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Southern African Large Telescope
Prime Focus Imaging Spectrograph
Optical Integration and Test Plan
Eric B. Burgh
University of Wisconsin - Madison
Oct 17, 2001
SALT PFIS Preliminary Design Review
Optical Integration and Test Plan
1
Opto-Mechanical Issues
• Lens mount design
– Sealed triplets, thermal effects, coating issues, etc.
• Assembly, alignment, and testing
– Collimator, camera, gratings, etalons, etc.
• Integration with mechanisms
Oct 17, 2001
SALT PFIS Preliminary Design Review
Optical Integration and Test Plan
2
Instrument Breakdown
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Optics (Lenses/Filters)
Gratings
Fabry-Perot etalons
Polarimetric components
Detector Subsystem
Oct 17, 2001
SALT PFIS Preliminary Design Review
Optical Integration and Test Plan
3
Optics
Lens mounting:
• Coefficient of thermal expansion
– Fused silica
– NaCl
 0.5 x 10-6 K-1
 44 x 10-6 K-1
• Sealed NaCl triplets
– Protection from moisture
– Mounting issues
• AR Coatings
– SolGel/MgF2
– Ruggedness
– Application within mounts
Oct 17, 2001
SALT PFIS Preliminary Design Review
Optical Integration and Test Plan
4
Optics (continued..)
• Alignment
– Collimator (degree of collimation, focus travel)
– Camera (focus)
• Transmission / image quality
– Integrated collimator / camera setup
– Various combinations of filters
– (Image quality testing with Detector Subsystem?)
• Slit mask verification
– Measure width, edge roughness, relative slit positions
to verify within tolerances
Oct 17, 2001
SALT PFIS Preliminary Design Review
Optical Integration and Test Plan
5
Grating Tests
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Throughput
Dispersion
Scattering
Reproducibility of a
VPH
Monochromatic beam
a
PMT/CCD
Oct 17, 2001
SALT PFIS Preliminary Design Review
Optical Integration and Test Plan
6
Fabry-Perot Etalons
• Initial testing performed at Rutgers University
• Integration with PFIS at UW-Madison
– Assembly with structure
– Alignment with optics
– Sensitivity to degree of collimation
Oct 17, 2001
SALT PFIS Preliminary Design Review
Optical Integration and Test Plan
7
Polarimetric Components
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Repeatability of wave-plate rotation
Wave-plate throughput
Polarimetric efficiency
Alignment and efficiency of mosaic beamsplitter
Oct 17, 2001
SALT PFIS Preliminary Design Review
Optical Integration and Test Plan
8
Detector Subsystem
Tests that need the Detector Subsystem:
• Image quality v. field position
• Field flatness/distortions
• Instrumental scattered light
• Detector pixel scale
• Grating resolution
• End-to-end throughput/detection efficiency
Oct 17, 2001
SALT PFIS Preliminary Design Review
Optical Integration and Test Plan
9
Integration
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Mechanism mechanical integration
Control system integration
Verification of reproducible alignments
Change out of slits/gratings/filters
Oct 17, 2001
SALT PFIS Preliminary Design Review
Optical Integration and Test Plan
10
Required Lab Equipment
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Monochromator
Continuum and Arc lamps
Phototubes/CCD detector
Multiple axis and rotating stages
Oct 17, 2001
SALT PFIS Preliminary Design Review
Optical Integration and Test Plan
11