Séminaire IPAG

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High-contrast imaging: from equations to instruments

jeudi 14 avril 2022 - 11h00

Lucie Leboulleux - IPAG
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Imaging and characterizing exoplanets down to Earth-like planets relies on instrument able to access objects with a contrast to their host star of the order of 10-10-10-8, at short angular separations (<0.1’’). However, such instruments are complex to design, extremely sensitive to optical aberrations and instabilities, and tend to be set on giant telescopes with a segmented mirror that increases the number of possible sources of instabilities: the Extremely Large Telescope (39m and 798 segments), the Thirty Meter Telescope (30m, 492 segments), the Giant Magellan Telescope (24m, 7 segments), possibly the LUVOIR space telescope (6m)… Among other sources of errors, their coronagraphic instruments will be impacted by segment phasing errors: on LUVOIR, for instance, a 10-10 contrast implies phasing constraints down to 10pm RMS, which can currently not be accessed and maintained. During this seminar, I develop an innovative approach to this problematic, by telling the story of PASTIS (Pair-based Analytical model for Segmented Telescopes Imaging from Space), an analytical model first invented to characterize coronagraphic instruments and to set constraints on the telescope segment alignment, and then used to directly design instruments robust to segment phasing errors. This approach is also extended to two other types of aberrations expected on coming ground-based telescopes: post-adaptive optics system petaling effects and the low-wind effect, the latest already limiting VLT/SPHERE and Subaru telescope high-contrast performance.

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Hôtes : Alexis Carlotti

Salle Manuel Forestini, 414 rue de la piscine, 38400 Saint Martin d'Hères