building a spectral irradiance scale - the basis for the ......corm 2008 #1 building a spectral...

CORM 2008 #1

Building a Spectral Irradiance Scale

- the basis for the measurement of light

Arnold A. Gaertner

Institute for National Measurement Standards

National Research Council Canada

Ottawa, Ontario, Canada

CORM 2008

Rensselaer Polytechnic Institute

Troy, New York, USA

2008-June-10

CORM 2008 #2

Outline

1. Basic light measurement

• spectral irradiance

2. Calibration Chains

• light sources

• basic NMI techniques

3. NRC-INMS Spectral Irradiance

• present scale

• comparison results

• planned scale

CORM 2008 #3

Photometry

- how much?

- absolute measurement of a quantity (Q) of light

Colorimetry

- what colour?

Basic Light Measurement:

Q Km S( ) V ( ) d

X Km S( ) x ( ) d

Y Km S( ) y ( ) d

Z Km S( ) z ( ) d

x_

z_

y_

V,defined

S( ) = measured output of light source

CORM 2008 #4

Photometric and Colorimetric detectors are not easy to make

Basic Light Measurement: filtered detectors

V( )

detector R( )ST ( ) V ( ) d

ST ( ) R( ) d

SS ( ) R( ) d

SS ( ) V ( ) d

Spectral Correction Factor

ST( ) and SS( ) need to be measured

CORM 2008 #5

Basic Light Measurement: S( )

ib

ig

ir

ib

ig

ir

CORM 2008 #6

ibig

ir

Basic Light Measurement: S( )

measured

expected

Require a known S( ) source

- absolute spectral measurements

- relative spectral measurements

ib

ig

ir

CORM 2008 #7

Basic Light Measurement: known S( ) source

• reproducible

• stable during operation

• uniform spatial output

• sensitivity to alignment

• inverse square law behaviour

• uniform (‘smooth’) spectral output

• sensitivity to electrical operating parameters (current, voltage)

• robust

• sensitivity to handling

• small aging effect

• safety

• high internal pressure ?

• kilowatts of UV ?

• ease of use

• simple to operate

CORM 2008 #8


vacuum lamps

gas-filled lamps

tungsten-halogen lamps

high-temperature black-bodies

(HTBB)

CORM 2008 #9


- geometrical quantity- what part of (flux from) the light from the lamp is to be measured?

- total flux

- intensity

- radiance

- irradiance

CORM 2008 #10


- total flux

CORM 2008 #11


- intensity

Iflux

solidangle

CORM 2008 #12


- radiance

LAp

CORM 2008 #13


- irradiance

EA

flux

receiverarea

distance

orientation

unit watt m 2

CORM 2008 #14


EA

unit watt m 2

d

d

dE E dE

EdE

dunit watt m 2 m 1

watt cm 2 nm 1

irradiance spectral irradiance

CORM 2008 #15

Calibration Chain: measurement of unknown lamp

Estandard

Eunknown

istandard

iunknown

E unknown

E standard

iunknown

istandard

E unknown E standard

istandardiunknown

calibration factor

CORM 2008 #16

Calibration Chain: one link

Standard Lamp

Unknown Lamp

transfer instrument

CORM 2008 #17

Calibration Chain: links to ‘Standard Lamp’

Standard Lamp

Unknown Lamp

transfer instrument

National Measurement Institute (NMI)

NMIs provide the ‘top’ of the calibration chain

CORM 2008 #18

Calibration Chain: links to ‘Standard Lamp’

Possible methods of calibrating the ‘Standard Lamp’

Standard Lamp

Unknown Lamp

Absolute Radiometer

Calibrated Detector

(filter radiometer)

detector based

Primary Standard Source

Standard Lamp

Unknown Lamp

source based

CORM 2008 #19

Calibration Chain: detector based - direct

Standard Lamp

Unknown Lamp

Absolute Radiometer

Calibrated Detector

(filter radiometer)

detector based

i

filter radiometer

narrow wavelength band

CORM 2008 #20

Calibration Chain: detector based - direct

Standard Lamp

Unknown Lamp

Absolute Radiometer

Calibrated Detector

(filter radiometer)

detector based

To calibrate over an extended spectral range many filter radiometers are required

extrapolation is not valid

interpolation formula

least-squares fit to data

CORM 2008 #21

Calibration Chain: source based


Standard Lamp

Unknown Lamp

source based

Synchrotron Source

e-

Black-Body Source

T

Output can be calculated from first principles

CORM 2008 #22

Calibration Chain: source based - HTBB


Standard Lamp

Unknown Lamp

source based

L ,Tc1

5 expc2

T1

T=?

