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Proceedings Paper

Speckle lifetimes in high-contrast adaptive optics
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Paper Abstract

The main noise source in detection of faint companions such as extrasolar planets near bright stars with AO is speckle noise--residual PSF structure caused by wavefront errors due to the atmosphere, the AO system, and static optical effects. Of these, the most fundamental are atmospheric speckles--even given infinite wavefront SNR and a perfect DM, timelag between sensing and correction will always lead to a residual atmospheric speckle pattern. There have been several suggestions as to the lifetime of these atmospheric speckles, none strongly supported by theory or simulation. We have carried out a systematic series of simulations and analysis to explore this question. We show that speckles have different behavior in the regime in which diffraction is significant (first-order speckles, which are rapidly modulated as a phase error translates across the aperture) and in the coronagraphic regime (second-order speckles, which evolve only as the phase screen completely clears the aperture.). We use simulations to analyze the behavior of speckles in a variety of regimes, showing that the second-order atmospheric speckle lifetime is almost constant irrespective of the properties of the AO system, and is set primarily by the atmospheric clearing time of the telescope aperture.

Paper Details

Date Published: 8 October 2005
PDF: 8 pages
Proc. SPIE 5903, Astronomical Adaptive Optics Systems and Applications II, 59030J (8 October 2005); doi: 10.1117/12.627854
Show Author Affiliations
Bruce Macintosh, NSF Ctr. for Adaptive Optics (United States)
Lawrence Livermore National Lab. (United States)
Lisa Poyneer, NSF Ctr. for Adaptive Optics (United States)
Lawrence Livermore National Lab. (United States)
Anand Sivaramakrishnan, NSF Ctr. for Adaptive Optics (United States)
Space Telescope Science Institute (United States)
The American Museum of Natural History (United States)
Christian Marois, NSF Ctr. for Adaptive Optics (United States)
Lawrence Livermore National Lab. (United States)


Published in SPIE Proceedings Vol. 5903:
Astronomical Adaptive Optics Systems and Applications II
Robert K. Tyson; Michael Lloyd-Hart, Editor(s)

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