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287 results on '"Gérard Rousset"'

101. Temporal convergence of phase spatial covariance matrix measurements in tomographic adaptive optics

Author: O. Martin, Eric Gendron, Fabrice Vidal, Gérard Rousset, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Haute résolution angulaire en astrophysique, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Tomographic reconstruction, Covariance function, Computer science, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, System identification, Phase (waves), Estimator, Matrix (mathematics), Convergence (routing), Computer vision, Tomography, Artificial intelligence, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Adaptive optics, business, Algorithm
Abstract: International audience; The identification of spatial covariance matrices is required in adaptive optics in order to perform tomographic reconstruction with optimal estimators. We use on-sky measurements from Canary, the on-sky demonstrator of MOAO for EAGLE, to study the statistical convergence of the spatial covariance of Shack-Hartmann measurements. We describe a new, faster, analytical approximated model for this spatial covariance, and finally bring into light a new procedure for model identification, reducing the tomographic error. We quantify the gain brought by the new approach on both numerical simulations and on-sky data.
Published: 2012

102. Vibrations in AO control: a short analysis of on-sky data around the world

Author: Jean Pierre Veran, Henri-François Raynaud, Carlos Correia, Benoit Neichel, Guido Agapito, Gaetano Sivo, Fabrice Vidal, Olivier Guyon, Simone Esposito, Fernando Quiros-Pacheco, Lorenzo Pettazzi, Frantz Martinache, Jean Marc Conan, Richard Clare, Julian C. Christou, Caroline Kulcsár, Tim Morris, Eric Gendron, Andrés Guesalaga, Gérard Rousset, Enrico Fedrigo, Serge Meimon, Francois Rigaut, Riccardo Muradore, Laboratoire de Traitement et Transport de l'Information (L2TI), Université Paris 13 (UP13)-Institut Galilée-Université Sorbonne Paris Cité (USPC), ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), Gemini Observatory, University of Hawai'i [Hilo], Universidad Católica de la Santísima Concepción (UCSC), NRC Herzberg Institute of Astrophysics, National Research Council of Canada (NRC), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Physics [Durham University], Durham University, INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), European Southern Observatory (ESO), Department of Computer Science [Verona] (UNIVR | DI), University of Verona (UNIVR), Subaru Telescope, National Astronomical Observatory of Japan (NAOJ), ONERA, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Dipartimento di Informatica [Verona], and Università degli Studi di Verona
Subjects: Optical telescopes, Tip-tilt, Vibration peak, Astrophysics::Cosmology and Extragalactic Astrophysics, Residual, 01 natural sciences, [SPI.AUTO]Engineering Sciences [physics]/Automatic, 010309 optics, Vibrations (mechanical), Optics, Power spectral density, Control theory, 0103 physical sciences, William Herschel Telescope, Discrete time control systems, LQG control, Adaptive optics, 010303 astronomy & astrophysics, High frequency vibration, ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics, Very large telescope, Physics, Very Large Telescope, Large binocular telescope, Controllers, business.industry, Disturbance identification, Atmospheric turbulence, Astrophysics::Instrumentation and Methods for Astrophysics, Identification (control systems), Large Binocular Telescope, Ranging, Vibration mitigation, H2 control, Spectrum analysis, William herschel telescopes, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Residual vibrations, Vibration, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Adaptive Optics, Adaptive optics systems, business, [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing, Telescopes
Abstract: We present in this paper an analysis of several tip-tilt on-sky data registered on adaptive optics systems installed on different telescopes (Gemini South, William Herschel Telescope, Large Binocular Telescope, Very Large Telescope, Subaru). Vibration peaks can be detected, and it is shown that their presence and location may vary, and that their origin is not always easy to determine. Mechanical solution that have been realized to mitigate vibrations are presented. Nevertheless, residual vibrations may still affect the instruments' performance, ranging from narrow high frequency vibration peaks to wide low frequency windshake-type perturbations. Power Spectral Densities (PSDs) of on-sky data are presented to evidence these features. When possible, indications are given regarding the gain in performance that could be achieved with adequate controllers accounting for vibration mitigation. Two examples of controller identification and design illustrate their ability to compensate for various types of disturbances (turbulence, windshake, vibration peaks, ...), showing a significant gain in performance. © 2012 SPIE., Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, the Netherlands, Series: Proceedings of SPIE; no. 8447
Published: 2012

103. The EAGLE instrument for the E-ELT: developments since delivery of Phase A

Author: Phil Parr-Burman, Simon L. Morris, Chris Evans, Gérard Rousset, Pascal Jagourel, Hermine Schnetler, Marc Dubbeldam, Richard M. Myers, Jean-Gabriel Cuby, Thierry Fusco, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Haute résolution angulaire en astrophysique, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), Galactic astronomy, Computer science, FOS: Physical sciences, Astronomy, First light, Redshift, Galaxy, Integral field spectrograph, Observatory, Extremely Large Telescope, William Herschel Telescope, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Spectrograph, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: The EAGLE instrument is a Multi-Object Adaptive Optics (MOAO) fed, multiple Integral Field Spectrograph (IFS), working in the Near Infra-Red (NIR), on the European Extremely Large Telescope (E-ELT). A Phase A design study was delivered to the European Southern Observatory (ESO) leading to a successful review in October 2009. Since that time there have been a number of developments, which we summarize here. Some of these developments are also described in more detail in other submissions at this meeting. The science case for the instrument, while broad, highlighted in particular: understanding the stellar populations of galaxies in the nearby universe, the observation of the evolution of galaxies during the period of rapid stellar build-up between redshifts of 2-5, and the search for 'first light' in the universe at redshifts beyond 7. In the last 2 years substantial progress has been made in these areas, and we have updated our science case to show that EAGLE is still an essential facility for the E-ELT. This in turn allowed us to revisit the science requirements for the instrument, confirming most of the original decisions, but with one modification. The original location considered for the instrument (a gravity invariant focal station) is no longer in the E-ELT Construction Proposal, and so we have performed some preliminary analyses to show that the instrument can be simply adapted to work at the E-ELT Nasmyth platform. Since the delivery of the Phase A documentation, MOAO has been demonstrated on-sky by the CANARY experiment at the William Herschel Telescope., 10 pages, SPIE Conference proceedings, Amsterdam, July 2012
Published: 2012

104. Deformable mirrors for open-loop adaptive optics

Author: A. Kellerer, Z. Hubert, D. Perret, Gérard Rousset, Fabrice Vidal, Eric Gendron, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Haute résolution angulaire en astrophysique, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Physics, Test bench, Optics, Observatory, business.industry, Open-loop controller, Linearity, Adaptive optics, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Deformable mirror
Abstract: International audience; We characterize the performance of deformable mirrors for use in open-loop regimes. This is especially relevant for Multi Object Adaptive Optics (MOAO), or for closed-loop schemes that require improved accuracies. Deformable mirrors are usually characterized by standard parameters, such as influence functions, linearity, hysteresis, etc. We show that these parameters are insufficient for characterizing open-loop performance and that a deeper analysis of the mirror's behavior is then required. The measurements on the deformable mirrors were performed in 2007 on the AO test bench of the Meudon observatory, SESAME.
Published: 2012

105. Tests of open-loop LGS tomography with CANARY

Author: Colin Dickson, Eric Gendron, Tim Morris, Paul Clark, Fabrice Vidal, Richard M. Myers, Gérard Rousset, Brian Stobie, Zoltan Hubert, David Henry, Fanny Chemla, Alastair Basden, M. Cohen, Andy Longmore, David Atkinson, J. M. Huet, Andrew P. Reeves, Nigel Dipper, E. Younger, Stephen Todd, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Haute résolution angulaire en astrophysique, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Wavefront, Physics, business.industry, Phase (waves), Field of view, Deformable mirror, Laser guide star, Optics, Calibration, Tomography, Adaptive optics, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Remote sensing
Abstract: CANARY is an on-sky demonstrator adaptive optics (AO) system that in 2010 provided the first on-sky demonstration of open-loop tomographic adaptive optics correction using natural guide stars (NGS). Phase B of the CANARY experiment aims to extend the instrument from its original configuration by also measuring wavefronts from four offaxis Rayleigh laser guide stars (LGS). This upgrade allows CANARY to perform tomographic wavefront sensing over a 2.5arcminute field of view using any mix of up to seven off-axis wavefront sensors (four LGS and three NGS) simultaneously. AO correction within CANARY is performed on-axis along a single line of sight using a 52-actuator deformable mirror being controlled in open-loop. Here we give an overview of the Phase B LGS system, discuss the calibration of a mixed NGS/LGS tomographic system and present the recent laboratory and on-sky results from the Phase B commissioning.
Published: 2012

106. GPUs for adaptive optics: simulations and real-time control

Author: Gérard Rousset, Damien Gratadour, J. Brulé, Arnaud Sevin, Eric Gendron, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Haute résolution angulaire en astrophysique, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Wavefront, Turbulence, Computer science, Real-time computing, Degrees of freedom (mechanics), Computational science, law.invention, System model, Telescope, Real-time Control System, Control theory, law, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Massively parallel, Data transmission
Abstract: International audience; With the emergence of General Purpose computations on Graphic Processing Units (GP-GPUs) this architecture has become amazingly attractive for large scale applications such as numerical simulations of complex systems. While the number of degrees of freedom of an adaptive optics (AO) system scales with the square of the telescope diameter, the system model exhibits a rather high level of parallelism especially when simulating Shack-Hartmann (SH) wavefront sensors (WFS). The use of massively parallel devices such as GPUs to simulate next generation AO systems for the European Extremely Large Telescope (E-ELT) thus makes a lot of sense. Our team has developed such simulation tools and first results show that speeds of about a thousand of iterations per second were achievable on a single high-end GPU for an eXtreme (X)AO system such as SPHERE including a single layer turbulence model generated on-the-fly. These numerical models include all the operations executed by the real-time controller (RTC) of a real system. The achieved simulation speeds show that a single high-end GPU could drive a XAO system on the VLT and, depending on the centroiding algorithm and the control scheme chosen, could even drive a classical AO system on the E-ELT. While the main challenge resides in the data transfer speed to and from the GPU, developing and testing AO control algorithms for the simulation code on the same hardware as the system RTC would bring a lot of benefits. In this paper we present the simulation results as well as strategies to build GPU-powered AO systems.
Published: 2012

