AO4ELT5 Proceedings
ZELDA, a Zernike sensor for accurate calibration of aberrations in coronagraphic instruments: validation in VLT/SPHERE and preliminary on-sky results
Vigan, A. (Aix Marseille Univ, CNRS, LAM, Laboratoire dAstrophysique de Marseille, Marseille, France), NDiaye, M. (Universite Cote dAzur, Observatoire de la Cote dAzur, CNRS, Laboratoire Lagrange, UMR 7293, CS 34229, 06304 Nice Cedex 4), Dohlen, K. (Aix Marseille Univ, CNRS, LAM, Laboratoire dAstrophysique de Marseille, Marseille, France), Sauvage, J.-F. (Aix Marseille Univ, CNRS, LAM, Laboratoire dAstrophysique de Marseille, Marseille, France), Caillat, A. (Aix Marseille Univ, CNRS, LAM, Laboratoire dAstrophysique de Marseille, Marseille, France), Costille, A. (Aix Marseille Univ, CNRS, LAM, Laboratoire dAstrophysique de Marseille, Marseille, France), Beuzit, J.-L. (Universite Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France), Blanchard, P. (Aix Marseille Univ, CNRS, LAM, Laboratoire dAstrophysique de Marseille, Marseille, France), Fusco, T. (Aix Marseille Univ, CNRS, LAM, Laboratoire dAstrophysique de Marseille, Marseille, France), Girard, J. (European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile), Kasper, M. (European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany), Le Merrer, J. (Aix Marseille Univ, CNRS, LAM, Laboratoire dAstrophysique de Marseille, Marseille, France), Le Mignant, D. (Aix Marseille Univ, CNRS, LAM, Laboratoire dAstrophysique de Marseille, Marseille, France), Madec, F. (Aix Marseille Univ, CNRS, LAM, Laboratoire dAstrophysique de Marseille, Marseille, France), Mouillet, D. (Universite Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France), Zins, G. (European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile)
Gas giant planets, brown dwarfs, and debris disks around nearby stars are now routinely observed by dedicated high-contrast imaging instruments on large, ground-based observatories. These facilities combine extreme adaptive optics and coronagraphy to achieve unprecedented sensitivities for exoplanet detection and spectral characterization. However, residual quasi-static phase aberrations in these coronagraphic systems represent a critical limitation for the detection of giant planets with a contrast lower than a few 10^(-6) at very small separations (<0.300) from their host star. In 2013 we proposed ZELDA, a Zernike wavefront sensor to measure these phase aberrations at a nanometric level. Relying on a prototype installed in VLT/SPHERE in 2014, we performed multiple tests in December 2015 and demonstrated the capability of our concept to accurately measure well-known aberrations on internal source. We also showed a contrast improvement by a factor of 10 at 0.200 for this instrument by calibrating its residual aberrations with our device. After a brief review of this experimental validation, we present preliminary on-sky results on SPHERE obtained in March 2017. This new data set relies on ZELDA estimate of quasi-static aberrations on the internal source. We finally discuss perspectives for future ELT instrumentation with ZELDA.
DOI: 10.26698/AO4ELT5.0180- Proceeding PDF
