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Proceedings Paper

Using multifield measurements to eliminate alignment degeneracies in the JWST testbed telescope
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Paper Abstract

The primary mirror of the James Webb Space Telescope (JWST) consists of 18 segments and is 6.6 meters in diameter. A sequence of commissioning steps is carried out at a single field point to align the segments. At that single field point, though, the segmented primary mirror can compensate for aberrations caused by misalignments of the remaining mirrors. The misalignments can be detected in the wavefronts of off-axis field points. The Multifield (MF) step in the commissioning process surveys five field points and uses a simple matrix multiplication to calculate corrected positions for the secondary and primary mirrors. A demonstration of the Multifield process was carried out on the JWST Testbed Telescope (TBT). The results show that the Multifield algorithm is capable of reducing the field dependency of the TBT to about 20 nm RMS, relative to the TBT design nominal field dependency.

Paper Details

Date Published: 20 September 2007
PDF: 10 pages
Proc. SPIE 6687, UV/Optical/IR Space Telescopes: Innovative Technologies and Concepts III, 668707 (20 September 2007); doi: 10.1117/12.736309
Show Author Affiliations
Erin Sabatke, Ball Aerospace (United States)
Scott Acton, Ball Aerospace (United States)
John Schwenker, Ball Aerospace (United States)
Tim Towell, Ball Aerospace (United States)
Larkin Carey, Ball Aerospace (United States)
Duncan Shields, Ball Aerospace (United States)
Adam Contos, Ball Aerospace (United States)
Doug Leviton, NASA Goddard Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 6687:
UV/Optical/IR Space Telescopes: Innovative Technologies and Concepts III
Howard A. MacEwen; James B. Breckinridge, Editor(s)

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