Limits of adaptive optics for high-contrast imaging

Research output: Contribution to journalArticle

161 Scopus citations

Abstract

The effects of photon noise, aliasing, wave front chromaticity, and scintillation on the point-spread function (PSF) contrast achievable with ground-based adaptive optics (AO) are evaluated for different wave front sensing schemes. I show that a wave front sensor (WFS) based on the Zernike phase contrast technique offers the best sensitivity to photon noise at all spatial frequencies, while the Shack-Hartmann WFS is significantly less sensitive. In AO systems performing wave front sensing in the visible and scientific imaging in the near-IR, the PSF contrast limit is set by the scintillation chromaticity induced by Fresnel propagation through the atmosphere. On an 8 m telescope, the PSF contrast is then limited to 10 -4 to 10-5 in the central arcsecond. Wave front sensing and scientific imaging should therefore be done at the same wavelength, in which case, on bright sources, PSF contrasts between 10-6 and 10 -7 can be achieved within 1″ on an 8 m telescope in optical/near-IR. The impact of atmospheric turbulence parameters (seeing, wind speed, turbulence profile) on the PSF contrast is quantified. I show that a focal plane wave front sensing scheme offers unique advantages, and I discuss how to implement it. Coronagraphic options are also briefly discussed.

Original languageEnglish (US)
Pages (from-to)592-614
Number of pages23
JournalAstrophysical Journal
Volume629
Issue number1 I
DOIs
StatePublished - Aug 10 2005
Externally publishedYes

Keywords

  • Instrumentation: adaptive optics
  • Instrumentation: interferometers
  • Methods: data analysis
  • Techniques: high angular resolution
  • Techniques: interferometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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