Mid-order wavefront control for exoplanet imaging: preliminary characterization of the segmented deformable mirror and Zernike wavefront sensor on HiCAT

Benjamin Buralli; Mamadou N'Diaye; Raphaël Pourcelot; Marcel Carbillet; Emiel H. Por; Iva Laginja; Ludovic Canas; Sarah Steiger; Peter Petrone; Meiji M. Nguyen; Bryony Nickson; Susan F. Redmond; Ananya Sahoo; Laurent Pueyo; Marshall D. Perrin; Rémi Soummer

doi:10.1117/12.3018900

23 August 2024 Mid-order wavefront control for exoplanet imaging: preliminary characterization of the segmented deformable mirror and Zernike wavefront sensor on HiCAT

Benjamin Buralli, Mamadou N'Diaye, Raphaël Pourcelot, Marcel Carbillet, Emiel H. Por, Iva Laginja, Ludovic Canas, Sarah Steiger, Peter Petrone, Meiji M. Nguyen, Bryony Nickson, Susan F. Redmond, Ananya Sahoo, Laurent Pueyo, Marshall D. Perrin, Rémi Soummer

Author Affiliations +

Proceedings Volume 13092, Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave; 1309268 (2024) https://doi.org/10.1117/12.3018900
Event: SPIE Astronomical Telescopes + Instrumentation, 2024, Yokohama, Japan

Conference Poster

Abstract

We study a mid-order wavefront sensor (MOWFS) to address fine cophasing errors in exoplanet imaging with future large segmented aperture space telescopes. Observing Earth analogs around Sun-like stars requires contrasts down to 10−10 in visible light. One promising solution consists of producing a high-contrast dark zone in the image of an observed star. In a space observatory, this dark region will be altered by several effects, and among them, the small misalignments of the telescope mirror segments due to fine thermo-mechanical drifts. To correct for these errors in real time, we investigate a wavefront control loop based on a MOWFS with a Zernike sensor. Such a MOWFS was installed on the high-contrast imager for complex aperture telescopes (HiCAT) testbed in Baltimore in June 2023. The bench uses a 37-segment Iris-AO deformable mirror to mimic telescope segmentation and some wavefront control strategies to produce a dark zone with such an aperture. In this contribution, we first use the MOWFS to characterize the Iris-AO segment discretization steps. For the central segment, we find a minimal step of 125 ±31 pm. This result will help us to assess the contribution of the Iris-AO DM on the contrast in HiCAT. We then determine the detection limits of the MOWFS, estimating wavefront error amplitudes of 119 and 102 pm for 10 s and 1 min exposure time with a SNR of 3. These values inform us about the measurement capabilities of our wavefront sensor on the testbed. These preliminary results will be useful to provide insights on metrology and stability for exo-Earth observations with the Habitable Worlds Observatory.

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

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Benjamin Buralli, Mamadou N'Diaye, Raphaël Pourcelot, Marcel Carbillet, Emiel H. Por, Iva Laginja, Ludovic Canas, Sarah Steiger, Peter Petrone, Meiji M. Nguyen, Bryony Nickson, Susan F. Redmond, Ananya Sahoo, Laurent Pueyo, Marshall D. Perrin, and Rémi Soummer "Mid-order wavefront control for exoplanet imaging: preliminary characterization of the segmented deformable mirror and Zernike wavefront sensor on HiCAT", Proc. SPIE 13092, Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave, 1309268 (23 August 2024); https://doi.org/10.1117/12.3018900

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