerSwitch

Keyswitch

Power OnEmissionIndicator

Lamp InhibitSwitch

Spectra-Physics Lasers1330 TERRA BELLA AVENUEMOUNTAIN VIEW, CALIF. 94043

0004-0363

4,156,209 4,32,27624,197,513 4,955,7254,935,932 4,232,2724,310,808 4,342,1134,360,925 5,001,716

THIS PRODUCT IS MANUFACTUREDUNDER ONE OR MORE OF THEFOLLOWING U.S.A. PATENTS:

190 – 260V~,60/50Hz, 50 A

190 – 260V~,60/50Hz, 30 A

REPLACE THE BATTERY WITH THE SAME OR EQUIVALENT

TYPE RECOMMENDED BY THE MANUFACTURER.

DISPOSE OF USED BATTERIES ACCORDING

TO THE MANUFACTURER'S INSTRUCTIONS.

Battery ReplacementLabel (9)

Fuse LabelNear Fuses Inside (8)

10


AVOID EYE OR SKIN EXPOSURE TO DIRECT OR

SCATTERED RADIATION

CLASS 4 LASER PRODUCT

Nd: YAG/1.5J/8ns

12

F U S E S5 0 A / 2 5 0 V A C

F U S E S3 0 A / 2 5 0 V A C

AVOID EXPOSUREAVOID EXPOSURE

V I S I B L E A N D I N V I S I B L E *

L A S E R R A D I A T I O N I SE M I T T E D F R O M T H I S A P E R T U R E

*SEE MANUAL*SEE MANUAL

AVOID EXPOSUREAVOID EXPOSURE

V I S I B L E A N D I N V I S I B L E *

L A S E R R A D I A T I O N I SE M I T T E D F R O M T H I S A P E R T U R E

*SEE MANUAL*SEE MANUAL

o r

o r

START 10 START 10 MIN MAX MIN MAX MIN MAX

OSC AMP ADV SYNC VARIABLE Q-SW DELAY

MODESOURCE

SINGLE SHOT

LAMP ENERGY

FIRE REP COMPUTER

INT

LAMP ON STOP ENABLE

FIXED Q-SW EXT

ONOFF

EXTVAR

SIMMER ERROR

LP

INHIBIT

Quanta-Ray

F U S E S3 0 A / 2 5 0 V A C


2-8

Label Translations

For safety, the following translations are provided for non-English speak-ing personnel. The number in parenthesis in the first column corresponds tothe label number listed on the previous page.

Table 2-1: Label Translations

Label # French German Spanish Dutch

Aperture Label

(1)

Ouverture Laser - Expo-sition Dangereuse - UnRayonnement laser visi-ble et invisible est emispar cette ouverture.

Austritt von sichtbarerund unsictbarer Laser-strahlung; nicht demStrahl aussetzen.

Por esta abertura seemite radiacion laservisible e invisible; evitela exposicion.

Vanuit dit apertuur wordtzichtbare en niet zicht-bare laser-straling gee-miteerd; vermijdblootstellilng.

European Safety

(4)

Rayonnement Laser vis-ible et invisible. Expos-tion dangereuse de l’oeilou de la peau au Rayon-nement direct ou diffus.Laser de classe 4; Nd:YAG/1.5 J/8 ns.

Sichtbare und/oderunsichtbare Laserstrahl-ung. Bestrahlung vonAude oder Haut durchdirekte oder Streustrahl-ung vermeiden. Laser-classe 4; Nd: YAG/1.5 J/8 ns.

Radiacion Laser visibley/o invisible. Evite quelos ojos y la piel quedenexpuestos tanto a laRadaicion derecta comoa la dispersa. ProductoLaser Clase 4; Nd: YAG/1.5 J/8 ns.

Zichtbare en niet zicht-bare laserstraling. Ver-mijd blootstelling vanhuid of oog aan directestraling of weerkaatsin-gen. Klasse 4 LaserProdukt; Nd: YAG/1.5 J/8 ns.

Caution,Defeatable Interlock

(EMI)(5)

Attention. Rayonne-ment visible et invisibledangereux en casd’ouverture et lorsque lasécurité est neutralisée.

Achtung! Sichtbare undunsichtbare schädlicheelektromagnetischeStrahlung wenn Abdec-kung geöffnet und Sich-erheitsverriegelungüberbrückt. Bedienung-sanleitung beachten!

Precaución, radiaciónpeligrosa electromag-nética visible e invisiblecon el dispositivo deseguridad abierto o consu indicación alterada.

Let op. Zichtbare enonzichtbare gevaarlijkeelectromagnetischestraling indien geopenden interlock overbrugd.

Danger, Defeatable Interlock

(6)

Attention. Rayonne-ment Laser visible etinvisible en casD’Ouverture et lorsquela securite est neutra-lisse; exposition dan-gereuse de l’oeil ou dela peau au rayonnementdirct ou diffus.

Vorsicht; Austritt vonsichtbarer un unsicht-barer Laserstruhlung,wenn Abdeckung geoff-net und Sicherhetiss-chalter uberbruckt;Bestrahlung von Augeoder Haut durch direkteoder Streustreustrahl-ung vermeiden.

Peligro, al abrir y retirerel dispositivo de segu-ridad exist radiacionlaser visible e invisible;evite que los ohos o lapiel queden expuestostanto a la radiaciondircta como a la dis-persa.

Gevaar; zichtbare enniet zichtbare laser-straling wanneer geo-pend en bij uitgeschak-elde interlock; Vermijdblootstelling van oog ofhuid aan directe stral-ing of weerkaatsingendaarvan.

Danger,Non-

Interlocked(7)

Attention; RayonnementLaser Visible et Invisi-ble en Cas D’Ouverture;Exposition Engereusede L’Oeil ou de la Peauau Rayonnement Directou Diffus.

Vorsicht; beim OffnenAustritt von sichtbareund unsichtbare Laser-strahlung; Bestrahlungvon Auge oder Hautdurch direkte oder Streu-strahlung vermeiden.

Peligro, Cuando se abreexiste Radiacion LaserVisible e Invisible; Eviteque los ojos y la pielqueden expuestos tantoa la radaicion directacomo a la dispersa.

Gevaar; zichtbare enniet zichtbare laser-straling wanneer geo-end; vermijd blootstelingaan huid of oog aan dis-ecte straling of weer-kaatsingen.

Battery Warning

Label(9)

Remplacer la pile par lemême modèle ou unmodèle équivalent. Sedébarasser des pilesusagées conformémentau recommandations dufabricant.

Batterie nur durch gle-ichen oder baugleichenTyp gemäß Herstelle-rangaben ersetzen. Ver-brauchyte Batterienordnungsgemäß entsor-gen.

Reemplazar la bateríacon el mismo tipo, oequivalente, recomen-dado por el fabricante.Pelegro. Deshacerse delas baterías usadas deacuerdo con las instruc-ciones del fabricante.

Vervang batteryen doorde zelfde, of door defabrikant geadviseerdeequivalente typen. Voerde gebruikte battereienaf volgens de instructiesvan de fabrikant.

Patent Label(12)

Ce produits est fabriquésous l’un ou plusieursdes brevets suivants.

Dieses Produkt wurdeunter Verwendung eineroder mehrerer der fol-genden US-Patentehergestellt.

Este producto esta fab-ricado con una o másde las siguientes pat-entes de los EstadosUnidos.

Dit product is gefabri-ceerd met een of meervan de volgende USApatenten.

Laser Safety

2-9

CE Declaration of Conformity

We,

Spectra-Physics, Inc.Solid-State Lasers1330 Terra Bella AvenueMountain View, CA. 94043United States of America

declare under sole responsibility that the:Quanta-Ray Lab-Series pulsed Nd:YAG laser system with power supply,

analog remote, or pc-based controller running Windows-based GUIcontrol software,

Manufactured after December 1, 1995,

meets the intent of EMC Directive 89/336/EEC: 1989, for electromagnetic com-patibility and Directive 73/23/EEC, the Low Voltage directive. Compliance wasdemonstrated to the following specifications as listed in the official Journal ofthe European Communities:

EMC Directive 89/336/EEC: 1989EN 50081-2:1993 Emissions:

EN55011 Class A RadiatedEN55011 Class A Conducted

EN 50082-1:1992 Immunity:IEC 801-2 Electrostatic DischargeIEC 801-3 RF RadiatedIEC 801-4 Fast Transients

Low Voltage Directive 73/23/EEC: 1973EN 61010-1: 1993 Safety Requirements for Electrical Equipment for

Measurement, Control and Laboratory use:EN 60825-1: 2001 Safety for Laser Products.

I, the undersigned, hereby declare that the equipment specified above conformsto the above Directives and Standards.

Bruce CraigVice President and General Manager

Spectra-Physics, Inc.Solid-State LasersJanuary 1, 2003


2-10

Sources for Additional Information

The following are some sources for additional information on laser safetystandards, safety equipment, and training.

Laser Safety Standards

Safe Use of Lasers (Z136.1: 1993)American National Standards Institute (ANSI)11 West 42nd StreetNew York, NY 10036Tel: (212) 642-4900

Occupational Safety and Health Administration (Publication 8.1-7)U. S. Department of Labor200 Constitution Avenue N. W., Room N3647Washington, DC 20210Tel: (202) 693-1999

A Guide for Control of Laser Hazards, 4th Edition, Publication #0165American Conference of Governmental andIndustrial Hygienists (ACGIH)1330 Kemper Meadow DriveCincinnati, OH 45240Tel: (513) 742-2020Internet: www.acgih.org/home.htm

Laser Institute of America13501 Ingenuity Drive, Suite 128Orlando, FL 32826Tel: (800) 345-2737Internet: www.laserinstitute.org

Compliance Engineering70 Codman Hill RoadBoxborough, MA 01719Tel: (978) 635-8580

International Electrotechnical CommissionJournal of the European CommunitiesEN60825-1 TR3 Ed.1.0—Laser Safety Measurement and InstrumentationIEC-309—Plug, Outlet and Socket Coupler for Industrial UsesTel: +41 22-919-0211Fax: +41 22-919-0300Internet: http://ftp.iec.c.h/

CenelecEuropean Committee for Electrotechnical StandardizationCentral Secretariatrue de Stassart 35B-1050 Brussels

Document Center1504 Industrial Way, Unit 9Belmont, CA 94002-4044Tel: (415) 591-7600

Laser Safety

2-11

Equipment and Training

Laser Safety GuideLaser Institute of America12424 Research Parkway, Suite 125Orlando, FL 32826Tel: (407) 380-1553

Laser Focus World Buyer's GuideLaser Focus WorldPenwell Publishing10 Tara Blvd., 5th FloorNashua, NH 03062Tel: (603) 891-0123

Lasers and Optronics Buyer's GuideLasers and OptronicsGordon Publications301 Gibraltar DriveP.O. Box 650Morris Plains, NJ 07950-0650Tel: (973) 292-5100

Photonics Spectra Buyer's GuidePhotonics SpectraLaurin PublicationsBerkshire CommonPO Box 4949Pittsfield, MA 01202-4949Tel: (413) 499-0514


2-12

3-1

Chapter 3 Laser Description

A Brief Review of Ion Laser Theory

Emission and Absorption of Light*

Laser is an acronym derived from Light Amplification by Stimulated Emis-sion of Radiation. Thermal radiators, such as the sun, emit light in all direc-tions, the individual photons having no definite relationship with oneanother. But because the laser is an oscillating amplifier of light, andbecause its output comprises photons that are identical in phase and direc-tion, it is unique among light sources. Its output beam is singularly direc-tional, monochromatic, and coherent.

Radiant emission and absorption take place within the atomic or molecularstructure of materials. The contemporary model of atomic structuredescribes an electrically neutral system composed of a nucleus with one ormore electrons bound to it. Each electron occupies a distinct orbital thatrepresents the probability of finding the electron at a given position relativeto the nucleus. Each orbital has a characteristic shape that is defined by theradial and angular dependence of that probability, e.g., all s orbitals arespherically symmetrical, and all p orbitals surround the x, y, and z axes ofthe nucleus in a double-lobed configuration (Figure 3-1). The energy of anelectron is determined by the orbital that it occupies, and the over-allenergy of an atom—its energy level—depends on the distribution of itselectrons throughout the available orbitals. Each atom has an array ofenergy levels: the level with the lowest possible energy is called the groundstate, and higher energy levels are called excited states. If an atom is in itsground state, it will stay there until it is excited by external forces.

Movement from one energy level to another—a transition—happens whenthe atom either absorbs or emits energy. Upward transitions can be causedby collision with a free electron or an excited atom, and transitions in bothdirections can occur as a result of interaction with a photon of light. Con-sider a transition from a lower level whose energy content is E1 to a higherone with energy E2. It will only occur if the energy of the incident photonmatches the energy difference between levels, i.e.,

hν = E2 – E1 [1]

where h is Planck’s constant, and ν is the frequency of the photon.

* “Light” will be used to describe the portion of the electromagnetic spectrum from farinfrared to ultraviolet.


3-2

Figure 3-1: Electrons occupy distinct orbitals that are defined by theprobability of finding an electron at a given position, the shape of theorbital being determined by the radial and angular dependence of theprobability. Shown is an “s” orbital on the left, a “p” type on the right.

Likewise, when an atom excited to E2 decays to E1, it loses energy equal toE2 – E1. The atom may decay spontaneously, emitting a photon with energyhν and frequency

[2]

Spontaneous decay can also occur without emission of a photon, the lostenergy taking another form, e.g., transfer of kinetic energy by collisionwith another atom. An atom excited to E2 can also be stimulated to decay toE1 by interacting with a photon of frequency ν, emitting energy in the formof a pair of photons that are identical to the incident one in phase, fre-quency, and direction. This is known as stimulated emission. By contrast,spontaneous emission produces photons that have no directional or phaserelationship with one another.

A laser is designed to take advantage of absorption, and both spontaneousand stimulated emission phenomena, using them to create conditions favor-able to light amplification. The following paragraphs describe these condi-tions.

Population Inversion

The net absorption at a given frequency is the difference between the ratesof emission and absorption at that frequency. It can be shown that the rateof excitation from E1 to E2 is proportional to both the number of atoms inthe lower level (N1) and the transition probability. Similarly, the rate ofstimulated emission is proportional to the population of the upper level (N2)and the transition probability. Moreover, the transition probability dependson the flux of the incident wave and a characteristic of the transition calledits “cross section.” The absorption coefficient depends only on the differ-ence between the populations involved, N1 and N2, and the flux of the inci-dent wave.

νE2 E1–

h------------------=

Laser Description

3-3

When a material is at thermal equilibrium, there exists a Boltzmann distri-bution of its atoms over the array of available energy levels with mostatoms in the ground state. Since the rate of absorption of all frequenciesexceeds that of emission, the absorption coefficient at any frequency is pos-itive.

If enough light of frequency ν is supplied, the populations can be shifteduntil N1 = N2. Under these conditions the rates of absorption and stimulatedemission are equal, and the absorption coefficient at frequency ν is zero. Ifthe transition scheme is limited to two energy levels, it is impossible todrive the populations involved beyond equality; that is, N2 can never exceedN1 because every upward transition is matched by one in the opposite direc-tion.

However, if three or more energy levels are employed, and if their relation-ship satisfies certain requirements described below, additional excitationcan create a population inversion where N1 > N2.

A model four-level laser transition scheme is depicted in Figure 3-2. Aphoton of frequency ν1 excites—or “pumps”—an atom from E1 to E4. If theE4 to E3 transition probability is greater than that of E4 to E1, and if E4 isshort lived, the atom will decay almost immediately to E3. If E3 is metasta-ble, i.e., atoms that occupy it have a relatively long lifetime, the populationwill grow rapidly as excited atoms cascade from above. The E3 atom willeventually decay to E2, emitting a photon of frequency ν2. Finally, if E2 isunstable, its atoms will rapidly return to the ground state, E1, keeping thepopulation of E2 small and reducing the rate of absorption of ν2. In this waythe population of E3 is kept large and that of E2 remains low, thus establish-ing a population inversion between E3 and E2. Under these conditions, theabsorption coefficient at ν2 becomes negative. Light is amplified as itpasses through the material, which is now called an “active medium.” Thegreater the population inversion, the greater the gain.

Figure 3-2: A Typical Four-level Transition Scheme

A four-level scheme has a distinct advantage over three-level systems,where E1 is both the origin of the pumping transition and the terminus ofthe lasing transition. Also, the first atom that is pumped contributes to thepopulation inversion in the four-level arrangement, while over half of theatoms must be pumped from E1 before an inversion is established in thethree-level system.

E4

E3

E2

E1

4I11/2

4F3/2

4I9/2

2111 cm-1

11502 cm-1

Nd3+

ν1ν2


3-4

Nd:YAG as an Excitation Medium

The properties of neodymium-doped yttrium aluminum garnet (Nd:YAG)are the most widely studied and best understood of all solid-state lasermedia. Its transition scheme is compared to the model in Figure 3-2b andits energy level diagram is depicted in Figure 3-3. The active medium is tri-ply ionized neodymium, which is optically pumped by a flash lamp whoseoutput matches principle absorption bands in the red and near infrared.Excited electrons quickly drop to the F3/2 level, the upper level of the lasingtransition, where they remain for a relatively long time (about 230 µs).

Figure 3-3: Energy Level Scheme for the Nd:YAG Laser Source

The most probable lasing transition is to the I11/2 state, emitting a photon at1064 nm. Because electrons in that state quickly relax to the ground state,its population remains low. Hence, it is easy to build a population inversion.At room temperature the emission cross section of this transition is high, soits lasing threshold is low. While there are competing transitions from thesame upper state—most notably at 1319, 1338, and 946 nm––all havelower gain and a higher threshold than the 1064 nm transition. In normaloperation, these factors and wavelength-selective optics limit oscillation to1064 nm.

A laser comprising just an active medium and resonator will emit a pulse oflaser light each time the flash lamp fires. However, the pulse duration willbe long, about the same as the flash lamp, and its peak power will be low.When a Q-switch is added to the resonator to shorten the pulse, output peakpower is raised dramatically.

20

18

16

14

12

10

8

6

4

2

0

4F3/2

PumpBands

LaserTransition

4I15/2

4I13/2

4I11/24I9/2

4I15/2

4I13/2

4I11/2

4I9/2

4F3/2

Laser Transition

~6000 cm-1

~4000 cm-1

2526247321462111202920018483111971340

11502 cm-1 R211414 R1

Ground Level

Laser Description

3-5

Q-switching

Because the upper level of the transition has a long lifetime, a large popula-tion of excited neodymium ions can build up in the YAG rod, much in thesame way a capacitor stores electrical energy. If oscillation is preventedwhile the population inversion builds, and if the stored energy can bequickly released, the laser will emit a short pulse of high intensity light. Todo this, an electro-optic device (a Q-switch) is added to the cavity, whichintroduces high cavity loss and prevents oscillation. This allows energy tobuild up. It is then quickly switched to a very low loss state that allowsoscillation to occur and the cavity dumps its energy in the form of a lightpulse.

As shown in Figure 3-4, the Q-switch comprises a polarizer, a quarter-waveplate, and a Pockels cell. A high voltage applied to the Pockels cell crystalchanges its polarization retardation characteristics, which determinewhether the Q-switch is open (low loss) or closed (high loss).

Figure 3-4: The Q-switch comprises a polarizer, a quarter-wave polar-ization rotator, and a Pockels cell.