Planck equation

High Temperature Black Body Source

T L( ,T)

CORM 2008 #23

Calibration Chain: detector and source based


Standard Lamp

Unknown Lamp

Lm m,Tc1

m

5 expc2

mT1

m measured value

T

Lm

msource based

Absolute Radiometer

Calibrated Detector

(filter radiometer)

detector based

and

Measure the BB output at one wavelength

HTBB

T Lm ( m,T)i

filter radiometer

CORM 2008 #24

Calibration Chain: present NRC scale

FEL

1000W

incandescent

quartz-halogen

1975 19901987

1985

CORM 2008 #25

International Comparisons (CCPR)

FEL

1000W

incandescent

quartz-halogen

(2000-2004)

CCPR = Consultative Committee for Photometry and Radiometry

CORM 2008 #26


FEL

1000W

incandescent

quartz-halogen

CORM 2008 #27


FEL

1000W

incandescent

quartz-halogen

CORM 2008 #28

Calibration Chain: next NRC spectral irradiance scale

transfer lamps(incandescent)

working standard lamps(incandescent)

client lamps(incandescent)

Cryogenic Radiometer

Transfer Radiometer

High-Temperature

Black-Body

Filter Radiometer

absolute detector

transfer detector

calibrated source (irradiance mode)

(incandescent)

temperature measuring detector

Detectorand

Sourcebased

CORM 2008 #29

Calibration Chain: measurement of HTBB temperature

HTBB

T Lm ( m,T)i

filter radiometer

5 filter radiometers

- all should give same T

HTBB output

CORM 2008 #30


CORM 2008 #31


HTBB

T Lm ( m,T)i

filter radiometer

Initial Measurements

- 5 filter radiometers

- linear pyrometer (LP3)

- Thermometry Group

CORM 2008 #32

Calibration Chain: present/next NRC scale comparison

CORM 2008 #33

Calibration Chain: next NRC spectral irradiance scale

transfer lamps(incandescent)

working standard lamps(incandescent)

client lamps(incandescent)


Transfer Radiometer

High-Temperature

Black-Body

Filter Radiometer

absolute detector

transfer detector

calibrated source (irradiance mode)

(incandescent)

temperature measuring detector

Detectorand

Sourcebased

transfer facility

CORM 2008 #34

Calibration Chain: transfer facility (under construction)

Transfer standard lamps

(incandescent)

High-Temperature

Black-Body

Filter Radiometer

high temperature

blackbodytransfer standard lamps

spectroradiometerfilter radiometers

CORM 2008 #35


high temperature




(incandescent)

High-Temperature

Black-Body

Filter Radiometer

transfer instrument

CORM 2008 #36


high temperature




(incandescent)

High-Temperature

Black-Body

Filter Radiometer

transfer instrument

CORM 2008 #37


1. Basic light measurement

• why spectral irradiance

2. Calibration Chains

• light sources

• basic NMI techniques

3. NRC-INMS Spectral Irradiance

• present scale

• comparison results

• planned scale

transfer lamps

(incandescent)

working standard lamps

(incandescent)

client lamps

(incandescent)


Transfer Radiometer

High-Temperature

Black-Body

Filter Radiometer

Summary

CORM 2008 #38


C. Bamber

L.P. Boivin

F. Gauthier

R. Gerson

D.J. Woods

J.R. Pekelsky

J.C. Zwinkels

transfer lamps

(incandescent)

working standard lamps

(incandescent)

client lamps

(incandescent)


Transfer Radiometer

High-Temperature

Black-Body

Filter Radiometer

Acknowlegments

building a spectral irradiance scale - the basis for the ......corm 2008 #1 building a spectral...

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