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Étude de techniques d'imagerie à haut contraste basées sur la cohérence

Abstract : Only 3% of known exoplanets have been directly detected up to now for several reasons. First, they are very close to their parent star, which sets a minimum telescope size and requires the use of an atmospheric turbulence compensator. Then, the star is so bright compared to its planets (one million to ten billions) that the reduction of its light through a coronagraph is mandatory. Finally, we need to compensate or estimate optical aberrations which drastically limit the coronagraph performances. During my PhD Thesis, I worked on two instruments: the Multi-stage Four Quadrant Phase Mask (MFQPM) coronagraph to reduce the star light, and the Self-Coherent Camera (SCC) which minimizes optical errors using incoherence between star and planet lights. In a laboratory experiment, I showed that 1000-- 10,000 star flux reduction is possible from 550 and 750nm with a non-optimized MFQPM. Then, I numerically demonstrated that SCC can be associated with a Lyot style coronagraph to provide Earth-like planet detection from space and under realistic assumptions. That technique works in two steps: focal plane wavefront sensing and differential imaging. Finally, I provided a SCC phase measurement in a laboratory experiment.
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Contributor : Raphaël Galicher <>
Submitted on : Friday, December 11, 2009 - 8:56:38 PM
Last modification on : Monday, December 14, 2020 - 9:48:24 AM
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  • HAL Id : tel-00436293, version 2


Raphaël Galicher. Étude de techniques d'imagerie à haut contraste basées sur la cohérence. Astrophysique [astro-ph]. Université Paris-Diderot - Paris VII, 2009. Français. ⟨tel-00436293v2⟩



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