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Design considerations for a novel phase-contrast adaptive-optic wavefront sensor

Bloemhof, E. E. and Westphal, J. A. (2002) Design considerations for a novel phase-contrast adaptive-optic wavefront sensor. In: Adaptive Optics Systems and Technology II. Proceedings of SPIE. No.4494. Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, pp. 363-370. ISBN 9780819442086.

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The wavefront sensor (WFS) is perhaps the most critical adaptive-optic subsystem, particularly for astronomical applications with natural guide stars, where current WFS sensitivity limitations seriously restrict sky coverage. In this paper, we discuss the possibility of a WFS based on a phase-contrast principle of the sort employed by Zernike for microscopy. Such a WFS would be implemented by inserting a focal-plane filter with a (pi) /2 phase-shifting central spot having a transverse size of the order of the diffraction limit. The result would be an image of the pupil in which intensity is directly proportional to the seeing- and aberration-induced phase variations over the pupil. In comparison, the signals produced by the two most common current WFS schemes, Shack-Hartmann and curvature sensing, are proportional to the phase slope and to the second derivative, respectively. The phase-contrast approach might derive some advantages stemming from its more natural match to the control eigenvectors of the electrostrictive deformable mirrors that are expected to predominate in high-order adaptive optics systems, in the same way that curvature sensors are currently well matched to bimorph mirrors. It may thus yield substantial performance improvements with simpler hardware and lighter computational loads. We examine this and other possible advantages of the phase-contrast WFS, and investigate some of the practical design issues involved in its implementation.

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Additional Information:© 2002 Society of Photo-Optical Instrumentation Engineers (SPIE). We thank the Palomar mountain crew for their support of adaptive optics, the team at JPL that built PALAO, and the team at Cornell that built its science camera, PHARO.
Subject Keywords:adaptive optics, wavefront sensor
Series Name:Proceedings of SPIE
Issue or Number:4494
Record Number:CaltechAUTHORS:20181213-143632330
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Official Citation:Eric E. Bloemhof, James A. Westphal, "Design considerations for a novel phase-contrast adaptive-optic wavefront sensor," Proc. SPIE 4494, Adaptive Optics Systems and Technology II, (4 February 2002); doi: 10.1117/12.454812
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91808
Deposited By: George Porter
Deposited On:19 Dec 2018 18:44
Last Modified:16 Nov 2021 03:44

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