With no voltage applied, the Pockels cell does not affect the polarization oflight passing through it, and the Q-switch functions as follows. The polar-izer horizontally polarizes light entering the Q-switch, and the quarter-wave plate converts it to circular polarization. As the circularly polarizedlight returns from the high reflector, the quarter-wave plate converts it tovertical polarization. Because the polarizer only transmits horizontallypolarized light, it reflects the light out of the resonator, so the cavity loss ishigh. With voltage applied, the Pockels cell cancels the polarization retar-dation of the quarter-wave plate, so the light remains horizontally polarizedand suffers minimal loss.

During Q-switched operation, the flash lamp excites the Nd ions forapproximately 200 µs to build up a large population inversion. At the pointof maximum population inversion, a fast high-voltage pulse applied to thePockels cell changes the Q-switch from high to low loss. The resultantpulse width is <10 ns, and the peak optical power is tens of megawatts.

This short pulse of high peak power is the key to the usefulness of thepulsed Nd:YAG laser. Its high peak power permits wavelength conversionthrough several nonlinear processes, e.g., frequency doubling, frequencymixing, dye laser pumping, or Raman frequency conversion. A short pulseprovides excellent temporal resolution of fast phenomena like rapid chemi-cal reactions or high-speed motion.

HighReflector

Quarter-WavePlate

Pockels Cell Polarizer

4 kV

5 µs


3-6

An alternative “long pulse” mode of operation is built in to the Lab-Serieslaser. Voltage is applied to the Pockels cell as soon as the flash lamp fires,and the Q-switch is held open for the entire lamp firing. The result is a trainof pulses about 200 µs long, with a separation between individual pulses of2 to 4 µs. The total energy of the pulse train is similar to that of a single Q-switched pulse. This long pulse mode allows safer alignment and set-up,and is useful in experiments where total pulse energy, not its distribution intime, is the critical factor.

Resonant Optical Cavity

A resonant cavity, which is defined by two mirrors, provides feedback tothe active medium. Photons emitted parallel to the optical axis of the cavityare reflected, returning to interact with other excited ions. Stimulated emis-sion produces two photons of equal energy, phase and direction from eachinteraction. The two become four, four become eight, and the numbers con-tinue to increase geometrically until an equilibrium between excitation andemission is reached.

Both mirrors are coated to reflect the wavelength, or wavelengths, of inter-est while transmitting all others. One of the mirrors (the output coupler)transmits a fraction of the energy stored in the cavity, and the escaping radi-ation becomes the output beam of the laser.

There are two major types of optical resonators: stable and unstable (seeFigure 3-5). The difference between them lies in what happens to a ray oflight traveling close to, and parallel with the optical axis. In the stable reso-nator the ray is reflected toward the optical axis by its cavity mirrors, so itis always contained along the primary axis of the laser. By contrast, a raytravelling in an unstable resonator can be reflected away from the axis byone of the cavity mirrors.

Figure 3-5: Stable and Unstable Resonator Configurations

Stable resonators can only extract energy from a small volume near theoptical axis of the resonator, which limits the energy of the output. Con-versely, unstable resonators can have large beam diameters. Thus, they canefficiently extract energy from active media whose cross-sectional area islarge, like that of typical Nd:YAG laser rods.

The output coupler in an unstable resonator can take one of three forms. Inthe first case, a small high reflector is mounted on a clear substrate andplaced on the optical axis of the resonator. Energy escapes the resonator bydiffracting around this dot, which gives the “diffraction coupled resonator”

Unstable

Stable

Laser Description

3-7

(DCR) its name. A second form employs a partially reflective coating thatuniformly covers the whole substrate. The third is a variation on the first,where the small high reflector is replaced by a partial reflector with radiallyvariable reflectivity (an RVR optic). This reflector is capable of producinggaussian or near-gaussian spatial profile at the laser output, and is, there-fore a gaussian coupled resonator, or GCR. This Lab-Series laser uses thelatter variation.

If the energy of the output beam is to be uniformly distributed, the Nd:YAGrod must be uniformly illuminated. Placing the flash lamp at one focus ofan elliptical chamber causes all the light it produces to be reflected throughthe rod, which is placed at the other focus.

Uniform cooling is also essential to optimal performance of pulsedNd:YAG lasers. When heated, the Nd:YAG rod becomes a lens whose focallength depends on the average power absorbed. For optimal performance,the high reflector must be matched to the focal length of the rod, whichmust remain stable during operation. The thermal gradient of the rod alsocauses a radially variable polarization rotation that must be carefully con-trolled for the best beam quality.

Longitudinal Modes and Linewidth

A laser oscillates within a narrow range of frequencies around the transi-tion frequency. The width of the frequency distribution—the linewidth—and its amplitude depend on the active medium, its temperature and themagnitude of the population inversion. Linewidth is determined by plottingthe net gain of each frequency and measuring the width of the curve wherethe gain has fallen to one-half maximum (full width at half maximum) asshown in Figure 3-6.

Figure 3-6: Frequency distribution of longitudinal modes for a single line

The output of the laser is discontinuous within the homogeneously broad-ened line. A standing wave propagates within the optical cavity, and anyfrequency that satisfies the resonance condition

[3]

Laser Gain Profile

Laser CavityLongitudinal Modes

ν

Half-max point 30 GHz Linewidth

200 MHz Spacing

νmmc2L-------=


3-8

will oscillate, where νm is the frequency, c is the speed of light, L is theoptical cavity length and m is an integer. Thus, the output of a given line isa set of discrete frequencies—called “longitudinal modes”—spaced suchthat

[4]

Producing Other Wavelengths

The high peak power of Q-switched pulses permit frequency conversion innonlinear crystals like potassium dideuterium phosphate (KD*P). In thesimplest case, the 1064 nm Nd:YAG fundamental interacts with the crystalto produce a secondary wave with half the fundamental wavelength.

For maximum efficiency the waves must maintain the same speed andphase relationship throughout the crystal. The index of refraction of mostmaterials depends on the wavelength and decreases as the wavelength getslonger. However, some materials are birefringent, i.e., their index of refrac-tion depends on the polarization of the propagating waves. In these materi-als, if the ordinary index of one wavelength matches the extraordinaryindex of the other, the waves propagate in phase and at the same speed. Fre-quency conversion is most efficient under these “phase matching” condi-tions.

Phase matching is critically dependent on the temperature of the crystaland on the angle between the direction of polarization and the axes of thecrystal.

With KD*P, two phase matching alternatives exist. In type I phase match-ing, the input is along the ordinary axis and the output is polarized alongthe extraordinary axis. This leaves the residual input wavelength linearlypolarized. In type II, the input polarization is at an angle between theextraordinary and ordinary axes, while the output remains polarized alongthe extraordinary axis. The residual input wavelength is elliptically polar-ized. Although either type of phase matching can be used to generate thesecond harmonic of Nd:YAG in KD*P, type II is more widely used becauseof its higher conversion efficiency. However, some experiments require lin-ear polarization of the residual 1064 nm light for highest efficiency and, forthese cases, Type I doubling may yield better overall system performance.

The resultant 532 nm wave can be doubled again by passing it through asecond crystal to yield a 266 nm wave. It can also be mixed in KD*P withthe residual 1064 nm fundamental to produce a 355 nm wave. These fourwavelengths—1064, 532, 355, and 266 nm—cover the electromagneticspectrum from the near infrared to the ultraviolet, which enhances the use-fulness of the Nd:YAG laser. 532 and 355 nm light is useful for pumpingdye lasers with high conversion efficiency. 355 and 266 nm light is usefulfor dissociation and photodestructive studies of many molecules. 1064 nmand 266 nm light is widely used for optical modification of materials andprobing of semiconductors.

These fixed frequencies can be extended further through Raman shifting orby using them to pump a dye laser or an OPO. The latter results in continu-ously tunable output over a wide range of wavelengths.

∆ν c2L------=

Laser Description

3-9

Resonator Structural Considerations

The stability of the oscillating frequency depends on the design of the reso-nator structure. Small changes in cavity length caused by temperaturechanges and mechanical shifts, among other sources, cause correspondingchanges in the resonant frequency. Cavity length changes due to tempera-ture can be expressed as

∆L = αL∆T [5]

where L is the cavity length, α is the thermal expansion coefficient of theresonator structure and ∆T is temperature change. In order to eliminate fre-quency drift, either α or ∆T must be zero.

The choice of materials affects the length stability of the structure. Theideal material has both a low thermal expansion coefficient and a high abil-ity to distribute heat evenly, causing a constant ∆T along the length of thestructure.

Graphite composite, such as that used in the Lab-Series resonator, has thelowest thermal expansion coefficient of any currently used structural mate-rial. Since its coefficient is also negative, the thermal compensation systemof the resonator structure can be kept simple. The negative expansion of thegraphite rods offsets the positive expansion of the metal parts, so the netchange remains near zero over a wide range of temperatures.

Frequency stability also depends on the mechanical rigidity of the resona-tor structure. Modulation due to “jitter,” the microphonic movement of cav-ity mirrors, can be caused by an external shock to the resonator structure oracoustic noise. Isolation of the resonator from the case that surrounds thelaser helps reduce this jitter.

Pulse Triggering Sequence and Timing

Figure 3-7 is a block diagram of the Lab-Series electrical system. It alsodepicts the order and timing of control signals within the system. This sim-plified diagram provides a means for understanding the operation of thelaser and the nomenclature of its input and output signals. Figure 3-8 showsthe Lab-Series timing relationships.

The source switch selects one of three possible lamp triggering sources: afixed rate setting (10, 30, 50), a variable setting that is ±10% of the laserdesign frequency (using an internal oscillator), or an externally set setting(applied to the lamp trigger input) that can vary the laser frequency ±10%of its design frequency.

Signal A is the trigger source for all subsequent functions. It fires the SCRgate current generator for the pulse forming network and the Q-switchdelay. SCR gate current B fires the pulse forming network, whose dischargeproduces a critically damped current pulse C through the lamp. The Q-switch delay prevents the opening of the Q-switch until the populationinversion has built up in the Nd:YAG rod. After approximately 210 ns, itsoutput D increases the Q of the cavity to maximum by applying high volt-age I to the Pockels cell.


3-10

Figure 3-7: Simplified Block Diagram of the Lab-Series electronics.

The mode switch selects the configuration of the Q-switch. The Pockelscell can be fired internally (normal mode), externally by a trigger pulse atthe Q-SW TRIG input (external mode), or in a long pulse mode that providesa pulse of low peak power that is useful for system alignment.

In normal mode, the Q-switch delay D fires a fixed delay G. Subsequently,the pulse generator is fired H, providing a sync signal and triggering theelectro-optic driver (Marx bank). The high voltage output of the Marx bankI changes the polarization retardation characteristic of the Pockels cell,which opens the Q-switch after a total delay of D+G.

The Q-switch advanced sync signal is also derived from the Q-switch delayD. Signal D triggers both the fixed delay G described above and a variabledelay E, setting up a race between these two pulses. The variable delaypulse is adjustable, so it can end either before or after the end of the fixeddelay pulse. The variable delay pulse triggers the advanced sync pulse gen-erator F, whose output either precedes or follows the opening of the Q-switch I. This creates a pre- or post-trigger pulse with a range of 0 to 500 ns.

In the long pulse mode, the Pockels cell is triggered at the moment of lampfiring. It is internally charged to provide a long, high voltage pulse thatyields a long optical pulse. The Q-switch sync output is inhibited in thismode.

SwitchingSupply

PulseGenerator

SimmerCurrent

C

B

Lamp

PulseGenerator

PulseGenerator

VariableDelay

FixedDelay

MarxBank

Q-switchDelay

FixedRepetition

Rate

VariableRepetition

Rate

Q-switchAdv. Sync.

OutE F

H IQ-switch

H.V.

JLamp

Sync. Out

D

PulseGenerator

AExternal

Input Q-switchSync.Out

Ext Q-SWtrig input Pulse

Generator

K

Q-SW

Laser Description

3-11

Figure 3-8: Lab-Series Timing Schematic

General Note on Specifications

Specifications for Lab-Series pulsed Nd:YAG lasers are given in good faithand are set at levels that ensure manufacturability and allow reliable long-term operation. Due to the complexity involved in measuring many of theindividual specifications, we cannot demonstrate all performance parame-ters at your site. We will ensure that all energy specifications are met bymaking the appropriate energy measurements, and that copies of our finaltest beam profiles and burn patterns are included with the installation ofeach laser. Pulse width and single-mode operation can also be demon-strated. All other specifications can be demonstrated either at your site or atthe Spectra-Physics manufacturing facility. Contact your local Spectra-Physics representative for further information.

L Ext. Q-Switch Trigger Input

A Ext. Lamp Trigger Input

J Lamp Sync Output

C Lamp Current

D Q-Switch Delay

K Q-Switch Sync Output

F Q-Switch Advanced Sync Ouput

H Marx Bank Trigger

I Q-Switch High Voltage

1064 nm Light Output (Normal)

1064 nm Light Output (Fast)

>500 ns

2.5 – 6 V

50 Ω InputPositive Edge TriggerTTL Compatible

5 ms

2.5 V Into 50 Ω

FWHM = 180 µs

500 µs Max

210 µs Nom60 ms Min

5 ms

2.5 V Into 50 Ω

>500 ns

2.5 – 6 V

– 700 to +500 ns

500 ns

3.5 kV8 – 12 ns FWHM

2.5 ns FWHM

50 Ω InputTTL Compatible

50 Ω InputPositive Edge TriggerTTL Compatible

50 Ω InputTTL Compatible

2.5 V Into 50 Ω

50 Ω Input5 ms Pulse WidthTTL Compatible

6.5 V Into 50 Ω

T = 0


3-12

Laser Output Specifications

Note that, unlike ion lasers, the output power of the Lab-Series YAG laser isnot variable and is based on the model of laser purchased. Output fre-quency can be varied ±10% of the nominal frequency.

Table 3-1: Power Specifications

Model1

1 All specifications, unless otherwise stated, are for Q-switched operation at 1064 nm, and are subject to change withoutnotice.

Lab-130- Lab-150- Lab-170- Lab-190-

Rep Rate (Hz) 10 30 50 10 30 50 10 30 50 10 30 50 100

Energy (mJ/p)2

2 Harmonic energies are specified after separation using dichroic mirror pairs. 532 nm energies are specified usingtype II second harmonic generation (SHG). 355 nm energies are specified using type II SHG. A 10% increase in 355 nmenergies can be specified when type I SHG is used.

1064 nm 450 275 200 650 500 300 850 700 550 1000 800 600 325

532 nm 200 100 70 300 200 100 450 325 210 500 400 250 120

355 nm 90 40 30 150 100 40 220 175 100 250 200 100 50

EEO-3553

3 High UV output option designed for OPO pumping, including injection seeder, harmonic generator, 355 nm dichroicseparators and beam dump.

– – – – – – 240 – – 300 – – –

266 nm 50 25 15 70 35 25 90 60 30 110 60 25 20

Table 3-2: Performance

Wavelength Pulse Width1

1 Nominal full width half maximum (FWHM) pulse width 8–10 ns, except Lab-130 and -190 10 Hz versions, which will be9–12 ns. The short pulse mode, standard on all Lab-series lasers, reduces the 1064 nm pulse width to approximately2.5 ns and reduces the pulse energy by approximately 10%. (Short pulse mode is available on seeded versions by specialrequest only).

Short-Term Energy Stability2

2 Pulse-to-pulse stability for >99% of pulses, measured over a 1-hour period.

Long-Term Power Drift3

3 Over an 8-hour period with temperature variations of less than ±3°C.

1064 nm 8–12 nm ±2% <3%

532 nm 1–2 nm <1064 nm ±3% <5%

355 nm 2–3 nm <1064 nm ±4% <6%

266 nm 3–4 nm <1064 nm ±8% <10%

Laser Description

3-13

Table 3-3: Mode and Pulse Specifications

Mode Pulse

Spatial Mode Profile1

Near Field (1 m)Far Field (∞)Modulation2

1 Near field spatial profiles measured 1 m from laser using a commercially available beam diagnostic system. 70% refersto the correlation between the actual beam profile and the best least-squares fit Gaussian profile. Far field profiles aremeasured at the focal plane of a 2 m focal length lens.

2 Refers to the maximum deviation from the best-fit Gaussian profile measured in the near field (1 m) between the FWHMpoints.

Standard Fit>70%>95%<40%

ESM Fit3

>85% ±5%>95%<20%

3 Enhanced spatial mode options can be tailored to meet your application needs. To obtain >85% Gaussian fits, energycan be reduced by 30%.

Line Width4

Standard <1.0 cm-1

Injection Seeded <0.003 cm-1

4 Insertion losses for systems using the Model 6350 injection seeder are <15% at 1064 nm, 532 nm and 266 nm.

Beam Diameter5

5 Actual beam diameter will vary depending on laser configuration.

<10 mm – Timing Jitter6 <0.5 ns

6 rms jitter from Q-switch sync pulse. Jitter is ≤1 nm rms when using the Model 6350 injection seeder at 10 Hz, ≤1.5 ns at30 Hz, and ≤2 ns at 50 Hz.

Table 3-4: Beam Specifications

Pointing Stability1

1 Long-term average pointing drift after warm-up over 8 hours ±3°C. Shot-to-shot point-ing stability <±25 µrad.

<±50% µrad

Beam Divergence2

2 Full angle measured at FWHM points.

<0.5 mrad

Lamp Lifetime3

3 IR energy within 10% of specified value.

30 million pulses

Table 3-5: Service Requirements

Water Service10 Hz1, 30 Hz, 50 Hz

1 Lab 130-10 and 150-10 Hz units are air-cooled as standard. Water-cooled versionsrequire WAT 100 (3.8 liters/min. or 1.0 U.S. gal/min.). All seeded lasers must be water-cooled.

7.6 l/min (2.0 US gal/min)2

2Minimum pressure 40 psi. Maximum pressure 60 psi.

Electrical Service10 Hz30 Hz50 Hz

<35 A<40 A<55 A

Voltage3

3 Input transformer has taps at 190, 200, 210, 220, 230, 240, 250 and 260 V. Once a tap ischosen, actual input voltage differing by more than ±10% from nominal voltage mayaffect operation of the laser.

190–260 Vac, Single Phase, 50/60 Hz

Umbilical Length 3 m (10 ft)

Controller Cord Length 3 m (10 ft)

WeightLaser HeadPower Supply

55 kg (120 lb)68 kg (150 lb)


3-14

Outline Drawing

Figure 3-9: Outline Drawing

30.3770

21.2538

19.850225.2640

2.564

17.22437

All dimensions ininches

mm

46.161172

7.0178

32.0813

2.0652,3

9.00228

12.04306 7.62

193

13.00330

4.00102

5.01127

Lab-Series Laser Head

Lab-Series Power Supply

Controller

7.90201

3.2582,5

7.28185



MODESOURCE

SINGLE SHOT

LAMP ENERGY

FIRE REP COMPUTER

INT

LAMP ON STOP ENABLE

FIXED Q-SW EXT

ONOFF

EXTVAR

SIMMER ERROR

LP

INHIBIT

Quanta-Ray

4-1

Chapter 4 Controls, Indicators and Connections

This chapter describes the controls, indicators and connections of the Lab-Series laser head, power supply, controller and GUI control software. Fig-ure 4-1 shows the various components inside the Lab-Series laser head.

The Laser Head

Figure 4-1: An isometric view of the internal components of the Lab-series laser head.

Polarizer

Injection Seeder

HG TemperatureController

High Reflector M1and /4 Plate

Pockels Cell(Q-Switch)

Pump Chambers (2 Places)

Harmonic Generator (HG)

Injection Seeder Controls

Output Coupler M2

AluminumBase Plate

Marx Bank Location

Dichroic Mirror DM2

Base Pan

Beam Dump

Dichroic Mirror DM1

λ

1

2


4-2

Referring to Figure 4-1, the laser head components are described, startingfrom the rear mirror and moving forward.

