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Proceedings Paper

Phase retrieval on broadband and under-sampled images for the JWST testbed telescope
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Paper Abstract

The James Webb Space Telescope (JWST) consists of an optical telescope element (OTE) that sends light to five science instruments. The initial steps for commissioning the telescope are performed with the Near-Infrared Camera (NIRCam) instrument, but low-order optical aberrations in the remaining science instruments must be determined (using phase retrieval) in order to ensure good performance across the entire field of view. These remaining instruments were designed to collect science data, and not to serve as wavefront sensors. Thus, the science cameras are not ideal phase-retrieval imagers for several reasons: they record under-sampled data and have a limited range of diversity defocus, and only one instrument has an internal, narrowband filter. To address these issues, we developed the capability of sensing these aberrations using an extension of image-based iterative-transform phase retrieval called Variable Sampling Mapping (VSM). The results show that VSM-based phase retrieval is capable of sensing low-order aberrations to a few nm RMS from images that are consistent with the non-ideal conditions expected during JWST multi-field commissioning. The algorithm is validated using data collected from the JWST Testbed Telescope (TBT).

Paper Details

Date Published: 26 August 2009
PDF: 12 pages
Proc. SPIE 7436, UV/Optical/IR Space Telescopes: Innovative Technologies and Concepts IV, 74360D (26 August 2009); doi: 10.1117/12.825636
Show Author Affiliations
J. Scott Smith, NASA Goddard Space Flight Ctr. (United States)
David L. Aronstein, NASA Goddard Space Flight Ctr. (United States)
Bruce H. Dean, NASA Goddard Space Flight Ctr. (United States)
D. Scott Acton, Ball Aerospace & Technologies Corp. (United States)

Published in SPIE Proceedings Vol. 7436:
UV/Optical/IR Space Telescopes: Innovative Technologies and Concepts IV
Howard A. MacEwen; James B. Breckinridge, Editor(s)

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