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Proceedings Paper

Interferometric validation of image-based wavefront sensing for NGST
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Paper Abstract

To achieve and maintain excellent imaging performance, the Next Generation Space Telescope (NGST) will employ image-based phase retrieval methods to control its segmented primary mirror. In this paper, we present the experimental validation of a focus-diverse wave front sensing (WFS) algorithm with comparative interferometric measurements of a perturbed test mirror. Using sets of defocused point-spread functions measured with the NGST phase retrieval camera, we estimate the aberrations of the test optic in a perturbed and unperturbed state. Interleaved with the focus-diverse sets, we measure the surface figure of the mirror using a ZYGO interferometer. After briefly reviewing the basic WFS algorithm and describing the experimental setup, we show that we can obtain agreement that is better than 1/100th of a wave rms in the difference of the wave front estimates obtained in the perturbed and unperturbed states. Although this experiment does not establish the errors that are solely attributable to our WFS approach, it nevertheless validates the accuracy of our image-based methods for NGST, demonstrating that they are generally competitive with standard industrial optical metrology instruments.

Paper Details

Date Published: 5 March 2003
PDF: 8 pages
Proc. SPIE 4850, IR Space Telescopes and Instruments, (5 March 2003); doi: 10.1117/12.461157
Show Author Affiliations
Joseph Jacob Green, Jet Propulsion Lab. (United States)
David C. Redding, Jet Propulsion Lab. (United States)
Yuri Beregovski, Jet Propulsion Lab. (United States)
Andrew E. Lowman, Jet Propulsion Lab. (United States)
Catherine Mayumi Ohara, Jet Propulsion Lab. (United States)

Published in SPIE Proceedings Vol. 4850:
IR Space Telescopes and Instruments
John C. Mather, Editor(s)

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