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Proceedings Paper

High contrast imaging with an arbitrary aperture: active correction of aperture discontinuities: fundamental limits and practical trade- offs
Author(s): Laurent Pueyo; Colin Norman; Rémi Soummer; Marshall Perrin; Mamadou N'Diaye; Élodie Choquet; Jordan Hoffmann; Alexis Carlotti; Dimitri Mawet
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Paper Abstract

We present a new method to achieve high-contrast images using segmented and/or on-axis telescopes. Our approach relies on using two sequential Deformable Mirrors to compensate for the large amplitude excursions in the telescope aperture due to secondary support structures and / or segment gaps. We solve the highly non-linear Monge-Ampere equation that is the fundamental equation describing the physics of phase induced amplitude modulation. We determine the optimum configuration for our two sequential Deformable Mirror system and show that high-throughput and high contrast solutions can be achieved using realistic surface deformations that are accessible using existing technologies. We name this process Active Compensation of Aperture Discontinuities (ACAD). We show that for geometries similar to JWST, ACAD can attain at least 10-7 in contrast and an order of magnitude higher for future Extremely Large Telescopes, even when the pupil features a "missing segment" . Because the converging non-linear mappings resulting from our Deformable Mirror shapes damps near-field diffraction artifacts in the vicinity of the discontinuities this solution is particularly appealing in terms of spectral bandwidth. We present preliminary results that illustrate the performances of ACAD in the presence of diffraction for apertures for with secondary support structures of varying width and argue that the ultimate contrast achieved can by combining ACAD with modern wavefront control algorithms.

Paper Details

Date Published: 28 August 2014
PDF: 15 pages
Proc. SPIE 9143, Space Telescopes and Instrumentation 2014: Optical, Infrared, and Millimeter Wave, 914321 (28 August 2014); doi: 10.1117/12.2056925
Show Author Affiliations
Laurent Pueyo, Space Telescope Science Institute (United States)
Colin Norman, Johns Hopkins Univ. (United States)
Rémi Soummer, Space Telescope Science Institute (United States)
Marshall Perrin, Space Telescope Science Institute (United States)
Mamadou N'Diaye, Space Telescope Science Institute (United States)
Élodie Choquet, Space Telescope Science Institute (United States)
Jordan Hoffmann, Johns Hopkins Univ. (United States)
Alexis Carlotti, Univ. Joseph Fourier (France)
Dimitri Mawet, European Southern Observatory (Chile)

Published in SPIE Proceedings Vol. 9143:
Space Telescopes and Instrumentation 2014: Optical, Infrared, and Millimeter Wave
Jacobus M. Oschmann Jr.; Mark Clampin; Giovanni G. Fazio; Howard A. MacEwen, Editor(s)

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