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Proceedings Paper

Verification of the James Webb Space Telescope coarse phase sensor using the Keck Telescope
Author(s): Marc Albanese; Allan Wirth; Andrew Jankevics; Tom Gonsiorowski; Catherine Ohara; Fang Shi; Mitchell Troy; Gary Chanan; Scott Acton
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Paper Abstract

The James Webb Space Telescope (JWST) Coarse Phase Sensor utilizes Dispersed Hartmann Sensing (DHS)1 to measure the inter-segment piston errors of the primary mirror. The DHS technique was tested on the Keck Telescope. Two DHS optical components were built to mate with the Keck optical and mechanical interfaces. DHS images were acquired using 20 different primary mirror configurations. The mirror configurations consisted of random segment pistons applied to 18 of the 36 segments. The inter-segment piston errors ranged from phased (approximately 0 μm) to as large as ±25 μm. Two broadband exposures were taken for each primary mirror configuration: one for the DHS component situated at 0°, and one for the DHS component situated at 60°. Finally, a "closed-loop" DHS sensing and control experiment was performed. Sensing algorithms developed by both Adaptive Optics Associates (AOA) and the Jet Propulsion Laboratory (JPL)2 were applied to the collected DHS images. The inter-segment piston errors determined by the AOA and JPL algorithms were compared to the actual piston steps. The data clearly demonstrates that the DHS works quite well as an estimator of segment-to-segment piston errors using stellar sources.

Paper Details

Date Published: 10 June 2006
PDF: 9 pages
Proc. SPIE 6265, Space Telescopes and Instrumentation I: Optical, Infrared, and Millimeter, 62650Z (10 June 2006); doi: 10.1117/12.672055
Show Author Affiliations
Marc Albanese, Adaptive Optics Associates (United States)
Allan Wirth, Adaptive Optics Associates (United States)
Andrew Jankevics, Adaptive Optics Associates (United States)
Tom Gonsiorowski, Adaptive Optics Associates (United States)
Catherine Ohara, Jet Propulsion Lab. (United States)
Fang Shi, Jet Propulsion Lab. (United States)
Mitchell Troy, Jet Propulsion Lab. (United States)
Gary Chanan, Univ. of California, Irvine (United States)
Scott Acton, Ball Aerospace & Technologies Corp. (United States)

Published in SPIE Proceedings Vol. 6265:
Space Telescopes and Instrumentation I: Optical, Infrared, and Millimeter
John C. Mather; Howard A. MacEwen; Mattheus W. M. de Graauw, Editor(s)

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