107. Estimation of errors on the PSF reconstruction process for myopic deconvolution

Author: Damien Gratadour, Gérard Rousset, Yann Clénet, Laurent M. Mugnier, J. Exposito, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Haute résolution angulaire en astrophysique, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), ONERA - The French Aerospace Lab [Châtillon], and ONERA-Université Paris Saclay (COmUE)
Subjects: Wavefront, Point spread function, business.industry, Computer science, Gaussian, Image processing, Covariance, symbols.namesake, Aliasing, Optical transfer function, symbols, Computer vision, Deconvolution, Artificial intelligence, business, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: International audience; Images obtained with adaptive optics (AO) systems can be improved by using restoration techniques, the AO correction being only partial. However, these methods require an accurate knowledge of the system point spread function (PSF). Adaptive optics systems allow one to estimate the point spread function (PSF) during the science observation. Using data from the wave-front sensor (WFS), a direct estimation of the averaged parallel phase structure and an estimation of the noise on the measurements are provided. The averaged orthogonal phase structure (not seen by the system), and the aliasing covariance are estimated using an end-to-end AO simulation. Finally, the estimated PSF is reconstructed using the algorithm of Veran et al. (1997). 1 However, this reconstruction is non perfect. Several approximations are done (stationary resudual phase, gaussian phase, simulated aliasing, etc...) and can impact the optical transfer function (OTF) in the case of a rather poor correction. Our aim is to give an error budget for the whole PSF reconstruction process and to link this PSF reconstruction with a deconvolution algorithm that take into account this PSF variability. Indeed, a myopic deconvolution algorithm can be feed with a priori on the object and the PSF. The latter can be obtained by studying the PSF reconstruction error budget as follows in this paper. Finally, this work will lead to an estimation of the error on the deconvolved image allowing one to perform an accurate astrometry/ photometry on the observed objects and to strengthen the contrast in the images. We concluded that to neglect the global cross term or to estimate the aliasing on the measurements using simulations has no effect on the PSF reconstruction.
Published: 2012

108. Tip-tilt estimation and correction using FQPM coronagraphic images

Author: Gérard Rousset, M. Mas, Raphael Galicher, Pierre Baudoz, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 01 natural sciences, law.invention, adaptive optics, 010309 optics, Optics, law, 0103 physical sciences, Upstream (networking), Angular resolution, Adaptive optics, 010303 astronomy & astrophysics, Coronagraph, ComputingMilieux_MISCELLANEOUS, Wavefront, Physics, [PHYS]Physics [physics], business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Wavefront sensor, image processing, Tilt (optics), Cardinal point, Space and Planetary Science, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], high angular resolution
Abstract: Context. Direct imaging of exoplanets located a few AU from their hosting star requires angular resolution at the diffraction limit of large telescopes and a contrast level in the image of 105 to 1010 . Simultaneous use of adaptive optics and coronagraphy is mandatory to fulfil these requirements.Aims. Coronagraphs are usually very sensitive to pointing errors upstream of their focal plane mask. Approaches to measuring these errors in conventional adaptive optics systems consist in setting a wavefront sensor in an additional channel. Differential aberrations between the coronagraphic channel and the additional one induce a loss in performance. To tackle this limitation, we propose a new technique for measuring the tip-tilt errors directly from the coronagraphic image.Methods. Our method uses the relations between the intensity distribution in the coronagraphic image and upstream tip-tilt errors. We also propose a method of estimating the tip-tilt errors downstream of the focal plane mask. We validate at visible wavelength our upstream and downstream tip-tilt estimation and compensation techniques with numerical simulation images and on laboratory images.Results. Numerical simulations predict that our techniques correct for the tip-tilt errors to a 1.3 × 10-2 λ /D level when considering a λ /40 wavefront error upstream of the coronagraph. In laboratory, where the coronagraph is mostly limited by wavefront errors, we correct for the tip-tilt errors with an accuracy better than 6.5 × 10-2 λ /D . Conclusions. We demonstrate in numerical simulations and in laboratory that our technique can efficiently estimate the tip-tilt errors directly from the coronagraphic image with no additional channel. It is robust and can be used with small wavefront errors. It should be applicable to planet imager systems currently in preparation, such as SPHERE and MIRI/JWST.
Published: 2012

109. A star in a 15.2-year orbit around the supermassive black hole at the centre of the Milky Way

Author: Eric Gendron, Wolfgang Brandner, Reiner Hofmann, Tal Alexander, Nelly Mouawad, Anne-Marie Lagrange, Daniel Rouan, Karl M. Menten, Markus Hartung, Andreas Eckart, Reinhard Genzel, Jason Spyromilio, Gérard Rousset, Christopher Lidman, Matt Lehnert, Francois Lacombe, T. Ott, Rainer Schödel, A. F. M. Moorwood, N. Ageorges, Rainer Lenzen, Norbert Hubin, Mark J. Reid, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Physics, Supermassive black hole, Multidisciplinary, Astrophysics::High Energy Astrophysical Phenomena, Milky Way, Galactic Center, Astronomy, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Astrometry, Quasi-star, General Relativity and Quantum Cosmology, Intermediate-mass black hole, Stellar black hole, Astrophysics::Earth and Planetary Astrophysics, Orbit (control theory), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics::Galaxy Astrophysics
Abstract: Many galaxies are thought to have supermassive black holes at their centres-more than a million times the mass of the Sun. Measurements of stellar velocities and the discovery of variable X-ray emission have provided strong evidence in favour of such a black hole at the centre of the Milky Way, but have hitherto been unable to rule out conclusively the presence of alternative concentrations of mass. Here we report ten years of high-resolution astrometric imaging that allows us to trace two-thirds of the orbit of the star currently closest to the compact radio source (and massive black-hole candidate) Sagittarius A*. The observations, which include both pericentre and apocentre passages, show that the star is on a bound, highly elliptical keplerian orbit around Sgr A*, with an orbital period of 15.2 years and a pericentre distance of only 17 light hours. The orbit with the best fit to the observations requires a central point mass of (3.7 +/- 1.5) x 10(6) solar masses (M(*)). The data no longer allow for a central mass composed of a dense cluster of dark stellar objects or a ball of massive, degenerate fermions.
Published: 2002

110. First star images corrected by multi-object adaptive optics

Author: Richard H. Myers, Eric Gendron, Tim Morris, and Gérard Rousset
Subjects: business.industry, Computer science, Computer vision, Artificial intelligence, Star (graph theory), Object (computer science), Adaptive optics, business
Published: 2011

111. MOAO first on-sky demonstration with CANARY

Author: David Henry, Philippe Laporte, C. N. Dunlop, Tim Morris, Arnaud Sevin, M. Brangier, Timothy Butterley, Richard M. Myers, Damien Gratadour, Z. Hubert, D. Perret, Deli Geng, Alastair Basden, Andy Longmore, Gérard Rousset, N. Looker, Fanny Chemla, Fabrice Vidal, Nigel Dipper, E. Younger, Eric Gendron, G. Talbot, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Haute résolution angulaire en astrophysique, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Ingénierie, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Centre for Advanced Instrumentation, Department of Physics, Durham University (CfAI), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Pôle instrumental, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), and UK Astronomy Technology Centre, Royal Observatory Edinburgh (UKATC)
Subjects: Wavefront, Physics, business.industry, Strehl ratio, Astronomy and Astrophysics, Context (language use), Astrophysics, 01 natural sciences, Deformable mirror, 010309 optics, Optics, Space and Planetary Science, 0103 physical sciences, William Herschel Telescope, Guide star, business, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Spectrograph
Abstract: International audience; Context. A new challenging adaptive optics (AO) system, called multi-object adaptive optics (MOAO), has been successfully demonstrated on-sky for the first time at the 4.2 m William Herschel Telescope, Canary Islands, Spain, at the end of September 2010. Aims: This system, called CANARY, is aimed at demonstrating the feasibility of MOAO in preparation of a future multi-object near infra-red (IR) integral field unit spectrograph to equip extremely large telescopes for analysing the morphology and dynamics of high-z galaxies. Methods: CANARY compensates for the atmospheric turbulence with a deformable mirror driven in open-loop and controlled through a tomographic reconstruction by three widely separated off-axis natural guide star (NGS) wavefront sensors, which are in open loop too. We compared the performance of conventional closed-loop AO, MOAO, and ground-layer adaptive optics (GLAO) by analysing both IR images and simultaneous wave-front measurements. Results: In H-band, Strehl ratios of 0.20 are measured with MOAO while achieving 0.25 with closed-loop AO in fairly similar seeing conditions (r0 ≈ 15 cm at 0.5 mum). As expected, MOAO has performed at an intermediate level between GLAO and closed-loop AO.
Published: 2011

112. Stellar metallicities beyond the Local Group: the potential of J-band spectroscopy with extremely large telescopes

Author: Gérard Rousset, Rolf-Peter Kudritzki, M. Puech, Donald F. Figer, Ben Davies, M. D. Lehnert, Jean-Gabriel Cuby, Yunming Yang, Simon L. Morris, Chris Evans, UK Astronomy Technology Centre, Royal Observatory Edinburgh (UKATC), Rochester Institute of Technology, Institute for Astronomy, University of Hawaii, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique des Galaxies et Cosmologie, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), National Astronomical Observatoires-CAS, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Department of Physics, University of Durham, South Road, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Haute résolution angulaire en astrophysique, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Royal Observatory Edinburgh (ROE), University of Edinburgh, European Southern Observatory (ESO), Sciences pour l'environnement (SPE), Université Pascal Paoli (UPP)-Centre National de la Recherche Scientifique (CNRS), Department of Physics, Durham University, ANR-06-BLAN-0191,MAUI,The High Redshift Universe & the Mass Assembly of Galaxies: towards a French leadership in the ELT era.(2006), Beaussier, Catherine, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Centre National de la Recherche Scientifique (CNRS)-Université Pascal Paoli (UPP), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES)
Subjects: [PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Cosmology and Nongalactic Astrophysics (astro-ph.CO), Metallicity, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 7. Clean energy, 01 natural sciences, Spectral line, [SDU.ASTR.IM] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Red supergiant, Spectroscopy, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, Physics, 010308 nuclear & particles physics, Local Group, Astronomy and Astrophysics, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Red-giant branch, Stars, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, Supergiant, Astrophysics - Instrumentation and Methods for Astrophysics, [PHYS.ASTR.IM] Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: We present simulated J-band spectroscopy of red giants and supergiants with a 42m European Extremely Large Telescope (E-ELT), using tools developed toward the EAGLE Phase A instrument study. The simulated spectra are used to demonstrate the validity of the 1.15-1.22 micron region to recover accurate stellar metallicities from Solar and metal-poor (one tenth Solar) spectral templates. From tests at spectral resolving powers of four and ten thousand, we require continuum signal-to-noise ratios in excess of 50 (per two-pixel resolution element) to recover the input metallicity to within 0.1 dex. We highlight the potential of direct estimates of stellar metallicites (over the range -1, Comment: Accepted by A&A, 13 pages
Published: 2011