Rear mirror M1—one of two oscillator cavity end mirrors. It reflects alllaser light back into the cavity. Vertical and horizontal controls allow you toalign the oscillator cavity and to optimize output power and mode quality.These controls are only accessible when the cover is off.λ/4 (quarter-wave) plate—rotates the polarized cavity light 90° and isused in conjunction with the polarizer and Pockels cell to set the Q-switchholdoff, i.e., when properly aligned, there will be no laser oscillation untilthe Q-switch is fired, no matter how much oscillator PFN voltage there is(8 V max.).The waveplate is aligned by rotating the knurled ring around thehigh reflector.

Pockels cell—a high-voltage device (crystal) used as an optical high-speedshutter to Q-switch pulses. It is opaque (blocks light) until voltage isapplied to it. There are no local controls.

Polarizer—a coated optic placed in the beam path that allows only polar-ized light with a select polarization alignment to pass through. It is used inconjunction with the λ/4 plate to select light of a certain polarization fortransmission. The polarizer is aligned by rotating the optic in its holder. Aclamping screw holds it in place.

Pump chambers (1 to 2 chambers in one of 2 types)—a rectangular boxthat contains a single parabolic chamber with a flash lamp placed at onefocus point and a YAG rod at the other, or a dual parabolic chamber with aflash lamp at the focus of each chamber and the rod placed at the focuscommon to each chamber. The YAG rod is the lasing media which ispumped by the lamp(s).

The number and type of chambers found in the oscillator depends on thelaser model and its output power capacity. There are no controls on thechambers. Two terminals provide attachment for the high-voltage wires forthe lamp(s).

Marx bank—provides power to drive the Pockels cell and uses a TTL-trigger source from the power supply controller to turn on and off the cell.

Injection seeder—(optional) provides a small amount of single-frequencylaser light of the desired wavelength to stimulate emission at that wave-length in the oscillator once the proper threshold for lasing is reached in therod. Its controls are provided on one of the laser side panels. Refer to “SidePanel” later in this chapter for a description of these controls.

Base pan—encloses the bottom of the laser to keep it clean and to provideemf and safety shielding.

Output coupler M2—one of two cavity end mirrors. Whereas rear mirrorM1 reflects all light back into the cavity, output coupler M2 allows a smallpercentage of it to pass through as the oscillator output laser beam. Its ver-tical and horizontal controls allow you to align the oscillator cavity and tooptimize output power and mode quality. These controls are only accessi-ble when the cover is off.

Harmonic generator (HG)—contains various crystals that, depending ontheir sequence and orientation to the incoming beam, generate second,

Controls, Indicators and Connections

4-3

third and fourth harmonics from the primary wavelength. There are twocontrol arms for positioning and rotating the optics inside. Refer to Chapter7, “Harmonic Generator,” for detailed information on using this device.

HG temperature controller—stabilizes the temperature of the HG crys-tals, thus maintaining stable output despite changes in ambient tempera-ture. Refer to Chapter 7, “Harmonic Generator,” for information describingthe use and setting of these controls.

Dichroic mirror 1 (DM1)—reflects certain wavelengths and routes this out-put to DM2 for transmission while transmitting residual 1064 and/or 532 nmto the beam dump. Vertical and horizontal controls allow you to adjust therouting of the beam.

Dichroic mirror 2 (DM2)—like DM1, it selects certain wavelengths forreflection, then routes this output beam out the laser. Vertical and horizon-tal controls allow you to adjust the routing of the beam.

Beam dump (BD-6) — water-cooled, absorbs the residual 1064 nm output.

Aluminum base plate—provides a rigid and thermally stable platformupon which to mount the laser components.

End Connector Panel

Figure 4-2: Laser Head Rear Panel Controls and Connections.

Coolant input connector—provides attachment for the umbilical malehose connector to bring coolant to the laser head from the power supply.

Coolant output connector—provides attachment for the umbilical femalehose connector that returns the coolant to the power supply.

Q-Switch input connector (BNC)—provides attachment for the umbilicalcoaxial connector to receive the Q-switch triggering signal from the powersupply.

Nitrogen purge input connector—attaches to the nitrogen flow regulatorunit provided in the accessory kit. Nitrogen is used to purge the laser headand harmonic generator to keep them clean longer.

Control cable connector—attaches to one of the large umbilical connec-tors from the power supply and provides controls signals for the variouscomponents in the laser head.

Inlet OutletCoolant

Connector

High VoltageConnector

Neutral/Ground

Connector

ControlCable

Connector

InletPurge

Connector

Q-SwitchConnector


4-4

High voltage connector—attaches to one of the large umbilical connec-tors from the power supply that provides high voltage for the flash lamps,simmer supply, and Q-switch.

Neutral/ground connector—attaches to one of the large umbilical con-nectors from the power supply and provides a return path and safetygrounding for the high voltage system.

The Marx Bank

The the Marx bank control box is located inside the laser head near the rearpanel. The connections are made at the factory, but instructions are pro-vided here in the event they are accidentally disconnected.

Marx bank INPUT connector (BNC)––accepts the Q-switch control sig-nal from the end panel connector.

Marx bank OUTPUT: FAST connector (MHV)––transmits a Q-switchcontrol signal for a 2.5 ns optical pulse from the cavity.

Marx bank OUTPUT: SLOW connector (MHV)––transmits a Q-switchcontrol signal for an 8 ns (nominal) optical pulse from the cavity.

The Seeder Control Panel

Located on the side of the laser (Figure 4-3), this panel provides control ofthe optional Model 6350 injection seeder. Refer to the Seeder user’s man-ual for signal level requirements and instructions on using the seeder. Thefollowing control descriptions are provided here for convenience.

Figure 4-3: The Laser Head Side Panel Injection Seeder Controls

Power ON indicator—glows amber to show the seeder is powered on.

STANDBY/ON switch—sets the system to standby (STBY) or active mode(ON). In standby, all temperature control circuits are operational but thelaser seeder is disabled. In active mode, the seeder is enabled.

Mode switch—allows you set the seeder to manual mode (MNL) or auto-matic mode (AUTO), or to disable it (DSBL). Use the MNL position to set thepiezoelectric voltage to the center of its range. The AUTO position allows aservo to reset the piezoelectric to its center whenever the piezoelectric volt-age reaches the end of its range (auto-centering). DISABLE prevents theservo from resetting the system automatically.

5 kV is present at the Marx bank connectors. Shut off the laser (pressthe stop button) before changing outputs.

Danger!

STBY ON RESET Q-SW PIEZO FREQ

OFFSETVOLTBLD UP TIMEDSBLMNLAUTO

ON


4-5

RESET indicator—glows yellow whenever the servo is resetting the piezo-electric voltage to the center of its range.

RESET connector (BNC)—(output) provides a means to remotely monitorwhen the servo reset is active. Output is a 5 V active high TTL-level signal.

Q-switch buildup timing connector (BNC)—(output) provides attach-ment for an oscilloscope cable for sweep timing. A TTL-level output pulseis presented to the connector and remains high for the duration of the Q-switch hold-off.

PIEZO/VOLT connector — (output) not used on this system.

FREQuency OFFSET connector—(input) provides connection for a user-supplied input voltage that fine tunes the injection seeder to center it on thegain bandwidth of the YAG laser. It works in conjunction with the manualfrequency adjustment (see below).

Manual frequency adjust—provides local control to fine tune the injec-tion seeder to center it on the gain bandwidth of the YAG laser. This signalis summed with any signal applied to the FREQuency OFFSET connector(see above).

The Emission Indicator

The EMISSION ENABLE indicator on the side panel glows whenever thelaser is capable of emitting laser radiation.

Figure 4-4: Laser Head Emission Indicator


4-6

The Power Supply Front Panel

Figure 4-5: The Power Supply Front Control Panel

MONITOR: PWR ON indicator—glows when utility power is applied to thesystem and the circuit breaker and key switch are turned on.

MONITOR: INTERLOCK FAULT indicator—glows when there is a systeminterlock fault: either the laser head or power supply cover is off, or theremote interlock is open (see Remote Interlock Connector below). Oncethe fault is corrected, the light turns off.

MONITOR: LOW WATER indicator—glows when water in the reservoirfalls below the safety level. When this happens, turn off the system and adddistilled water immediately.

MONITOR: LASER ID indicator—glows when there is a mismatch betweenthe power supply and laser head with regard to the optimized repetitionrate. When glowing, the power supply cannot be turned on. Requested fre-quency must be within ±10% of the laser design frequency.

INPUT: Q-SWitch TRIGger connector (BNC)—accepts a 5 V signal to firethe Q-switch (input impedance = 700 Ω). The circuit is overload protected.An external time delay is required.

INPUT: LAMP TRIGger connector (BNC)—accepts a 5 V signal to triggerthe flash lamp ±10% of the rated frequency rate of the laser (input imped-ance = 700 Ω). The circuit is isolated and overload protected.

INPUT: ANALOG STROBE connector (BNC)—provides connection for anenabling signal that gates analog information from the controller to allowanalog programming to be completed before the laser fires. A high TTL-level signal enables transmission, a low level disables it. It may be operatedas a level or edge-triggered device. The circuit is overload protected (input

OUTPUT REMOTEINPUTMONITOR

SHOTS X100

PWRON

INTERLOCKFAULT

LOWWATER

LASERID

Q-SWTRIG

LAMPTRIG

ANALOGSTROBE

Q-SWSYNC

LAMPSYNC

Q-SWADV SYNC

COMPUTERRS232C

POWER

I

0


4-7

impedance = 16 kΩ). Refer to Chapter 10, “Service and Repair: AnalogSignals,” for details on using this strobe function.

OUTPUT: LAMP SYNC connector (BNC)—provides an output timing pulsesynchronous with lamp firing for use with other equipment. The pulsewidth is approximately 0.5 ms and has an amplitude of 2 V and a rise timeof approximately 20 ns (into a 50 Ω load).

OUTPUT: Q-SWitch SYNC connector (BNC)—provides an output timingpulse synchronous with the Q-switching of the laser for use with otherequipment. Pulse width is approximately 4.5 ms with an amplitude of 2 Vand a rise time of approximately 20 ns (into a 50 Ω.load).

OUTPUT: Q-SWitch ADVance SYNC connector (BNC)—adjusts the outputsync signal from 700 ns before Q-switch firing to 500 ns after it fires toallow synchronization to auxiliary equipment. The pulse width is approxi-mately 4.5 ms with an amplitude of 2 V and a rise time of approximately20 ns (into a 50 Ω load).

REMOTE connector—provides attachment for the 37-pin D-sub connectorof the controller cable.

COMPUTER: RS-232C connector—provides attachment for a 9-pin, RS-232Cserial control device. Any computer or terminal that is compliant with theIBM 9-pin standard can use this port to control the laser system. The pinoutand specifications for this connector are given in Table 4-1 below. Chapter6, “Operation,” provides information on operating the laser using a Win-dows*-compatible computer using the GUI software provided with this sys-tem. “The GUI Software Menus” section later in this chapter explains thesoftware menus. Appendix B is a Programming Guide for those wishing towrite a program to operate the laser directly and automatically.

Figure 4-6: The 9-Pin SERIAL COM Port

*Windows is a registered trademark of the Microsoft corporation.

Table 4-1: The SERIAL COM Port Connections

Computer or Terminal Lab Power SupplyRS-232-CSignal Name

Signal Pin No.(25-Pin)

Pin No.(9-Pin)

Pin No. Signal

Transmit Data TXD 2 3 3 RXDReceive Data RXD 3 2 2 TXDNot Connected RTS 4 7 – CTSNot Connected CTS 5 8 – RTSNot Connected DSR 6 6 – DTRNot Connected DCD 8 1 – DCDNot Connected DTR 20 4 – DSRSignal Ground 7 5 5Protective Ground 1 SHELL SHELL

1 5

6 9


4-8

POWER: ON key switch—applies power to the control electronics. Boththe circuit breaker and key switch must be turned on before the controllercan provide control to the system. When the key switch is turned on, thepower LED on the power supply front panel and the OFF lamp on the ana-log controller turn on.

POWER circuit breaker—applies ac power to the power supply circuitryand turns on the MONITOR: PWR ON lamp.

The Power Supply Rear Panel

Reservoir level indicator—shows how much water is in the power supplyreservoir. When the water level falls midway between the level markers, theMONITOR: LOW WATER lamp on the front panel turns on to warn you thatthe water is getting low. Always maintain the water level between the twolevel markers during operation.

Umbilical connector—provides connection for the umbilical to the laserhead.

Power cord—provides facility ac power to the laser system. The cord ispermanently attached to the power supply. Refer to the Specification tablesin Chapter 3 for electrical service requirements.

Figure 4-7: The Power Supply Rear Connector Panel

Remote interlock connector—allows other safety interlock devices to beincluded in the interlock chain, e.g., a safety switch mounted on the door ofthe laser operation area. If this were the case, the laser would automaticallyshut off when the door was opened. Wire remote interlocks using shieldedtwisted-pair wires that are isolated from ground. If no auxiliary interlock isto be used, verify the black shorting plug is inserted to close the interlockcircuit. The laser will not operate while these pins are open.

System WATER IN connector—allows attachment for a facility water hoseto provide cooling water to the laser and power supply. For reliable opera-tion, do not swap the hose attached to this connection with the one attachedto the WATER OUT connector. Refer to the Specifications table in Chapter 3for required flow rates.



MANUFACTURING DATE:

MODEL

S/N


MADE IN U.S.A.

REMOTEINTERLOCK

WATER IN

WATER OUT

NORMALOPERATING

RANGE

Umbilical Connector

Power Cord

Power Requirement Label

Reservoir LevelIndicator Remote Interlock

System WATER IN Connector

System WATER OUT Connector


4-9

System WATER OUT connector—allows attachment for a facility waterhose for removing the laser-heated water from the system. Attach the otherend of this hose to a drain or to a water-to-air cooling device, such as theModel WA-1. For reliable operation, do not swap the hose attached to thisconnection with the one attached to the WATER IN connector. Hose usedshould be designed for hot water usage.

The Controller

The controller plugs into the 37-pin REMOTE connector on the power sup-ply. Its controls and indicators are shown in Figure 4-8 and are listed anddescribed here from top to bottom, left to right.

OSCillator SIMMER indicator—glows whenever the oscillator flash lampsimmer current is on.

AMPlifier SIMMER indicator— (is not used on the Lab-Series system)

OSCillator LAMP ENERGY control—sets the output energy of the oscilla-tor flash lamp(s). The scale is relative and is marked START – 10.

AMPlifier LAMP ENERGY control—(is not used on the Lab-Series system)

Figure 4-8: The Controller

ADVanced SYNC control—adjusts the output sync signal from 700 nsbefore Q-switch firing to 500 ns after it fires to allow synchronizing to aux-iliary equipment. The signal is available at the Q-SW ADV SYNC output con-nector on the power supply.

Rep Rate ERROR indicator—blinks if the remote control source has sel-ected more than one source to fire the lamp.



MODESOURCE

SINGLE SHOT

LAMP ENERGY

FIRE REP COMPUTER

INT

LAMP ON STOP ENABLE

FIXED Q-SW EXT

ONOFF

EXTVAR

SIMMER ERROR

LP

INHIBIT

Quanta-Ray


4-10

Rep Rate VARIABLE control—sets the lamp firing rate in a range that isapproximately 1 Hz to +5% from the system fundamental FIXED frequencysetting as denoted by the laser model number.

Q-SWITCH ERROR indicator—blinks if the remote control source hasselected more than one mode to trigger the Q-switch.

Q-SWitch DELAY control—adjusts the Q-switch firing delay timing from50 to 300 µs.

Rep Rate SOURCE selector—selects the source of the lamp firing pulse:FIXED, VARIABLE, or EXTernal source. FIXED selects the repetition rate asdenoted by the laser model number. VARIABLE allows you to vary the pulserate from approximately 1 Hz to +5% of the system fixed frequency. TheEXTERNAL setting requires a firing pulse to be presented at the LAMP TRIGinput on the power supply, but is constrained by the same limitations of theVARIABLE setting. Do not exceed this rating.

Q-switch MODE selector—selects the source for the timing of the Pockelscell firing: Q-SW, LP and EXT. When set to Q-SW, the Pockels cell is firedafter the flash lamps with a time delay set by the Q-SW DELAY control (seeabove). When set to LP (Long Pulse), the Pockels cell and flash lamp arefired synchronously. When set to EXT (external), the Pockels cell is fired bya signal presented at the power supply Q-SW TRIG input.

SINGLE SHOT/FIRE switch—when pressed, a single pulse is triggered thatis synchronized to the next available flash lamp firing signal, regardless ofits source.

SINGLE SHOT/REP switch—sets the laser to fire repetitively or one pulseat a time. When set to the REP position, the rep rate SOURCE selector con-trols the firing rate and the FIRE switch is defeated. When set to the SINGLESHOT position, the FIRE button is enabled.

INTernal/COMPUTER switch—selects the controller or a remote terminalor computer for the control source. This switch remains active when thelaser is under computer control, thus allowing you to restore manual con-trol by simply switching it back to INTernal.

INHIBIT indicator—glows when the LAMP ON switch has been pressed toturn off the flash lamp. It is off when the lamp is flashing.

LAMP ON switch—turns on and off the flash lamp power supply and,therefore, the lamp. If the switch is in the INHIBIT position (up position), thelamps cannot flash and the INHIBIT indicator glows. This button is func-tional even when the INTernal/COMPUTER switch is set to COMPUTER.

OFF indicator—glows whenever the power supply is on but the laser isoff.

STOP switch—turns off the laser (sets it to standby) but power is stillapplied to the system. The OFF indicator glows when this button is pressed.This button is functional even when the INTernal/COMPUTER switch is setto COMPUTER.

Be careful when using the Q-switch MODE selector that the Q-switchDELAY setting above it is not disturbed, since laser output power is sen-sitive to the DELAY setting.

Note


4-11

ON indicator—glows whenever the laser is on and capable of emittinglight. This indicator also serves as the CDRH emission indicator.

ENABLE switch—allows the laser to begin emission and turns on the ONindicator. The ENABLE switch operates only after the power supply circuitbreaker is closed and its keyswitch is set to the on position. This button isfunctional even when the INTernal/COMPUTER switch is set to COMPUTER.

The GUI Software Menus

When using the GUI software, the Main menu is the primary monitor andcontrol device. Figure 4-9 shows all the controls available on that menu.These controls can be hidden or displayed by toggling the check next to theassociated name in the pull-down list under the View tab. Two other menus,Setup and Info, are available under the Window tab. These three menus andtheir controls are described below. The program “Exit” button is under theFile tab.

Figure 4-9: The Main Menu Showing all Controls

Main Menu

This is the first menu that appears when the software is started. It will“remember” the controls that were present the last time the program wasused.

INTERLOCK fault indicator—turns on whenever an interlock fault hasoccurred. To clear the fault, turn off the laser (press the ON/OFF button), fixthe fault (refer to the MONITOR lamps on the power supply), then turn thelaser on again.

ADVANCED SYNC control—adjusts the output sync signal from 700 nsbefore Q-switch firing to 500 ns after it fires to allow synchronizing to aux-


4-12

iliary equipment. This signal is available at the Q-SW ADV SYNC outputconnector on the power supply.

QSWITCH selector—selects the source for the timing of the Pockels cellfiring.

