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287 results on '"Gérard Rousset"'

51. Deriving comprehensive error breakdown for wide field adaptive optics systems using end-to-end simulations

Author: Florian Ferreira, 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), 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: Point spread function, Computer simulation, Computer science, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, Astrophysics::Instrumentation and Methods for Astrophysics, Graphics processing unit, 01 natural sciences, 010309 optics, Acceleration, Compass, 0103 physical sciences, Electronic engineering, Extremely Large Telescope, Deconvolution, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Simulation
Abstract: The future European Extremely Large Telescope (E-ELT) adaptive optics (AO) systems will aim at wide field correction and large sky coverage. Their performance will be improved by using post processing techniques, such as point spread function (PSF) deconvolution. The PSF estimation involves characterization of the different error sources in the AO system. Such error contributors are difficult to estimate: simulation tools are a good way to do that. We have developed in COMPASS (COMputing Platform for Adaptive opticS Systems), an end-to-end simulation tool using GPU (Graphics Processing Unit) acceleration, an estimation tool that provides a comprehensive error budget by the outputs of a single simulation run.
Published: 2016

52. Getting ready for the first on sky experiment using an ELT-scaled elongated sodium laser guide star

Author: Tristan Buey, Alastair Basden, James Osborn, Domenico Bonaccini Calia, Richard M. Myers, Damien Gratadour, Eric Stadler, R. G. Talbot, Tim Morris, Fanny Chemla, Andrew P. Reeves, Eric Gendron, Jean-Luc Gach, Thomas Pfrommer, Mauro Centrone, Gérard Rousset, Lisa Bardou, Fabrice Vidal, Philippe Feautrier, 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, business.industry, media_common.quotation_subject, 01 natural sciences, 010309 optics, Laser guide star, Optics, Sky, Fiber laser, 0103 physical sciences, William Herschel Telescope, Extremely Large Telescope, Adaptive optics, Adaptive optics systems, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, media_common
Abstract: The use of sodium laser guide star for Extremely Large Telescopes (ELT) adaptive optics systems is a key concern due to the perspective effect that produces elongated images in the Shack-Hartmann pattern. In order to assess the feasibility of using an elongated sodium beacon on an ELT, an on-sky experiment reproducing the extreme off-axis launch conditions of the European ELT is scheduled for summer and autumn 2016. The experiment will use the demonstrator CANARY installed on the William Herschel Telescope and the ESO transportable 20W CW fiber laser, embedded in the Wendelstein LGS unit. We will discuss here the challenges this experiment addresses as well as the details of its implementation and the derivation of the error budget.
Published: 2016

53. Adaptive optics for MOSAIC: design and performance of the wide(st)-field AO system for the E-ELT

Author: Gérard Rousset, Thierry Fusco, Richard M. Myers, Alastair Basden, Ewan Fitzsimons, Carine Morel, Tristan Buey, Francois Hammer, Tim Morris, Fanny Chemla, Cyril Petit, Eric Gendron, Benoit Neichel, Jean-Marc Conan, Myriam Rodrigues, P. Jagourel, 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, business.industry, Computer science, Field of view, Active optics, 01 natural sciences, Encircled energy, Deformable mirror, law.invention, 010309 optics, Telescope, law, 0103 physical sciences, business, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Spectrograph, Computer hardware, Remote sensing
Abstract: MOSAIC is the proposed multiple-object spectrograph for the E-ELT that will utilise the widest possible field of view provided by the telescope. In terms of adaptive optics, there are two distinct operating modes required to meet the top-level science requirements. The MOSAIC High Multiplex Mode (HMM) requires either seeing-limited or GLAO correction within a 0.6 (NIR) and 0.9 (VIS) arcsecond sub-fields over the widest possible field for a few hundred objects. To achieve seeing limited operation whilst maintaining the maximum unvignetted field of view for scientific observation will require recreating some of the functionality present in the Pre-Focal Station relating to control of the E-ELT active optics. MOSAIC High Definition Mode Control (HDM) requires a 25% Ensquared Energy (EE) within 150mas in the H-band element for approximately 10 targets distributed across the full E-ELT field, implying the use of Multiple Object AO (MOAO). Initial studies have shown that to meet the EE requirements whilst maintaining high-sky coverage will require the combination of wavefront signals from both high-order NGS and LGS to provide a tomographic estimate for the correction to be applied to the open-loop MOAO DMs. In this paper we present the current MOSAIC AO design and provide the first performance estimates for the baseline instrument design. We then report on the various trade-offs that will be investigated throughout the course of the Phase A study, such as the requirement to mix NGS and LGS signals tomographically. Finally, we discuss how these will impact the AO architecture, the MOSAIC design and ultimately the scientific performance of this wide-field workhorse instrument at the E-ELT.
Published: 2016

