the design improvement of tmt laser guide star facility
DESCRIPTION
The Design Improvement of TMT Laser Guide Star Facility. Kai Wei Institute of Optics and Electronics (IOE),CAS. International Colloquium on Thirty-Meter Telescope Beijing, May 25 2011. Presentation Outline. Simple Description of the LGSF main Requirement - PowerPoint PPT PresentationTRANSCRIPT
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The Design Improvement of TMT Laser Guide Star Facility
Kai WeiInstitute of Optics and Electronics (IOE),CAS
International Colloquium on Thirty-Meter TelescopeBeijing, May 25 2011
2011 May 25
2
Simple Description of the LGSF main Requirement Why we need update the LGSF conception design? The updated LGSF conception design
– Optical design– Mechanical design– Electronics and Control
Management Plan
Presentation Outline
2011 May 25
3
TMT.LGSF main Requirement
The LGSF is composed of 3 main sub-systems: – The Laser System (LAS), which includes the lasers, the Laser
Service Enclosure (LSE) and all associated electronics (TIPC);– The Beam Transfer Optics (BTO) and LGSF Top End:
– The Beam Transfer Optical (BTO) ;– Diagnostic Optical Bench system (DOB);– Asterism Generation system (AG);– Laser Launch Telescope (LLT);– Acquisition Telescope (AT);
– The Laser Safety System (LSS), which will copy the Gemini’s LSS;
2011 May 25
4
TMT.LGSF main Requirement
The LGSF is composed of 3 main sub-systems: – The Laser System (LAS), which includes the lasers, the Laser
Service Enclosure (LSE) and all associated electronics(TIPC);– The Beam Transfer Optics (BTO) and LGSF Top End:
– The Beam Transfer Optical (BTO) ;– Diagnostic Optical Bench system (DOB);– Asterism Generation system(AG);– Laser Launch Telescope (LLT);– Acquisition Telescope (AT);
– The Laser Safety System (LSS), which will copy the Gemini’s LSS;
2011 May 25
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TMT.LGSF main Requirement
2011 May 25
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TMT.LGSF main Requirement
Main System Functions– Project the early light NFIRAOS asterism– Project other asterisms as required by the AO modes – Switch rapidly between the four asterisms– Use conventional optics for the Beam Transfer Optics and launch
the AO asterisms from a Laser Launch Telescope located behind the TMT secondary mirror
2011 May 25
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Asterism generation requirement– NFIRAOS asterism: consists of 6 LGS, 5
equally spaced on a circle of radius of 35 arcsec and one additional on-axis guide star. (black)
– MIRAO asterism: consists of 3 LGS equally spaced on a circle of radius of 70 arcsec. (red)
– MOAO asterism: consists of 8 LGS, 3 equally spaced on a circle of radius of 70 arcsec and 5 equally spaced on a circle of radius of 150 arcsec. (blue)
– GLAO asterism: consists of 5 LGS, 4 equally spaced on a circle of radius of 510 arcsec and one additional on-axis guide star. (green)
switch between asterisms within 2 minutes
TMT.LGSF main Requirement
2011 May 25
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Why we need update the LGSF conception design
~50m Beam Transfer Optics Optical Path with 110 total actuators.
2006: LGSF Conceptual Design with Launch Telescope behind M2 and Laser System attached to Elevation Journal 2008: LGSF Update Work
– Redesign of LGSF Top End to compensate for telescope top end flexure
– Relocation of Laser System to azimuth structure to allow the lasers to operate in fixed gravity orientation
2010: Intensive trade study to compare center launch versus side launch
– Center Launch confirmed– Relocation of Laser System to Elevation
Journal due to progress toward smaller, lighter and more robust 20 to 25W lasers with a design compatible with a changing gravity orientation
Our work begins at 2010.11 based on NOAO’s Conceptual Design
2011 May 25
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LGSF Top End Issues
LGSF Top End:– 0.4m telescope instead of 0.5m– repackage the sub-system at the Top End structure– Launch Telescope field of view trade study(increase the FOV from 5’ to 17’)– No optical path to observe with natural guide stars for calibrations– Wind jitter goal < 27.5m(Old 2008 LGSF structure design ~ 27.82m)– New Acquisition System: independent LGS acquisition system with small telescope
2800
0
2359
3 2592
6
2011 May 25
1010
Several issues with the old path:Interference with the (-X, -Y) edge of the -X Nasmyth platform for elevation angles > 80 deg
Requires a notch in the Nasmyth platform
Interference between EJFA2 and (-X, +Y) part of the –X Nasmyth platform for elevation angles < -3 deg
Requires another notch in the Nasmyth platform
Tight clearance between Elevation Journal and Nasmyth platform edge of 350mm.