• NORMAL (Q-switched)—the Pockels cell is fired after the flash lampswith a time delay set by the Q-SW DELAY control on the Setup menu.

• LONG PULSE—the Pockels cell and flash lamp are fired synchro-nously.

• EXTERNAL—the Pockels cell is fired by a signal presented at thepower supply Q-SW TRIG input.

EMISSION indicator—when the laser is on or capable of emitting laserlight, “Emission” is displayed in black letters on a red background, warn-ing that laser output is available or imminent.

PUMPS indicator—when on, indicates the pump is on and system haspressure. If this lamp turns off, either the pump has failed, the reservoir islow on fluid or there is a blockage or kink in the coolant line.

SIMMER indicator— glows whenever the oscillator flash lamp simmer cur-rent is on and turns off if simmer current is not available.

HIGH VOLTAGE indicator—when on, indicates the high-voltage circuitsare working properly; when off, the high-voltage system is not on yet orhas failed.

ON/OFF switch—toggles the laser on and off. When the button has beenpushed to turn on the laser, the button turns green. Otherwise, the button isgray when the laser is off.

REPETITIVE/SINGLE/FIRE slide control—provides a means to set the lasersystem to repetitive pulse mode or single shot mode, and to fire single shotsat will. To select the desired mode, click on the lever and slide it to thatposition. To fire single shots, click on the lever while it is in the single-shotposition.

• REPETITIVE—this position fires the lamps automatically at a rate setby either the VAR RATE control or the source selected using the LAMPSTRIGGER selector.

• SINGLE—this position takes the system out of repetitive pulse modeand allows the operator to fire the lamps one pulse at time.

• FIRE—fires the lamp(s) a single time when the lever is pressed. Actualfiring is synchronized to the next pulse from the selected lamp triggersource.

VAR RATE control—sets the lamp firing rate in a range that is approxi-mately 1 Hz to +5% above the system fundamental FIXED frequency set-ting as denoted by the laser model number.

LAMPS TRIGGER selector—inhibits firing or selects the source of the lampfiring pulse.

• INHIBIT—prevents the lamps from firing.• FIXED—sets the repetition rate to that denoted by the laser model num-

ber.


4-13

• VARIABLE—allows the pulse rate to be varied from approximately1 Hz to +5% above the system fixed frequency rate using the VARRATE control.

• EXTERNAL—requires a pulse to be presented at the LAMP TRIG inputon the power supply to fire a laser pulse, but this function is con-strained by the same limitations of the VAR RATE setting. Do notexceed this rating.

Setting Menu

Figure 4-10: The Setup Menu

This menu allows the operator to set the oscillator pfn in terms of percentof available power, set the Q-Switch delay time and to tell the system that anew lamp has been installed.

OSC PFN window—allows the user to enter the PFN voltage in terms ofpercent of total power by pressing the up/down arrows on the window or bytyping the desired value from 0 to 100 percent in the window.

Q-SWITCH DELAY selector— allows the operator to delay the firing of theQ-Switch down to 60 and up to 500 µs from the actual firing pulse andshows the delay time in the window. Use this timing function to optimizethe output pulse. Enter the setting by turning the knob, pressing the up/down arrows on the window, or typing the desired time delay in the win-dow.

NEW LAMP INSTALLED button—tells the system that a new lamp has beeninstalled and resets the shot counter.

Information Menu

Figure 4-11: The Information Menu


4-14

This menu displays information about the Lab-Series system.

LASER MODEL number—is the model number as read from the system.The last number denotes the standard firing repetition rate.

LAB SOFTWARE REVision number—displays the current software revi-sion for the control pc board in the power supply.

SOFTWARE REVision number—displays the current GUI software revi-sion.

LAMP SHOTS number—displays the total shots fired since the lamp wasinstalled, which gives the operator an idea of how long he can expect thelamp(s) to last. This number cannot be changed on-screen. However, if alamp is replaced, this number must be reset to zero using the “Shots” com-mand described in Appendix B, “The Programming Reference Guide.”This command can also be used to reset to the count to a number other thanzero if a lamp is replaced with a lamp that has already been used in the sys-tem.

HISTORY buffer window—displays the last 16 status/error code entriesmade by the system (refer to Appendix A. These codes are used for diag-nostic purposes only. The most recent entry is to the left.

5-1

Chapter 5 Installation and Alignment

Installing the Laser

The following installation procedure is provided for reference only; it is notintended as a guide to the initial installation and set-up of your laser. Pleasecall your service representative to arrange an installation appointment,which is part of your purchase agreement. Allow only personnel qualifiedand authorized by Spectra-Physics to install and set up your laser system.

1. Place the laser head on a suitable optical table and place the controllernear it.

2. Place the power supply on the floor within 3 m (10 ft) of the facilitypower source (the length of the power cord) and within 3 m of the laserhead (the length of the umbilical).

3. Loosen the two screws on each side of the power supply and carefullylift off the cover.

Connecting the Electrical Service

The main autotransformer is located in the power supply on the lower traynear the heat exchanger (Figure 5-1).

1. Connect the white wire to the tap that most closely matches your facil-ity line voltage. The autotransformer has several taps, each markedwith a different operating voltage (Figure 5-1). The range of the auto-transformer is 190 to 260 Vac. The operating range of the laser is ±10%of this voltage.

The use of controls or adjustments or the performance of proceduresother than those specified herein may result in hazardous radiationexposure.

Caution!

Purge the laser with dry nitrogen only or you will void your warranty!Warning!

The air vents on the power supply provide cooling for componentsinside. These vents are strategically placed for air flow management.Allow about 0.5 m (2 ft) clearance around the power supply for properair movement.

Caution!


5-2

Figure 5-1: The location of the autotransformer in the power supply.Taps shown for operating voltages ranging from 190 to 260 Vac.

2. Verify the correct fuses are installed for your system configuration.

Figure 5-2 shows the location of the fuses in the power supply. A labellisting the proper fuse size is located near the fuses. The specificationtables at the end of Chapter 3 list the system power requirements forthe different configurations.

Figure 5-2: Location of system fuses.

3. Connect the 3 m (10 ft.) power cord to your facility service outlet. Ver-ify the green wire is connected to earth ground, not neutral.

Main Fuses

Installation and Alignment

5-3

Connecting the Power Supply and Laser Head

Connecting the power supply and laser head entails attaching the umbilicalto the laser head and hooking up a nitrogen purge to the laser head. All theumbilical connections at the laser head are polarized so that they cannot beinadvertently swapped. In addition, the three electrical connections containinterlock sensors that prevent the laser from starting if one or more is dis-connected. Refer to Figure 5-3.

Figure 5-3: The Lab-series laser head showing connections for theumbilical.

1. Connect the three large electrical connectors by pushing them in, thenscrewing on the outer shell.

2. Connect the input to the nitrogen purge flow regulator (included in theaccessory kit) to the dry nitrogen tank.

You need to supply the hose fittings for attaching the regulator hose toyour nitrogen supply.

3. Connect the flow regulator output hose to the purge input port on thelaser head.

Simply push the hose fitting in until it clicks. To remove the hose, pushin on the retaining wire clip and pull the hose out.

4. Connect the Q-switch BNC control cable to the laser head panel.

5. Connect the two coolant water hoses to the laser head connector panel.

The hoses are polarized. Simply push the hoses on until they click. toremove a hose, push on the metal retaining tab and pull the hose out.Be careful of water spillage when removing hoses.

This completes the procedure to connect the power supply to the laser head.

Connecting the Harmonic Generator

If a harmonic generator (HG) was ordered with the laser or ordered later, orif the HG was removed for some reason, mount it after completing theinstallation of the laser. When ready, refer to Chapter 7, “HG HarmonicGenerator: Installing the HG.” The HG must be purged with nitrogen. Agauge and hose fittings are part of your accessory kit. Connect the nitrogentank to the gauge and the gauge to the Inlet Purge Connector on the umbili-cal end of the laser head (see Figure 5-3).

Inlet OutletCoolant

Connector


Neutral/Ground

Connector

ControlCable

Connector

InletPurge

Connector

Q-SwitchConnector


5-4

Filling the Cooling System

During the following process, water will have to be added to the reservoirin the power supply (Figure 5-4) several times as the system fills. Ratherthan remove and replace the reservoir cover several times, it is easier to usea long-necked funnel placed in the return hose entry of the reservoir coverto add water as needed.

Figure 5-4: Cooling System Component Identification

1. Pull the small return hose from the coolant reservoir cover.

Take care not to spill any water that may still be in the hose.

2. Place a long-necked funnel in the vacated hole in the reservoir cover.

3. Fill the reservoir with distilled water.

4. Set these system controls as follows:

Control Setting

Circuit breaker (power supply) Closed

Keyswitch (power supply) ON

LAMP ON switch (controller) OFF (INHIBIT light is on)

To prevent damage caused by freezing, the laser cooling system wasdrained before initial shipment. The system must be filled with waterbefore operating the laser for the first time. Your Spectra-Physics ser-vice representative will perform this task during initial installation.Before he arrives, obtain 20 l (5 gal) of distilled water for filling andflushing the system.

Warning!

Reservoir

Particle Filter

Deionizing Filter

Return Hose

Level Sensor

Cooling Pump

Avoid spilling water on any electrical components. When power is reap-plied, some components will contain high voltage and damage canoccur. If you do spill water, clean it up immediately.

Warning!

Installation and Alignment

5-5

Refer to Chapter 4, “Controls, Indicators and Connections,” for controldescriptions.

5. Hold the coolant return hose over a drain or bucket, then press theENABLE button on the controller to start the cooling system pump.

6. As water is pumped to the head and removed from the reservoir, addwater, keeping it full, until water flows from the return hose.

Do not let the reservoir run dry. If the reservoir gets close to empty,press the POWER OFF button immediately, then add water and tryagain.

7. Once water flows from the return hose, allow the water in the reservoirto drop to below the upper fill level on the power supply rear panel,then press the POWER OFF button.

If the water dropped below the upper fill level, add water.

8. Remove the funnel and shove the return line back into the hole in thereservoir cover.

9. Replace the power supply cover and tighten the screws.

Air vents—provide air cooling for components inside the power supply.These vents are strategically placed for air flow management. Allow about0.5 m (2 ft) clearance around the power supply for proper air movement.

This completes the installation of the Lab-Series laser.

Installing the Lab-Series GUI Software for Remote Control

The Lab-Series GUI control software is supplied on CD-ROM for installa-tion on your own Windows®*-based personal computer or notebook. Alter-natively, a remote computer or terminal can be used to run your ownsoftware program to control the Lab-Series laser automatically. If youchoose the latter, refer to Appendix B, “Programming Reference Guide,”for instructions on using the programing commands.

1. If you are going to use the GUI control software to control your sys-tem, verify your computer meets these minimum requirements.

• 486 (or higher) processor, 66 MHz or higher• 16 MB RAM or more, (32 MB RAM recommended)• 3 MB available disk space for installation• a Windows-compatible pointing device, such as a mouse• a video display with 640 x 480 (VGA) or higher resolution (800 x

600 to 1024 x 768 preferred)• an available RS-232 serial port properly configured for 9600 baud,

8 bits, 2 stop bits, no parity.• Microsoft® Windows 95, 98, ME, 2000 or XP operating system.

2. Place your computer in a convenient location.

3. Using a standard 9-pin serial extension cable, connect the computer tothe RS-232 connector on the front of the power supply. Refer to Chap-ter 4 for connector and pin specifications.

*Windows and Microsoft are registered trademarks of Microsoft Corporation.


5-6

4. Install the GUI control software:

a. Place the CD-ROM in the drive, then double-click “My Computer”> “D:” > “Setup.exe.” The software will create a directory on driveC by default, but will allow you to place it wherever you wish. Itwill then install itself in that directory.

b. Follow the on-screen instructions to complete the installation. Itwill install LabWindows run-time components into the “c:/win-dows/system” directory and place an icon on the desktop for con-venient program startup.

An uninstall program is also placed in the selected directory in theevent you wish to remove these program components from yoursystem at a later date (e.g., when you wish to change or upgradethe host computer).

5. Refer to Chapter 6, “Operation: Operation Using the GUI Interface”for instructions on setting the computer to communicate with thepower supply and to run the laser. Refer to Chapter 4 for descriptionsof the menus and their controls.

Alignment

Your Lab-Series laser was aligned at the factory by specially trainedprofessionals and again when it was first set up at your site. It should notrequire further alignment in the field. Furthermore, the laser containslethal high voltage and generates an enormous amount of optical powerthat can cause damage and even injury. Therefore, do not attempt toalign the laser yourself, you may void your warranty. Instead, call yourSpectra-Physics service representative.

Danger!

6-1

Chapter 6 Operation

The Lab-Series Nd:YAG laser system is controlled locally using the table-top controller provided with the system. It can be controlled remotely viathe 9-pin RS-232 serial port on the power supply using the Windows®*-based software provided with the system. It emulates the controller func-tions on a computer. It also can be controlled remotely using your own soft-ware program running on a computer. Appendix B, “ProgrammingReference Guide,” explains the Lab-Series RS-232 command language andhow it is used to control the laser system. (Note: an optional IEEE-488 portis also available for remote control of the system.)

Chapter 5 explains how to connect the system and explains how to installthe Lab-Series GUI software. This chapter assumes this has already beendone if you are going to use it.

This chapter is divided into two major sections. The first describes laseroperation using the provided local controller. The second describes laseroperation using the GUI software provided. The

Operation Using the Controller

Figure 6-1: The Controller

*Windows is a registered trademark of the Microsoft Corporation



MODESOURCE

SINGLE SHOT

LAMP ENERGY

FIRE REP COMPUTER

INT

LAMP ON STOP ENABLE

FIXED Q-SW EXT

ONOFF

EXTVAR

SIMMER ERROR

LP

INHIBIT

Quanta-Ray


6-2

Quick Start/Stop Procedure

The standard start-up procedure follows this section.

Start-up

1. Turn on the power supply front panel POWER circuit breaker.

2. Turn on the power supply front panel POWER key switch.

3. Set the controller as follows:

4. Verify all covers are on.

5. Temporarily depress the ENABLE switch.

6. After the start-up delay, slowly increase the OSC LAMP ENERGY knobto 10.

7. Adjust the Q-SWitch DELAY knob until energy output is at its max.

Shut-down

1. Decrease OSC LAMP ENERGY to START.

2. Press the STOP switch.

3. Allow the water to flow for an additional 5 to 10 minutes to cool downthe lamp(s) and rod(s). This is important for proper cool-down!

4. Turn off the external cooling water supply, or the heat exchanger, ifone is used.

Standard Operation

Start-up

For day to day operation after you have some experience operating this sys-tem, you may want to use the Quick Start/Stop Procedures above to savetime. The following detailed procedures are provided for those who are notfamiliar with the system.


Control Setting

OSC LAMP ENERGY knob START

SOURCE switch FIXED

MODE switch Q-SW

INT/COMPUTER switch INT

SINGLE SHOT/REP switch REP

LAMP ON switch Lamp on (INHIBIT lamp is off)

Q-SWitch DELAY knob mid-range

Control Setting

Oscillator (OSC) LAMP ENERGY knob START

Rep rate SOURCE switch FIXED

Q-SWitch MODE switch Q-SW

Operation

6-3

2. Verify the power supply POWER circuit breaker is open (off), thenapply utility power to the system.

3. Close the power supply POWER circuit breaker.

4. Turn on POWER key switch.

5. Press the ENABLE button.

6. When the simmer light turns on, turn the OSC LAMP ENERGY knob toposition 7.

7. Obtain a burn pattern to check for proper alignment and any opticaldamage.

a. Place a piece of unexposed but developed Polaroid film into atransparent plastic bag, then place it in the beam path about 1 mfrom the laser.

b. Press the SINGLE SHOT: FIRE button once.

8. If the burn pattern is symmetrical (Figure 6-2), set the MODE switch toQ-SW and adjust the Q-SW DELAY control for maximum output energy.You can safely raise the LAMP ENERGY control to maximum andincrease the repetition rate by setting the SOURCE switch to VARiableand increasing the rate to the level desired.

Figure 6-2: Burn Patterns

If the burn pattern is asymmetrical or has flared edges, set the MODEswitch to Q-SW and adjust the Q-SW DELAY control for maximum out-put energy, then reset the system for single shot and repeat these lasttwo steps to take a second burn pattern. If this pattern is asymmetricalor has flared edges, call your Spectra-Physics service representative.)

INT/COMPUTER switch INT

SINGLE SHOT/REP switch SINGLE SHOT

LAMP ON switch Lamp on (INHIBIT lamp is off)

Control Setting

In the following step, do not look at the film when taking a burn pattern.The light will be very bright.


Good Clipped Diffraction Evident Misaligned HR Misalligned OC

Only allow personnel trained and authorized by Spectra-Physics to alignyour Lab-Series laser. Misalignment can permanently damage cavityoptics. Such damage is not covered by warranty.

Warning!


6-4

Interlock Faults

An interlock fault shuts off the laser to minimize the risk of damage to sys-tem components. This is either caused by something that has failed, orthere is a possibility of laser radiation exposure. Interlocks include: waterflow sensor, auxiliary interlock connector, laser head water temperaturesensor, power supply cover switch, and laser head cover switches. Alsoincluded in the interlock chain are the cables to the power supply Controlpc board and Power pc board (both inside the power supply), the controllerand the laser head. When a fault occurs, the interlock fault MONITOR lampson the power supply glow.

Restarting the Laser after an Interlock Fault

1. Clear the fault.

Refer to the MONITOR indicators on the power supply to find out whatcaused the fault.

2. Turn the OSC LAMP ENERGY control to START.

3. Press the ENABLE switch to start the laser, or issue a start command viathe computer if the system is set for computer control.

Single-Shot Operation

Single-shot operation is typically only used for setup and test. Firing a sin-gle shot requires two signals: an enabling signal, such as pressing the SIN-GLE SHOT switch on the controller panel or issuing a fire command from aremote computer, and one to fire it, which is the next available pulse fromthe continuously running system frequency generator. This pulse fires theMarx bank once, and until the firing circuit is armed again, subsequentpulses are inhibited. (Remote operation is covered in Appendix A.)

This completes the procedures for standard laser start-up using the control-ler.

Shut-down

You can damage the laser if you do not shut it down properly. When fin-ished using the laser, perform the following steps in the order they are pre-sented.

1. Reduce the output to zero by turning the LAMP ENERGY control toSTART.

2. Allow the water to flow for an additional 5 to 10 minutes to cool downthe lamp(s) and rod(s). This is important for long lamp and rod life!

3. Press the STOP button, turn off the key switch on the power supply,and turn off the circuit breaker.

It is normal for the INTERLOCK FAULT indicator to glow when the circuitbreaker and key switch are on but the laser is off because there is nocooling water flow. Press the ENABLE button to start the coolant pumpand clear the fault.

Note

Operation

6-5

4. Turn off the external cooling water supply (or the heat exchanger if oneis used).

5. Do not turn off the purge supply.

Let it flow 24 hours a day at 2 scfm.

This completes the shut down procedure using the controller.

Operation Using the GUI Interface

Refer to Figure 6-3 while performing these procedures. Refer to Chapter 4for descriptions of the controls.

Figure 6-3: The Main Menu

Quick Start/Stop Procedure

The standard start-up procedure follows this section.

