The non-linear curvature wavefront sensor reconstruction speed and the broadband design

Mala Mateen, Olivier Guyon, José Sasián, Vincent Garrel, Michael Hart

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Scopus citations

Abstract

In this paper we explain why a non-linear curvature wavefront sensor (nlCWFS) is more sensitive than conventional wavefront sensors such as the Shack Hartmann wavefront sensor (SHWFS) and the conventional curvature wavefront sensor (cCWFS) for sensing mV < 14 natural guide stars. The non-linear approach builds on the successful curvature wavefront sensing concept but uses a non-linear Gerchberg-Saxton (GS) phase diversity algorithm to reconstruct the wavefront. The nonlinear reconstruction algorithm is an advantage for sensitivity but a challenge for fast computation. The current speed is a factor of 10 to 100 times slower than needed for high performance groundbased AO. We present a two step strategy to increase the speed of the algorithm. In the last paper3 we presented laboratory results obtained with a monochromatic source, here we extend our experiment to incorporate a broadband source. The sensitivity of the nlCWFS depends on the ability to extract wavefront phase from diffraction limited speckles therefore it is essential that the speckles do not suffer from chromatic aberration when used with a polychromatic source. We discuss the design for the chromatic re-imaging optics, which through chromatic compensation, allow us to obtain diffraction limited speckles in Fresnel propagated planes on either side of the pupil plane.

Original languageEnglish (US)
Title of host publicationAstronomical Adaptive Optics Systems and Applications IV
DOIs
StatePublished - Oct 21 2011
EventAstronomical Adaptive Optics Systems and Applications IV - San Diego, CA, United States
Duration: Aug 21 2011Aug 24 2011

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume8149
ISSN (Print)0277-786X

Other

OtherAstronomical Adaptive Optics Systems and Applications IV
CountryUnited States
CitySan Diego, CA
Period8/21/118/24/11

Keywords

  • Shack-Hartmann wavefront sensor
  • extreme-adaptive optics
  • non-linear curvature wavefront sensor
  • wavefront sensitivity

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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