Beam Transfer Optics Path Issues
2011 May 25
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The updated LGSF conception design
2008 LGSF Design 2011 LGSF Design2011 May 25
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The updated LGSF conception design
2008 LGSF Design 2011 LGSF Design2011 May 25
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The updated LGSF conception design
2008 LGSF Top end Design
Flexure Compensation
SystemLLT
Side View Flexure Compensation
SystemTop View
2011 LGSF Top end Design
Side View
2011 May 25
Top View
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LLT Optical Redesign (1/3)
Reduce the Diameter from 500mm to 400mmChange the Angular Magnification from 60 to 48Change the Primary Mirror from hyperboloid to paraboloidRemove the two Aspheric surfaces in the systemReduce the Distance between the M1 and M2 for about 50mmShift the pupil position nearly about 100mm
Side View Side View
2011 May 25
15
LLT Optical Redesign (2/3)
Radius of field angle (arc-sec)
90Km 210Km
WFE Sr WFE Sr
0 0.017 0.990 0.005 0.999
35 (+y direction)
0.017 0.989 0.007 0.998
35 (-y direction) 0.017 0.989 0.007 0.998
35 (+x direction)
0.017 0.989 0.007 0.998
35 (-x direction) 0.017 0.989 0.007 0.998
70 (+y direction)
0.018 0.987 0.011 0.996
70 (-y direction) 0.018 0.987 0.010 0.996
70 (+x direction)
0.018 0.987 0.010 0.996
70 (-x direction) 0.018 0.987 0.010 0.996
Radius of field angle (arc-sec)
90Km 210Km
WFE Sr WFE Sr
150 (+y direction)
0.021 0.982 0.019 0.985
150 (-y direction) 0.021 0.982 0.018 0.988
150 (+x direction)
0.021 0.982 0.019 0.986
150 (-x direction) 0.021 0.982 0.019 0.986
510 (+y direction)
0.039 0.942 0.045 0.923
510 (-y direction) 0.011 0.995 0.014 0.992
510 (+x direction)
0.028 0.969 0.033 0.958
510 (-x direction) 0.028 0.969 0.033 0.958
Image quality of the new LLT
2011 May 25
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LLT Optical Redesign (3/3)NOAO Design(2008)
M1/M2 Hyperboloid
M1 Paraboloid
M2 Hyperboloid
M1 Paraboloid
M2 Paraboloid
M1 Hyperboloid Paraboloid Paraboloid
M2 Hyperboloid Hyperboloid Paraboloid
Exit Pupil Diameter 500 400 400
Angular Magnification 60 48 48
Fields Φ17′ Φ17′ Φ17′Image wavelength Both 550nm&589nm 589nm 589nm
Elements quantities — — Add one lens near the collimator
Aspheric Surface 2 None None
Image Quality
(Gauss Beam
Sr@589nm)
0 arc-second Near 0.97 0.9883 0.9888
35 arc-seconds Near 0.97 0.9881 0.9758
70 arc-seconds Near 0.97 0.9875 0.9643
150 arc-seconds Near 0.97 0.9846 0.9651
510 arc-seconds 0.86 0.9558 0.5359
M1 parameters
Radius No Data 1677.19 1708.40
Conic coefficient No Data -1 -1
Off axis decenter No Data 420 420
Aperture No Data 450 460
M2 parameters
Radius No Data 213.91 155
Conic coefficient No Data -1.269 -1
Off axis decenter No Data 50.4 38.1
Aperture No Data 56(±3.2mm more) 43(±3.2mm more)
Fabrication Tolerance
for M1
Radius No Data ±10mm(AM-47.7~48.3 ) ±10mm(AM-47.7~48.3 )
Conic coefficient No Data ±0.0002(PV error 0.0068) ±0.0002(PV error 0.0083)*
Fabrication Tolerance
for M2
Radius No Data ±1.6mm(AM-47.7~48.3 ) ±1.6mm(AM-47.6~48.2)
Conic coefficient No Data ±0.004(PV error 0.0015) ±0.002(PV error 0.0093)
Focus adjustments(90Km to 210Km) No Data Collimator move 0.983mm Collimator move 0.109mm
On axis image quality (Without focus adjustment) No Data 0.9883—0.9244 0.9888—0.8339