Start-up

1. Turn on the power supply front panel POWER circuit breaker.

2. Turn on the power supply front panel POWER key switch.

3. Set the Main menu controls as follows:

Control Setting

LAMPS TRIGGER knob FIXED

QSWITCH knob NORMAL

INT/COMPUTER switch (on controller if plugged into the power supply)

COMPUTER

Single shot/rep switch REPETITIVE

Q-SWITCH DELAY knob (on Setup menu) mid-range


6-6

4. Verify the laser head and power supply covers are on.

5. Click on the ON/OFF button to start the cooling pump and start the laser.

6. Once the system is at full power, adjust the Q-SWITCH DELAY knobuntil energy output is at its max.

Shut-down

1. Press the ON/OFF button.

2. Once the laser has turned off, allow the water to flow for an additional5 to 10 minutes to cool down the lamp(s) and rod(s). Proper cool-down is important for long lamp and rod life!


Standard Operation

Start-up

For day-to-day operation after you have gained some experience operatingthis system, use the Quick Start/Stop Procedures above to save time. Thefollowing detailed procedures are provided in the event you are not yetfamiliar with the system.


2. Verify the power supply POWER circuit breaker is open (off), thenapply utility power to the system.

3. Close the power supply POWER circuit breaker.

4. Turn on POWER key switch.

5. Click on the ON/OFF button.

6. Obtain a burn pattern to check for proper alignment and any opticaldamage.

a. Place a piece of unexposed but developed Polaroid film into atransparent plastic bag, then place it in the beam path about 1 mfrom the laser.

b. Press the FIRE button once.

Control Setting

LAMPS TRIGGER knob FIXED

QSWITCH knob NORMAL

INT/COMPUTER switch (on controller if plugged into the power supply)

COMPUTER

Single shot/rep switch SINGLE

Q-SWITCH DELAY knob (on Setup menu) mid-range

In the following step, do not look at the film when taking a burn pattern.The light will be very bright.


Operation

6-7

7. If the burn pattern is symmetrical (Figure 6-4), set the QSWITCH knobto NORMAL and adjust the Q-SW DELAY control for maximum outputenergy. You can safely increase the repetition rate by setting theLAMPS TRIGGER switch to VARIABLE and increasing the rate to thelevel desired.

Figure 6-4: Burn Patterns

If the burn pattern is asymmetrical or has flared edges, set theQSWITCH knob to NORMAL and adjust the Q-SW DELAY control formaximum output energy, then reset the system for single shot andrepeat these last two steps to take a second burn pattern. If this patternis asymmetrical or has flared edges, call your Spectra-Physics servicerepresentative.)

Interlock Faults

If an interlock fault is detected, the laser shuts off to minimize the risk ofdamage to system components. Such a fault is caused either by somethingthat has failed or a condition where there is a possibility of laser radiationexposure. Interlocks include: water flow sensor, auxiliary interlock connec-tor (for a user-installed switch), laser head water temperature sensor, powersupply cover switch, and laser head cover switches. Also included in theinterlock chain are the signal cables to the power supply Control and Powerpc boards, the controller and the laser head. When a fault occurs, the inter-lock fault MONITOR lamps on the power supply glow.

When an interlock fault occurs, an interlock warning window will pop upon the computer screen with a list of possible fault areas.

Restarting the Laser after an Interlock Fault

1. Refer to the interlock warning pop-up window for a list of possiblefaults. Also refer to the MONITOR indicators on the power supply tofind out what caused the fault.

Good Clipped Diffraction Evident Misaligned HR Misalligned OC

Only allow personnel trained and authorized by Spectra-Physics to alignyour Lab-Series laser. Misalignment can permanently damage cavityoptics. Such damage is not covered by warranty.

Warning!

It is normal for the power supply INTERLOCK indicator to glow when thecircuit breaker and key switch on the power supply are on and the laseris off because there is no cooling water flow. Click on the ON/OFF but-ton to start the coolant pump and start the laser.

Note


6-8

2. Once resolved, press the ON/OFF button to clear the fault and start thelaser. If multiple faults have occurred, the system will refuse to startand a second pop-up window will appear. When all faults have beenresolved, press the ON/OFF button to clear the final fault and start thelaser


Single-shot operation is typically only used for setup and test. Otherwisethe system is set to repetitive mode.

Shut-down

The laser can be damaged if it is not shut down properly. When finishedusing the laser, perform the following steps in the order presented.

1. Click on the on/off button to turn off the laser.

2. Allow the water to flow for an additional 5 to 10 minutes to cool downthe lamp(s) and rod(s). Proper cool-down is important for long lampand rod life!

3. Turn off the key switch on the power supply, and turn off the circuitbreaker.


5. Do not turn off the purge supply.

Let it flow 24 hours a day at 2 scfm.

Moving the Laser System

Take extreme care when moving the laser system to another location. Typi-cally, the laser head can be placed on top of the power supply along withthe controller, and the whole system can be moved to another nearby loca-tion.

If the unit is to be shipped anywhere, or if it is to be moved off site (out ofthe building), it is highly recommended that the system be disconnectedand each component moved separately. Refer to Chapter 5, “Installationand Alignment,” and disconnect the power supply, laser head and controllerin reverse order of assembly. Refer to Chapter 10, “Service and Repair:Shipping the Laser and Power Supply,” for information on draining thecoolant from the power supply and laser head.

Make sure that, before shipping the laser or the power supply, the cool-ant is completely drained from each. The temperature in an aircraftcargo hold can freeze the coolant and can cause several components toburst. Such damage is not covered under your warranty!

Warning!

7-1

Chapter 7 Harmonic Generator

Harmonic Generator Controls

Figure 7-1: HG and Temperature Controller Component Identifica-tion. The controller is located inside the laser head near the HG.

The harmonic generator (HG) uses KD*P crystals. These crystals aresensitive to thermal shock, so change temperatures slowly. They are alsohygroscopic, i.e., they are water soluble. Avoid getting them wet, andkeep the humidity in their environment low. To ensure a low-humidityenvironment, it is recommended the power supply circuit breaker be lefton even when the other equipment is turned off (including the powersupply keyswitch) so that the HG heater remains on. This also dramati-cally reduces warm-up time when the system is used the next time.

Warning!

2nd Stage CrystalTranslation Arm

1st Stage CrystalTranslation Arm

Output Window(Shown Covered)

Input Window(Shown Covered)

HG TEMPERATURE CONTROLLER

ON

PWR INCTEMP

HTR HTR INCTEMP

OFF

SHG THG/FHG ON

SHG Adjust

Power Switch

Power ON LED

Warming LED Warming LED THG/FHG Adjust

Power Switch


7-2

Figure 7-2: Controller shown behind the HG.

Input polarization rotator—rotates the polarization of the 1064 nm inputbeam to optimize it with the crystal for maximum conversion efficiency.

Crystal translation arm (one for each stage)—slides the crystals in andout of the beam path and serves as a lever for angle tuning the crystals. Thefirst stage crystal translation arm serves as an indicator of the polarizationof the output beam. Notches in the arms lock the crystals in position. Referto Table 7-2 and Table 7-3 at the end of this chapter for arm settings.

Angle tuning knob (one for each tuning arm)—adjusts the angle of thecrystal for the most efficient harmonic generation, optically aligning it withthe input beam.

Main housing—rotates about the optical axis to change the polarizationfor different harmonic crystals. The output polarization is always vertical.Clamping screws lock the HG in the desired orientation.

As a rule, the polarization of the harmonic is perpendicular to the tuningaxis of the crystal.

Note

Harmonic Generator

7-3

Harmonic Generator Temperature Controller Controls

The temperature controller provides power to heat the HG crystals, thenstabilizes their temperature to maintain a stable output despite changes inambient temperature. And because the crystals are hygroscopic, keepingthe crystals warm also minimizes unwanted optical effects caused by waterabsorption. It also dramatically reduces system warm-up time. The idealtemperature setting is one that allows the affected crystal to produce themost harmonic generated light.

PWR ON switch—turns on the temperature controller and the Channel 1heater.

SHG HEATER indicator—glows as the controller heats the second har-monic generator (SHG) crystals. The lamp will turn on and off periodicallyas the controller maintains the temperature.

SHG INCrease TEMPerature control—sets the temperature of the secondharmonic crystals. Its range is approximately 30–50° C over 20 turns.

THG/FHG HEATER indicator—glows as the controller heats the third andfourth harmonic generator (THG and FHG) crystals. The lamp turns on andoff periodically as the controller maintains the temperature.

THG/FHG INCrease TEMPerature control—sets the temperature of thethird and fourth harmonic crystals. Its range is approximately 30–50° Cover 20 turns.

THG/FHG ON/OFF switch—turns on the heater for the third and fourth har-monic crystals.

Control cable—attaches to the HG heater input connector to providepower from the controller for the heaters in the HG and sensor signals fromthe HG to the controller.

Installing the Harmonic Generator

The HG was optically aligned at the factory. Therefore, the following pro-cedure should allow optimal harmonic generation from all crystals in theunit. If the HG was not purchased with the Lab-Series laser but added later,a Spectra-Physics service representative will install both the HG and thetemperature controller as part of your warranty agreement.

1. Remove wrapping, tie-downs and restrainers from the HG.

2. Install the HG base plate on the L-frame (three spring-loaded screwshold it down).

Three setscrews, each located next to a hold-down screw, work againstthe springs to adjust the HG vertically.

3. Plug the control cable from the temperature controller into the back ofthe HG.

The connector is keyed and only goes in one way.

Never move the crystal into or out of the beam while the laser is run-ning.

Warning!


7-4

4. Place the HG so that the four elongated holes on its yoke line up withthe corresponding threaded holes in the base plate. Start all fourmounting screws, but leave them loose to allow horizontal movementof the HG.

5. Slide both crystal translation arms to the “0” position (pushed all theway in: note the markings on the arm) to move the crystals out of thebeam path.

6. Start the laser, then set controls on the controller as follows (do not usethe GUI interface during this installation):

7. Adjust the HG horizontally and vertically to center the input and exitwindows on the laser beam. Reduce the ambient light in the room anduse an infrared (IR) card as a detector for the input beam. If the HGmust be moved vertically more than its spring-loaded screws allow,“walk” the vertical adjustment by simultaneously loosening onespring-loaded screw and tightening the vertical adjustment screw nextto it. Repeat with the other vertical adjustments.

8. Connect the purge system to the HG and purge for 15 minutes beforeproceeding.

9. Check for clipping of the output beam (use an IR card.) Adjust thebase plate of the HG if the crystal clips the beam. Turn the HG to theother polarization orientation and check again for clipping.

Table 7-1: Controller Settings

Control Setting

LAMP ENERGY Near threshold

Q-SW DELAY Optimum

SOURCE FIXED

MODE Long Pulse

INT-COMPUTER switch INTernal

SINGLE SHOT switch REPetitive

LAMP ON switch OFF (INHIBIT light is on)

Use protective eyewear throughout the rest of this procedure. Make alladjustments with the laser near the lasing threshold and in Long Pulsemode.


The rate of rotation of the beam polarization is twice that of the polar-ization rotator.

Note

Harmonic Generator

7-5

Operation

1. Verify purge flow is set to 0.5 SCFH, and purge the system for 15 min-utes before proceeding.

2. Set the crystal translation arms for the wavelength of interest (refer toTable 7-2 and Table 7-3 at the end of this chapter for arm settings).

Example: to obtain the second harmonic from a type I SHG crystal:

a. Slide the first stage crystal translation arm to “I,” which places thetype I crystal in the beam path.

b. Slide the second stage crystal translation arm to “O,” which movesthe second stage crystals out of the beam path.

3. Turn the main housing on its yoke to orient the output for verticalpolarization (it should always be vertical).

Example: to obtain vertically polarized second harmonic output, turnthe main housing on its yoke until the first stage translation arm is ver-tical. This orients the axis of rotation horizontally for tuning the crystal.

4. Switch to Q-SWitch mode, then angle-tune the crystal for maximumoutput at the wavelength of interest.

5. Adjust the polarization rotator for maximum output.

Type I and II Crystals

The type I crystal creates a 1064 nm residual fundamental that is linearlypolarized and is useful when mixing frequencies. It produces up to 10%more third harmonic power than a type II crystal, even though its doublingprocess is less efficient.

The type II crystal creates a 1064 nm residual fundamental that is ellipti-cally polarized and has a slightly higher conversion efficiency than a type I.It is typically used for dye laser applications.

Second Harmonic (types I and II),and Third and Fourth Harmonic Generation

1. Turn on the temperature controller and the SHG channel heater.

2. Select crystals and output polarization as described in Table 7-2 andTable 7-3 for the desired wavelength.

3. Turn on the laser and adjust the HG for maximum output at this wave-length.

4. Watch the HEATER indicators. They should remain on for several min-utes while the crystals warm up, and both lamps will blink periodicallywhen the temperature is stable (there is a slow oscillation around a setpoint as the controller turns the heater on and off to keep the crystaltemperature constant). Set the crystal temperature just above roomtemperature, and monitor the indicators to make sure the crystal tem-perature remains stable.


7-6

If either lamp turns off and stays off, turn the associated INC TEMPcontrol clockwise to increase the temperature a little. The lamp shouldturn on, glow continuously for a short time, and blink after that.

If either lamp continues to glow after 10 minutes of operation, turn theassociated INC TEMP pot counterclockwise just until the lamp shutsoff. It should stay off for a short time and blink after that.

5. The fourth harmonic crystal is temperature dependent. In addition togenerating UV, it also absorbs IR. When too warm, it approaches itscritical phase-matching angle and output power will diminish. At thispoint, either reduce the input power or turn off the SHG channel heaterand let the crystal cool off.

In the tables below, find the combination of wavelength, polarization, andSHG crystal for the output of interest on the left-hand side of the table andset the HG as described on the right-hand side. All output wavelengths arecollinear; they can be separated by dichroic beam splitters or dispersiveprisms (or equivalent optics).

Table 7-2: Summary of Translation Arm Positions1

1 Table describes an HG with a full complement of harmonic generation crystals.

Stage Arm Position Crystal Position

1st O First stage crystals out of beam path

I Type I SHG2 crystal in beam path

2 Second Harmonic Generation (532 nm).

II Type II SHG2 crystal in beam path

2nd O Second stage crystals out of beam path

T THG3 crystal in beam path

3 Third Harmonic Generation (355 nm)––occurs by summing the fundamental (1064 nm)and its second harmonic. Type I second harmonic produces optimal third harmonic per-formance.

F FHG4 crystal in beam path

4 Fourth Harmonic Generation (266 nm)––occurs by generating the second harmonic ofthe second harmonic of the fundamental. Type II second harmonic produces optimalfourth harmonic performance.

It is easy to determine the polarization plane of the last harmonic gener-ated by the HG. It is in the same plane as (in-line with) the long controlarm that is associated with the crystal generating that harmonic.

Note

Harmonic Generator

7-7

Table 7-3: Summary of HG Settings

Output ofInterest

HG Settings1

1 Table describes an HG with a full complement of harmonic generation crystals.

λ (nm) PolarizationCrystal

SHGHousingPosition

MainStage

Position

1stStage

Position

2ndStage

Position

1064 Horizontal 0 0

532 Vertical I Horizontal I 0

Horizontal I Vertical I 0

Vertical II Horizontal II 0

Horizontal II Vertical II 0

355 Vertical I Vertical I T

Horizontal I Horizontal I T

Vertical II Vertical II T

Horizontal II Horizontal II T

266 Vertical I Vertical I F

Horizontal I Horizontal I F

Vertical II Vertical II F

Horizontal II Horizontal II F

The table below provides both vertical and horizontal polarizationoptions available from your HG unit. The IHS dichroics have been opti-mized for vertical polarization.

Caution!


7-8

8-1

Chapter 8 Internal Harmonic Separator

Dichroics

Dichroic mirrors are used to separate the second, third and fourth harmonicfrom the Nd:YAG fundamental in the Lab-Series laser. The small amountof unwanted harmonics in the beam is regarded as inconsequential for OPOoperation, and the convenience and flexibility of dichroic separation whenused in other applications has led to the creation of the internal dichroicharmonic separator for general-purpose use.

Dichroic mirrors are characterized by high reflectivity at one range ofwavelengths and low reflectivity elsewhere. Advanced optical coating tech-niques now allow excellent color separation with high damage thresholds,even into the ultraviolet (UV).

IHS System Description

The IHS system provides high throughput of various combinations of thesecond, third and fourth harmonics as well as the fundamental 1064 nmbeam. The system has two basic parts: the optics sets that transmit thedesired wavelengths and the wave plate sets that adjust the polarizationstate of residual beams. The illustrations on the following pages show thepossible combinations. Note: some setups require the removal of the beamdump.

Dichroic mirrors DM1 and DM2 are mounted in standard mounts and havevertical and horizontal mirror adjustments. For repeatability, a knurled ringholds each mirror against a 3-ball seating surface. Refer to “Replacing theDichroic Mirrors” later in this chapter for instructions on changing mirrors.

The following components comprise the IHS system:

IHS-532—a pair of mounted 532 nm dichroic beam splitters that separatethe second harmonic from the fundamental. This set is included in the basicIHS but is also available separately.

IHS-355—a pair of optional, mounted 355 nm dichroic beam splitters thatseparate the third harmonic from the fundamental and second harmonic.

The internal harmonic separator (IHS) transmits and modifies Class IV-High Power Laser beams. These beams are eye, skin, and fire hazards;therefore, take precautions to prevent accidental exposure to both directand reflected beams. Diffuse as well as specular reflections can causesevere eye or skin damage.

Warning!


8-2

IHS-266—a pair of optional, mounted 266 nm dichroic beam splitters thatseparate the fourth harmonic from the fundamental and second harmonic.

WP-3—an optional waveplate set that orients the polarization of 532 nmoutput. The orientation of the harmonic generator on the pump laser deter-mines the polarization of the shortest harmonic input.

WP-4—an optional wave plate set that linearly polarizes the 1064 nm resid-ual fundamental output of the Lab-Series laser after type II second har-monic generation. It orients the polarization after type I second harmonicgeneration.

System Configurations

The modularity of the IHS allows several system configurations by using acombination of the optics sets listed above to provide selected output. Themore common configurations are shown in Figure 8-1 to Figure 8-3. Twowindows in the front bezel on 4 in. standard Quanta-Ray spacing provideselected wavelength output. Figure 8-1 shows the possible placement ofthese optics. Some configurations require the removal of the beam dump(refer to “Removing the Beam Dump” below).

Figure 8-1: The various mounting and output options for the Lab-Series laser.

Single wavelength—for second, third or fourth harmonic only, use the IHS-532 or IHS-266 or IHS-355 as shown in Figure 8-2.

Figure 8-2: Single wavelength: second, third or fourth harmonic.

HG

Laser Head

Beam Dump

4 in.

HG

Laser Head

Beam Dump

1064, 532, 355 or 266 nmIHS-XXX

4 in.

Internal Harmonic Separator

8-3

Dual wavelengths––for second, third, or fourth harmonic plus fundamental,use the IHS-532, IHS-355 or IHS-266, and the WP-4 as shown in Figure 8-3.

Figure 8-3: Dual wavelength: Second, third or forth harmonic plus thefundamental.

Removing the Beam Dump

Some configurations require that the water-cooled beam dump be removed.When removing the beam dump, remove one cooling line at the harmonicgenerator and the other at the beam dump. Then attach the end removed atthe beam dump to the vacant barb on the HG. Verify you have properlyreattached the water lines to the harmonic generator before you turn on thelaser. When replacing the beam dump, reverse this process to include thebeam dump in the cooling loop.

Installing the IHS Mirror Mounts

There are times when a different wavelength or output port must be usedand a different mirror arrangement is required. Use the following instruc-tions when the IHS mirror mounts were removed and must be re-installedor when they have to be moved to another location.

HG

4 in.

