[Techniques de réduction du bruit de tavelures pour l'imagerie à haute dynamique]
L'imagerie à haute dynamique dans le visible et depuis l'espace, visant en particulier à la détection d'exoplanètes telluriques, nécessite non seulement l'utilisation d'un coronographe, mais aussi d'une optique adaptative pour corriger les défauts optiques en temps réel. En effet, ces défauts diffusent la lumière et donnent naissance à des tavelures dans le plan image. Les tavelures peuvent être supprimées en pilotant un miroir déformable pour mesurer, puis compenser les aberrations du front d'onde. Dans une première approche, la suppression ciblée de tavelures, les tavelures sont supprimées itérativement en commençant par les plus brillantes. Cette première méthode a permis d'atteindre un contraste de 109 en laboratoire. Dans une deuxième approche, la suppression zonale de tavelures, l'énergie totale du champ de tavelures est minimisée dans une certaine zone du plan image. Cette seconde méthode a pour avantage de s'attaquer simultanément à toutes les tavelures de la zone visée, mais elle doit encore faire ses preuves expérimentalement.
High-dynamic range imaging from space in the visible light range, aiming, in particular, at the detection of terrestrial exoplanets, necessitates not only the use of a coronagraph, but also of adaptive optics to correct optical defects in real time. Indeed, these defects scatter light and give birth to speckles in the image plane. Speckles can be cancelled by driving a deformable mirror to measure and compensate wavefront aberrations. In a first approach, targeted speckle nulling, speckles are cancelled iteratively by starting with the brightest ones. This first method has demonstrated a contrast better than 109 in laboratory. In a second approach, zonal speckle nulling, the total energy of speckles is minimized in a given zone of the image plane. This second method has the advantage of tackling simultaneously all speckles from the targeted zone, but it still needs better experimental demonstration.
Mot clés : Exoplanètes, Coronographie, Tavelures
Pascal Bordé 1 ; Wesley Traub 2
@article{CRPHYS_2007__8_3-4_349_0,
author = {Pascal Bord\'e and Wesley Traub},
title = {Speckle noise reduction techniques for high-dynamic range imaging},
journal = {Comptes Rendus. Physique},
pages = {349--354},
publisher = {Elsevier},
volume = {8},
number = {3-4},
year = {2007},
doi = {10.1016/j.crhy.2007.04.004},
language = {en},
}
Pascal Bordé; Wesley Traub. Speckle noise reduction techniques for high-dynamic range imaging. Comptes Rendus. Physique, Volume 8 (2007) no. 3-4, pp. 349-354. doi : 10.1016/j.crhy.2007.04.004. https://comptes-rendus.academie-sciences.fr/physique/articles/10.1016/j.crhy.2007.04.004/
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