113. Foreword

Author: Gérard Rousset and Pierre Léna
Subjects: Ground level, Physics, Interferometry, Optics, business.industry, General Physics and Astronomy, business
Published: 2001

114. Intrinsic limitations of Shack-Hartmann wavefront sensing on an extended laser guide source

Author: Gérard Rousset, Damien Gratadour, Eric Gendron, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Wavefront, Physics, business.industry, Laser, Atomic and Molecular Physics, and Optics, Uncorrelated, Electronic, Optical and Magnetic Materials, law.invention, Formalism (philosophy of mathematics), Center of gravity, Optics, law, Correlation method, Computer Vision and Pattern Recognition, Spatial frequency, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Adaptive optics, business
Abstract: In this paper we investigate the behavior of various centroiding methods (weighted center of gravity, matched filtering, and correlation) classically used in Shack–Hartmann wavefront sensing when dealing with an elongated asymmetric spot. We study the impact of model errors on these centroiding methods at high signal-to-noise ratios, and, using a one-dimensional formalism, we show that the associated estimates all suffer from a bias uncorrelated with the actual spot displacement if its shape is not known precisely. Additionally, we show that the correlation method provides an estimate with a unitary gain whatever the parameters used, while the other two methods introduce a non-unitary gain in the estimation process. Finally, we show that the sampling of the spot structures after filtering by some convolution kernels is crucial to get an unbiased estimate of the spot displacement.
Published: 2010

115. DIORAMAS: a wide-field visible and near-infrared imaging multi-slit spectrograph for the EELT

Author: Stéphane Charlot, B. Meneux, Adriano Fontana, O. Ilbert, David Le Mignant, Florence Roman, Benedetta Ciardi, Jarle Brinchmann, Omar Almaini, L. Genolet, Bernard Delabre, Olivier Le Fevre, Gérard Rousset, Vincenzo De Caprio, Bianca Garilli, L. Hill, Laurence Tresse, Francisco Garzón López, Marc Jaquet, Laurent Martin, Jesús Gallego, D. Maccagni, and Stéphane Paltani
Subjects: Telescope, Physics, law, Aperture, Field of view, Astrophysics, First light, Spectral resolution, Extremely large telescope, Spectrograph, Galaxy, law.invention
Abstract: We present the science, design and performances of DIORAMAS, an imager and multi-slit spectrograph for the European Extremely Large Telescope. It covers a wide 6.8x6.8 arcmin² field, a large wavelength range 0.37 to 1.6 microns. The exceptional performances of this concept will enable extremely deep images to magnitudes AB~30 and high multiplex spectroscopy with up to ~500 slits observed simultaneously at spectral resolutions from R~300 to more than 120 slits at R~3000. The technical design is robust with only proven technology, and DIORAMAS could be developed on a timescale compatible with the EELT first light. Keywords : extremely large telescopes, spectroscopy, multi-slit spectroscopy, wide field imager, deep surveys 1. INTRODUCTION The study of first light in the Universe, the seeds of galaxies, as well as the main phases of galaxy evolution are some of the main science goals of the EELT, as identified in the Design Reference Mission (http://www.eso.org/sci/facilities/eelt/science/drm/). The sheer collecting power of the EELT will enable to observe very faint objects, with a gain in performance far superior to the gain when the 8-10m class telescopes surpassed the 4m class. On a point source, with a similar seeing, one can expect a 1.8 magnitude gain with the EELT compared to the VLT, or a factor about 27 in exposure time, a considerable advantage. However, a gain in performance is not only related to the telescope gathering power, but also, for many science investigations, to the capability of assembling large statistically representative samples of stars, galaxies, AGN, or any other (rare) categories of objects in the Universe. If one is able to observe more than one object at once, the performance gain is proportional to the number of objects observed simultaneously, and a key instrument driver is the size of the field of view adapted to the science. Large wide field imagers have been very powerful even on smaller telescopes (e.g. CFHT, VISTA, PanStarrs, soon VST, leading to LSST), where the etendue A : combining the aperture of the telescope
Published: 2010

116. Dimensioning the Gravity adaptive optics wavefront sensor

Author: António Amorim, Karine Perraut, Guy Perrin, Gérard Rousset, Stefan Hippler, Eric Gendron, Wolfgang Brandner, Yann Clénet, Stefan Gillessen, Frank Eisenhauer, Christian Straubmeier, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Institut für Extraterrestriche Physik (MPE), Universidade de Lisboa, Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Universität zu Köln
Subjects: Physics, Pixel, business.industry, Detector, Astrophysics::Instrumentation and Methods for Astrophysics, Filter (signal processing), Wavefront sensor, Noise (electronics), Optics, Band-pass filter, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Adaptive optics, business, Dimensioning
Abstract: International audience; We present the adaptive optics simulations we have performed to dimension the Gravity adaptive optics wavefront sensor. We first computed the optimal WFS bandpass, depending on the sampling frequency, detector readout noise and reference source colour/temperature. We then performed adaptive optics simulations with the YAO simulation tool for different WFS parameters (number of subpupils, number of pixels per subpupil, loop frequency, reference source magnitude, etc). Results demonstrate that the Gravity adaptive optics top-level requirements can be fulfilled with a 9×9 subaperture Shack-Hartmann with 4 pixels per subaperture using an H K filter, a larger filter being recommended for sources bluer than 770 K reference source of the Galactic Centre.
Published: 2010

117. Comparing centroiding methods for Shack-Hartmann wavefront sensing with laser guide stars on an ELT

Author: Serge Meimon, Damien Gratadour, Gérard Rousset, Thierry Fusco, Eric Gendron, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, ONERA - The French Aerospace Lab [Châtillon], and ONERA-Université Paris Saclay (COmUE)
Subjects: Physics, Wavefront, business.industry, Gaussian, Matched filter, Sodium layer, Laser, law.invention, Normal distribution, symbols.namesake, Optics, Laser guide star, law, symbols, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Adaptive optics, business
Abstract: International audience; In this paper we present the results of a study comparing the performance of various centroiding methods on an extended spot. Various spot shapes, in good agreement with measurements of the Sodium layer density profile are investigated. We compare the performance of center-of-gravity (COG) based ad cross-correlation (CC) based methods and the matched filter (MF) algorithm. While their performance are comparable in the case of a Gaussian Sodium profile, we show that, above 15 to 20m off-axis, substantial differences appear in the case of a known non-Gaussian Sodium density profile. CC based and MF methods seem to have comparable or better performance with various spot shapes while non-Gaussian shapes have dramatic impact on COG based methods.
Published: 2010

118. Wavefront sensing with laser guide stars on the ELTs

Author: Gérard Rousset, Thierry Fusco, Nicolas Muller, Vincent Michau, S. Thomas, Clélia Robert, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Wavefront, Physics, business.industry, Perturbation (astronomy), Sodium layer, Laser, law.invention, Telescope, Stars, Nonlinear system, Optics, law, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Adaptive optics
Abstract: Adaptive Optics (AO) relies on aWave Front Sensor (WFS) to measure properly the perturbations induced by the turbulence on the wavefront. Yet, source extension may limit its performance. In the case of a Shack-Hartmann (SH) WFS associated to one or more Laser Guide Stars (LGS), this extension becomes all the more problematic as the diameter of the telescope tends to increase. In order to mitigate the effects induced by the spot elongation on the quality of the WFS measurements, various algorithms are used. Most of them are non-linear, and require a reference. The design of the SH WFS itself has an influence on the measurement quality, as it also induces non-linearities. In addition, the time-evolving structure of the LGS, due to the fluctuations of the Sodium layer, has an impact on the measurements as well. Eventually, both influences are coupled in the wavefront sensing process. The present study is aimed at optimizing a whole set of carefully chosen parameters defining the design of a SH WFS, in the particular case of a LGS on an ELT. The relative impact of these parameters are studied first at the subaperture level, and then on the reconstructed wavefront.
Published: 2010

119. ATLAS: the E-ELT laser tomographic adaptive optics system

Author: Jerome Paufique, Norbert Hubin, Gérard Rousset, P. Jagourel, Thierry Fusco, Mathieu Cohen, Jean-Philippe Amans, Clélia Robert, Hermine Schnetler, Jean-Marc Conan, Vincent Michau, Serge Meimon, Damien Gratadour, Eric Gendron, Yann Clénet, Cyril Petit, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Physics, Diffraction, business.industry, Atlas (topology), media_common.quotation_subject, Modular design, Laser, law.invention, Optics, law, Sky, Tomography, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Adaptive optics, Extremely large telescope, Remote sensing, media_common
Abstract: ATLAS is a generic Laser Tomographic AO (LTAO) system for the E-ELT. Based on modular, relatively simple, and yet innovative concepts, it aims at providing diffraction limited images in the near infra-red for a close to 100 percent sky coverage.
Published: 2010