WP4

Laser Head

Beam DumpRemoved

532, 355 or 266 nm

1064 nm

IHS-XXX

During installation, always operate the Nd:YAG laser at low levels toprevent injury to yourself or damage to the system or both. To pumpwith the second harmonic, the low level setting should be un-Q-switched. The same conditions apply to the third and fourth harmonic,except that a UV fluorescent card can be used to detect the beam. Safetygoggles or glasses are required any time the laser is on, even at lowenergy.

Danger!


8-4

Figure 8-4: The IHS dichroic mirrors shown in the “normal” position.

1. Remove the laser head cover (4 screws) and install the shortest wave-length dichroics at this time.

2. Install the optic mounts in the desired location (refer to Figure 8-1through Figure 8-3). Use two screws to fasten the mount to the baseplate.

3. Put a power meter or beam dump at the output ports to be used.

4. Turn on the laser in Long Pulse mode.

5. Adjust the dichroic mirror mounts vertically and horizontally to centerthe harmonic beam on the selected output port.

6. If you want to use additional second-harmonic dichroics, turn off thelaser and install them along with the required wave plates (WP-3 orWP-4). Turn on the laser and set it to a safe power level again.

7. Check the alignment of the second harmonic beam and wave plates.

8. Verify the harmonic generator is set so that the shortest harmonic isvertically polarized (refer to Chapter 7).

9. Turn off the laser.

10. Install the appropriate windows and absorption filters in the beampaths as required, or enclose the beam path in dust tubes.

11. Replace the cover.

This completes the installation procedure.

HarmonicGenerator

HG Temperature Controller

AluminumBase Plate

Beam Dump

IHS Dichroic Mirror DM2

IHS Dichroic Mirror DM1

Internal Harmonic Separator

8-5

Replacing the Dichroic Mirrors

When changing output wavelengths of the harmonic generator, (from 2nd to3rd or 3rd to 4th etc.), it is necessary to change dichroic separator mirrors.

Note: a change in HG setting typically causes the output beam to be dis-placed from its original path. A slight offset can be compensated for byadjusting the IHS mirrors.

1. Prior to changing the HG setting and the dichroic mirrors, note thelocation of the beam on a far-field target.

2. Unscrew the knurled retaining ring on DM2 (see Figure 8-5).

Figure 8-5: The IHS Mirror Holder

3. Remove the finger spring and dichroic optic.

4. Install the new dichroic optic with the arrow on the barrel facingtowards the incoming laser beam. The optic should rest against the 3-ball mirror seat.

5. Place the finger spring into the knurled retaining ring with the fingersfacing towards the dichroic optic.

6. Tighten the retaining ring to compress the finger spring against thedichroic optic and hold it in place.

7. Repeat the procedure for the second dichroic optic.

8. Change the HG setting to the desired wavelength(s).

9. Slightly readjust the vertical and horizontal controls of DM2 to place thebeam back on target.

Mounting Holes

AdjustmentsHoriz. Vert.

Mirror MountRing


8-6

Operating the IHS

Since the IHS is a completely passive device, no special procedures oralignments are required during routine operation. When harmonic separa-tion is required, install the appropriate mirror set into the mounts.

Removing/Replacing the Beam Dump

The optional Model BD-6 water-cooled beam dump is positioned after thefirst dichroic mirror, DM1. It lets you dump the residual 1064 and 532 nmlight and allows you to position the OPO, dye laser, experiments, etc.,closer to the output of the Lab-Series laser. Water cooling removes excessheat that would otherwise build up in the laser head.

The beam dump can be conveniently moved out of the beam path by simplyloosening the two 8-32 beam dump mounting screws and sliding the beamdump assembly down (see Figure 8-6).

Use the following procedure to remove the beam dump entirely.

1. Turn off the laser.

2. Disconnect one of the beam block water hose connections at the in-line coupler between the HG and the beam dump and, holding bothhose ends as high as possible for a moment, allow the water inside todrain back to the power supply. Wipe up any spilled water.

3. Disconnect the second hose from the HG, then connect the two systemhose connectors together, leaving the beam dump out of the coolingloop. Connect the two beam dump hoses together to prevent dripping.

4. Remove the 10-32 base mounting screw from the beam dump base.

5. Lift the beam dump out and set it aside.

To install the beam dump, reverse this procedure.

Figure 8-6: Model BD-6 water-cooled beam dump showing mountingscrews.

8-32 Beam DumpMounting Screws

10-32 BaseMounting Screw

9-1

Chapter 9 Maintenance

Preventive Maintenance

• The top cover of the Lab-Series laser protects the internal componentsfrom outside contamination and also prevents unwanted stray opticalradiation from escaping the system. Always operate the unit with thetop cover in place.

• Inspect daily all windows for contamination or damage. The windowsshould be cleaned with acetone and lens tissue any time contaminationis suspected or observed. Damaged windows should be immediatelyreplace.

• It is highly recommended that you annually check the safety featuresof the laser to ensure safety is maintained (see Chapter 2, “LaserSafety,” for details).

Cleaning Laser Optics

Losses due to unclean optics, which might be negligible in ordinary opticalsystems, can disable a laser. Dust on mirror surfaces can reduce outputpower or cause total failure due to damage. Cleanliness is essential, and themaintenance techniques used with laser optics must be applied withextreme care and attention to detail.

“Clean” is a relative description; nothing is ever perfectly clean, and nocleaning operation ever completely removes contaminants. Cleaning is aprocess of reducing objectionable material to acceptable levels.

Since cleaning simply dilutes contamination to the limit set by solventimpurities, solvents must be as pure as possible. Use spectroscopic, electricor reagent grate solvents and leave as little solvent on the surface as possi-ble. As any solvent evaporated, it leaves impurities behind in proportion toits volume. Avoid re-wiping a surface with the same swab; a used swab andsolvents will redistribute contamination, it won’t remove it.

Both methanol and acetone collect moisture during prolonged exposure toair. Avoid storage in bottles where large volume of air is trapped above thesolvent; instead, store solvents in squeeze bottles from which trapped aircan be removed.

Laser optics are made by vacuum-deposited microthin layers of materialsof varying indices of refraction on glass substrates. If the surface isscratched to a depth as shallow as 0.01 nm, the operating efficiency of theoptical coating will be reduced significantly.


9-2

The condition of the laboratory environment is the primary factor affectingyour periodic maintenance schedule. The coated surfaces of the dichroicmirrors, windows, and wave plates are the elements most subject to envi-ronmental contamination. In these laser systems, where the peak power isvery high, contaminated optics damage much more easily than clean optics.Do not allow smoking in the laboratory.

Careful handling of optics during installation and configuration changes isthe best maintenance. Always use clean finger cots or powder-free latexgloves when handling optics, and do not remove the dichroics and waveplates from their mounts except for cleaning.

Stick to the following principles whenever you clean any optical surface:

• Remove and clean one optical element at a time. If all of the optics areremoved and replaced as a group, all reference points will be lost,making realignment extremely difficult.

• Work in a clean environment, over and area covered by a soft cloth orpad.

• Wash you hands thoroughly with liquid detergent and use finger cots.Body oils and contaminants can render otherwise fastidious cleaningpractices useless.

• Use dry nitrogen, canned air or a rubber squeeze bulb to blow dust orlint from the surface before cleaning with solvent. Permanent damagemay occur if dust scratches the glass or mirror coating.

• Use spectroscopic, electronic or regent grade solvents. Do not try toremove contamination with a cleaning solvent that may leave otherimpurities behind.

• Use photographic lens tissue to clean optics. use each piece only once:dirty tissue merely redistributes contamination.

Equipment Required

• Dry nitrogen, canned air or rubber squeeze bulb• Photographic lens tissue• Spectroscopic grade methanol• Forceps• Hemostat

Figure 9-1: Lens Tissue Folded for Cleaning

Maintenance

9-3

Cleaning Prisms, Mirrors and Windows

1. Blow away dust particles or lint using nitrogen or air.

2. Fold a piece of lens tissue into a pad about 1 cm in a side and clamp itin a hemostat (see Figure 9-1). Saturate the pad with methanol, shakeoff the excess, resaturate and shake again.

3. Wipe one surface—bottom to top—in a single motion. Be careful thatthe tip of the hemostat does not scratch the surface. Repeat the opera-tion with a clean tissue on the second optic surface. A clean opticalsurface will scatter little or no light when the laser is operating.

4. Install the optical assembly back into its base and adjust the mirrorvertically and horizontally for maximum optical output power.

Maintaining the Cooling System

Figure 9-2: Cooling system component identification.

1. Circulate water through the system for 30 minutes every week whenthe laser is not in use.

Always follow the instructions in Chapter 6, “Operation,” for turning offthe laser. Ignoring the shutdown procedure can permanently damage thelamps and/or rods.

Warning!

Reservoir

Particle Filter

Deionizing Filter

Return Hose

Level Sensor

Cooling Pump

Be wary every time you remove the power supply cover that there islethal high voltage inside.

Danger!


9-4

2. Inspect the water level in the reservoir through the window in thepower supply rear panel every time you use the laser.

Keep the reservoir at least half full. Drain the coolant and replace itwith fresh deionized, water every three months.

3. Check the deionizing filter (Figure 9-2) monthly and replace the filterwhen all the yellow resin in it has changed color to light brown.

Refer to “Replacing the Deionizing Water Filter” later in this chapter.

4. Replace the particulate filter whenever you replace the deionizing filter.

Refer to “Replacing the Particulate Filter” later in this chapter.

5. Replace the air filter monthly or when the blue indicator turns pink.

Maintaining the Harmonic Generator

1. Keep the crystals sealed, purged and heated at all times.

2. Use only spectroscopic grade methanol and photographic lens tissue toclean window surfaces.

Replacing the Deionizing Water Filter

To prevent air from getting into the water pump and causing the pump tolose prime, the deionizing filter cartridge must be replaced while water isstill in the system. Doing so means there is the possibility of water spillage.The following procedure allows you to replace the filter cartridge with min-imum chance of spillage. Table 10-1 lists the part number for the cartridge.After you replace the deionizing filter, proceed to “Replacing the ParticleFilter” below for instructions on replacing this filter as well.

Tools needed:

• 5/32 in. Allen (hex) wrench• Small cork for plugging end of cartridge• Small bucket• An absorbent towel

It is important that you follow this instruction for the well-being of yoursystem. Failure to do so can cause sediment build-up and restricted cool-ing.

Warning!

Do not attempt to clean, remove, replace or add crystals. Allow only fac-tory-trained service engineers to open your harmonic generator (HG).

Warning!

Maintenance

9-5

Procedure

1. Loosen the two screws on each side of the power supply, and lift offthe cover.

2. Remove the “T” Clip-Lok™ fitting from the top of the filter cartridge,and allow the water in the filter to drain back into the reservoir. Thismay take several minutes.

3. Place a towel under the bottom “T” fitting to catch any water that mayleak from the hose or cartridge when the lower fitting is removed.

4. Remove the “T” Clip-Lok fitting from the bottom of the filter car-tridge, and place the cork in the now vacant hole on the “T” fitting.Allow the remaining water in the filter to drain into the absorbenttowel.

5. Loosen the two 5/32 in. screws located on the filter restraint structureand remove the filter. Place the filter in the bucket.

6. Place the new filter cartridge in the restraint structure and tighten thescrews.

7. Install both “T” fittings onto the new cartridge and verify they sealproperly.

8. Clean up any spilled water.

9. Turn on the power supply circuit breaker and key switch, and press theENABLE button on the controller to start the pump.

If the pump does not prime itself, prime it by removing the large sup-ply hose from the reservoir and, using a long-necked funnel, pouringwater into the hose.

10. Run the pump for about 10 minutes.

11. If the MONITOR: LOW WATER indicator lights, shut off the power sup-ply and add deionized water to the reservoir.

Refer to Chapter 5, “Installation and Alignment: Filling the CoolingSystem.”

12. Replace the power supply cover.

13. Dispose of the used filter cartridge properly.

This completes the procedure for replacing the deionizing filter. Continuewith “Replacing the Particle Filter” below.

Clip-Lok™ is a registered trademark of Anarak, Inc.


9-6

Replacing the Particulate Filter

Replace the particulate filter (Figure 9-2) in the power supply whenever thedeionizing filter is replaced. Follow the instructions in the above procedurefor purging the cooling system of water.

Tools needed:

• Wire cutters• Needle-nose pliers

Procedure

1. Loosen the two clamping screws on each side of the power supply, andlift off the cover.

2. Locate the opaque plastic particulate filter next to the deionizing filteron the upper tray.

3. Remove the output hose from the reservoir.

4. Remove the input hose where it is attached to the Clip-Lok fitting onthe deionizing filter.

5. Cut the two tie-wraps holding the existing filter in place with the wirecutters, and discard the tie-wraps.

6. Thread the new tie-wraps through the fasteners.

7. Note the orientation of the existing filter, then replace it with the newone so the new filter is oriented in the same direction.

8. Place the long output hose into the reservoir.

9. Attach the remaining hose to the Clip-Lok fitting, and verify it issecurely seated.

10. Using the needle-nose pliers, tighten the tie-wraps around the filter soit is securely fastened to the tray.

11. Install the power supply cover.

This completes the procedure for replacing the cooling system particle filter.

Maintenance

9-7

Replacing the Air Filters

Three air filters in the laser head comprise a single filter assembly: theinput oil filter, the output particle filter, and the desiccant filter. Replace allof them at one time, not individually. Table 10-1 lists the part number forthis assembly.

Tools needed:

• Wire cutters

Procedure

1. Verify the system is off and that there is no power to the system.

2. Remove the laser head cover by removing the 4 screws, then lifting offthe cover.

3. Locate the air purge filter assembly under the tray. It is toward theumbilical end of the laser head, below the Marx bank.

4. Detach the assembly Clip-Lok fittings from the input panel fitting andfrom the manifold “T.”

5. Lift up on the small black tap on the desiccant filter restraining strapsto release the catch mechanism, and remove the straps.

6. If there is a tie-wrap holding the desiccant filter in place (used onlyduring initial shipment), use wire cutters to remove it.

7. Note the orientation of the filter assembly, then remove it.

8. Lay the new filter assembly in place, then refasten the black restrain-ing straps around the desiccant filter.

9. Fasten the input hose to the input panel fitting and the output hose tothe manifold “T.” Pull on the fittings to verify they latched properly.

10. Install the head cover and tighten the 4 screws.

This completes the procedure for replacing the air filter assembly.


9-8

Replacing the Flash Lamps

For optimal performance, lamps should be replaced after 1000 hours for10 Hz systems, 330 hours for 30 Hz systems, and 200 hours for 50 Hz sys-tems. Table 10-1 lists the part number for this assembly.

Procedure

1. Turn off the laser according to the instructions in Chapter 6, then openthe power supply circuit breaker.

2. Allow 5–10 minutes for the heads to cool.

3. Remove the laser head cover by removing the 4 screws, then lifting offthe cover.

4. Remove the plastic high voltage shield that covers the lamp housings.

5. Short together terminal posts A and B (Figure 9-3) on each pumpchamber using shorting wires.

6. Disconnect the lamp leads from the terminal posts.

7. Disconnect the water hose located at the top of the lamp house assem-bly.

This allows the water in the head to drain back into the power supply.Use a towel to catch or wipe up any spilled water.

Figure 9-3: Short together posts A and B to prevent shock when servic-ing the flash lamps.

Be wary every time you remove the power supply cover that there islethal high voltage inside.

Danger!

As an extra precaution, open the circuit breaker and disconnect thepower cord.

Danger!

Terminal PostsA B

Terminal PostsA B

Maintenance

9-9

8. Loosen and remove the thumb screws and block from both ends of thelamp(s).

9. Remove each lamp by moving it toward the middle and pulling it out.

10. Clean the new lamp with methanol.

11. Reverse Steps 6 through 10 to install each lamp.

a. Depending on clearance, insert the proper end of the lamp first.

The anode end is identified by a red mark on its electrode and an“A” on the red anode lead. The anode electrode is solid, while thecathode electrode is segmented and cone-shaped.

b. Make sure all O-rings are seated snugly in the groove of the lamphousing.

c. Tighten all thumb screws evenly and snugly. Do not overtighten.

d. Bend the ends of the lamp wire down at 90 degrees.

12. Remove the shorting connector from terminal posts A and B.

13. Connect the water hose to the top of the rod assemblies.

14. After installation, test for water leaks as follows:

a. Defeat the cover interlock.

b. Press the ON button long enough to move cooling water into thelamp housing.

c. If no leaks occur, turn on the water pump and inspect for leaksagain at full pressure.

If there are no leaks after 5 seconds, the seals are tight.

d. Turn off the laser, deactivate the cover interlock defeat, and installthe laser head cover.

15. If a leak occurs:

a. Turn off the laser and observe the danger warning in Step 1.

b. Remove the thumb screws and blocks.

c. Center the lamp in its housing, and check the seating of the O-rings.

This completes the procedure for replacing the flash lamps.


9-10

10-1

Chapter 10 Service and Repair

This chapter is divided into four parts. The first is a general description togive you a better idea of how the system works at the technical level in theevent you encounter problems while operating your unit. Do not attemptrepairs yourself while the unit is still under warranty; instead, report allproblems to Spectra-Physics for warranty repair.

The second part contains the troubleshooting guide that is for you, the user.It is meant to assist in isolating some of the problems that might arise whileusing the system. A complete repair procedure is beyond the scope of thismanual. For information concerning the repair of your unit by Spectra-Physics, please call your local service representative or refer to Chapter 11,“Customer Service.”

The third part is a replacement parts list of components (and their partnumbers) that are most likely to break or get lost, as well as those you maysimply want to order as spares or substitutes.

The final part gives directions on how to drain and disassemble the systemfor shipping. Be sure to read this section before you move your system.

General Operation

This section describes briefly how various parts of the system operate andwhat modifications, if any, can be made. References are made throughoutthis section to control devices. The first reference is to the control on thecontroller provided with the system. The second reference (in parentheses)is to the control on the GUI interface software also shipped with the system.

Enabling Signals

Enabling signals are used to control laser start-up, analog strobe triggering,flash lamp firing, select the lamp trigger oscillator, set the Q-switch trigger-ing mode and to select single-shot or repetitive operation. The controllersupplies enabling signals directly. When the system is operated remotely,enabling commands may be sent via the RS-232C port or the optionalIEEE-488 interface. Refer to Appendix A for instructions.

Analog Signals

Analog voltages control the flash lamp energy, the variable oscillator, theQ-switch triggering delay, and the timing of the Q-switch advanced syncsignal. The controller supplies analog signals directly. The computer con-trol interface (CCI) supplies these analog signals when commanded to doso by the attached computer or terminal.


10-2

The analog strobe function can be either edge-triggered or level controlled,depending on the placement of jumper W3 on the Control pc board. Thestandard Lab-Series laser is shipped from the factory set for level-con-trolled, which provides continuous analog data transfer. Changing JumperW3 to its alternative setting allows edge triggering of a 5 ms gate aperture.This mode accepts triggered analog data transfers from the computer buswith a time-restricted window.

When the standard Lab-Series laser is set to internal control and the INPUT:ANALOG STROBE connector terminals are either shorted or have a logic 0(0 V) signal applied to them, the system holds (latches) the last data settingand does not respond to any subsequent change in signal.

Alternatively, when the system is set to internal control and the INPUT:ANALOG STROBE connector terminals are either not terminated or have alogic 1 (5 V) signal applied to them, the system responds immediately tochanges in input signal.

When set for computer control, an Analog Strobe logic 1 command allowsdata to transfer while a logic 0 command latches the last data entered.