54. Final two-stage MOAO on-sky demonstration with CANARY

Author: Eric Stadler, Arnaud Sevin, James Osborn, D. Perret, David Henry, Andrew P. Reeves, Nigel Dipper, J. M. Huet, Urban Bitenc, Richard M. Myers, Damien Gratadour, Stephen Todd, Gérard Rousset, Colin Dickson, G. Talbot, Carine Morel, Alastair Basden, Eric Gendron, Tristan Buey, Tim Morris, Philippe Feautrier, Simon L. Morris, M. Cohen, David Atkinson, Jean-Luc Gach, E. Younger, Fanny Chemla, 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), 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), and Technique
Subjects: Physics, media_common.quotation_subject, 01 natural sciences, Woofer, Tweeter, Deformable mirror, law.invention, 010309 optics, Stars, Laser guide star, law, Sky, 0103 physical sciences, William Herschel Telescope, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Remote sensing, media_common
Abstract: CANARY is an on-sky Laser Guide Star (LGS) tomographic AO demonstrator in operation at the 4.2m William Herschel Telescope (WHT) in La Palma. From the early demonstration of open-loop tomography on a single deformable mirror using natural guide stars in 2010, CANARY has been progressively upgraded each year to reach its final goal in July 2015. It is now a two-stage system that mimics the future E-ELT: a GLAO-driven woofer based on 4 laser guide stars delivers a ground-layer compensated field to a figure sensor locked tweeter DM, that achieves the final on-axis tomographic compensation. We present the overall system, the control strategy and an overview of its on-sky performance.
Published: 2016

55. Experience with wavefront sensor and deformable mirror interfaces for wide-field adaptive optics systems

Author: C. N. Dunlop, Nigel Dipper, Serge Meimon, Philippe Laporte, Carine Morel, Tim Morris, J. M. Huet, B. Le Roux, Alastair Basden, Andrew P. Reeves, C. Petit, Alan H. Greenaway, Timothy Butterley, O. Martin, Henri-François Raynaud, M. L. Sánchez Rodríguez, Urban Bitenc, Fabrice Vidal, M. Cohen, Brian Stobie, Jesús Daniel Santos, A. Guesalaga, Tristan Buey, Z. Hubert, Andy Longmore, N. Looker, Philippe Feautrier, Diego Cano, Paul Clark, M. Brangier, Eric Gendron, C. D. Guzman, Arnaud Sevin, Fanny Chemla, Deli Geng, Aglae Kellerer, Jean-Luc Gach, Stephen J. Goodsell, Nazim Ali Bharmal, Caroline Kulcsár, M. Marteaud, James Osborn, David Henry, Daniel Hölck, Gaetano Sivo, Colin Dickson, Richard M. Myers, Damien Gratadour, Eric Stadler, F. J. de Cos, E. Younger, Gérard Rousset, Jean-Marc Conan, D. Perret, F. Sánchez Lasheras, G. Talbot, Stephen Todd, David Atkinson, T. Fusco, Department of Physics, Centre for Advanced Instrumentation, Durham University, Royal Observatory (UKATC), 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), Issac Newton Group, 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), Universidad de Oviedo [Oviedo], Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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 Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), 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), Herriot watt university, Pontificia Universidad Católica de Chile (UC), Cambridge University, Laboratoire Charles Fabry / Spim, Laboratoire Charles Fabry (LCF), Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), Institut d'Optique Graduate School (IOGS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), ONERA, Oviedo University, 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), 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), Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), and Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS)-Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS)
Subjects: Physics - Instrumentation and Detectors, ASTRONOMICAL INSTRUMENTATION, FOS: Physical sciences, 02 engineering and technology, 01 natural sciences, Deformable mirror, Optics, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Electronic engineering, Instrumentation (computer programming), METHOD, Adaptive optics, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), DETECTOR, Physics, Wavefront, ADAPTIVE OPTICS, business.industry, Detector, Astronomy and Astrophysics, Wavefront sensor, Instrumentation and Detectors (physics.ins-det), Space and Planetary Science, Control system, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, 020201 artificial intelligence & image processing, Adaptive optics systems, business, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: Recent advances in adaptive optics (AO) have led to the implementation of wide field-of-view AO systems. A number of wide-field AO systems are also planned for the forthcoming Extremely Large Telescopes. Such systems have multiple wavefront sensors of different types, and usually multiple deformable mirrors (DMs). Here, we report on our experience integrating cameras and DMs with the real-time control systems of two wide-field AO systems. These are CANARY, which has been operating on-sky since 2010, and DRAGON, which is a laboratory adaptive optics real-time demonstrator instrument. We detail the issues and difficulties that arose, along with the solutions we developed. We also provide recommendations for consideration when developing future wide-field AO systems., Accepted for publication in MNRAS
Published: 2016

