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Speckle statistics in direct and coronagraphic imaging

Published online by Cambridge University Press:  02 May 2006

Rémi Soummer ,
Claude Aime ,
André Ferrari ,
Anand Sivaramakrishnan ,
Laurent Jolissaint ,
James Lloyd ,
Ben R. Oppenheimer ,
Russell Makidon  and
Marcel Carbillet
Rémi Soummer
Affiliation:
American Museum of Natural History, 79th St at Central Park West, New York, USA email: rsoummer@amnh.org, anand@amnh.org, bro@amnh.org
Claude Aime
Affiliation:
Laboratoire Universitaire d'Astrophysique de Nice, Parc Valrose, Nice, France email: Claude.Aime@unice.fr, Andre.Ferrari@unice.fr
André Ferrari
Affiliation:
Laboratoire Universitaire d'Astrophysique de Nice, Parc Valrose, Nice, France email: Claude.Aime@unice.fr, Andre.Ferrari@unice.fr
Anand Sivaramakrishnan
Affiliation:
American Museum of Natural History, 79th St at Central Park West, New York, USA email: rsoummer@amnh.org, anand@amnh.org, bro@amnh.org
Laurent Jolissaint
Affiliation:
Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, B.C. V9E 2E7, Canada email: laurent.jolissaint@nrc-cnrc.gc.ca
James Lloyd
Affiliation:
Department of Astronomy, Cornell University, Ithaca, NY 14853, USA email: jpl@astro.cornell.edu
Ben R. Oppenheimer
Affiliation:
American Museum of Natural History, 79th St at Central Park West, New York, USA email: rsoummer@amnh.org, anand@amnh.org, bro@amnh.org
Russell Makidon
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, USA email: makidon@stsci.edu
Marcel Carbillet
Affiliation:
Laboratoire Universitaire d'Astrophysique de Nice, Parc Valrose, Nice, France email: Claude.Aime@unice.fr, Andre.Ferrari@unice.fr
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Abstract

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In this communication, we study the statistical properties of the light intensity in direct and coronagraphic images, in the context of ground-based Extreme Adaptive Optics observations. The same approach can also be used for space observations with different scales. We show that a coronagraph only affects the perfect part of the wave and leaves the uncorrected part of the wavefront almost unaffected. This statistical model can explain the ‘speckle pinning’ effect (presence of speckles at the position of the diffraction rings), as an amplification of the speckle noise. This statistical approach can be verified on real adaptive optics data.

Keywords

instrumentation: high angular resolutioninstrumentation: adaptive optics