High-contrast imager for complex aperture telescopes (HiCAT): 5. first results with segmented-aperture coronagraph and wavefront control

Rémi Soummer (1) , Gregory R. Brady (1) , Keira Brooks (1) , Thomas Comeau (1) , Elodie Choquet (2) , Thomas Dillon (3) , Sylvain Egron (4) , Rob Gontrum (1) , John Hagopian (5) , Iva Laginja (1) , Lucie Leboulleux (1, 6, 7) , Marshall D. Perrin (1) , Peter Petrone (1, 8) , Laurent Pueyo (1) , Johan Mazoyer (9) , Mamadou N'Diaye (10, 11) , A.J. Eldorado Riggs (12) , Ron Shiri (13) , Anand Sivaramakrishnan (1) , Kathryn St. Laurent (1) , Ana-Maria Valenzuela (1) , Neil Zimmerman (13)

1 STSci - Space Telescope Science Institute
2 Caltech Department of Astronomy [Pasadena]
3 University of Delaware [Newark]
4 Iridescence SARL
5 Advanced Nanophotonics
6 LAM - Laboratoire d'Astrophysique de Marseille
7 DOTA, ONERA, Université Paris Saclay (COmUE) [Châtillon]
8 SigmaSpace Corporation [Lanham, MD]
9 JHU - Johns Hopkins University
10 OCA - Observatoire de la Côte d'Azur
11 LAGRANGE - Joseph Louis LAGRANGE
12 JPL - Jet Propulsion Laboratory
13 GSFC - NASA Goddard Space Flight Center

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 the central obstruction, support structures and segment gaps, makes high-contrast imaging very challenging. The High-contrast imager for Complex Aperture Telescopes (HiCAT) testbed was designed to study and develop solutions for such telescope pupils using wavefront control and coronagraphic 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, including various concepts for a Large UV, Optical, IR telescope (LUVOIR). In the past year, HiCAT has made significant hardware and software updates in order to accelerate the development of the project. In addition to completely overhauling the software that runs the testbed, we have completed several hardware upgrades, including the second and third deformable mirror, and the first custom Apodized Pupil Lyot Coronagraph (APLC) optimized for the HiCAT aperture, which is similar to one of the possible geometries considered for LUVOIR. The testbed also includes several external metrology features for rapid replacement of parts, and in particular the ability to test multiple apodizers readily, an active tip-tilt control system to compensate for local vibration and air turbulence in the enclosure. On the software and operations side, the software infrastructure enables 24/7 automated experiments that include routine calibration tasks and high-contrast experiments. In this communication we present an overview and status update of the project, both on the hardware and software side, and describe the results obtained with APLC wavefront control.

Mots clés: SPACE TELESCOPES; WAVEFRONTS; TELESCOPES; METROLOGY; PHASE RETRIEVAL; CARBON NANOTUBES; Segmented telescopes; coronagraphy; exoplanet; high-contrast imaging; coronagraphy testbed; Apodized Pupil Lyot Coronagraph; APLC

Domaines: Sciences de l'ingénieur [physics]; Physique [physics]

Rémi Soummer, Gregory R. Brady, Keira Brooks, Thomas Comeau, Elodie Choquet, et al.. High-contrast imager for complex aperture telescopes (HiCAT): 5. first results with segmented-aperture coronagraph and wavefront control. SPIE Astronomical Telescopes + Instrumentation, 2018, Jun 2018, AUSTIN, United States. ⟨10.1117/12.2314110⟩. ⟨hal-02333032⟩