56. Focal plane wavefront sensor achromatization : The multireference self-coherent camera

Author: R. Galicher, Pierre Baudoz, Johan Mazoyer, Gérard Rousset, O. Dupuis, J. R. Delorme, 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), 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), Technologies et systèmes d'information pour les agrosystèmes (UR TSCF), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Centre Hospitalier Lyon Sud [CHU - HCL] (CHLS), Hospices Civils de Lyon (HCL), 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: FOS: Physical sciences, 01 natural sciences, 010309 optics, Speckle pattern, Optics, 0103 physical sciences, Chromatic scale, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Optical path length, ComputingMilieux_MISCELLANEOUS, Wavefront, Physics, [PHYS]Physics [physics], Angular distance, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Wavefront sensor, Exoplanet, Cardinal point, 13. Climate action, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: High contrast imaging and spectroscopy provide unique constraints for exoplanet formation models as well as for planetary atmosphere models. But this can be challenging because of the planet-to-star small angular separation and high flux ratio. Recently, optimized instruments like SPHERE and GPI were installed on 8m-class telescopes. These will probe young gazeous exoplanets at large separations (~1au) but, because of uncalibrated aberrations that induce speckles in the coronagraphic images, they are not able to detect older and fainter planets. There are always aberrations that are slowly evolving in time. They create quasi-static speckles that cannot be calibrated a posteriori with sufficient accuracy. An active correction of these speckles is thus needed to reach very high contrast levels (>1e7). This requires a focal plane wavefront sensor. Our team proposed the SCC, the performance of which was demonstrated in the laboratory. As for all focal plane wavefront sensors, these are sensitive to chromatism and we propose an upgrade that mitigates the chromatism effects. First, we recall the principle of the SCC and we explain its limitations in polychromatic light. Then, we present and numerically study two upgrades to mitigate chromatism effects: the optical path difference method and the multireference self-coherent camera. Finally, we present laboratory tests of the latter solution. We demonstrate in the laboratory that the MRSCC camera can be used as a focal plane wavefront sensor in polychromatic light using an 80 nm bandwidth at 640 nm. We reach a performance that is close to the chromatic limitations of our bench: contrast of 4.5e-8 between 5 and 17 lambda/D. The performance of the MRSCC is promising for future high-contrast imaging instruments that aim to actively minimize the speckle intensity so as to detect and spectrally characterize faint old or light gaseous planets., 14 pages, 20 figures
Published: 2016

57. Tomography for Astronomical Adaptive Optics using the CANARY On-Sky Demonstrator

Author: Andy Longmore, Richard Wilson, Timothy Butterley, Simon L. Morris, Colin Dickson, Eric Stadler, David Atkinson, Fabrice Vidal, Carine Morel, G. Talbot, Tim Morris, J-M. Huet, Urban Bitenc, Nigel Dipper, Stephen Todd, D. Perret, Gérard Rousset, Eric Gendron, Arnaud Sevin, P. Feautrier, F. Chemlac, M. Cohen, James Osborn, David Henry, Andrew P. Reeves, Richard M. Myers, Damien Gratadour, Tristan Buey, J-L. Gach, Alastair Basden, and E. Younger
Subjects: Wavefront, business.industry, Deformable mirror, law.invention, Telescope, Optics, Geography, Laser guide star, law, Extremely Large Telescope, William Herschel Telescope, Guide star, business, Adaptive optics, Remote sensing
Abstract: CANARY is an on-sky demonstrator instrument for the investigation of novel forms of tomographic Adaptive Optics (AO) which are required by the prospective European Extremely Large Telescope (E-ELT). CANARY is deployed on the 4.2m William Herschel Telescope in the Canary Islands, Spain. In its most evolved variant (Phase C2), CANARY employs four Laser Guide Star (LGS) Wavefront Sensors (WFS) and three Natural Guide Star (NGS) WFS to perform tomography on the turbulent atmospheric volume above the telescope. The projected wavefront phase error for a particular line of sight is then corrected by two Deformable Mirrors (DMs), and the resultant residual wavefront error is monitored by a further NGS WFS and an image recording camera. We outline the CANARY design, and present the most recent results obtained with a novel open/closed loop control approach designed to mimic the E-ELT.
Published: 2016

