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Proceedings Paper

Cryogenic focal plane flatness measurement with optical zone slope tracking
Author(s): Jerry Edelstein; Martin Sirk; Patrick N. Jelinsky; Robert W. Besuner; Matthew Hoff; Paul Perry; Henry D. Heetderks; Christopher J. Bebek; Michael E. Levi
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Paper Abstract

We describe a non-contact optical measurement method used to determine the surface flatness of a cryogenic sensor array developed for the JDEM mission. Large focal planes envisioned for future visible to near infra-red astronomical large area point-source surveys such as JDEM, WFIRST, or EUCLID must operate at cryogenic temperatures while maintaining focal plane flatness within a few 10's of μm over half-meter scales. These constraints are imposed by sensitivity conditions that demand low noise observations from the sensors and the large-field, fast optical telescopes necessary to obtain the science yield. Verifying cryogenic focal plane flatness is challenging because μm level excursions need to be measured within and across many multi-cm sized sensors using no physical contact and while situated within a high-vacuum chamber. We have used an optical metrology Shack-Hartmann scheme to measure the 36x18 cm focal plane developed for the JDEM mission at the Lawrence Berkeley National Laboratory. The focal plane holds a 4x8 array of CCDs and HgCdTe detectors. The flatness measurement scheme uses a telescope-fed micro-lens array that samples the focal plane to determine slope changes of individual sensor zones.

Paper Details

Date Published: 16 September 2011
PDF: 10 pages
Proc. SPIE 8155, Infrared Sensors, Devices, and Applications; and Single Photon Imaging II, 81550N (16 September 2011); doi: 10.1117/12.892521
Show Author Affiliations
Jerry Edelstein, Univ. of California, Berkeley (United States)
Martin Sirk, Univ. of California, Berkeley (United States)
Patrick N. Jelinsky, Univ. of California, Berkeley (United States)
Robert W. Besuner, Univ. of California, Berkeley (United States)
Matthew Hoff, Lawrence Berkeley National Lab. (United States)
Paul Perry, Lawrence Berkeley National Lab. (United States)
Henry D. Heetderks, Univ. of California, Berkeley (United States)
Christopher J. Bebek, Lawrence Berkeley National Lab. (United States)
Michael E. Levi, Lawrence Berkeley National Lab. (United States)


Published in SPIE Proceedings Vol. 8155:
Infrared Sensors, Devices, and Applications; and Single Photon Imaging II
Manijeh Razeghi; Paul D. LeVan; Ashok K. Sood; Priyalal S. Wijewarnasuriya, Editor(s)

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