Local/Remote Operation

The INT/COMPUTER button on the controller selects the attached computer/terminal for remote control, or the controller for manual local control. TheRS-232C serial and optional IEEE-488 parallel ports are enabled whenCOMPUTER is selected, but only one port can be used at a time.

Q-switch Delay

After the firing signal emerges from the computer test delay, it passesthrough a one-shot pulse generator that shapes the wave form to meet thedrive requirements of the voltage-programmable Q-switch delay. The Q-SWITCH: DELAY control provides an adjustable delay of 50 to 300 ms thatallows the population inversion to develop before Q-switch triggering. thisallows the Q-switch to open at the peak of stored energy.

Q-switch Advanced Sync Generator

The signal splits, passing through a pair of delays, one fixed (850 ns) andone voltage-programmable (300 to 1300 ms). The variable delay controlsthe timing of the “pre-trigger” signal at the Q-SWitch ADVance SYNC con-nector on the power supply panel. The fixed delay provides the timing ref-erence against which the variable delay is compared. The advance syncpulse generator shapes the waveform to meet output signal requirements:

pulse width = 5 ms

2 V (50 Ω) rise time = 20 ns (50 Ω oscilloscope input)

Service and Repair

10-3

Mode Switch

The MODE switch on the controller (or the QSWITCH knob on the Mainmenu) enables one of three sources of Q-switch trigger signals. When set toQ-SW (NORMAL), a signal from the voltage-programmable delay opens theQ-switch momentarily at the point of maximum inversion. When set toLONG PULSE, the flash lamp and Pockels cell are triggered simultaneously,holding the Q-switch open throughout the lamp pulse. When set to EXTER-NAL, a signal at the INPUT: Q-SW TRIG connector on the power supply firesthe Pockels cell.

The source of the enabling signal depends on the setting of the INT/COM-PUTER selector on the controller and, if set to COMPUTER, on the computerwhen a computer is connected to the RS-232 interface and the REMOTEjumper plug is installed (see “Local/Remote Operation” above). All exter-nal Q-switch triggering signals enter through the INPUT: Q-SW TRIG con-nector on the power supply regardless of the INT/COMPUTER setting.

Q-switch Drivers

The output of the SOURCE: FIXED delay switch (LAMPS TRIGGER) passesthrough the MODE switch (QSWITCH) when Q-switch mode is enabled andfires the Marx bank pulse generator. The result is a pulse a few millisec-onds long that becomes amplified by the Marx bank buffer to produce thesignal that drives the Marx bank. The Q-switch pulse generator stretchesthe output of the Marx bank pulse generator to produce a signal thatappears at the OUTPUT: Q-SW SYNC connector on the power supply:

2 V (50 Ω) pulse width

5 ms with 20 ns rise time


Firing a single shot requires two signals: one to enable the single-shot flip-flop and one to fire it. The enabling signal is from either the SINGLE SHOT:REP switch on the controller or the slide bar control on the Main menu. Thearming signal (get ready to fire signal) is from either the SINGLE SHOT:FIRE button on the controller or the FIRE position on the Main menu slidebar control. Once armed, the single-shot circuit fires the Marx bank on thenext available pulse from the lamp trigger signal. Until it is armed again,the flip-flop prevents the passage of subsequent lamp trigger pulses.

LAMP ON Switch

When the LAMP ON switch (GUI: ON button) is turned off, voltage isapplied to the reset line of the lamp sync pulse generator to prevent lampfiring. It also turns on the INHIBIT lamp (GUI: LAMPS TRIGGER knob pointsto INHIBIT). The inhibit and source fault signals pass through an OR gatethat allows either of them to inhibit firing. The LAMP ON switch remainsactive even when under computer control so that the laser can always beshut off at the controller.


10-4

STOP/ENABLE buttons

The function of the STOP and ENABLE buttons (ON/OFF SWITCH) dependseither on the INT/COMPUTER selector on the controller and, if set to COM-PUTER, on the computer when a computer is connected to the RS-232interface and the REMOTE jumper plug is installed (see “Local/RemoteOperation” above). Under INT control, pressing the ENABLE button (toggleON) closes the main relay and activates all power supply circuits. After a 10second delay, the laser starts. Under COMPUTER control, two signals arerequire: an enabling signal that is derived by pressing the controllerENABLE button or by using the REMOTE jumper plug, and an “on” signalfrom the computer by toggling the ON/OFF SWITCH to “on.” The lightedbuttons on the controller identify the operating status of the laser, regard-less of the position of the INT/COMPUTER switch.

The line dropout detector shuts off the laser if it senses a loss of line volt-age. The initializing circuits prevent transfer of laser control until all powersupplies have energized. They also prevent mishaps due to errors in logicstart-up.

Interlock Logic

The interlock logic examines several sensors to ensure safe, trouble-freeoperation: external interlock, laser head and power supply cover switches,and cooling water temperature and flow. The auxiliary interlock connectoron the back of the power supply is included for simple installation of envi-ronmental safety devices such as a door switch. If an interlock fault occurs,the logic trips the main contactor, shutting off power to the switching sup-ply and simmer transformer. Logic power remains on.

The logic circuit also receives input from the lamp voltage level sensorwhich prevents the laser from starting until lamp energy is reduced tonearly zero. This prevents accidental high power output upon start-up.

If no interlock faults occur, the logic circuit enables the turn-on delay, and,after 10 seconds, the laser starts.

If one or more faults occur, the laser will not start and the INTERLOCKFAULT lamp on the power supply and Main menu turn on.

The auxiliary interlock connector operates from a 15 Vdc source in thepower supply and must be wired to a sensing switch using twisted-pairwire. Because the auxiliary interlock is a possible source of noise, shieldthe wire in hostile environments. This shield should be grounded to thepower supply chassis near the auxiliary interlock connector. Use any one ofthe chassis mounting screws. Do not attach the shield at any other point.

Pulse-Forming Network

The pulse-forming network (PFN) produces a critically-damped pulse whenthe SCR is fired. This pulse drives the flash lamp(s) that pump the Nd:YAGrods. The switching power supply transforms line voltage (208 Vac, nomi-nal) into dc voltage for the PFN. The PFN voltage (Vpfn) is programmable:

Vpfn = 187.5 x V

where V = 0 to 8 Vdc.

Service and Repair

10-5

A PFN voltage monitor is provided at TP24 on the Control pc board in thepower supply. The value can also be obtained by query via the computer(see Appendix A).

A resistive network is connected across the PFN capacitor as a bleeder todischarge the energy stored in the capacitor when the laser is switched off.

The lamp sync pulse generator provides a 5 ms signal to the SCR pulsegenerator, to the OUTPUT: LAMP SYNC connector on the power supply, andto the lamp-triggered signal for the PFN voltage monitor. The SCR pulsegenerator conditions the output of the lamp sync pulse generator for theSCR driver. This sends a 1 A pulse through the pulse transformer to fire theSCR.

Flash Lamp Simmer Supply

This supply provides dc voltage to the flash lamp start circuit (200 V), theMarx bank (550 V), and the flash lamp simmer current circuit. The startcircuit supplies a capacitively-coupled, high-voltage pulse through thelamp housing which breaks down the lamp. After the lamp starts, simmercurrent flows, is sensed, and the start circuit shuts off. For information onmonitoring the simmer supply via the computer, refer to Appendix A.

Shipping the Laser and Power Supply

Draining the Cooling System

1. Move the power supply into an open area.

2. Loosening the two screws on each side of the power supply, and care-fully lift off the cover.

3. Pull the small return hose from the coolant reservoir cover (Figure 10-1).

Take care not to spill any water that may still be in the hose.

4. Using the controller, set its controls as follows:

Control Setting

Power supply POWER circuit breaker Closed (On)

Power supply POWER key switch On

LAMP ON switch Off (INHIBIT lamp on)

Before shipping the laser or the power supply, completely drain thecoolant from each. The temperature in an aircraft cargo hold can freezethe coolant and can cause several components to burst. Such damage isnot covered under your warranty!

Warning!


10-6

Figure 10-1: Cooling system component identification.

5. Hold the coolant return hose over a drain or bucket, then press theENABLE button to start the cooling system pump.

6. When the system runs dry, press the STOP button to shut off the pump.

Figure 10-2: Laser head showing coolant connections on the left.

7. Decouple the inlet coolant hose from the laser head (Figure 10-2) andallow the remaining fluid to drain back down into the reservoir.

8. Use a siphon or hand pump to remove the rest of the water from thereservoir.

9. Replace the return hose back into the reservoir cover.

10. Replace the power supply cover.

This completes the procedure for draining the coolant from the system.

Reservoir

Particle Filter

Deionizing Filter

Return Hose

Level Sensor

Cooling Pump

Inlet OutletCoolant

Connector


Neutral/Ground

Connector

ControlCable

Connector

InletPurge

Connector

Q-SwitchConnector

Service and Repair

10-7

Replacement Parts

Table 10-1: Replacement Parts

Description Part Number

Maintenance

Flash lamps 0450-9080

Deionizing cartridge, cooling system 9800-0600

Particle filter, cooling system 9800-0620

Air filter assembly, Includes: desiccant filter assembly, particle (micron) filter, and oil filter.

9800-0610

Electrical

Control pc board assembly 0449-7900S

Power pc board assembly 0447-0510S

Fan controller pc board assembly 2203-0071

Simmer pc board 0447-2220

Start circuit assembly 0004-2986S

Marx bank assembly 0004-2087-2S

Contactor 4501-0361

Thyristor, dual, SCR 4802-2482

Switch, circuit breaker 5102-0640

Fuse kit with 0.25 A FB, 0.5 A FB, 0.5 A SB, 1.5 A SB, 4 A SB, switching regulator, 1 A SB, 1 A FB, 1/8 A SB, 1/16 A FB, and 30 A SB

9850-0650

Optical

Thin film polarizer 0005-0021

Output mirror contact factory

Q-switch, 10 mm 0100-4460

Q-switch, 13 mm 0447-3300

Gold pump cavity consult factory

High reflector contact factory

Nd:YAG rods consult factory

Dichroic mirror, 532 nm 0441-6070



Half-wave plate, 1064 nm 0002-0053

Half-wave plate, 532 nm 0002-0050

Quarter-wave plate, 1064 nm, Laser 0005-0140

HG WIndow 0002-0061

HG Window Quartz 0002-0061-1

Mechanical

Model BD-5 Beam Dump BD-5

Model BD-6 Beam Dump BD-6


10-8

11-1

Chapter 11 Customer Service

Customer Service

At Spectra-Physics, we take great pride in the reliability of our products.Considerable emphasis has been placed on controlled manufacturing meth-ods and quality control throughout the manufacturing process. Neverthe-less, even the finest precision instruments will need occasional service. Wefeel our instruments have excellent service records compared to competi-tive products, and we hope to demonstrate, in the long run, that we provideexcellent service to our customers in two ways: first by providing the bestequipment for the money, and second, by offering service facilities that getyour instrument repaired and back to you as soon as possible.

Spectra-Physics maintains major service centers in the United States,Europe, and Japan. Additionally, there are field service offices in majorUnited States cities. When calling for service inside the United States, dialour toll free number: 1 (800) 456-2552. To phone for service in other coun-tries, refer to the “Service Centers” listing located at the end of this section.

Order replacement parts directly from Spectra-Physics. For ordering orshipping instructions, or for assistance of any kind, contact your nearestsales office or service center. You will need your instrument model andserial numbers available when you call. Service data or shipping instruc-tions will be promptly supplied.

To order optional items or other system components, or for general salesassistance, dial 1 (800) SPL-LASER in the United States, or 1 (650) 961-2550 from anywhere else.

Warranty

This warranty supplements the warranty contained in the specific salesorder. In the event of a conflict between documents, the terms and condi-tions of the sales order shall prevail.

Unless otherwise specified, all parts and assemblies manufactured by Spectra-Physics, except optics, are unconditionally warranted to be free of defectsin workmanship and materials for a period of two years following deliveryof the equipment to the F.O.B. point. All optics are warranted for 90 days.

Liability under this warranty is limited to repairing, replacing, or givingcredit for the purchase price of any equipment that proves defective duringthe warranty period, provided prior authorization for such return has beengiven by an authorized representative of Spectra-Physics. Spectra-Physicswill provide at its expense all parts and labor and one-way return shipping


11-2

of the defective part or instrument (if required). In-warranty repaired orreplaced equipment is warranted only for the remaining unexpired portionof the original warranty period applicable to the repaired or replaced equip-ment.

This warranty does not apply to any instrument or component not manufac-tured by Spectra-Physics. When products manufactured by others areincluded in Spectra-Physics equipment, the original manufacturer's war-ranty is extended to Spectra-Physics customers. When products manufac-tured by others are used in conjunction with Spectra-Physics equipment,this warranty is extended only to the equipment manufactured by Spectra-Physics.

This warranty also does not apply to equipment or components that, uponinspection by Spectra-Physics, discloses to be defective or unworkable dueto abuse, mishandling, misuse, alteration, negligence, improper installa-tion, unauthorized modification, damage in transit, or other causes beyondthe control of Spectra-Physics.

Simple misalignment and unclean optics are the most probable causes oflow power or instrument failure and are excluded from warranty protection.A service charge will be assessed if an instrument shipped to Spectra-Physicsfor warranty repair can be returned to operating condition by routine clean-ing or adjustment.

This warranty is in lieu of all other warranties, expressed or implied, anddoes not cover incidental or consequential loss.

The above warranty is valid for units purchased and used in the UnitedStates only. Products with foreign destinations are subject to a warrantysurcharge.

Return of the Instrument for Repair

Contact your nearest Spectra-Physics field sales office, service center, orlocal distributor for shipping instructions or an on-site service appointment.You are responsible for one-way shipment of the defective part or instru-ment to Spectra-Physics.

We encourage you to use the original packing boxes to secure instrumentsduring shipment. If shipping boxes have been lost or destroyed, we recom-mend that you order new ones. Spectra-Physics can return instruments onlyin Spectra-Physics containers.

Always drain the cooling water from the laser head and power supplybefore shipping. Water expands as it freezes and will damage the laser.Even during warm spells or summer months, freezing may occur at highaltitudes or in the cargo hold of aircraft. Such damage is excluded fromwarranty coverage.

Warning!

Customer Service

11-3

Service Centers

Benelux

Telephone: (31) 40 265 99 59

France

Telephone: (33) 1-69 18 63 10

Germany and Export Countries*

Spectra-Physics GmbHGuerickeweg 7D-64291 DarmstadtTelephone: (49) 06151 708-0Fax: (49) 06151 79102

Japan (East)

Spectra-Physics KKEast Regional OfficeDaiwa-Nakameguro Building4-6-1 NakameguroMeguro-ku, Tokyo 153Telephone: (81) 3-3794-5511Fax: (81) 3-3794-5510

Japan (West)

Spectra-Physics KKWest Regional OfficeNishi-honmachi Solar Building3-1-43 Nishi-honmachiNishi-ku, Osaka 550-0005Telephone: (81) 6-4390-6770Fax: (81) 6-4390-2760e-mail: [email protected]

United Kingdom

Telephone: (44) 1442-258100

United States and Export Countries**

Spectra-Physics1330 Terra Bella AvenueMountain View, CA 94043Telephone: (800) 456-2552 (Service) or

(800) SPL-LASER (Sales) or(800) 775-5273 (Sales) or(650) 961-2550 (Operator)

Fax: (650) 964-3584e-mail: [email protected]

[email protected]: www.spectra-physics.com

*And all European and Middle Eastern countries not included on this list.**And all non-European or Middle Eastern countries not included on this list.


11-4

A-1

Appendix A Status/Error Codes

Table A-1 lists the status and error codes for the Lab-Series laser system.The codes are generated by the embedded controller in the power supply.

When Spectra-Physics GUI control software is used, these codes are dis-played in the history buffer window located at the bottom of the Info panel.When user-written software is used, these codes can be accessed via que-ries. Appendix B, “Programming Reference Guide,” at the end of this man-ual contains information on how to do this.

These codes are three-digit numbers. The fist digit relates to internal laserconditions that are useful for Spectra-Physics diagnostics and debugging,but may be ignored by the system operator. The second and third digitsindicate the actual error being reported. Thus, error codes 101, 201 and 301should all be interpreted as reporting the same error, 01, which is “interlockerror.”

Table A-1: Status/Error Codes

Status Code Description

01 Interlock error

02 Laser ID mismatch

03 Low water

04 Reserved

05 AC dropout detected

06 Unexpected loss of internal power.

07 Oscillator SIMMER failure

08 N/A

09 Reserved

10 Reserved

11 Watchdog timeout

12–98 Reserved

99 Unknown error

B-1

Appendix B Lab-Series Programming Guide

Introduction ...................................................................................................................................................... B-2 Conventions for this manual, and the Lab-Series laser ................................................................................... B-2 Section 1: General Purpose Commands ......................................................................................................... B-3

Section 1.1: Basic Commands ..................................................................................................................... B-3 HELP......................................................................................................................................................... B-3 *IDN?......................................................................................................................................................... B-3 ON............................................................................................................................................................. B-3 OFF........................................................................................................................................................... B-4 LAMPs <m> .............................................................................................................................................. B-4 LAMPs? .................................................................................................................................................... B-4 QSWitch <m>............................................................................................................................................ B-4 QSWitch <t>.............................................................................................................................................. B-4 QSWitch ADVance [value] ........................................................................................................................ B-4 QSWitch DELay [value] ............................................................................................................................ B-4 QSWitch ADVance?.................................................................................................................................. B-4 QSWitch DELay? ...................................................................................................................................... B-4 QSWitch?.................................................................................................................................................. B-4 APFN<n> .................................................................................................................................................. B-5 APFN?....................................................................................................................................................... B-5 OPFN<n>.................................................................................................................................................. B-5 OPFN? ...................................................................................................................................................... B-5 *STB?........................................................................................................................................................ B-5 *RST?........................................................................................................................................................ B-5 SHOTs? .................................................................................................................................................... B-6

Section 1.2: Communications Setup ............................................................................................................ B-6 ECHo <n> ................................................................................................................................................. B-6 ECHo?....................................................................................................................................................... B-6 WATChdog <n> ....................................................................................................................................... B-7 BAUD<n>.................................................................................................................................................. B-7

Section 1.3: Diagnostics ............................................................................................................................... B-7 READ:OPFN? ........................................................................................................................................... B-7 READ:APFN? ........................................................................................................................................... B-7 READ:OMON?.......................................................................................................................................... B-8 READ:AMON? .......................................................................................................................................... B-8 READ: QSWADV?.................................................................................................................................... B-8 READ: QSWDEL? .................................................................................................................................... B-8 READ: SHOTs? ........................................................................................................................................ B-8 READ: VARiable? ..................................................................................................................................... B-8

Section 2: Status/Error Reporting Commands................................................................................................. B-9 Section 2.1: Status Registers ....................................................................................................................... B-9

*STB?........................................................................................................................................................ B-9 STATus:QUEStionable? .........................................................................................................................B-10 *CLS........................................................................................................................................................B-11 READ:HISTory?......................................................................................................................................B-11

Section 2.2: ‘C’ Language Example – Using the Status Byte to check for Interlocks ................................B-11


B-2

Introduction The command language for the Quanta-Ray laser system is based on the SCPI (Standard Commands for Programmable Instruments) protocol. The specification for that language can be found at www.SCPIConsortium.org. The Quanta-Ray laser is not 100% compliant with the standard, but does use it as a guide. Conventions for this manual, and the Lab-Series laser

indicates a line of text sent to the laser indicates the laser’s response

<n> indicates an integer parameter <f> indicates a floating-point parameter <CR> is the ASCII Carriage Return character (hex 0x0D) <LF> is the ASCII Line Feed character (hex 0x0A) <SP> is the Space character Commands to the laser may be terminated with <CR>, <LF>, or both. Responses from the laser are normally terminated with <LF> can be modified (refer to ECHO Command). Every command has both a “short” and “long” form. This document uses a special notation to differentiate the short form command from the long form of the same command. The long form of the command is shown, with the short form portion shown in uppercase characters, and the rest of the keyword is shown in lowercase characters. However, commands sent to the laser are not case sensitive. Consider the listing for the command to set lamp trigger mode. The laser would consider any of these commands to be equivalent: lamp fix (all lower case, all short form) lamps fixed (all lower case, all long form) LAMP fixed (part upper case short form, part lower case long form) LaMpS fIX (mixture of upper & lower case, short & long form) However,

LAMPs FIXE? would be invalid ---- “FIXE” doesn’t match either the short form “fix” or the long form (“fixed”) subcommand. Most commands take parameters, separated by a space. The READ and STATus commands take subcommands separated by a colon. Queries return a value and “units.” The units can be used to verify that the laser’s answers are synchronized with your control computer’s questions. Units may consist of a traditional unit. For example, “QSWitch DELay?” returns a string such as “191.075 171.1 231.1 µs ”. “191.075 µs” is the value that Q-switch delay is set for and “171.1 231.1 µs ” are the minimum and maximum value of Q-switch delay respectively.