58. Les défis de l’optique adaptative en astronomie

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), 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: [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Depuis son introduction en astronomie il y a une vingtaine d’annees, l’optique adaptative a permis des avancees spectaculaires en termes de qualite d’image et a conduit a des decouvertes majeures dans le domaine de l’astrophysique : cartographie du sol de Titan, confirmation de la presence d’un trou noir massif au centre de la Voie lactee, etude de sources extra-galactiques…Les developpements recents visent d’une part a augmenter la qualite de la correction afin d’imager des exoplanetes, et d’autre part a etendre le champ corrigeable. De nouvelles techniques d’optique adaptative, comme l’optique adaptative multi-objets ou l’optique adaptative multi-conjuguee, ont ainsi ete developpees ouvrant la voie a de nouvelles observations et a la construction de telescopes extremement grands, avec un diametre de 30 metres ou plus.
Published: 2012

59. Anisoplanatism effect on the E-ELT SCAO point spread function. A preserved coherent core across the field

Author: Eric Gendron, Damien Gratadour, Gérard Rousset, Fabrice Vidal, Yann Clénet, 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: Physics, Point spread function, [PHYS]Physics [physics], Scale (ratio), business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Strehl ratio, Astronomy and Astrophysics, Field of view, Context (language use), law.invention, Telescope, Optics, Space and Planetary Science, law, [SDU]Sciences of the Universe [physics], Extremely Large Telescope, business, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], ComputingMilieux_MISCELLANEOUS
Abstract: Context. The science case studies and the optimized designing of the future adaptive optics-fed extremely large telescope instruments require the precise simulation of their adaptive optics system, potentially over their whole field of view, whatever the adaptive optics flavor the instruments will be equipped with.Aims. We simulate the anisoplanatism effect on the extremely large telescope single conjugate adaptive optics point spread function. Our interest in this expected degradation of the correction performance with respect to the off-axis distance is in terms of the point spread function Strehl ratio and profile.Methods. Adaptive optics simulations at the scale of extremely large telescopes are challenging given the large parameter space to explore for the adaptive optics dimensioning and the large number of degrees of freedom at play for a given set of simulation parameters. To address this problem, we have used three different simulation tools with increasing degree of fidelity compared to a real adaptive optics system. The first is based on analytical formulae and allowed us to derive the Strehl ratio degradation with the off-axis distance. The second is a Fourier-based code and provided us with both the Strehl ratio and the point spread function profile in the field. The last is an end-to-end code based on the graphical processing unit technology and also provided us with the Strehl ratio and the point spread function profile in the field.Results. The three tools we used demonstrated a fast execution time even at the extremely large telescope scale. Cross-checks between the different codes were performed and demonstrated the coherency of the results. In addition to the expected degradation of the adaptive optics performance with the field angle, we demonstrated that in the simulation conditions applicable to the E-ELT, the single conjugate adaptive optics point spread function remains topped with a coherent core even at off-axis distances as large as 60 arcsec and consequently very low Strehl ratios. We also studied the impact of the outer scale on the point spread function profile, demonstrating that the aforementioned Airy-like pattern is observable even when the outer scale is larger than the telescope diameter.Conclusions. These results could push for the preservation over a large field of the optical quality of any common path optics between the telescope and the instruments in single conjugate adaptive optics mode. This could offer some astrometric capabilities to these instruments operating in this adaptive optics mode.
Published: 2015

