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Proceedings Paper

Post-coronagraph wavefront sensor for Gemini Planet Imager
Author(s): J. Kent Wallace; John Angione; Randall Bartos; Paul Best; Rick Burruss; Felipe Fregoso; B. Martin Levine; Bijan Nemati; Michael Shao; Chris Shelton
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Paper Abstract

The Gemini Planet Imager (GPI)1 will employ an apodized-pupil coronagraph to make direct detections of faint companions of nearby stars to a contrast level of the 10-7 within a few λ/D of the parent star. Such high contrasts from the ground require exquisite wavefront sensing and control both for the AO system as well as for the coronagraph. Un-sensed non-common path phase and amplitude errors after the wavefront sensor dichroic but before the coronagraph lead to speckles which limit the contrast2. The calibration wavefront system for GPI will measure the complex wavefront at the system pupil before the apodizer and provide slow phase corrections to the AO system to mitigate errors that would cause a loss in contrast. Here we describe the low-order and high-order wavefront sensors that compose the calibration wavefront sensor, how they operate, and how their information is combined to form the wavefront estimate before the coronagraph. Detailed simulations that show the expected performance for this wavefront sensor will be described for typical observing scenarios. Finally, we will show preliminary lab results from our calibration testbed that demonstrate the operation of the key hardware.

Paper Details

Date Published: 15 July 2008
PDF: 12 pages
Proc. SPIE 7015, Adaptive Optics Systems, 70156N (15 July 2008); doi: 10.1117/12.787258
Show Author Affiliations
J. Kent Wallace, Jet Propulsion Lab. (United States)
John Angione, Jet Propulsion Lab. (United States)
Randall Bartos, Jet Propulsion Lab. (United States)
Paul Best, Jet Propulsion Lab. (United States)
Rick Burruss, Jet Propulsion Lab. (United States)
Felipe Fregoso, Jet Propulsion Lab. (United States)
B. Martin Levine, Jet Propulsion Lab. (United States)
Bijan Nemati, Jet Propulsion Lab. (United States)
Michael Shao, Jet Propulsion Lab. (United States)
Chris Shelton, Jet Propulsion Lab. (United States)

Published in SPIE Proceedings Vol. 7015:
Adaptive Optics Systems
Norbert Hubin; Claire E. Max; Peter L. Wizinowich, Editor(s)

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