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Imagerie à travers la turbulence : mesure inverse du front d'onde et centrage optimal

Abstract : Diffraction-limited imaging with Extremely Large ground-based Telescopes is a major challenge of modern astrophysics. But it requires the correction of the wavefront corrugations due to the atmospheric turbulence. I present a global optimization algorithm to solve the non-linear inverse problem of phase retrieval from a speckle image, and I show the benefit of polychromatic diversity (images at different wavelengths) to deal with more degrees of freedom. In the Polychromatic Laser Guide Star framework, I address the problem of assessing the chromatic differential tip-tilt with more accuracy than centroïds. The benefit of the full wavefront joint estimation from the images is evidenced in the case the PLG Star is unresolved. Otherwise I develop an estimator of the star's differential movement, based on the bichromatic cross-spectrum. Finally, I present an optimal real-time data processing of a photon counting detector with an inverse problem formulation (gain of 4 in spatial resolution).
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https://tel.archives-ouvertes.fr/tel-00220467
Contributor : Xavier Rondeau <>
Submitted on : Monday, January 28, 2008 - 11:23:42 AM
Last modification on : Wednesday, November 20, 2019 - 3:01:09 AM
Long-term archiving on: : Thursday, April 29, 2010 - 7:42:19 PM

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  • HAL Id : tel-00220467, version 1

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Xavier Rondeau. Imagerie à travers la turbulence : mesure inverse du front d'onde et centrage optimal. Modélisation et simulation. Université Claude Bernard - Lyon I, 2007. Français. ⟨tel-00220467⟩

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