60. Resolving faint structures in the debris disk around TWA 7

Author: Francois Menard, Maud Langlois, Markus Janson, R. G. van Holstein, R. G. Gratton, Philippe Feautrier, Claudio Caceres, Wolfgang Brandner, D. Mawet, Graeme Salter, Th. Henning, E. Sissa, Amelia Bayo, Dino Mesa, M. Feldt, A. Roux, A. Pavlov, C. A. Grady, Gael Chauvin, Silvano Desidera, C. Perrot, David Mouillet, J. Lannier, Ch. Ginski, Philippe Thébault, Johan Olofsson, Thibaut Moulin, A-L. Maire, D. Le Mignant, A-M. Lagrange, T. Schmidt, Matthias R. Schreiber, C. Lazzoni, R. Ligi, Julien Milli, N. Godoy, C. Thalmann, Stephen Durkan, P. Rabou, Janis Hagelberg, Christophe Pinte, Quentin Kral, Anthony Boccaletti, L. Abe, Esther Buenzli, N. Engler, Hector Canovas, Arthur Vigan, Gérard Rousset, J. C. Augereau, Joshua E. Schlieder, S. Peretti, Ruben Asensio-Torres, and Mickael Bonnefoy
Subjects: Physics, Debris disk, Spiral galaxy, 010504 meteorology & atmospheric sciences, instrumentation: polarimeters, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Position angle, circumstellar matter, 01 natural sciences, Stars, instrumentation: high angular resolution, Space and Planetary Science, Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Spectral energy distribution, Astrophysics::Earth and Planetary Astrophysics, Low Mass, 010303 astronomy & astrophysics, Planetary mass, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences
Abstract: Context. Debris disks are the intrinsic by-products of the star and planet formation processes. Most likely due to instrumental limitations and their natural faintness, little is known about debris disks around low mass stars, especially when it comes to spatially resolved observations. Aims. We present new VLT/SPHERE IRDIS dual-polarization imaging (DPI) observations in which we detect the dust ring around the M2 spectral type star TWA 7. Combined with additional angular differential imaging observations we aim at a fine characterization of the debris disk and setting constraints on the presence of low-mass planets. Methods. We modeled the SPHERE DPI observations and constrain the location of the small dust grains, as well as the spectral energy distribution of the debris disk, using the results inferred from the observations, and performed simple N-body simulations. Results. We find that the dust density distribution peaks at ~0.72′′ (25 au), with a very shallow outer power-law slope, and that the disk has an inclination of ~13° with a position angle of ~91° east of north. We also report low signal-to-noise ratio detections of an outer belt at a distance of ~1.5′′ (~52 au) from the star, of a spiral arm in the southern side of the star, and of a possible dusty clump at 0.11′′. These findings seem to persist over timescales of at least a year. Using the intensity images, we do not detect any planets in the close vicinity of the star, but the sensitivity reaches Jovian planet mass upper limits. We find that the SED is best reproduced with an inner disk at ~0.2′′ (~7 au) and another belt at 0.72′′ (25 au). Conclusions. We report the detections of several unexpected features in the disk around TWA 7. A yet undetected 100M⊕ planet with a semi-major axis at 20−30 au could possibly explain the outer belt as well as the spiral arm. We conclude that stellar winds are unlikely to be responsible for the spiral arm.
Published: 2018

