Wavefront sensing and correction with the Gemini Planet Imager

  1. Get@NRC: Wavefront sensing and correction with the Gemini Planet Imager (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1117/12.926680
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Proceedings titleAdaptive Optics Systems III
Series titleProceedings of SPIE; Volume 8447
ConferenceAdaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands
Article number844714
SubjectAdaptive optics systems; Aliasing; Calibration system; Contrast ratio; Deformable mirrors; Extra solar planets; Extrasolar planet detection; Extreme adaptive optics; High contrast imaging; High-accuracy; Image sharpening; MEMS deformable mirror; Shack-Hartmann wavefront sensors; Spatial filters; Sub-apertures; Temporal frequency; Wave-front sensing; Wavefront correction; Adaptive optics; Calibration; Instrument testing; Interferometry; Piezoelectric actuators; Wavefronts
AbstractHigh-contrast imaging is a growing observational technique aimed at discovering and characterizing extrasolar planets. The Gemini Planet Imager (GPI) is designed to achieve contrast ratios of 10-6 - 10 -7 and requires unprecedented wavefront correction and coronagraphic control of diffraction. GPI is a facility instrument now undergoing integration and testing and is scheduled for first light on the 8-m Gemini South telescope towards the end of 2012. In this paper, we focus on the wavefront sensing and correction aspects of the instrument. To measure the wavefront, GPI combines a Shack-Hartmann wavefront sensor and a high-accuracy infrared interferometric wavefront calibration system. The Shack-Hartmann wavefront sensor uses 1700 subapertures to precisely sample the wavefront at 1.5 kHz and features a spatial filter to prevent aliasing. The wavefront calibration system measures the slower temporal frequency errors as well as non-common path aberrations. The wavefront correction is performed using a two-stage adaptive optics system employing a 9x9 piezoelectric deformable mirror and a 43x43 actuators MEMS deformable mirror operating in a woofer-tweeter configuration. Finally, an image sharpening technique is used to further increase the contrast of the final image. In this paper, we describe the three wavefront sensing methods and how we combine their respective information to achieve the best possible contrast.
Publication date
AffiliationNational Research Council Canada (NRC-CNRC); National Science Infrastructure
Peer reviewedYes
NPARC number21270282
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Record identifier0e3914ba-405b-482e-ac68-c914650eeda9
Record created2014-01-20
Record modified2016-05-09
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