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Proceedings Paper

Aberration correction of segmented-aperture telescopes by using phase diversity
Author(s): David A. Carrara; Brian J. Thelen; Richard G. Paxman
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Paper Abstract

There is currently much interest in deploying large space- based telescopes for various applications including fine- resolution astronomical imaging and earth observing. Often a large primary mirror is synthesized by the precise alignment of several smaller mirror segments. Misalignment or misfigure of these segments results in phase error which degrade the resolution of collected imagery. Phase diversity (PD) is a technique used to infer unknown phase aberrations form image data. It requires the collection of two or more images of the same object, each incorporating a known phase perturbation in addition to the unknown aberrations. Statistical estimation techniques are employed to identify a combination of object and aberrations that is consistent with all of the collected images. The wavefront- sensing performance of PD is evaluated through simulation for a variety of signal and aberration strengths. The aberrations are parameterizes by piston and tilt misalignment of each segment. An unknown extended scene is imaged, complicating the estimation procedure. Since wavefront correction is often an iterative process, moderate estimation errors can be corrected by subsequent estimates. The interpretation of iterative wavefront adjustments as creating new phase-diversity channels suggests a more sophisticated processing approach, called Actuated Phase Diversity. This technique is shown to significantly improve PD wavefront-sensing performance.

Paper Details

Date Published: 16 November 2000
PDF: 8 pages
Proc. SPIE 4123, Image Reconstruction from Incomplete Data, (16 November 2000); doi: 10.1117/12.409286
Show Author Affiliations
David A. Carrara, Veridian ERIM International, Inc. (United States)
Brian J. Thelen, Veridian ERIM International, Inc. (United States)
Richard G. Paxman, Veridian ERIM International, Inc. (United States)

Published in SPIE Proceedings Vol. 4123:
Image Reconstruction from Incomplete Data
Michael A. Fiddy; Rick P. Millane, Editor(s)

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