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Proceedings Paper

Novel method of high-accuracy wavefront-phase and amplitude correction for coronagraphy
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Paper Abstract

Detection of extra-solar, and especially terrestrial-like planets, using coronagraphy requires an extremely high level of wavefront correction. For example, the study of Woodruff et al. (2002) has shown that phase uniformity of order 10-4λ(rms) must be achieved over the critical range of spatial frequencies to produce the ~1010 contrast needed for the Terrestrial Planet Finder (TPF) mission. Correction of wavefront phase errors to this level may be accomplished by using a very high precision deformable mirror (DM). However, not only phase but also amplitude uniformity of the same scale (~10-4) and over the same spatial frequency range must be simultaneously obtained to remove all residual speckle in the image plane. We present a design for producing simultaneous wavefront phase and amplitude uniformity to high levels from an input wavefront of lower quality. The design uses a dual Michelson interferometer arrangement incorporating two DM and a single, fixed mirror (all at pupils) and two beamsplitters: one with unequal (asymmetric) beam splitting and one with symmetric beam splitting. This design allows high precision correction of both phase and amplitude using DM with relatively coarse steps and permits a simple correction algorithm.

Paper Details

Date Published: 19 November 2003
PDF: 15 pages
Proc. SPIE 5170, Techniques and Instrumentation for Detection of Exoplanets, (19 November 2003); doi: 10.1117/12.532515
Show Author Affiliations
Charles W. Bowers, NASA Goddard Space Flight Ctr. (United States)
Bruce E. Woodgate, NASA Goddard Space Flight Ctr. (United States)
Richard G. Lyon, NASA Goddard Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 5170:
Techniques and Instrumentation for Detection of Exoplanets
Daniel R. Coulter, Editor(s)

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