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Proceedings Paper

ZELDA, a Zernike wavefront sensor for the fine measurement of quasi-static aberrations in coronagraphic systems: concept studies and results with VLT/SPHERE
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Paper Abstract

The high-contrast imaging instruments VLT/SPHERE and GPI have been routinely observing gas giant planets, brown dwarfs, and debris disks around nearby stars since 2013-2014. In these facilities, low-wind effects or differential aberrations between the extreme Adaptive Optics sensing path and the science path represent critical limitations for the observation of exoplanets orbiting their host star with a contrast ratio larger than 106 at small separations. To circumvent this problem, we proposed ZELDA, a Zernike wavefront sensor to measure these quasistatic aberrations at a nanometric level. A prototype was installed on VLT/SPHERE during its integration in Chile. We recently performed measurements on an internal source with ZELDA in the presence of Zernike or Fourier modes introduced with the deformable mirror of the instrument. In this communication, we present the results of our experiment and report on the contrast gain obtained with a first ZELDA-based wavefront correction. We finally discuss the suitability of such a solution for a possible upgrade of VLT/SPHERE and for its use with future E-ELT instruments or space missions with high-contrast capabilities (e.g. WFIRST-AFTA, HDST).

Paper Details

Date Published: 27 July 2016
PDF: 14 pages
Proc. SPIE 9909, Adaptive Optics Systems V, 99096S (27 July 2016); doi: 10.1117/12.2232463
Show Author Affiliations
M. N'Diaye, Space Telescope Science Institute (United States)
A. Vigan, Aix-Marseille Univ., CNRS, LAM (France)
European Southern Observatory (Chile)
K. Dohlen, Aix-Marseille Univ., CNRS, LAM (France)
J.-F. Sauvage, ONERA (France)
Aix-Marseille Univ., CNRS, LAM (France)
A. Caillat, Aix-Marseille Univ., CNRS, LAM (France)
A. Costille, Aix-Marseille Univ., CNRS, LAM (France)
J. H. V. Girard, European Southern Observatory (Chile)
J.-L. Beuzit, CNRS, IPAG, Univ. Grenoble Alpes (France)
T. Fusco, ONERA (France)
Aix-Marseille Univ., CNRS, LAM (France)
P. Blanchard, Aix-Marseille Univ., CNRS, LAM (France)
J. Le Merrer, Aix-Marseille Univ., CNRS, LAM (France)
D. Le Mignant, Aix-Marseille Univ., CNRS, LAM (France)
F. Madec, Aix-Marseille Univ., CNRS, LAM (France)
G. Moreaux, Aix-Marseille Univ., CNRS, LAM (France)
D. Mouillet, CNRS, IPAG, Univ. Grenoble Alpes (France)
P. Puget, CNRS, IPAG, Univ. Grenoble Alpes (France)
G. Zins, European Southern Observatory (Chile)
CNRS, IPAG, Univ. Grenoble Alpes (France)


Published in SPIE Proceedings Vol. 9909:
Adaptive Optics Systems V
Enrico Marchetti; Laird M. Close; Jean-Pierre Véran, Editor(s)

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