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Proceedings Paper

Advances in detector technologies for visible and infrared wavefront sensing
Author(s): Philippe Feautrier; Jean-Luc Gach; Mark Downing; Paul Jorden; Johann Kolb; Johan Rothman; Thierry Fusco; Philippe Balard; Eric Stadler; Christian Guillaume; David Boutolleau; Gérard Destefanis; Nicolas Lhermet; Olivier Pacaud; Michel Vuillermet; Alexandre Kerlain; Norbert Hubin; Javier Reyes; Markus Kasper; Olaf Ivert; Wolfgang Suske; Andrew Walker; Michael Skegg; Sophie Derelle; Joel Deschamps; Clélia Robert; Nicolas Vedrenne; Frédéric Chazalet; Julien Tanchon; Thierry Trollier; Alain Ravex; Gérard Zins; Pierre Kern; Thibaut Moulin; Olivier Preis
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Paper Abstract

The purpose of this paper is to give an overview of the state of the art wavefront sensor detectors developments held in Europe for the last decade. The success of the next generation of instruments for 8 to 40-m class telescopes will depend on the ability of Adaptive Optics (AO) systems to provide excellent image quality and stability. This will be achieved by increasing the sampling, wavelength range and correction quality of the wave front error in both spatial and time domains. The modern generation of AO wavefront sensor detectors development started in the late nineties with the CCD50 detector fabricated by e2v technologies under ESO contract for the ESO NACO AO system. With a 128x128 pixels format, this 8 outputs CCD offered a 500 Hz frame rate with a readout noise of 7e-. A major breakthrough has been achieved with the recent development by e2v technologies of the CCD220. This 240x240 pixels 8 outputs EMCCD (CCD with internal multiplication) has been jointly funded by ESO and Europe under the FP6 programme. The CCD220 and the OCAM2 camera that operates the detector are now the most sensitive system in the world for advanced adaptive optics systems, offering less than 0.2 e readout noise at a frame rate of 1500 Hz with negligible dark current. Extremely easy to operate, OCAM2 only needs a 24 V power supply and a modest water cooling circuit. This system, commercialized by First Light Imaging, is extensively described in this paper. An upgrade of OCAM2 is foreseen to boost its frame rate to 2 kHz, opening the window of XAO wavefront sensing for the ELT using 4 synchronized cameras and pyramid wavefront sensing. Since this major success, new developments started in Europe. One is fully dedicated to Natural and Laser Guide Star AO for the E-ELT with ESO involvement. The spot elongation from a LGS Shack Hartman wavefront sensor necessitates an increase of the pixel format. Two detectors are currently developed by e2v. The NGSD will be a 880x840 pixels CMOS detector with a readout noise of 3 e (goal 1e) at 700 Hz frame rate. The LGSD is a scaling of the NGSD with 1760x1680 pixels and 3 e readout noise (goal 1e) at 700 Hz (goal 1000 Hz) frame rate. New technologies will be developed for that purpose: advanced CMOS pixel architecture, CMOS back thinned and back illuminated device for very high QE, full digital outputs with signal digital conversion on chip. In addition, the CMOS technology is extremely robust in a telescope environment. Both detectors will be used on the European ELT but also interest potentially all giant telescopes under development. Additional developments also started for wavefront sensing in the infrared based on a new technological breakthrough using ultra low noise Avalanche Photodiode (APD) arrays within the RAPID project. Developed by the SOFRADIR and CEA/LETI manufacturers, the latter will offer a 320x240 8 outputs 30 microns IR array, sensitive from 0.4 to 3.2 microns, with 2 e readout noise at 1500 Hz frame rate. The high QE response is almost flat over this wavelength range. Advanced packaging with miniature cryostat using liquid nitrogen free pulse tube cryocoolers is currently developed for this programme in order to allow use on this detector in any type of environment. First results of this project are detailed here. These programs are held with several partners, among them are the French astronomical laboratories (LAM, OHP, IPAG), the detector manufacturers (e2v technologies, Sofradir, CEA/LETI) and other partners (ESO, ONERA, IAC, GTC). Funding is: Opticon FP6 and FP7 from European Commission, ESO, CNRS and Université de Provence, Sofradir, ONERA, CEA/LETI and the French FUI (DGCIS).

Paper Details

Date Published: 13 September 2012
PDF: 33 pages
Proc. SPIE 8447, Adaptive Optics Systems III, 84470Q (13 September 2012); doi: 10.1117/12.925067
Show Author Affiliations
Philippe Feautrier, Institut de Planétologie et d'Astrophysique de Grenoble, UJF-Grenoble I, CNRS-INSU (France)
First Light Imaging (France)
Jean-Luc Gach, Observatoire Astronomique de Marseille-Provence (France)
First Light Imaging (France)
Mark Downing, European Southern Observatory (Germany)
Paul Jorden, e2v technologies (United Kingdom)
Johann Kolb, European Southern Observatory (Germany)
Johan Rothman, CEA-LETI-Minatec (France)
Thierry Fusco, ONERA (France)
Philippe Balard, Observatoire Astronomique de Marseille-Provence (France)
First Light Imaging (France)
Eric Stadler, Institut de Planétologie et d'Astrophysique de Grenoble, UJF-Grenoble I, CNRS-INSU (France)
First Light Imaging (France)
Christian Guillaume, Observatoire de Haute-Provence (France)
First Light Imaging (France)
David Boutolleau, First Light Imaging (France)
Gérard Destefanis, CEA-LETI-Minatec (France)
Nicolas Lhermet, CEA-LETI-Minatec (France)
Olivier Pacaud, SOFRADIR (France)
Michel Vuillermet, SOFRADIR (France)
Alexandre Kerlain, SOFRADIR (France)
Norbert Hubin, European Southern Observatory (Germany)
Javier Reyes, European Southern Observatory (Germany)
Markus Kasper, European Southern Observatory (Germany)
Olaf Ivert, European Southern Observatory (Germany)
Wolfgang Suske, e2v technologies (United Kingdom)
Andrew Walker, e2v technologies (United Kingdom)
Michael Skegg, e2v technologies (United Kingdom)
Sophie Derelle, ONERA (France)
Joel Deschamps, ONERA (France)
Clélia Robert, ONERA (France)
Nicolas Vedrenne, ONERA (France)
Frédéric Chazalet, SHAKTI (France)
Julien Tanchon, Absolut Systems (France)
Thierry Trollier, Absolut Systems (France)
Alain Ravex, Absolut Systems (France)
Gérard Zins, Institut de Planétologie et d'Astrophysique de Grenoble, UJF-Grenoble I, CNRS-INSU (France)
Pierre Kern, Institut de Planétologie et d'Astrophysique de Grenoble, UJF-Grenoble I, CNRS-INSU (France)
Thibaut Moulin, Institut de Planétologie et d'Astrophysique de Grenoble, UJF-Grenoble I, CNRS-INSU (France)
Olivier Preis, Institut de Planétologie et d'Astrophysique de Grenoble, UJF-Grenoble I, CNRS-INSU (France)

Published in SPIE Proceedings Vol. 8447:
Adaptive Optics Systems III
Brent L. Ellerbroek; Enrico Marchetti; Jean-Pierre Véran, Editor(s)

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