120. Optimal method for exoplanet detection by spectral and angular differential imaging

Author: A. Eggenberger, Laurent M. Mugnier, David Mouillet, Gérard Rousset, G. Montagnier, Marcel Carbillet, Kjetil Dohlen, Arthur Vigan, Joseph C. Carson, Anthony Boccaletti, A. Cornia, T. Fusco, ONERA - The French Aerospace Lab [Châtillon], ONERA, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), European Southern Observatory (ESO), ONERA-Université Paris Saclay (COmUE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Astrophysics::Instrumentation and Methods for Astrophysics, Context (language use), Astrophysics, Star (graph theory), 01 natural sciences, Exoplanet, 010309 optics, Andromeda, Position (vector), Planet, 0103 physical sciences, SPHERES, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Adaptive optics, 010303 astronomy & astrophysics
Abstract: In the context of the SPHERE planet nder project, we further develop and characterize a recently proposedmethod for the ecient direct detection of exoplanets f rom the ground using spectral and angular dierentialimaging. The method, called ANDROMEDA, combines images appropriately into pseudo-data, then uses allof them in a Maximum-Likelihood framework to estimate the position and ux of potential planets orbitingthe observed star. The methods performance is assesse d on realistic simulations of images performed by theSPHERE consortium, and it is applied to experimental data taken by the VLT/NAOS-CONICA instrument.Keywords: exoplanets, detection, inverse pro blems, coronagraphy, angular imaging, dieren tial imaging, spec-tral imaging, high contrast, maximum likelihood, adaptive optics. 1. INTRODUCTION The direct detection of exoplanets from the ground is a very promising eld of astronomy today. A goal is thecharacterization of the physical composition of the exoplanets by a spectral analysis of their emitted and/orreected light. This observation from the ground is a t echnological challenge. I ndeed, in order to be able toobserve a sucient number of targets, it is required to cope with an intensity ratio (also called contrast) betweenthe star and its planet that may be as high as 10
Published: 2010

121. Symmetrically weighted center of gravity for Shack-Hartmann wavefront sensing on a laser guide star

Author: Damien Gratadour, Gérard Rousset, Eric Gendron, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Wavefront, Physics, Weight function, Cog, Optics, Laser guide star, business.industry, Position (vector), Wavefront sensor, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Adaptive optics, business, Weighting
Abstract: International audience; Phase local gradient measurements in a Shack-Hartmann (SH) wavefront sensor (WFS) are achieved by tracking the displacements of a spot in each sub-aperture. This can be done by comparing the position of its center-ofgravity (COG) to a reference position. A commonly used method for position tracking is the weighted (W) COG in which the original image is multiplied by a weighting function, before centroiding. However, it can be shown that, if the spot centered on its COG is not even, the WCOG estimator is biased. We propose a new method for spot centroiding with a direct application to wavefront sensing on a LGS: the symmetrically weighted (SW) COG, in which the weighting function is taken as the symmetrical version of the spot, with respect to its COG.
Published: 2010

122. GRAVITY: a four-telescope beam combiner instrument for the VLTI

Author: Laurent Jocou, Markus Schöller, R.-R. Rohloff, Sylvestre Lacour, Xavier Haubois, Philippe B. Gitton, Andreas Eckart, Guy Perrin, Christian Straubmeier, Th. Henning, Constanza Araujo-Hauck, H. Bartko, Frank Eisenhauer, Stefan Hippler, Pedro Carvas, O. Pfuhl, D. Moch, A. Gräter, Pierre Kervella, Nadia Kudryavtseva, Sebastian Rabien, M. Haug, Rainer Lenzen, Y. Clénet, Kevin Wagner, S. Kellner, M. Wiest, Damian Moratschke, Senol Yazici, P. Fédou, Arnaud Sevin, Stefan Gillessen, J. M. Rees, C. Collin, Gérard Rousset, F. Chapron, Juan-Luis Ramos, M. Thiel, António Amorim, D. Ziegler, Frédéric Gonté, Reiner Hofmann, A. Nolot, K. Perraut, Reinhard Genzel, Elodie Choquet, Ralf Klein, Vianak Naranjo, Eric Gendron, Pierre Léna, Pierre Haguenauer, Udo Neumann, Thibaut Moulin, T. Paumard, Harald Baumeister, J. P. Berger, Wolfgang Brandner, Sebastian Fischer, D. Rouan, Werner Laun, J. Lima, Vincent Lapeyrere, Frédéric Cassaing, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Ingénieurs, Techniciens et Administratifs
Subjects: Physics, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy, Field of view, Astrometry, Metrology, law.invention, Black hole, Telescope, Interferometry, law, Magnitude (astronomy), Astrophysics::Solar and Stellar Astrophysics, Adaptive optics, Astrophysics - Instrumentation and Methods for Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics
Abstract: GRAVITY is an adaptive optics assisted Beam Combiner for the second generation VLTI instrumentation. The instrument will provide high-precision narrow-angle astrometry and phase-referenced interferometric imaging in the astronomical K-band for faint objects. We describe the wide range of science that will be tackled with this instrument, highlighting the unique capabilities of the VLTI in combination with GRAVITY. The most prominent goal is to observe highly relativistic motions of matter close to the event horizon of Sgr A*, the massive black hole at center of the Milky Way. We present the preliminary design that fulfils the requirements that follow from the key science drivers: It includes an integrated optics, 4-telescope, dual feed beam combiner operated in a cryogenic vessel; near-infrared wavefrontsensing adaptive optics; fringe-tracking on secondary sources within the field of view of the VLTI and a novel metrology concept. Simulations show that 10 {\mu}as astrometry within few minutes is feasible for a source with a magnitude of mK = 15 like Sgr A*, given the availability of suitable phase reference sources (mK = 10). Using the same setup, imaging of mK = 18 stellar sources in the interferometric field of view is possible, assuming a full night of observations and the corresponding UV coverage of the VLTI., Comment: 20 pages, Proceedings SPIE Astronomical Telescopes and Instrumentation Conference 2010
Published: 2010

123. The real-time control system for the CANARY multi-object adaptive optics on-sky demonstrator

Author: D. Gratadour, Nigel Dipper, Eric Gendron, Z. Hubert, Gérard Rousset, Richard M. Myers, Fabrice Vidal, Arnaud Sevin, Deli Geng, E. Younger, Alastair Basden, N. Looker, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: business.industry, Computer science, Interface (computing), computer.software_genre, law.invention, Telescope, Common Object Request Broker Architecture, law, Real-time Control System, Embedded system, Middleware (distributed applications), Control system, William Herschel Telescope, Adaptive optics, Field-programmable gate array, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Spectrograph, computer
Abstract: CANARY is a Multi-Object Adaptive Optics (MOAO) system designed to demonstrate the AO aspects of proposed EELT instruments such as the multi-object spectrograph EAGLE. The first phase of Canary will be executed on the 4.2m William Herschel Telescope in 2010. We describe here the AO Real-time Control System (RTCS) for Canary. This is based on a distributed architecture of components interconnected by a fast serial fabric (sFPDP). The hardware used is a hybrid of FPGA and CPU technology. The middleware used for system data telemetry and control is based on CORBA and the publish/subscribe pattern. The system is designed to be easily modified and extended for the later, higher order, phases of CANARY. In order to provide the increase in computational power required in higher order systems, the current CPU technology can be readily replaced by acceleration hardware based on FPGA or GPU technologies. The Canary RTCS thus provides a test-bed for these new technologies that will be required for E-ELT instruments. These design concepts can be developed to provide an RTCS for E-ELT instruments and are in line with those under consideration by ESO for the E-ELT AO systems to which instruments such as EAGLE will be required to interface.
Published: 2010

124. Focal plane wavefront sensor sensitivity for ELT planet finder

Author: Pierre Baudoz, Raphaël Galicher, Gérard Rousset, M. Mas, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Groupement d'Intérêt Scientifique du Partenariat Haute résolution Angulaire Sol-Espace (GIS PHASE ), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire Univers et Théories (LUTH (UMR_8102)), and Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Wavefront, Physics, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Speckle noise, Wavefront sensor, Exoplanet, Speckle pattern, Optics, Planet, Astrophysics::Earth and Planetary Astrophysics, Adaptive optics, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Optical aberration
Abstract: International audience; In the framework of Extremely Large Telescope (ELT), several instruments are considered for the characterization of extrasolar planets. Since the performance of such an instrument is limited by wavefront errors, the use of extreme Adaptive Optic (AO) systems is mandatory. Studies for future planet finder instruments such as SPHERE/VLT or GPI/GEMINI show that one limitation of the performance for a planet finder is the differential aberrations that are not measured by the wavefront sensor, which is physically separated from the common optics by a beam splitter. These defects create a field of residual speckles in the focal plane that need to be calibrated to separate the planet signal from the speckle noise [1]. We propose here to simultaneously estimate these aberrations and also detect the planet directly from the final science image. To do so, we propose to couple the foreseen extreme high speed AO of an ELT planet Finder with a low speed Self-Coherent Camera (SCC [2-5]). The SCC which is based on the principle of light coherence can both estimate the wavefront errors and reduce speckle noise by calibration. After recalling the principle of the SCC, we present simulation results of the SCC performance in the context of EPICS.
Published: 2010

125. EAGLE MOAO system conceptual design and related technologies

Author: M. Cohen, Philippe Laporte, Richard M. Myers, Damien Gratadour, William Taylor, Gérard Rousset, Simon L. Morris, Chris Evans, P. Parr-Burman, D. Le Mignant, F. Assemat, Eric Gendron, T. Fusco, H. Schnetler, Mathieu Puech, Nigel Dipper, Fabrice Vidal, Tim Morris, Jean-Gabriel Cuby, P. Jagourel, M. D. Lehnert, Clélia Robert, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Groupement d'Intérêt Scientifique du Partenariat Haute résolution Angulaire Sol-Espace (GIS PHASE ), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), Duke University [Durham], ONERA, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, United Kingdom Astronomy Technology Ctr, Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, business.industry, media_common.quotation_subject, Astronomy, Encircled energy, Deformable mirror, Stars, Optics, Apparent magnitude, Laser guide star, Sky, business, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Spectrograph, media_common
Abstract: International audience; EAGLE is the multi-object spatially-resolved near-IR spectrograph instrument concept for the E-ELT, relying on a distributed Adaptive Optics, so-called Multi Object Adaptive Optics. This paper presents the results of a phase A study. Using 84×84 actuator deformable mirrors, the performed analysis demonstrates that 6 laser guide stars (on an outer ring of 7.2' diameter) and up to 5 natural guide stars of magnitude R < 17, picked-up in a 7.3' diameter patrol field of view, allow us to obtain an overall performance in terms of Ensquared Energy of 35% in a 75×75mas2 resolution element at H band whatever the target direction in the centred 5' science field for median seeing conditions. In terms of sky coverage, the probability to find the 5 natural guide stars is close to 90% at galactic latitudes |b| ~ 60 deg. Several MOAO demonstration activities are also on-going.
Published: 2010

