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Cryogenic Pupil Alignment Test Architecture for Aberrated Pupil ImagesA document describes cryogenic test architecture for the James Webb Space Telescope (JWST) integrated science instrument module (ISIM). The ISIM element primarily consists of a mechanical metering structure, three science instruments, and a fine guidance sensor. One of the critical optomechanical alignments is the co-registration of the optical telescope element (OTE) exit pupil with the entrance pupils of the ISIM instruments. The test architecture has been developed to verify that the ISIM element will be properly aligned with the nominal OTE exit pupil when the two elements come together. The architecture measures 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 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. Pupil alignment references (PARs) are introduced into the instrument, and their reflections are checked using the instrument's mirrors. After the pupil imaging module (PIM) captures a reflected PAR image, the image will be analyzed to determine the relative alignment offset. The instrument pupil alignment preferences are specularly reflective mirrors with non-reflective fiducials, which makes the test architecture feasible. The instrument channels have fairly large fields of view, allowing PAR tip/tilt tolerances on the order of 0.5deg.
Document ID
20090041772
Acquisition Source
Goddard Space Flight Center
Document Type
Other - NASA Tech Brief
Authors
Bos, Brent
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Kubalak, David A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Antonille, Scott
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Ohl, Raymond
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hagopian, John G.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 24, 2013
Publication Date
December 1, 2009
Publication Information
Publication: NASA Tech Briefs, December 2009
Subject Category
Man/System Technology And Life Support
Report/Patent Number
GSC-15650-1
Distribution Limits
Public
Copyright
Public Use Permitted.
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