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Proceedings Paper

Amplitude variations on the ExAO testbed
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Paper Abstract

High-contrast adaptive optics systems, such as those needed to image extrasolar planets, are known to require excellent wavefront control and diffraction suppression. At the Laboratory for Adaptive Optics on the Extreme Adaptive Optics testbed, we have already demonstrated wavefront control of better than 1 nm rms within controllable spatial frequencies. Corresponding contrast measurements, however, are limited by amplitude variations, including those introduced by the micro-electrical-mechanical-systems (MEMS) deformable mirror. Results from experimental measurements and wave optic simulations of amplitude variations on the ExAO testbed are presented. We find systematic intensity variations of about 2% rms, and intensity variations with the MEMS to be 6%. Some errors are introduced by phase and amplitude mixing because the MEMS is not conjugate to the pupil, but independent measurements of MEMS reflectivity suggest that some error is introduced by small non-uniformities in the reflectivity.

Paper Details

Date Published: 19 September 2007
PDF: 12 pages
Proc. SPIE 6693, Techniques and Instrumentation for Detection of Exoplanets III, 669312 (19 September 2007); doi: 10.1117/12.735741
Show Author Affiliations
Julia W. Evans, Lawrence Livermore National Lab. (United States)
Sandrine Thomas, Univ. of California/Santa Cruz (United States)
Daren Dillon, Univ. of California/Santa Cruz (United States)
Donald Gavel, Univ. of California/Santa Cruz (United States)
Donald Phillion, Lawrence Livermore National Lab. (United States)
Bruce Macintosh, Lawrence Livermore National Lab. (United States)


Published in SPIE Proceedings Vol. 6693:
Techniques and Instrumentation for Detection of Exoplanets III
Daniel R. Coulter, Editor(s)

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