126. Status update of the CANARY on-sky MOAO demonstrator

Author: D. Perret, Philippe Laporte, N. Looker, Laura K. Young, Timothy Butterley, Alastair Basden, Gérard Rousset, Kevin Dee, Stephen Todd, Fanny Chemla, Z. Hubert, M. Marteaud, Heather I. C. Dalgarno, M. Brangier, Andrés Guesalaga, Nigel Dipper, Dani Guzman, G. Talbot, Alan H. Greenaway, Fabrice Vidal, Deli Geng, C. N. Dunlop, Tim Morris, Jure Skvarč, Andy Longmore, Nicolas Vedrenne, Brian Stobie, E. Younger, David Atkinson, T. Fusco, Colin Dickson, Arnaud Sevin, Eric Gendron, Michael R. Harrison, David Henry, Richard M. Myers, Damien Gratadour, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Duke University [Durham], United Kingdom Astronomy Technology Ctr, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), Pontificia Universidad Católica de Chile (UC), Engineering and Project Solutions Ltd, Heriot-Watt Univ, and Isaac Newton Group of Telescopes
Subjects: business.industry, Computer science, media_common.quotation_subject, Deformable mirror, law.invention, Telescope, Optics, Laser guide star, Sky, law, William Herschel Telescope, Calibration, Device simulation, business, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], media_common, Remote sensing
Abstract: International audience; The CANARY on-sky MOAO demonstrator is being integrated in the laboratory and a status update about its various components is presented here. We also discuss the alignment and calibration procedures used to improve system performance and overall stability. CANARY will be commissioned at the William Herschel Telescope at the end of September 2010.
Published: 2010

127. Integrating AO in a performance budget: toward a global system engineering vision

Author: Gérard Rousset, Hermine Schnetler, Philippe Laporte, Observatoire de Paris, Université Paris sciences et lettres (PSL), Royal Observatory, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Physics, Wavefront, Document management system, computer.software_genre, Deformable mirror, law.invention, Telescope, Signal-to-noise ratio, Computer engineering, law, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Spectrograph, computer, Simulation, Communication channel
Abstract: EAGLE (Extremely large Adaptive telescope for GaLaxy Evolution) is one of the eight E-ELT instrument concepts that were developed as p art o f the Phase A E-ELT instrument studies. EAG LE is a near-infrared wide field multi object spectrograph[4]. It includes its own multi-object adaptive optics system (MOAO) and its subsystems are cooled down so as to ens ure th at t he i nstrument ca n both ac hieve t he des ired s patial res olution a nd to be s ure t hat t he i nstrument i s background limited, as required in the primary science case, to deliver the performance in the K-band. In this paper we discuss the performance matrix developed to allow us to partition and allocate the important characteristics to the various subsystems as well a s to d escribe th e p rocess to verify th at th e c urrent co ncept d esign will d eliver th e r equired performance. Du e to th e integrated nature of the instrument, a large number o f A O parameters have to be controlled. The performance matrix also has to deal with the added complexity of active and adaptive optical elements such as the science channel deformable mirrors (DMs). This paper also defines a method of how to convert the ensquared energy (EE) and signal-to-noise ratio (SNR) required by the science cases into the "as designed" wavefront error and the overall residue wavefront error. To ensure successful integration and verification of the next generation instruments for ELT it is of the utmost importance to have method to control and manage the instrument's critical performance characteristics at very early design steps.
Published: 2010

128. SAMI: the SCAO module for the E-ELT adaptive optics imaging camera MICADO

Author: Gérard Rousset, P. Bernardi, F. Chapron, Yann Clénet, Ric Davies, Eric Gendron, M. Thiel, Reinhard Genzel, Z. Hubert, Niels Tromp, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Ingénieurs, Techniciens et Administratifs, Max-Planck-Institut für Extraterrestriche Physik (MPE), and Netherlands Institute for Radio Astronomy (ASTRON)
Subjects: Telescope, Optics, business.industry, law, Computer science, Adaptive optics, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], law.invention
Abstract: International audience; SAMI, the SCAO module for the E-ELT adaptive optics imaging camera MICADO, could be used in the first years of operation of MICADO on the telescope, until MAORY is operational and coupled to MICADO. We present the results of the study made in the framework of the MICADO phase A to design and estimate the performance of this SCAO module.
Published: 2010

129. Self-coherent camera: first results of a high-contrast imaging bench in visible light

Author: Pierre Baudoz, Gérard Rousset, Marion Mas, Raphaël Galicher, Jacques Baudrand, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Laboratoire Univers et Théories (LUTH (UMR_8102)), and Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Wavefront, Physics, Speckle pattern, Optics, Cardinal point, business.industry, Reference beam, Speckle noise, business, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Deformable mirror, Optical aberration
Abstract: International audience; Extreme adaptive optics and coronagraphy are mandatory for direct imaging of exoplanets. Quasi-static aberrations limit the instrument performance producing speckle noise in the focal plane. We propose a Self-Coherent Camera (SCC) to both control a deformable mirror that actively compensates wavefront error, and calibrate the speckle noise. We create a reference beam to spatially modulate the coronagraphic speckle pattern with Fizeau fringes. In a first step, we are able to extract wavefront aberrations from the science image and correct for them using a deformable mirror. In a second step, we apply a post-processing algorithm to discriminate the companion image from the residual speckle field. To validate the instrumental concept, we developed a high contrast imaging bench in visible light. We associated a SCC to a four quadrant phase mask coronagraph and a deformable mirror (DM) with a high number of actuators (32x32 Boston Michromachines MEMS). We will present this bench and show first experimental results of focal plane wavefront sensing and high contrast imaging. The measurements are compared to numerical simulations.
Published: 2010

130. Tomography approach for multi-object adaptive optics

Author: Eric Gendron, Gérard Rousset, Fabrice Vidal, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Wavefront, Physics, Tomographic reconstruction, Covariance function, Covariance matrix, business.industry, Computation, Covariance, Atomic and Molecular Physics, and Optics, Deformable mirror, Electronic, Optical and Magnetic Materials, Optics, Computer Vision and Pattern Recognition, Adaptive optics, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Multi-object adaptive optics (MOAO) is a solution developed to perform a correction by adaptive optics (AO) in a science large field of view. As in many wide-field AO schemes, a tomographic reconstruction of the turbulence volume is required in order to compute the MOAO corrections to be applied in the dedicated directions of the observed very faint targets. The specificity of MOAO is the open-loop control of the deformable mirrors by a number of wavefront sensors (WFSs) that are coupled to bright guide stars in different directions. MOAO calls for new procedures both for the cross registration of all the channels and for the computation of the tomographic reconstructor. We propose a new approach, called "Learn and Apply (L&A)", that allows us to retrieve the tomographic reconstructor using the on-sky wavefront measurements from an MOAO instrument. This method is also used to calibrate the registrations between the off-axis wavefront sensors and the deformable mirrors placed in the science optical paths. We propose a procedure linking the WFSs in the different directions and measuring directly on-sky the required covariance matrices needed for the reconstructor. We present the theoretical expressions of the turbulence spatial covariance of wavefront slopes allowing one to derive any turbulent covariance matrix between two wavefront sensors. Finally, we discuss the convergence issue on the measured covariance matrices, we propose the fitting of the data based on the theoretical slope covariance using a reduced number of turbulence parameters, and we present the computation of a fully modeled reconstructor.
Published: 2010

131. Analytical expression of long-exposure adaptive-optics-corrected coronagraphic image. First application to exoplanet detection

Author: Laurent M. Mugnier, Gérard Rousset, Jean-François Sauvage, Thierry Fusco, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Physics, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Image processing, Atomic and Molecular Physics, and Optics, Exoplanet, Electronic, Optical and Magnetic Materials, law.invention, Optics, law, Planet, Astrophysics::Earth and Planetary Astrophysics, Computer Vision and Pattern Recognition, Spatial frequency, Sensitivity (control systems), business, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Coronagraph, Image restoration
Abstract: In this paper we derive an analytical model of a long-exposure star image for an adaptive-optics(AO)-corrected coronagraphic imaging system. This expression accounts for static aberrations upstream and downstream of the coronagraphic mask as well as turbulence residuals. It is based on the perfect coronagraph model. The analytical model is validated by means of simulations using the design and parameters of the SPHERE instrument. The analytical model is also compared to a simulated four-quadrant phase-mask coronagraph. Then, its sensitivity to a miscalibration of structure function and upstream static aberrations is studied, and the impact on exoplanet detectability is quantified. Last, a first inversion method is presented for a simulation case using a single monochromatic image with no reference. The obtained result shows a planet detectability increase by two orders of magnitude with respect to the raw image. This analytical model presents numerous potential applications in coronographic imaging, such as exoplanet direct detection, and circumstellar disk observation.
Published: 2010

132. The physics of galaxy evolution with EAGLE

Author: Jean-Gabriel Cuby, H. Flores, Gérard Rousset, M. D. Lehnert, Thierry Fusco, Benoit Neichel, M. Puech, Y. Yang, Simon L. Morris, Chris Evans, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Department of Physics [Durham University], Durham University, Royal Observatory Edinburgh (ROE), University of Edinburgh, DOTA, ONERA, Université Paris Saclay [Châtillon], ONERA-Université Paris-Saclay, Gemini Observatory [Southern Operations Center], Association of Universities for Research in Astronomy (AURA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Clénet, Y., Conan, J.-M., Fusco, T., and Rousset, G.
Subjects: Eagle, Cosmology and Nongalactic Astrophysics (astro-ph.CO), FOS: Physical sciences, OPTICAL TELESCOPES, Astrophysics::Cosmology and Extragalactic Astrophysics, 02 engineering and technology, 01 natural sciences, 010309 optics, [SPI]Engineering Sciences [physics], biology.animal, 0103 physical sciences, Galaxy formation and evolution, Instrumentation and Methods for Astrophysics (astro-ph.IM), Spectrograph, Astrophysics::Galaxy Astrophysics, ADAPTIVE OPTICS, [PHYS]Physics [physics], Physics, biology, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, 021001 nanoscience & nanotechnology, Redshift, Galaxy, Field (geography), Astrophysics - Instrumentation and Methods for Astrophysics, 0210 nano-technology, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: One of the prominent science goal of the ELTs will be to study the physics and mass assembly of galaxies at very high redshifts. Here, we present the galaxy evolution science case for EAGLE, which is a NIR multi-integral field spectrograph for the E-ELT currently under phase A study. We summarize results of simulations conducted to derive high-level requirements. In particular, we show how we have derived the specifications for the ensquared energy that the AO system needs to provide to reach the scientific goals of the instrument. Finally, we present future strategies to conduct galaxy surveys with EAGLE., 6 pages, 4 Figures, to appear in the proceedings of the AO4ELT meeting held in Paris, 22-26 June 2009
Published: 2010

