Post-coronagraph wavefront sensor for Gemini Planet Imager

J. Kent Wallace; John Angione; Randall Bartos; Paul Best; Rick Burruss; Felipe Fregoso; B. Martin Levine; Bijan Nemati; Michael Shao; Chris Shelton

doi:10.1117/12.787258

15 July 2008 Post-coronagraph wavefront sensor for Gemini Planet Imager

J. Kent Wallace, John Angione, Randall Bartos, Paul Best, Rick Burruss, Felipe Fregoso, B. Martin Levine, Bijan Nemati, Michael Shao, Chris Shelton

Author Affiliations +

Proceedings Volume 7015, Adaptive Optics Systems; 70156N (2008) https://doi.org/10.1117/12.787258
Event: SPIE Astronomical Telescopes + Instrumentation, 2008, Marseille, France

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.

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J. Kent Wallace, John Angione, Randall Bartos, Paul Best, Rick Burruss, Felipe Fregoso, B. Martin Levine, Bijan Nemati, Michael Shao, and Chris Shelton "Post-coronagraph wavefront sensor for Gemini Planet Imager", Proc. SPIE 7015, Adaptive Optics Systems, 70156N (15 July 2008); https://doi.org/10.1117/12.787258

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