On axis image quality (Witt focus adjustment) No Data 0.9883—0.9991 0.9888—0.9889
Entrance Pupil Position(Distance from K-Mirror) No Data 345mm 368mm
2011 May 25
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Beam Transfer Optical Redesign (1/2)
Old BTO Design New BTO Design
Laser System
LGSF TOP End
Laser System
LGSF TOP End
Move one mirror from the Nasmyth Platform to the LGSF Top End structure
2011 May 25
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Beam Transfer Optical Redesign (2/2)
Input beam shape Output Beam shape
Three relay lenses reimage the laser output pupil to the LLT entrance pupilLeft figure shows the input beam shape of the BTO which also is the laser output beam shape, right figure shows the output beam shape on the LLT entrance pupilThe line of sight wander between telescope pointing at zenith and 65 degrees is proceeded
2011 May 25
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Acquisition Telescope Optical Design(1/2)
One lens and two mirrors, total length is about 570mmField of the design is larger than 5 arcminsR band (556nm~696nm),Focal Length:5360mmAperture: Φ150mm
2011 May 25
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Acquisition Telescope Optical Design(2/2)
Radius of field angle (arc-sec) Image Quality(Sr)
@589nm @R Band
0 0.984 0.953
35 (+y direction) 0.977 0.947
35 (-y direction) 0.977 0.947
35 (+x direction) 0.977 0.947
35 (-x direction) 0.977 0.947
150 (-y direction) 0.972 0.942
150 (+x direction) 0.972 0.942
150 (+x direction) 0.972 0.942
150 (-x direction) 0.972 0.942
Image quality of the Acquisition Telescope
2011 May 25
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Throughput Budget of the End to End LGSF Optical System
Level 1 Level 2 Level 3 Elements Surface Surface throughput Throughput Total ThroughputLGSF (the Requirement of the total throughput is ≥ 0.75 REQ-2-LGSF-0650) 0.779
LOM (Laser System Output Mirrors) 1 1 0.999 0.999 0.999BTO 0.937
EJFA (EJ Fold Pointing Array) 1 1 0.999 0.999TA (Truss Array) 1 1 0.999 0.999TRIFA (Tripod Fold Array) 1 1 0.999 0.999TCA (Truss Centering Array) 1 1 0.999 0.999TEFA (Top End Fold Array) 1 1 0.999 0.999Relay Lenses 3 6 0.990 0.941
DOB 0.970QWP 1 2 0.995 0.990BS (Beam Splitter) 1 2 0.990 0.980
AG 0.992Fold Mirror 3 3 0.999 0.997Fast Mirror 1 1 0.995 0.995
LLT 0.864Collimator Lenses 2 4 0.990 0.961Fold Mirror 1 1 0.999 0.999K Mirror 3 3 0.999 0.997M2 1 1 0.980 0.980M1 1 1 0.960 0.960Window 1 2 0.980 0.960
End to end optical evaluation is in progress
2011 May 25
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LGSF Top End Mechanical Redesign (1/6)-DOB Repackaging
Old Design New Design
Periscope 2 1
Shutter 1 No
Beam Splitter 2 1
Beam Trap No 1
Dimension of the Bench 1100 X 800 1000 X 710
Repackaging
2011 May 25
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LGSF Top End Mechanical Redesign (2/6)-LLT Repackaging
2450mm
1170
mm
1040
mm
850m
m71
0mm
Repackaging
2011 May 25
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LGSF Top End Mechanical Redesign (3/6)-AG Repackaging
RepackagingD
=725
mm
D=6
25m
m17°
13.6°
2011 May 25
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LGSF Top End Mechanical Redesign (4/6)-AT packaging
Acquisition Telescope
The total length of the acquisition telescope is 736.5mm