61. OSIRIS – The Scientific Camera System Onboard Rosetta

Author: Marco Fulle, K.-P. Wenzel, Fritz Gliem, A. López, Jean-Pierre Sivan, Rafael Rodrigo, Detlef Koschny, U. Telljohann, Nicolas Thomas, G. Parzianello, Kjetil Dohlen, R. Muller, K. Stöckner, Michael Küppers, Gian Paolo Guizzo, Giampiero Naletto, J. J. López-Moreno, Werner Curdt, J.-R. Kramm, V. Timon, Mirco Zaccariotto, D. Germerott, P. Ramous, Francesco Angrilli, Joseph A. Burns, M. Angulo, K.-U. Reiche, M. D. Michelena, Sonia Fornasier, T. Wittrock, M. Reina, Marco Pertile, H. U. Keller, Michael F. A'Hearn, A. Sanz, C. Quintana, Luisa Lara, A. Llebaria, Wing-Huen Ip, Laurent Jorda, L. Sabau, Peter Barthol, M. E. Bailey, Harald Michalik, Gérard Rousset, Stubbe F. Hviid, I. Büttner, José María Bermúdez de Castro, Hans Rickman, Gabriele Cremonese, Alain Origne, Holger Sierks, Stefano Debei, Roberto Ragazzoni, M. De Cecco, A. Lopez-Jimenez, Jean-Loup Bertaux, Cesare Barbieri, V. Brown, M. A. Barucci, J.-L. Boit, J. E. Rodriguez, Philippe Lamy, R. Meller, G. Bianchini, V. Da Deppo, J. Tabero, Ekkehard Kührt, G. Tomasch, Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Università degli Studi di Padova = University of Padua (Unipd), 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 Astronomy and Space Physics [Uppsala], Uppsala University, Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Instituto Nacional de Técnica Aeroespacial (INTA), Armagh Observatory [Armagh], 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), Service d'aéronomie (SA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Cornell University [New York], INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Istituto di Fotonica e Nanotecnologie [Padova] (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), University of Trento [Trento], INAF - Osservatorio Astronomico di Trieste (OAT), Institut für Datentechnik und Kommunikationsnetze, Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Carlo Gavazzi Space SpA (CGS), Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Universidad Politécnica de Madrid (UPM), Observatoire de Haute-Provence (OHP), Institut Pythéas (OSU PYTHEAS), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Agence Spatiale Européenne = European Space Agency (ESA), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), Max-Planck-Institut für Sonnensystemforschung (MPS), Universita degli Studi di Padova, 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), European Space Agency (ESA)-European Space Agency (ESA), Consiglio Nazionale delle Ricerche [Roma] (CNR), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Cornell University, and Technische Universität Braunschweig [Braunschweig]
Subjects: 010504 meteorology & atmospheric sciences, Comet, Cometary activity, Coma (optics), Spectroscopic, Osiris, 7. Clean energy, 01 natural sciences, Aeronáutica, Data processing system, SOLAR-SYSTEM, Imaging system, comet, WIDE-ANGLE CAMERA, Shutter, Rosetta, 0103 physical sciences, SOUTHERN SPECTROPHOTOMETRIC STANDARDS, Angular resolution, Wide angle camera, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Remote sensing, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Physics, camera system, Spacecraft, biology, business.industry, Detector, Astronomy, Astronomy and Astrophysics, biology.organism_classification, COMET HALLEY, Narrow angle camera, Space and Planetary Science, DUST JETS, Camera, business
Abstract: The Optical, Spectroscopic, and Infrared Remote Imaging System OSIRIS is the scientific camera system onboard the Rosetta spacecraft (Figure 1). The advanced high performance imaging system will be pivotal for the success of the Rosetta mission. OSIRIS will detect 67P/Churyumov-Gerasimenko from a distance of more than 106 km, characterise the comet shape and volume, its rotational state and find a suitable landing spot for Philae, the Rosetta lander. OSIRIS will observe the nucleus, its activity and surroundings down to a scale of ~2 cm px−1. The observations will begin well before the onset of cometary activity and will extend over months until the comet reaches perihelion. During the rendezvous episode of the Rosetta mission, OSIRIS will provide key information about the nature of cometary nuclei and reveal the physics of cometary activity that leads to the gas and dust coma. OSIRIS comprises a high resolution Narrow Angle Camera (NAC) unit and a Wide Angle Camera (WAC) unit accompanied by three electronics boxes. The NAC is designed to obtain high resolution images of the surface of comet 67P/Churyumov-Gerasimenko through 12 discrete filters over the wavelength range 250–1000 nm at an angular resolution of 18.6 μrad px−1. The WAC is optimised to provide images of the near-nucleus environment in 14 discrete filters at an angular resolution of 101 μrad px−1. The two units use identical shutter, filter wheel, front door, and detector systems. They are operated by a common Data Processing Unit. The OSIRIS instrument has a total mass of 35 kg and is provided by institutes from six European countries. The support of the national funding agencies of Germany (DLR), France (CNES), Italy (ASI), Sweden (SNSB), and Spain (MEC) is gratefully acknowledged. Substantial support for the development of the Data Processing Unit was provided by the ESA Technical Directorate through the Technical Research Programme. In addition to the formal co-authors of this paper (comprising lead scientists, Co-Is, project managers, and lead engineers ), the project was supported by an enormous number of scientists, engineers, and technicians involved in the day-to-day development of the hardware. These include J. C. Blanc, D. Pouliquen, M. Saisse (France), A. Alvarez, A. L. Arteaga, A. Carretero, M. Fernández, H. Guerrero, P. Gutiérrez, J. L. Lizondo, V. Luengo, J. A. Martín, M. A. Martín, J. Meseguer, J. M. Mi, L. Moreno, J. Navarro, A. Núñez, E. Ragel, D. Rodríguez, G. Rosa, A. Sanchez, J. C. Sanmartín, G. Tonellotto (Spain), W. Boogaerts, W. Engelhardt, K. Eulig, B. Fiethe, A. Fischer, M. Gartner, K. Grabig, K. Kellner, A. Kiihn. W. Kiihn. J. Knollenberg, W. Neumann, J. Nitsch, P. Rüffer, H. Schüddekopf, U. Schiihlc. I. Sebastian, S. Stelzer, U. Strohmeyer, T. Tzscheetzsch, M. Wassermeyer (Germany), B. Johlander (ESTEC), M. Baessato, P. F. Brunello, S. Casotto, F. Don-, M. Lazzarin, E. Marchetti, F. Marzari, P. G. Nicolosi, F. Perón, F. Rampazzi, B. Saggin, G. Tondello, S. Verani, P. Zambolin ' (Italy), J. Lagerros, and B. Davidsson (Sweden). Peerreview
Published: 2007

