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Proceedings Paper

High-contrast imager for Complex Aperture Telescopes (HiCAT). 4. Status and wavefront control development
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Paper Abstract

Segmented telescopes are a possible approach to enable large-aperture space telescopes for the direct imaging and spectroscopy of habitable worlds. However, the increased complexity of their aperture geometry, due to their central obstruction, support structures and segment gaps, makes high-contrast imaging very challenging. The High-contrast imager for Complex Aperture Telescopes (HiCAT) was designed to study and develop solutions for such telescope pupils using wavefront control and starlight suppression. The testbed design has the flexibility to enable studies with increasing complexity for telescope aperture geometries starting with off-axis telescopes, then on-axis telescopes with central obstruction and support structures (e.g. the Wide Field Infrared Survey Telescope [WFIRST]), up to on-axis segmented telescopes e.g. including various concepts for a Large UV, Optical, IR telescope (LUVOIR), such as the High Definition Space Telescope (HDST). We completed optical alignment in the summer of 2014 and a first deformable mirror was successfully integrated in the testbed, with a total wavefront error of 13nm RMS over a 18mm diameter circular pupil in open loop. HiCAT will also be provided with a segmented mirror conjugated with a shaped pupil representing the HDST configuration, to directly study wavefront control in the presence of segment gaps, central obstruction and spider. We recently applied a focal plane wavefront control method combined with a classical Lyot coronagraph on HiCAT, and we found limitations on contrast performance due to vibration effect. In this communication, we analyze this instability and study its impact on the performance of wavefront control algorithms. We present our Speckle Nulling code to control and correct for wavefront errors both in simulation mode and on testbed mode. This routine is first tested in simulation mode without instability to validate our code. We then add simulated vibrations to study the degradation of contrast performance in the presence of these effects.

Paper Details

Date Published: 29 July 2016
PDF: 13 pages
Proc. SPIE 9904, Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave, 99043C (29 July 2016); doi: 10.1117/12.2233640
Show Author Affiliations
Lucie Leboulleux, Space Telescope Science Institute (United States)
Aix Marseille Univ., Lab. d'Astrophysique de Marseille, CNRS (France)
Office National d'Etudes et de Recherches Aérospatiales (France)
Mamadou N'Diaye, Space Telescope Science Institute (United States)
A. J. Eldorado Riggs, Princeton Univ. (United States)
Sylvain Egron, Space Telescope Science Institute (United States)
Aix Marseille Univ., Lab. d'Astrophysique de Marseille, CNRS (France)
Office National d'Etudes et de Recherches Aérospatiales (France)
Johan Mazoyer, Space Telescope Science Institute (United States)
Laurent Pueyo, Space Telescope Science Institute (United States)
Elodie Choquet, Jet Propulsion Lab. (United States)
Marshall D. Perrin, Space Telescope Science Institute (United States)
Jeremy Kasdin, Princeton Univ. (United States)
Jean-François Sauvage, Aix Marseille Univ., Lab. d'Astrophysique de Marseille, CNRS (France)
Office National d'Etudes et de Recherches Aérospatiales (France)
Thierry Fusco, Aix Marseille Univ., Lab. d'Astrophysique de Marseille, CNRS (France)
Office National d'Etudes et de Recherches Aérospatiales (France)
Rémi Soummer, Space Telescope Science Institute (United States)


Published in SPIE Proceedings Vol. 9904:
Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave
Howard A. MacEwen; Giovanni G. Fazio; Makenzie Lystrup; Natalie Batalha; Nicholas Siegler; Edward C. Tong, Editor(s)

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