Lab-Series Programming Guide

B-3

Section 1: General Purpose Commands General-purpose commands include all commands except those specifically relating to detecting errors. Examples of commonly used commands are turning the laser on and off, changing lamp trigger source, or changing Q-switch trigger mode. Section 1.1: Basic Commands HELP

Help command returns the available command.

HELP SETUP commands: ECHo HELP OPERATIONAL commands: *CLS *ESR *IDN *RST *STB APFN BAUD BLOK DLOK LAMPs OFF ON OPFN QSWitch READ SHOTs STATus WATChdog

*IDN?

This command returns the product identification string as defined by the SCPI standard. The response to the IDN command contains four fields (manufacturer, model, serial number, and firmware version) separated by commas. A typical response from the laser would be Spectra Physics,QUANTA-RAY-LAB170-10,2404l,0452-0023A/0456-6600A (company name) (product id) (Serial No) (GCR firmware) / (FPGA firmware)

Examples:

*IDN? <CR> Spectra Physics,QUANTA-RAY-LAB170-10, 2404l,0452-0023A/0456-6600A <LF>

ON

This command is used to turn on the laser. The normal sequence is:

1 Close the contactor. 2 Wait 15 seconds. 3 Simmer the lamps and begin firing. 4 Ramp up the PFN power supplies to the last commanded value.

The *STB? command can be used to monitor the turn-on sequence. Example:

ON <CR> turn on the system


B-4

OFF

This command is used to turn off the laser. The normal sequence is:

1 Turn off the PFN and simmer power supplies. 2 Turn off the water pump 20 seconds after the last lamp trigger.

The *STB? command can be used to monitor the turn off sequence. Example:

OFF <CR> turn off the system LAMPs <m> LAMPs?

Mode<m>=EXTernal, FIXed, VARiable, INHibit This command is used to select or identify the lamp trigger source. It is also used to set the variable trigger rate. Example:

LAMP FIX <CR> Lamp trigger is set to Fixed. LAMP EXT <CR> Lamp trigger is set to External Source. LAMP VAR <CR> Lamp trigger is set to Variable. LAMP VAR 8.2 <CR> Variable Rate is set to 8.2 pulses per second. LAMP VAR? <CR> To what value is the lamp Variable Rate trigger set? 10.0 VAR <CR> Lamp trigger is set to Variable and repetition rate is 8.2 pulses per sec. LAMP INH <CR> Lamp trigger(s) are Inhibited. LAMP? <CR> Identify lamp trigger. INHibit <LF> Indicates the lamp is Inhibited.

QSWitch <m> QSWitch <t> QSWitch ADVance [value] QSWitch DELay [value] QSWitch ADVance? QSWitch DELay? QSWitch?

Modes<m> = EXTernal, LONGpulse, NORMal Types<t> = FIRe, REPetitive, SINGleshot This command controls the Q-Switch modes, type and timing. The modes are: External, Long Pulse and Normal. The types are: Fire, Repetitive and Single-Shot Example:

QSW LONG <CR> Sets the Q-switch to its Long Pulse mode. QSW SING <CR> Sets the Q-switch to Single-Shot type. QSW FIRe <CR> Fires the Q-switch once. QSW? <CR> What is the Q-switch setting?


B-5

LONGpulse SINGleshot <LF> Indicates the Q-switch is set to Long Pulse mode and Single-Shot type.

Reminder: QSWitch DELay and ADVance are only meaningful in NORMal mode.

QSW ADV 250 <CR> Sets the Q-switch Advance Sync to 250.00. QSW ADV? <CR> To what value is Q-switch Advance Sync set? 250.00 –700.0 500.0 ns Indicates the Q-switch Advance Sync is 250.0, the min value is

–700.0 ns and the max value is 500.0 ns. QSW DEL? <CR> To what value is Q-switch Delay set? 210.00 120.0 250.0 µs Indicates the Q-switch Delay is set to 210.0 µs, the min value

is – 120.0 µs and the max value is 250.0 µs. APFN<n> APFN?

Range: n = 0 – 100% The APFN command sets the Amplifier PFN voltage as a percentage of factory full scale. Example:

APFN 100 <CR> Sets the APFN voltage to 100.0%. APFN? <CR> To what value is APFN set? 100.0 % <LF> Indicates APFN is set to 100.0%.

OPFN<n> OPFN?

Range: n = 0-100% The OPFN command sets the Oscillator PFN voltage as a percentage of factory full scale. Example:

OPFN 100 <CR> Sets the OPFN voltage to 100.0%. OPFN? <CR> To what value is OPFN set? 100.0 % <LF> Indicates OPFN is set to 100.0%.

*STB?

The status byte is the central component of the SCPI status system. Properly interpreting this byte allows the operator to determine the overall operating condition of the laser system. See “Section 2: Status/Error Reporting” for information on interpreting the status byte and other status registers. *RST?

This command resets the laser head pc board.


B-6

SHOTs? This command returns the number of shots on the lamps, or resets the counter when the lamp is replaced. Note: this command returns the actual number of shots while the mechanical counter on the front panel reports shots rounded to the nearest 100. Example:

SHOT? <CR> How many shots are on the lamps? 1134 <LF> 1134 (the mechanical counter on the power supply would report 1100) SHOT 0 <CR> resets the lamp shots counter to zero

Section 1.2: Communications Setup ECHo <n> ECHo? This command modifies the way the control computer interacts with the laser. The <n> parameter is an integer that specifies a bit pattern. The bits are defined as follows: Bit Description 0 show prompts 1 the laser echoes characters as they are received 2 shows error messages 3 output at least a line feed for every command (even ones that do not normally

generate a response) 4 terminate responses with <CR><LF>, rather than just <LF> 5 use XON/XOFF handshaking for data sent to the laser

(No handshaking is used for data sent from the laser) The previous Echo mode is replaced at power up and is unaffected by the *RST command. When Echo is set to zero, the laser will not issue a response unless a command requires it, and the response will be terminated with a <LF> character. Examples:

ECH? <CR> What is the current Echo mode? 0 <LF> The system responds: ECHO 0. ECH 1 <CR> Set to Echo 1 mode. !Ready <LF> Laser prompts that it is ready. ECH 17 <CR> Request both prompt and <CR><LF> termination. !Ready <CR><LF> Laser prompts that it is ready. ECH 21 <CR> Request prompt and error messages. !Ready <CR><LF> Laser prompts that it is ready. LMP FIX Send an illegal command (should be LAMPs FIXed). What? <LF> Laser prompts that it does not understand the command. !Ready <LF> Laser prompts that it is ready. ECH 8 <CR> Request <LF> for all commands, no prompts or warnings. <LF> The <LF> verifies that a command was received


B-7

WATChdog <n>

Range: 0 to 110 seconds. This is the RS-232 laser/control computer communication watchdog timer. If the laser does not receive communications from the control computer within the specified time, it turns itself off. The default value is zero (disabled). This command allows users to set their own comfort level for a safety check on their control computer. Values from 3 to 10 seconds are typical. Example:

WATC 5.1 <CR> BAUD<n>

Values for n = 2400, 4800, 9600, 19200, 38400 This command sets the communications speed between the laser embedded computer and the user’s control computer. At power-up, the laser always communicates at 9600 baud. The baud rate is not affected by the *RST command. Example:

BAUD 38400 Section 1.3: Diagnostics The READ commands are used to learn what the laser is actually doing, as opposed to what it has been asked to do. A few reasons the READ commands can return something different than what was commanded by a control computer are: 1 The control computer is not actually in control. A remote panel or an external BeamLok

controller is in control. 2 The system may be in a turn-on or turn-off sequence. For example: when the system is turned

off, it is normal for APFN? to indicate a commanded value of 100%, and READ:APFN to report an actual value of 0%.

3 Under certain conditions the system will automatically decrease the PFN voltages to 90% of the nominal settings in order to prevent optical damage. A typical example is when the Q-Switch is set to Single-Shot type.

READ:OPFN? READ:APFN? These queries return the oscillator or amplifier PFN command setting in percent (i.e., what the PFN power supply is being asked to do). Example:

READ: APFN? <CR> 0.0 % <LF>


B-8

READ:OMON? READ:AMON?

These queries return the oscillator or amplifier PFN monitor in percent (i.e., what the PFN power supply is actually doing). Example:

READ: AMON? <CR> 0.0% <LF>

READ: QSWADV?

This query returns the current Q-Switch Advanced Sync setting. Example:

READ:QSWADV? <CR> –200.0 ns <LF>

READ: QSWDEL?

This query returns the Q-Switch delay setting. Example:

READ:QSWDEL? <CR> 210.0 µs

READ: SHOTs?

This query returns the number of shots. Example:

READ:SHOT? <CR> 429 <LF>

READ: VARiable?

This query returns the lamp trigger rate, unless the lamp trigger source is external. Example:

READ:VAR? <CR> 10.1 VAR <LF>


B-9

Section 2: Status/Error Reporting Commands One of the most powerful (and therefore complex) parts of the SCPI protocol is its error reporting facility. Status is reported in a tree-like structure where the root of the tree is the status byte. Users should regularly check this byte for information about basic conditions such as laser emission, water pump on, and interlock status. It also discloses any “questionable” conditions that might exist. “Questionable” conditions are those that might raise doubts about laser system performance (such as a power supply that cannot properly charge the high voltage capacitor). If “questionable” conditions are reported, then further information can be requested. Section 2.1: Status Registers *STB?

This query returns the status byte, which is the top level of the SCPI information data structure. The value returned is an integer representing a 32-bit value, which, when properly interpreted, discloses the condition of the laser. A programming example of how to use this status byte to access the SCPI data structure is included at the end of this appendix.

Bit Number

Description

0 Laser emission can occur 1 (reserved) 2 Data is in the error log, use READ:HIST? 3 Check STAT:QUES bits 4 (reserved) 5 Check *ESR bits 6 (reserved) 7 Check STS:OPER bits 8 Main contactor is energized 9 Oscillator simmer is on 10 Amplifier simmer is on 11 Oscillator PFN is at target 12 The laser has recently fired 13 15 Vdc power supply failure 14 Laser cover interlock open 15 One or more of the following interlocks is open: CDRH plug, power supply cover,

laser head cover, laser head temperature, water pressure, water flow 16 Remote panel disconnected 17 Internal 208 Vac failure 18 CDRH enable failure 19 Laser ID fault 20 Low water fault


B-10

21 Interlock fault 22 A remote panel is connected 23 the remote panel indicates that the computer is in control. 24 The main contactor should be on

25-31 (reserved) To properly interpret the power supply interlock state, first consider bits 13 through 21. The laser has three interlock priorities: bits 19, 20, and 21, with bit 19 being the most important. Bits 13 through 18 do not contain useful information unless bit 21 is true (high). If bit 23 is low, the remote panel is in control, and commands that attempt to set a value (such as LAMPs or QSWitch) have no effect on the laser. Any command that asks for information (such as READ:SHOTs?) operate as expected. The ON and OFF commands will operate as expected, even if the remote panel is in control. Example:

*STB? <CR> Send status byte. 139 <LF> The requested status byte states that the laser has emission, the shutter is open

and something is questionable about the laser. Use the STATus:QUES com-mand to determine which conditions have set the questionable bit.

STATus:QUEStionable?

This query returns the questionable condition register. It is an extension of the basic status byte, and it can give more information about subsystems within the laser. Bit 3 of the status byte (*STB?) is a logical-OR of bits 9, 10, and 11. If Bit 3 of the status byte is false (low), there is no need to check the STATus:QUEStionable register for additional information. Bits 0 through 8 and 12 through 15 are undefined and are reserved for future use. Bit 9 is set if the oscillator high-voltage (HV) power subsystem does something unexpected. If bit 9 is true (high), then bits 16 through 23 should be examined to identify the fault. If Bit 9 is false, bits 16 through 23 should be ignored. Bit 10 is set high if the amplifier high-voltage (HV) power subsystem does something unexpected. If bit 10 is true, bits 24 through 31 should be examined to identify the fault. If bit 9 is false, bits 24 through 31 should be ignored. Bit 11 is set when an EXTernal LAMPs trigger has occurred at a rate that is outside the specified MIN and MAX limits.

Bit number

Description

0 – 8 (reserved) 09 Oscillator HV failure 10 Amplifier HV failure 11 External Trigger Rate out of range


B-11

12 De-ionized water low 16 OSC HVPS # 1 EndOfCharge 17 OVerLoad 18 OVerTemp 19 OVerVolt 20 OSC HVPS # 2 EndOfCharge 21 OVerLoad 22 OVerTemp 23 OVerVolt 24 AMP HVPS # 1 EndOfCharge 25 OVerLoad 26 OVerTemp 27 OVerVolt 28 AMP HVPS # 2 EndOfCharge 29 OVerLoad 30 OVerTemp 31 OVerVolt

Example:

STAT:QUES? <CR> What is the status of the system? 512 <LF> The system reports that the oscillator high-voltage is not ok.

*CLS

This command clears the status byte and status questionable register. Use it to make sure there is no “left over” information in these registers from a previous error. The history buffer (READ:HISTory) is not affected by *CLS, even though bit 2 of the status byte remains zero until a new error occurs. READ:HISTory?

This query returns up to 16 status/error codes from the system history buffer. If the laser has shut itself off or the system is behaving erratically, investigate the answer to this query. The first element in this history buffer is the most recent. A complete listing of the laser history buffer error codes is included in Appendix A. This query returns at lest two lines of information, each of which consists of two numbers. The first number in the first line is the number of items in the buffer. The second number in first line is the number of seconds since power up. The final line is always “0 0”. Intermediate lines contain the error code followed by the system time when the error occurred. Example:

READ:HIST? <CR> Request for history buffer 1 827 <LF> 1 error has occurred, current time is 827 sec 301 810 <LF> Error code 301 occurred at 810 sec 0 0 <LF> End of history buffer

Section 2.2: ‘C’ Language Example – Using the Status Byte to check for Interlocks


B-12

#defineSTB_LASER_ID BIT_19 #defineSTB_LO_WATR BIT_20 #defineSTB_ILK_NOK BIT_21 #defineSTB_INTERLOCK1 BIT_13 #defineSTB_INTERLOCK2 BIT_14 #defineSTB_INTERLOCK3 BIT_15 #defineSTB_INTERLOCK4 BIT_16 #defineSTB_INTERLOCK5 BIT_17 #defineSTB_INTERLOCK6 BIT_18 int StbTimer ( void) long stb; static char buff[255]; sprintf(buff, "*STB?\n\r"); WriteBuf_CurSerialPort(buff, strlen(buff));//This function writs the buffer to serial port ReciveBuf_CurSerialPor( );//This function receives the responds from laser and saves it in InputBuffer stb=atoi( InputBuffer); if(stb ^ Last_Stb) // Last_Stb is global variable and initially is sets to zero CheckStatus(stb); void CheckStatus(long stb) Last_Stb = stb; if(stb&STB_LASER_ID || stb&STB_LO_WATR || stb&STB_ILK_NOK ) if(stb&STB_LASER_ID )

sprintf (ErrorMessage, " LASER ID FAULT. \n\n" " Unable to run the laser,\n"); DisplayPanel(ErrorMessage); //This function displays the error message. if (stb&STB_LO_WATR)

sprintf (ErrorMessage, " LOW WATER INTERLOCK DETECTED. \n\n" " Unable to run the laser,\n" " Please fill up the reservoir \n" " Then Press OK"); DisplayPanel(ErrorMessage); //This function displays the error message.

if(stb&STB_ILK_NOK) if(stb & STB_INTERLOCK1 ) sprintf (ErrorMessage, " 15 VOLTS P.S INTERLOCK DETECTED. \n" " Unable to run the laser.\n\n\n\n");


B-13

DisplayPanel(ErrorMessage); //This function displays the error message. else if(stb & STB_INTERLOCK2)

sprintf (ErrorMessage, "P.S. COVER INTERLOCK DETECTED. \n\n" " Unable to run the laser,\n\n\n\n"); DisplayPanel(ErrorMessage); else if(stb & STB_INTERLOCK3)

sprintf (ErrorMessage, " ONE OR MORE OF THE FOLLOWING PROBLEMS HAS BEEN DETECTED. \n\n"

" 1-Water Flow \n" " 2-CDRH \n" " 3-Power Supply Cover Interlock \n" " 4-Head Cover \n" " 5-Head Thermistor \n" " 6-External Water Pressure \n\n" " Unable to run the laser."); DisplayPanel(ErrorMessage); else if(stb & STB_INTERLOCK4)

sprintf (ErrorMessage, " REMOTE CONTROL INTERLOCK DETECTED. \n"

" Unable to run the laser,\n\n\n\n"); DisplayPanel(ErrorMessage); else if(stb & STB_INTERLOCK5)

sprintf (ErrorMessage, " INTERNAL 208 AC POWER INTERLOCK DETECTED. \n"

" Unable to run the laser,\n\n\n\n"); DisplayPanel(ErrorMessage); else if(stb & STB_INTERLOCK6)

sprintf (ErrorMessage, "CDRH TRNSISTOR INTERLOCK DETECTED. \n\n"

" Unable to run the laser,\n\n\n\n"); DisplayPanel(ErrorMessage);


B-14

Notes-1

Notes


Notes-2

Notes

Notes-3


Notes-4

Notes

Notes-5


Notes-6

Report Form for Problems and Solutions

We have provided this form to encourage you to tell us about any difficul-ties you have experienced in using your Spectra-Physics instrument or itsmanual—problems that did not require a formal call or letter to our servicedepartment, but that you feel should be remedied. We are always interestedin improving our products and manuals, and we appreciate all suggestions.

Thank you.

From:

Name

Company or Institution

Department

Address

Instrument Model Number Serial Number

Problem:

Suggested Solution(s):

Mail To: FAX to:

Spectra-Physics, Inc. Attention: SSL Quality ManagerSSL Quality Manager (650) 961-71011330 Terra Bella Avenue, M/S 15-50Post Office Box 7013Mountain View, CA 94039-7013U.S.A.

E-mail: [email protected]

pulsed nd:yag lasers user’s manual -...

Documents