133. EAGLE Spectroscopy of Resolved Stellar Populations Beyond the Local Group

Author: Francois Assemat, Yanbin Yang, Annette M. N. Ferguson, Michael K. Barker, Jean-Gabriel Cuby, Simon L. Morris, Chris Evans, Matthew Lehnert, H. Flores, Gérard Rousset, Mathieu Puech, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Eagle, Stellar kinematics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), media_common.quotation_subject, FOS: Physical sciences, Context (language use), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, biology.animal, Galaxy formation and evolution, Extremely Large Telescope, Astrophysics::Solar and Stellar Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, media_common, Physics, [PHYS]Physics [physics], biology, Stellar collision, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Local Group, Astronomy and Astrophysics, Universe, Galaxy, Space and Planetary Science, instrumentation: adaptive optics – instrumentation: spectrographs – galaxies: abundances – galaxies: evolution – galaxies: kinematics & dynamics – galaxies: stellar content, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Geology, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: Valuable insights into galaxy evolution can be gleaned from studies of resolved stellar populations in the local Universe. Deep photometric surveys have provided tracers of the star-formation histories in galaxies from 0.8-16 Mpc, but without robust chemical abundances and stellar kinematics from spectroscopy, their sub-structures and assembly histories remain hidden from us. In this context, we introduce the EAGLE design study for a multi--integral-field-unit, near-infrared spectrograph for the European Extremely Large Telescope (E-ELT). EAGLE will exploit the unprecedented light-gathering power of the E-ELT to deliver AO-corrected spectroscopy across a large (38.5 sq. arcmin) field, truly revolutionising our view of stellar populations in the Local Volume., 6 pages, to appear in the proceedings of the AO4ELT conference, held in Paris, 22-26 June 2009
Published: 2009

134. EAGLE: an MOAO fed multi-IFU working in the NIR on the E-ELT

Author: Francois Assemat, Martyn Wells, Philippe Laporte, Stephen Rolt, Nigel Dipper, Clélia Robert, Simon L. Morris, Chris Evans, Tim Morris, Peter Hastings, Hermine Schnetler, Sébastien Vivès, Mark Swinbank, Emmanuel Hugot, Jean-Luc Gimenez, Matthew D. Lehnert, Stephen Beard, Gérard Rousset, Pascal Vola, Zoltan Hubert, H. McGregor, Jean-Philippe Amans, William Taylor, Marc Ferrari, Thierry Fusco, David Le Mignant, G. Talbot, Eric Gendron, Jean-Gabriel Cuby, P. Jagourel, P. Parr-Burman, Mathieu Puech, Benoit Neichel, François Vidal, Brice Leroux, Mathieu Cohen, Fabrice Madec, Richard M. Myers, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Physics, Eagle, Galactic astronomy, biology, James Webb Space Telescope, Astronomy, Field of view, law.invention, Telescope, law, biology.animal, Extremely Large Telescope, Astronomical seeing, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: EAGLE is an instrument for the European Extremely Large Telescope (E-ELT). EAGLE will be installed at the Gravity Invariant Focal Station of the E-ELT, covering a field of view of 50 square arcminutes. Its main scientific drivers are the physics and evolution of high-redshift galaxies, the detection and characterization of first-light objects and the physics of galaxy evolution from stellar archaeology. These key science programs, generic to all ELT projects and highly complementary to JWST, require 3D spectroscopy on a limited (~20) number of targets, full near IR coverage up to 2.4 micron and an image quality significantly sharper than the atmospheric seeing. The EAGLE design achieves these requirements with innovative, yet simple, solutions and technologies already available or under the final stages of development. EAGLE relies on Multi-Object Adaptive Optics (MOAO) which is being demonstrated in the laboratory and on sky. This paper provides a summary of the phase A study instrument design.
Published: 2009

135. Status of the LESIA High Contrast Bench development in the framework of the E-ELT

Author: Marion Mas, Pierre Baudoz, Jacques Baudrand, Gérard Rousset, C. Coton, F. Assémat, R. Galicher, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Physics, Test bench, business.industry, Phase (waves), Deformable mirror, law.invention, Speckle pattern, Optics, law, Pinhole (optics), business, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Coronagraph, Spectrograph
Abstract: In the framework of the instrument Exo-Planet Imaging and Spectrograph (EPICS), an optical bench is being set up in the Laboratoire d'Etudes Spatiales et d'Instrumentation e n Astrophysique (LESIA). With this bench, we will test a new high contrast technique, the Self-Coherent Camera (SCC). As already described in Galicher et al. (2008), the SCC is able to measure the incoming phase defects and, in the same time, detect a faint companion in the residual speckle field. To reach high contrast de tection, both coronagraphy and adaptive optics are used to make measurements with the SCC. The principle of the instrument is based on interferences between two beams. One of them is spatially filtered using a pinhole which filters the high frequencies of the star beam and stops the light from the companion. The recombination of these two beams takes place at the pupil plane in a Fizeau type setup. As a result, the speckles in the final focal plan e created by residual aberrations will be encoded with fringes. To test this instrument in laboratory environment, we are developing a test bench which will combine high performance coronagraph (four-quadrant phase mask coronagraph), an extreme adaptive optics (a Boston electrostatic deformable mirror with 32x32 actuators) and the SCC itself. After introducing the principle of the SCC, we show the first results of a numerical study. We eventually d escribe the status of the test bench development.
Published: 2009

136. Tomography reconstruction using the Learn and Apply algorithm

Author: Fabrice Vidal, Arnaud Sevin, M. Brangier, Eric Gendron, Gérard Rousset, Z. Hubert, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Wavefront, Scheme (programming language), Computer science, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Measure (physics), Covariance, A priori and a posteriori, Computer vision, Artificial intelligence, Tomography, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Algorithm, computer, SIMPLE algorithm, computer.programming_language
Abstract: In the framework of the MOAO demonstrator CANARY, we developped a new concept of tomogra- phy algorithm that allows to measure the tomographic reconstructor directly on-sky, using or not, a priori from the turbulence profile. This simple algorithm, working in open-loop, uses the measured covariance of slopes between all the wavefront sensors (WFS) to deduce the geometric and atmospheric parameters that are used to compute the tomographic reconstructor. This method called "Learn and Apply" (L&A) has also the advantage to measure and take into account all the misalignments between the WFSs in order to calibrate any MOAO instrument. We present the main principle of the algorithm and the last experimental results performed in MOAO scheme at the SESAME bench.
Published: 2009

137. The Self-Coherent Camera : a focal plane sensor for EPICS ?

Author: Gérard Rousset, Pierre Baudoz, Raphael Galicher, Marion Mas, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Physics, Wavefront, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Wavefront sensor, Exoplanet, law.invention, Speckle pattern, Optics, Cardinal point, Planet, law, Astrophysics::Earth and Planetary Astrophysics, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Beam splitter, Coherence (physics)
Abstract: In the framework of the European Extremely Large Telescope, EPICS is an ambitious instrument devoted to the direct detection and the characterization of extrasolar planets. Since the performance of such an instrument is limited by wavefront errors, the use of extreme Adaptive Optic (AO) systems is mandatory. Studies for future planet finder instruments such as SPHERE/VLT or GPI/GEMINI show that a strong limitation of the performance of a planet finder is the differential aberrations that are not measured by the wavefront sensor, which is physically separated from the common optics by a beam splitter. We propose here to efficiently estimate these aberrations by directly measuring the wavefront errors in the final science image. To do so, we propose to couple the foreseen extreme AO system at high speed of EPICS with a low speed Self-Coherent Camera (SCC) which can measure directly the differential aberrations at the final science focal plane. The SCC which is based on the principle of light coherence estimates the wavefront errors by spatially encoding the speckles with fringes in the final image. After recalling the principle of the SCC, we present simulation results of the SCC performance in the context of EPICS.
Published: 2009

138. Adding the third dimension on adaptive optics retina imager thanks to full-field optical coherence tomography

Author: Marie Glanc, Sarah Tick, Michel Pâques, Gérard Rousset, Ivan Maksimovic, José-Alain Sahel, Leonardo Blanco, Guillaume Chenegros, Jean-François Le Gargasson, Laurent M. Mugnier, Florence Pouplard, Francois Lacombe, Marie Blavier, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Ingénieurs, Techniciens et Administratifs, Sorbonne Université (SU), Groupement d'Intérêt Scientifique du Partenariat Haute résolution Angulaire Sol-Espace (GIS PHASE ), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), DOTA, ONERA, Université Paris Saclay [Châtillon], ONERA-Université Paris-Saclay, and Mauna Kea Technologies
Subjects: Physics, Retina, genetic structures, medicine.diagnostic_test, business.industry, Image registration, Image segmentation, eye diseases, Optics, medicine.anatomical_structure, Optical coherence tomography, medicine, Computer vision, sense organs, Time domain, Tomography, Artificial intelligence, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Adaptive optics, Coherence (physics)
Abstract: International audience; Retinal pathologies, like ARMD or glaucoma, need to be early detected, requiring imaging instruments with resolution at a cellular scale. However, in vivo retinal cells studies and early diagnoses are severely limited by the lack of resolution on eye-fundus images from classical ophthalmologic instruments. We built a 2D retina imager using Adaptive Optics to improve lateral resolution. This imager is currently used in clinical environment. We are currently developing a time domain full-field optical coherence tomograph. The first step was to conceive the images reconstruction algorithms and validation was realized on non-biological samples. Ex vivo retina are currently being imaged. The final step will consist in coupling both setups to acquire high resolution retina cross-sections.
Published: 2009