62. On-sky tests of the CuReD and HWR fast wavefront reconstruction algorithms with CANARY

Author: Richard M. Myers, Damien Gratadour, Nazim Ali Bharmal, Tim Morris, Gérard Rousset, Urban Bitenc, Eric Gendron, Fabrice Vidal, Alastair Basden, Nigel Dipper, Centre for Advanced Instrumentation, Durham University (CfA), Department of Physics [Durham University], Durham University, 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: Wavefront, Physics, [PHYS]Physics [physics], business.industry, Leaky integrator, Strehl ratio, Astronomy and Astrophysics, Wavefront sensor, Deformable mirror, Optics, Space and Planetary Science, Integrator, business, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Algorithm, Smoothing, ComputingMilieux_MISCELLANEOUS
Abstract: CuReD (Cumulative Reconstructor with domain Decomposition) and HWR (Hierarchical Wavefront Reconstructor) are novel wavefront reconstruction algorithms for the Shack–Hartmann wavefront sensor, used in the single-conjugate adaptive optics. For a high-order system they are much faster than the traditional matrix–vector-multiplication method. We have developed three methods for mapping the reconstructed phase into the deformable mirror actuator commands and have tested both reconstructors with the CANARY instrument. We find out that the CuReD reconstructor runs stably only if the feedback loop is operated as a leaky integrator, whereas HWR runs stably with the conventional integrator control. Using the CANARY telescope simulator we find that the Strehl ratio (SR) obtained with CuReD is slightly higher than that of the traditional least-squares estimator (LSE). We demonstrate that this is because the CuReD algorithm has a smoothing effect on the output wavefront. The SR of HWR is slightly lower than that of LSE. We have tested both reconstructors extensively on-sky. They perform well and CuReD achieves a similar SR as LSE. We compare the CANARY results with those from a computer simulation and find good agreement between the two.
Published: 2015

63. Comparison of centroid computation algorithms in a Shack-Hartmann sensor

Author: M. Nicolle, Andrei Tokovinin, Vincent Michau, Gérard Rousset, Thierry Fusco, and Sandrine Thomas
Subjects: Physics, Sampling (signal processing), Pixel, Space and Planetary Science, Noise (signal processing), Computation, Detector, Centroid, Estimator, Astronomy and Astrophysics, Algorithm, Thresholding
Abstract: Analytical theory is combined with extensive numerical simulations to compare different flavours of centroiding algorithms: thresholding, weighted centroid, correlation, quad cell (QC). For each method, optimal parameters are defined in function of photon flux, readout noise and turbulence level. We find that at very low flux the noise of QC and weighted centroid leads the best result, but the latter method can provide linear and optimal response if the weight follows spot displacements. Both methods can work with average flux as low as 10 photons per subaperture under a readout noise of three electrons. At high-flux levels, the dominant errors come from non-linearity of response, from spot truncations and distortions and from detector pixel sampling. It is shown that at high flux, centre of gravity approaches and correlation methods are equivalent (and provide better results than QC estimator) as soon as their parameters are optimized. Finally, examples of applications are given to illustrate the results obtained in the paper.
Published: 2006