2011 May 25
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LGSF Top End Mechanical Redesign (5/6)-Support Structure
DOBSupport
TCA Support
Tilt Compensation
LLTSupport
2011 May 25
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LGSF Top End Mechanical Redesign (6/6)-Wind Section and Mass budget
The maximum transverse cross sectional area of the LGSF Top End is 2.74m2 less than 4m2 (REQ-2-LGSF-0750)
The total mass of the LGSF Top End is 0.98t (REQ-2-LGSF-0900)
2011 May 25
Item Sub-system Mass/Kg
1 LLT 213
2 AG 95
3 DOB 331
4 TCA 55
5 Electronics Box 105
6 Support structure 185
7 LGSF Top End total 984
①
②③
④
⑤
⑥
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LGSF BTO Mechanical Redesign (1/4)
2011 May 25
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LGSF BTO Mechanical Redesign (1/4)
2011 May 25
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LGSF BTO Mechanical Redesign (3/4)
2011 May 25
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LGSF BTO Mechanical Redesign (4/4)
Duct’s structure and the NFIRAOS laser position in the 3X3 arrayLaser Beam diameter: 5mmMirror diameter: 50mm3x3 patternSeparation between beams:70mmDuct diameter:270mmDuct :1mm thickness material rolled into tubular section
2011 May 25
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Electronics and Control (1/3)-The topology of the LGSF
2011 May 25
The LGSF electronics elements are divided into two parts: – Top end electronic enclosure– Laser Platform electronic enclosure
The CPCI computer is the heart of the LGSF control
LGSF Topology CPCI Topology
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Electronics and Control (2/3)-Location of the Electronics Box
2011 May 25
Top EndElectronics BoxDimension:1000x500x500Weight:105Kg
Elements in this BoxMechanism Volume /weight
Network switch 1U / 2.5kg
Multi-view 2U / 5kg
Remote power switch 1U / 3kg
CPCI 3U / 15kg
Motion controller&lifier 8U / 40kg
Fast tip/tilt controller and driver
3U /20kg(supplied by JPL, ,need to be asserted.)
Total 18U /85.5kg
When all the devices are running in the full mode, the supplied power must be greater than 3063w.
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Electronics and Control (3/3)- Location of the Electronics Box
2011 May 25
Laser platformElectronics BoxDimension:400x500x500Weight:40Kg
Elements in this Box
Mechanism Volume /weight
Motion controller 2U / 5kg
Motion amplifier 3U / 15kg
Network switch 1U / 3kg
Remote power switch 1U / 3kg
Total 7U / 26kgAll the devices are running in the full mode, the supplied power must be greater than 74w.
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Management Plan
Conceptual Design Review at June 22 2011,BeijingCost Estimate of the LGSF will begin after CDR and finish in three monthsCost Estimate Review at the end of SeptemberPreliminary Design Part 1 will begin after Cost Estimate Review and finish in four monthPreliminary Design Part 1 Review at the end of January 2012
2011 May 25
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Management Plan
Schedule and Key milestone for this work package
Cost EstimateReview
PreliminaryDesign Review
2011 May 25
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Questions
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Thank you!
2011 May 25