139. EAGLE multi-object AO concept study for the E-ELT

Author: M. D. Lehnert, D. Gratadour, Tim Morris, Fabrice Vidal, Richard M. Myers, D. Le Mignant, Eric Gendron, Philippe Laporte, M. Cohen, M. Brangier, Gérard Rousset, Clélia Robert, Thierry Fusco, F. Assemat, Nigel Dipper, Mathieu Puech, P. Parr-Burmann, Hermine Schnetler, J. G. Cuby, P. Jagourel, Simon L. Morris, Chris Evans, W. D. Taylor, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), DOTA, ONERA, Université Paris Saclay [Châtillon], ONERA-Université Paris-Saclay, Durham University, Galaxies, Etoiles, Physique, Instrumentation (GEPI), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)
Subjects: media_common.quotation_subject, FOS: Physical sciences, Field of view, 02 engineering and technology, OPTICAL TELESCOPES, 01 natural sciences, Encircled energy, Optical telescope, Deformable mirror, 010309 optics, [SPI]Engineering Sciences [physics], Optics, 0103 physical sciences, Adaptive optics, Spectrograph, Instrumentation and Methods for Astrophysics (astro-ph.IM), media_common, Physics, [PHYS]Physics [physics], business.industry, LASER MIRRORS, 021001 nanoscience & nanotechnology, Stars, Sky, 0210 nano-technology, business, Astrophysics - Instrumentation and Methods for Astrophysics, STARS
Abstract: EAGLE is the multi-object, spatially-resolved, near-IR spectrograph instrument concept for the E-ELT, relying on a distributed Adaptive Optics, so-called Multi Object Adaptive Optics. This paper presents the results of a phase A study. Using 84x84 actuator deformable mirrors, the performed analysis demonstrates that 6 laser guide stars and up to 5 natural guide stars of magnitude R, 6 pages, to appear in the proceedings of the AO4ELT conference, held in Paris, 22-26 June 2009
Published: 2009

140. Self-coherent camera as a focal plane wavefront sensor: simulations

Author: Pierre Baudoz, Raphael Galicher, Marion Mas, Gérard Rousset, Julien Totems, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Groupement d'Intérêt Scientifique du Partenariat Haute résolution Angulaire Sol-Espace (GIS PHASE ), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), DOTA, ONERA, Université Paris Saclay [Palaiseau], and ONERA-Université Paris-Saclay
Subjects: Wavefront, Physics, Earth and Planetary Astrophysics (astro-ph.EP), business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Image processing, Wavefront sensor, Astrophysics, Deformable mirror, law.invention, Speckle pattern, Optics, Space and Planetary Science, law, High-dynamic-range imaging, Astrophysics - Instrumentation and Methods for Astrophysics, business, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Coronagraph, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics - Earth and Planetary Astrophysics
Abstract: Direct detection of exoplanets requires high dynamic range imaging. Coronagraphs could be the solution, but their performance in space is limited by wavefront errors (manufacturing errors on optics, temperature variations, etc.), which create quasi-static stellar speckles in the final image. Several solutions have been suggested for tackling this speckle noise. Differential imaging techniques substract a reference image to the coronagraphic residue in a post-processing imaging. Other techniques attempt to actively correct wavefront errors using a deformable mirror. In that case, wavefront aberrations have to be measured in the science image to extremely high accuracy. We propose the self-coherent camera sequentially used as a focal-plane wavefront sensor for active correction and differential imaging. For both uses, stellar speckles are spatially encoded in the science image so that differential aberrations are strongly minimized. The encoding is based on the principle of light incoherence between the hosting star and its environment. In this paper, we first discuss one intrinsic limitation of deformable mirrors. Then, several parameters of the self-coherent camera are studied in detail. We also propose an easy and robust design to associate the self-coherent camera with a coronagraph that uses a Lyot stop. Finally, we discuss the case of the association with a four-quadrant phase mask and numerically demonstrate that such a device enables the detection of Earth-like planets under realistic conditions. The parametric study of the technique lets us believe it can be implemented quite easily in future instruments dedicated to direct imaging of exoplanets., Comment: 15 pages, 14 figures, accepted in A&A (here is the final version)
Published: 2009
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141. CANARY: The NGS/LGS MOAO demonstrator for EAGLE

Author: Richard M. Myers, Damien Gratadour, C. N. Dunlop, Eric Gendron, Nicolas Vedrenne, Mark A. Harrison, David Henry, G. Talbot, Tim Morris, Fabrice Vidal, Ali Basden, Nigel Dipper, Steven Todd, Colin Dickson, Clélia Robert, Michel Marteaud, Jure Skvarč, Brian Stobie, Timothy Butterley, Deli Geng, Kevin Dee, Dani Guzman, Phillipe Laporte, Alan H. Greenaway, Aglae Kellerer, Gérard Rousset, Eddy Younger, Zoltan Hubert, Heather I. C. Dalgarno, Thierry Fusco, Fanny Chemla, Andrés Guesalaga, Andy Longmore, Centre for Advanced Instrumentation, Durham University (CfA), Observatoire de Paris - Site de Meudon (OBSPM), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Royal Observatory Edinburgh (ROE), University of Edinburgh, DOTA, ONERA, Université Paris Saclay [Châtillon], and ONERA-Université Paris-Saclay
Subjects: Eagle, DEMONSTRATIONS, [PHYS]Physics [physics], biology, Field of view, OPTICAL TELESCOPES, 01 natural sciences, 010309 optics, [SPI]Engineering Sciences [physics], Geography, biology.animal, TOMOGRAPHY, 0103 physical sciences, Extremely Large Telescope, William Herschel Telescope, Adaptive optics, 010303 astronomy & astrophysics, Remote sensing
Abstract: International audience; EAGLE is a multi-object 3D spectroscopy instrument currently under design for the 42-metre European Extremely Large Telescope (E-ELT). EAGLE will use open-loop Multi-Object Adaptive Optics (MOAO) to provide partial AO correction across a wide (5-10 arcmin) field of view. The novelty of this scheme is such that on-sky demonstration is required prior to final construction of an E-ELT instrument. The CANARY project will implement a single channel of an MOAO system on the 4.2m William Herschel Telescope. The CANARY project is undergoing a phased development plan that starts with demonstration of low-order open-loop AO correction using first NGS then Rayleigh LGS tomography, moving to a demonstration of high-order open-loop AO correction using LGS tomography. This final stage will also include 2 DMs in a woofer-tweeter configuration similar to that of EAGLE when installed at the E-ELT. We describe the requirements for the various phases of MOAO demonstration, the corresponding CANARY configurations and capabilities and the current designs of the various subsystems.
Published: 2009

142. CANARY: An on-sky laser guide star multiple object AO demonstrator

Author: Aglae Kellerer, Eddy Younger, Stephen Todd, Andy Longmore, Andrés Guesalaga, Colin Dickson, Dani Guzman, G. Talbot, Fabrice Vidal, Gérard Rousset, Nigel Dipper, Zoltan Hubert, Tim Morris, Richard M. Myers, Michel Marteaud, Thierry Fusco, Damien Gratadour, Ali Basden, Fanny Chemla, Mark A. Harrison, David Henry, Eric Gendron, C. N. Dunlop, Deli Geng, and Timothy Butterley
Subjects: Laser guide star, Optics, Geography, business.industry, Sky, media_common.quotation_subject, Strehl ratio, business, Object (computer science), Deformable mirror, Photon counting, media_common, Remote sensing
Abstract: CANARY is the on-sky LGS MOAO demonstrator for the proposed EAGLE E-ELT instrument. The CANARY design is described here for the initial experimental phases. Simulations of system performance predict an H-band Strehl ratio of 0.27-0.33.
Published: 2009

143. GRAVITY: Astrometry on the galactic center and beyond

Author: Xavier Haubois, Vianak Naranjo, J. Ziegleder, P. Fédou, António Amorim, Jose Ramos, S. Lacour, Fabien Malbet, Nico Hamaus, L. Jocou, Stefan Hippler, Eric Gendron, A. Böhm, Werner Laun, M. Thiel, Oliver Pfuhl, Stefan Gillessen, Sebastian Rabien, Guy Perrin, Daniel Rouan, Harald Baumeister, Katie Dodds-Eden, K. Houairi, Christian Straubmeier, Th. Henning, Markus Schöller, Rainer Lenzen, Jorge Lima, A. Gräter, J. Kolmeder, Udo Neumann, Reinhard Genzel, Gérard Rousset, Thibaut Paumard, Pierre Kervella, J.-P. Berger, Andrea Richichi, Reiner Hofmann, Frédéric Cassaing, R.-R. Rohloff, Andreas Eckart, Marcus Haug, Ralf Klein, Felix Hormuth, K. Perraut, H. Bartko, Frank Eisenhauer, Wolfgang Brandner, Yann Clénet, S. Kellner, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Ingénieurs, Techniciens et Administratifs, Groupement d'Intérêt Scientifique du Partenariat Haute résolution Angulaire Sol-Espace (GIS PHASE ), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Max-Planck-Institut für Astronomie (MPIA), Physikalisches Institut, Universität zu Köln, European Southern Observatory (ESO), Max-Planck-Institut für Extraterrestriche Physik (MPE), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), ONERA, and SIM/IDL, Faculdade de Ciências da Universidade de Lisboa
Subjects: Wavefront, Physics, Event horizon, Milky Way, Galactic Center, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Field of view, Astrometry, Black hole, Space and Planetary Science, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics::Galaxy Astrophysics
Abstract: International audience; We present the second-generation VLTI instrument GRAVITY, which currently is in the preliminary design phase. GRAVITY is specifically designed to observe highly relativistic motions of matter close to the event horizon of Sgr A*, the massive black hole at the center of the Milky Way. We have identified the key design features needed to achieve this goal and present the resulting instrument concept. It includes an integrated optics, four-telescope, dual feed beam combiner operated in a cryogenic vessel, near-infrared wavefront sensing adaptive optics, fringe tracking on secondary sources within the field of view of the VLTI and a novel metrology concept. Simulations show that the planned design matches the scientific needs; in particular that 10 muas astrometry is feasible for a source with a magnitude of mK = 15 like Sgr A*, given the availability of suitable phase reference sources.
Published: 2009

