High-contrast imager for complex aperture telescopes (HiCAT). 4. Status and wavefront control development

Lucie Leboulleux, Mamadou N'Diaye, A. J.E. Riggs, Sylvain Egron, Johan Mazoyer, Laurent Pueyo, Elodie Choquet, Marshall D. Perrin, Jeremy Kasdin, Jean François Sauvage, Thierry Fusco, Rémi Soummer

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations

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.

Original languageEnglish (US)
Title of host publicationSpace Telescopes and Instrumentation 2016
Subtitle of host publicationOptical, Infrared, and Millimeter Wave
EditorsHoward A. MacEwen, Makenzie Lystrup, Giovanni G. Fazio
PublisherSPIE
ISBN (Electronic)9781510601871
DOIs
StatePublished - 2016
EventSpace Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave - Edinburgh, United Kingdom
Duration: Jun 26 2016Jul 1 2016

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume9904
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Other

OtherSpace Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave
CountryUnited Kingdom
CityEdinburgh
Period6/26/167/1/16

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

Keywords

  • Exoplanets
  • High-contrast imaging
  • Speckle nulling
  • Vibration analysis
  • Wavefront control
  • Wavefront sensing

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