Oct 17, 2001 SALT PFIS Preliminary Design ReviewOptical Integration and Test Plan

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Southern African Large Telescope Prime Focus Imaging Spectrograph

Optical Integration and Test PlanEric B. Burgh

University of Wisconsin - Madison

Oct 17, 2001 SALT PFIS Preliminary Design ReviewOptical Integration and Test Plan

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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 ReviewOptical Integration and Test Plan

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Instrument Breakdown

• Optics (Lenses/Filters)• Gratings• Fabry-Perot etalons• Polarimetric components• Detector Subsystem

Oct 17, 2001 SALT PFIS Preliminary Design ReviewOptical Integration and Test Plan

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Optics

Lens mounting:

• Coefficient of thermal expansion– Fused silica 0.5 x 10-6 K-1

– NaCl 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 ReviewOptical Integration and Test Plan

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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 ReviewOptical Integration and Test Plan

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Grating Tests

• Throughput• Dispersion• Scattering• Reproducibility of

VPHMonochromatic beam

PMT/CCD

Oct 17, 2001 SALT PFIS Preliminary Design ReviewOptical Integration and Test Plan

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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 ReviewOptical Integration and Test Plan

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Polarimetric Components

• Repeatability of wave-plate rotation• Wave-plate throughput• Polarimetric efficiency• Alignment and efficiency of mosaic beamsplitter

Oct 17, 2001 SALT PFIS Preliminary Design ReviewOptical Integration and Test Plan

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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 ReviewOptical Integration and Test Plan

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Integration

• Mechanism mechanical integration• Control system integration• Verification of reproducible alignments• Change out of slits/gratings/filters

Oct 17, 2001 SALT PFIS Preliminary Design ReviewOptical Integration and Test Plan

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Required Lab Equipment

• Monochromator• Continuum and Arc lamps• Phototubes/CCD detector• Multiple axis and rotating stages