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SPHERE on-sky performance compared with budget predictions

Dohlen, Kjetil and Vigan, Arthur and Mouillet, David and Wildi, Francois and Sauvage, Jean Francois and Fusco, Thierry and Beuzit, Jean-Luc and Puget, Pascal and Le Mignant, David and Roelfsema, Ronald and Pragt, Johan and Schmid, Hands Martin and Gratton, Raffaele and Mesa, Dino and Claudi, Ricardo and Langlois, Maud and Costille, Anne and Hugot, Emmanuel and O'Neil, Jared and Guerra, Juan Carlos and N'Diaye, Mamadou and Girard, Julien and Mawet, Dimitri and Zins, Gerard (2016) SPHERE on-sky performance compared with budget predictions. In: Ground-based and Airborne Instrumentation for Astronomy VI. Proceedings of SPIE. No.9908. Society of Photo-Optical Instrumentation Engineers (SPIE) , Bellingham, WA, Art. No. 99083D. ISBN 978-1-5106-0196-3.

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The SPHERE (spectro-photometric exoplanet research) extreme-AO planet hunter saw first light at the VLT observatory on Mount Paranal in May 2014 after ten years of development. Great efforts were put into modelling its performance, particularly in terms of achievable contrast, and to budgeting instrumental features such as wave front errors and optical transmission to each of the instrument’s three focal planes, the near infrared dual imaging camera IRDIS, the near infrared integral field spectrograph IFS and the visible polarimetric camera ZIMPOL. In this paper we aim at comparing predicted performance with measured performance. In addition to comparing on-sky contrast curves and calibrated transmission measurements, we also compare the PSD-based wave front error budget with in-situ wave front maps obtained thanks to a Zernike phase mask, ZELDA, implemented in the infrared coronagraph wheel. One of the most critical elements of the SPHERE system is its high-order deformable mirror, a prototype 40x40 actuator piezo stack design developed in parallel with the instrument itself. The development was a success, as witnessed by the instrument performance, in spite of some bad surprises discovered on the way. The devastating effects of operating without taking properly into account the loss of several actuators and the thermally and temporally induced variations in the DM shape will be analysed, and the actions taken to mitigate these defects through the introduction of specially designed Lyot stops and activation of one of the mirrors in the optical train will be described.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Vigan, Arthur0000-0002-5902-7828
Hugot, Emmanuel0000-0002-5879-6318
N'Diaye, Mamadou0000-0002-1721-3294
Girard, Julien0000-0001-8627-0404
Mawet, Dimitri0000-0002-8895-4735
Additional Information:© 2016 Society of Photo-Optical Instrumentation Engineers (SPIE). SPHERE is an instrument designed and built by a consortium consisting of IPAG, MPIA, LAM, LESIA, Laboratoire Fizeau, INAF, Observatoire de Genève, ETH, NOVA, ONERA and ASTRON in collaboration with ESO. We are grateful to all the consortium members who contributed to build, test, and validate the instrument in Europe and in Chile. We also thank the ESO staff involved with the installation and operation of SPHERE on the VLT-UT3.
Subject Keywords:Extreme adaptive optics, High contrast imaging, System analysis, Wave front PSD budgeting
Series Name:Proceedings of SPIE
Issue or Number:9908
Record Number:CaltechAUTHORS:20170217-082008486
Persistent URL:
Official Citation:Kjetil Dohlen ; Arthur Vigan ; David Mouillet ; François Wildi ; Jean-François Sauvage ; Thierry Fusco ; Jean-Luc Beuzit ; Pascal Puget ; David Le Mignant ; Ronald Roelfsema ; Johan Pragt ; Hans Martin Schmid ; Raffaele Gratton ; Dino Mesa ; Riccardo Claudi ; Maud Langlois ; Anne Costille ; Emmanuel Hugot ; Jared O'Neil ; Juan Carlos Guerra ; Mamadou N'Diaye ; Julien Girard ; Dimitri Mawet ; Gerard Zins; SPHERE on-sky performance compared with budget predictions. Proc. SPIE 9908, Ground-based and Airborne Instrumentation for Astronomy VI, 99083D (August 9, 2016); doi:10.1117/12.2233953.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:74399
Deposited By: Ruth Sustaita
Deposited On:18 Feb 2017 04:30
Last Modified:11 Oct 2019 23:47

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