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12 July 2008 Cryogenic pupil alignment test architecture for the James Webb Space Telescope integrated science instrument module
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The James Webb Space Telescope (JWST) is a space-based, infrared observatory designed to study the early stages of galaxy formation in the Universe. It is currently scheduled to be launched in 2013 and will go into orbit about the second Lagrange point of the Sun-Earth system and passively cooled to 30-50 K to enable astronomical observations from 0.6 to 28 μm. The JWST observatory consists of three primary elements: the spacecraft, the optical telescope element (OTE) and the integrated science instrument module (ISIM). The ISIM Element primarily consists of a mechanical metering structure, three science instruments and a fine guidance sensor with significant scientific capability. One of the critical opto-mechanical alignments for mission success is the co-registration of the OTE exit pupil with the entrance pupils of the ISIM instruments. To verify that the ISIM Element will be properly aligned with the nominal OTE exit pupil when the two elements come together, we have developed a cryogenic pupil measurement test architecture to measure three of the most critical pupil degrees-of-freedom during optical testing of the ISIM Element. The pupil measurement scheme makes use of: specularly reflective pupil alignment references located inside of the JWST instruments; ground support equipment that contains a pupil imaging module; an OTE simulator; and pupil viewing channels in two of the JWST flight instruments. Current modeling and analysis activities indicate this measurement approach will be able to verify pupil shear to an accuracy of 0.5-1%.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Brent J. Bos, David A. Kubalak, Scott R. Antonille, Raymond G. Ohl, John G. Hagopian, Pamela S. Davila, Joseph Sullivan, Michael Sánchez, Derek Sabatke, Robert A. Woodruff, Maurice te Plate, Clinton Evans, Victor Isbrucker, Stephen Somerstein, Martyn Wells, and Samuel Ronayette "Cryogenic pupil alignment test architecture for the James Webb Space Telescope integrated science instrument module", Proc. SPIE 7010, Space Telescopes and Instrumentation 2008: Optical, Infrared, and Millimeter, 70103C (12 July 2008);


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