144. ATLAS: the Laser Tomographic Adaptive Optics module for the E-ELT

Author: N. Hubin, Pascal Jagourel, J.-P. Amans, Gérard Rousset, J.-M. Conan, Y. Clénet, Thierry Fusco, Hermine Schnetler, C. Robert, M. Cohen, Damien Gratadour, J. Paufique, C. Petit, J. L. Dournaux, V. Michau, Eric Gendron, Serge Meimon, DOTA, ONERA, Université Paris Saclay [Châtillon], ONERA-Université Paris-Saclay, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), ESO Garching, Royal Observatory Edinburgh (ROE), and University of Edinburgh
Subjects: Diffraction, media_common.quotation_subject, 02 engineering and technology, OPTICAL TELESCOPES, 7. Clean energy, 01 natural sciences, law.invention, 010309 optics, Telescope, [SPI]Engineering Sciences [physics], Optics, law, K band, TOMOGRAPHY, 0103 physical sciences, Adaptive optics, media_common, Physics, [PHYS]Physics [physics], Atlas (topology), business.industry, Significant part, 021001 nanoscience & nanotechnology, Laser, Sky, 0210 nano-technology, business
Abstract: International audience; ATLAS is the future Laser Tomographic AO system of the E-ELT. Its goal is to provide a diffraction limited PSF in K band for a significant part of the sky (typically more than 60%). A first concept of the module combined with opto-mechanical implementation and associated performance is presented. Results show the feasibility of the concept, its versatility and a relative simplicity which is a good first step toward a potential implementation in the early time of the telescope.
Published: 2009

145. Adaptive optics, a key-element of the VLT

Author: Gérard Rousset, Pierre Léna, and J. C. Fontanella
Subjects: Physics, Image quality, business.industry, Bandwidth (signal processing), Astrophysics::Instrumentation and Methods for Astrophysics, Strehl ratio, Image processing, Deformable mirror, law.invention, Telescope, Optics, law, Actuator, Adaptive optics, business
Abstract: The principle and the components of an adaptive optics system are presented. The system scaling parameters are: the Fried diameter and the average speed of the turbulence. They determine the number of actuators of the deformable mirror and the bandwidth of the servoloop. In addition, two fundamental limitations must be taken into account: the photon noise and the anisoplanatism error. Therefore, an adaptive optics strategy in astronomy can be defined from the observing conditions and the required image quality. The application to the ESO VLT project is presented and the 'COME-ON' prototype system is described: recently it was successfully operated. The main obtained results are given in terms of Strehl ratios, image profiles and modulation transfer functions.
Published: 1991

146. First steps toward 3D high resolution imaging using adaptive optics and full-field optical coherence tomography

Author: Marie Blavier, Michel Paques, Francois Lacombe, Guillaume Chenegros, Jean-François Le Gargasson, Ivan Maksimovic, Laurent M. Mugnier, Leonardo Blanco, José-Alain Sahel, Florence Pouplard, Marie Glanc, Sarah Tick, Gérard Rousset, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Ingénieurs, Techniciens et Administratifs, Centre d'Investigation Clinique (CIC - Brest), Université de Brest (UBO)-Institut National de la Santé et de la Recherche Médicale (INSERM), Groupement d'Intérêt Scientifique du Partenariat Haute résolution Angulaire Sol-Espace (GIS PHASE ), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), and Mauna Kea Technologies
Subjects: medicine.diagnostic_test, business.industry, Computer science, Image quality, Field of view, Iterative reconstruction, Optics, Optical coherence tomography, medicine, Computer vision, Tomography, Artificial intelligence, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Adaptive optics, Image restoration, Coherence (physics)
Abstract: International audience; We describe here two parts of our future 3D fundus camera coupling Adaptive Optics and full-field Optical Coherence Tomography. The first part is an Adaptive Optics flood imager installed at the Quinze-Vingts Hospital, regularly used on healthy and pathological eyes. A posteriori image reconstruction is performed, increasing the final image quality and field of view. The instrument lateral resolution is better than 2 microns. The second part is a full-field Optical Coherence Tomograph, which has demonstrated capability of performing a simple kind of "4 phases" image reconstruction of non biological samples and ex situ retinas. Final aim is to couple both parts in order to achieve 3D high resolution mapping of in vivo retinas.
Published: 2008

147. Retinal images using adaptive optics

Author: Jf Le Gargasson, Michel Paques, Ja Sahel, Gérard Rousset, and Marie Glanc
Subjects: Wavefront, Retina, genetic structures, business.industry, Computer science, Retinal, General Medicine, eye diseases, Ophthalmology, chemistry.chemical_compound, Optics, medicine.anatomical_structure, chemistry, medicine, Retinal imaging, sense organs, High order, business, Adaptive optics
Abstract: Purpose To image cells of the retina using adaptive optics. Methods Imaging the human retina in vivo is affected by the eye's natural aberrations, which limit the resolution of retinal images. Measuring these aberrations, including the high order ones, is possible using wavefront sensing techniques. Results A review of the rapid progress in this field is given. Once the aberrations are known, adaptive optics methods, developed for astronomical observing in the past 15 years, can be applied in order either to improve retinal imaging or to give hyper-vision to the subject. Progress in this domain is reviewed, and some original results are reported with a new instrument. Conclusion Applications are discussed, including a possible three-dimensional, high-resolution method to image the human retina in vivo.
Published: 2008

148. Persee: a nulling demonstrator with real-time correction of external disturbances

Author: T. Buey, Gérard Rousset, S. Jacquinod, J. P. Amans, Philippe Laporte, V. Coudé du Foresto, Frédéric Cassaing, J. M. Le Duigou, A. Marcotto, Jean-Michel Reess, Marc Ollivier, L. Pirson, Kamel Houairi, B. Sorrente, Marc Barillot, François Hénault, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Ingénieurs, Techniciens et Administratifs
Subjects: Cophasing, Interferometry, business.industry, Payload, Computer science, Control system, Satellite, Aerospace engineering, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Remote sensing
Abstract: Nulling interferometry is one of the most promising methods to study habitable extrasolar systems. Several projects, such as Darwin, TPF, Pegase, FKSI or Aladdin, are currently considered and supported by R&D programs. One of the main issues of nulling interferometry is the feasibility of a stable polychromatic null despite the presence of significant disturbances, induced by vibrations, atmospheric turbulence on the ground or satellite drift for spaceborne missions. To reduce cost and complexity of the whole system, it is necessary to optimize not only the control loop performance at platform and payload levels, but also their interaction. In this goal, it was decided in 2006 to build a laboratory demonstrator named Persee. Persee is mostly funded by CNES and built by a consortium including CNES, IAS, LESIA, OCA, ONERA and TAS. After a definition phase in 2006, the implementation of the sub-systems has now begun and the integration near Paris by GIS-PHASE (LESIA, ONERA and GEPI) is planned in 2009. This paper details the main objectives of PERSEE, describes the definition of the bench, presents the current status and reports results obtained with the first sub-systems.
Published: 2008

149. The SPHERE XAO system: design and performance

Author: Philippe Feautrier, David Mouillet, Julien Charton, Jean-François Sauvage, Markus Kasper, Cyril Petit, Norbert Hubin, Pierre Baudoz, Tristan Buey, P. Gigan, Gérard Rousset, Patrick Rabou, Jean-Luc Beuzit, Pascal Puget, Thierry Fusco, Enrico Fedrigo, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Ingénieurs, Techniciens et Administratifs
Subjects: Physics, Integration testing, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Polarimetry, Optics, Cardinal point, Planet, Field spectroscopy, Systems design, Multi-band device, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Adaptive optics, business
Abstract: Extreme adaptive optics system (SAXO) is the heart of the SPHERE instrument which aims at directly detect and characterize giant extra-solar planets from the ground. It should equip one of the four VLT 8-m telescopes at the end of 2010. We present a detailed design and architecture of the SAXO system. We focus on each critical point that has been solved during the preliminary design phase. It concerns the adaptive optics system itself but also the interaction with other SPHERE subsystems (such as coronagraphy) and focal plane instrumentation (dual band imager, integral field spectroscopy and polarimetric imager). Acceptance and integration tests of SAXO are discussed. Finally, detailed performance of the whole system and comparison to the science requirements are provided.
Published: 2008

150. Tests of the PSF reconstruction algorithm for NACO/VLT

Author: Nick Kornweibel, Eric Gendron, Y. Clénet, N. Ageorges, Gérard Rousset, Christopher Lidman, Thierry Fusco, Markus Kasper, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Groupement d'Intérêt Scientifique du Partenariat Haute résolution Angulaire Sol-Espace (GIS PHASE ), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), European Southern Observatory, ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), and European Southern Observatory (ESO)
Subjects: Wavefront, business.industry, Orientation (computer vision), Strehl ratio, Reconstruction algorithm, Optics, Aliasing, Noise (video), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Adaptive optics, Algorithm, Mathematics, Test data
Abstract: International audience; We have developed an PSF reconstruction algorithm for the NAOS adaptive optics system that is coupled with CONICA at ESO/VLT. We have modified the algorithm of Véran et al. (1997), originally written for PUEO at CFHT, to make use of the specific real-time wavefront-related data that observers with NACO receive together with their scientific images. In addition, we use the Vii algorithm introduced by Clénet et al. (2006) and Gendron et al. (2006) instead of the Uij algorithm originally used by Véran et al. (1997). Until now, tests on NAOS has been undertaken during technical time thanks to the NACO team at Paranal. A first test has been successfully performed to calibrate the orientation of reconstructed PSFs with respect to NACO images. We have also obtained two sets of PSF reconstruction test data with NACO in November 2006 and September 2007 to reconstruct PSFs. Discrepancies exist between the observed and reconstructed PSFs: their Strehl ratios are ~31% and ~39% respectively in Nov. 2006, ~31% and ~19% respectively in Sept. 2007. These differences may be at least partly explained by reconstructions that either did not account for the aliasing contribution or poorly estimated the noise contribution with the available noise information at that time. We have additionally just started to test our algorithm using the AO bench Sésame, at LESIA. Results are promising but need to be extended to a larger set of atmospheric conditions or AO correction qualities.
Published: 2008

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