64. Foreword

Author: Jean-Marc Conan and Gérard Rousset
Subjects: General Engineering, Energy Engineering and Power Technology
Published: 2005

65. Wavefront sensing issues in MCAO

Author: Jean-Marc Conan, Amandine Blanc, Vincent Michau, Gérard Rousset, Thierry Fusco, M. Nicolle, and Jean-Luc Beuzit
Subjects: Physics, Wavefront, Optics, business.industry, General Engineering, Electronic engineering, Ground layer, Energy Engineering and Power Technology, Wavefront sensor, Astronomical telescopes, business, Focus (optics), Adaptive optics
Abstract: The problematic of wavefront sensing in Multiconjugate Adaptive Optics (MCAO) is addressed in this article. We first focus on the sky coverage estimation which drives, in particular, the choice between natural and laser guide stars and therefore has a major impact on wavefront sensor design. Then a comparison between star oriented and layer oriented concepts is proposed. Analytical developments and optimization of the concepts are derived in the simplest MCAO case: the ground layer AO system. From this study, advantages and drawbacks of each concept are highlighted. To cite this article: T. Fusco et al., C. R. Physique 6 (2005).
Published: 2005

66. NAOS on-line characterization of turbulence parameters and adaptive optics performance

Author: Nancy Ageorges, Gérard Rousset, Anne-Marie Lagrange, Thierry Fusco, D. Rabaud, David Mouillet, P-Y Madec, Francois Lacombe, Gérard Zins, Eric Gendron, Norbert Hubin, Julien Charton, and D. Rouan
Subjects: Very Large Telescope, business.industry, Computer science, Wavefront sensor, Atomic and Molecular Physics, and Optics, Deformable mirror, law.invention, Telescope, Optics, law, Robustness (computer science), Adaptive system, business, Adaptive optics, Atmospheric optics
Abstract: An on-line estimation of turbulence parameters (r0, L0 and wind speed) and adaptive optics (AO) performance is presented. The method is based on the reconstruction of open-loop data from deformable mirror voltages and residual wavefront sensor slopes obtained in closed loop. This dedicated tool implemented in the real time computer of the NAOS (Nasmyth adaptive optics system) system (first AO of the very large telescope) allows us without any loop opening to automatically monitor and display (every 15 s) both the atmospheric conditions and the system performance. We have validated the algorithm and tested its robustness on simulated and experimental data (both in the laboratory and on sky). Using data obtained over more than one year (from January 2002 to June 2003), a statistical study on NAOS performance and turbulence characteristics is proposed.
Published: 2004

67. Discovery of a Candidate for the Central Star of the Ultracompact H <scp>ii</scp> Region G5.89-0.39

Author: Wolfgang Brandner, Elena Puga, Rainer Lenzen, Th. Henning, Eric Gendron, Bringfried Stecklum, Anne-Marie Lagrange, Gérard Rousset, Markus Feldt, 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, Very Large Telescope, H II region, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Star (graph theory), Space and Planetary Science, Primary (astronomy), Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Exact location, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Adaptive optics, Astrophysics::Galaxy Astrophysics
Abstract: We present high-resolution, near-infrared images of the ultracompact H II region G5.89-0.39 that were taken during a commissioning run of the NACO adaptive optics/near-infrared camera system at the Very Large Telescope. For the first time, these data reveal the exact location of a very promising candidate for the primary, ionizing star of this region and provide a good estimate of its spectral type. We very briefly discuss the morphology of the region and the implications of finding the star at a location where it was quite unexpected, namely, off-center of a shell.
Published: 2003

68. Signal to noise ratio of layer-oriented measurements for multiconjugate adaptive optics

Author: Gérard Rousset, Jean-Marc Conan, Roberto Ragazzoni, and D. Bello
Subjects: Physics, Wavefront, business.industry, Astronomy and Astrophysics, Field of view, Wavefront sensor, Noise (electronics), Deformable mirror, Signal-to-noise ratio, Optics, Space and Planetary Science, Guide star, business, Adaptive optics
Abstract: Multiconjugate adaptive optics (MCAO) employing several deformable mirrors conjugated to different altitudes has been proposed in order to extend the size of the corrected field of view. A three dimensional measurement ofthe turbulent volume is needed in order to collect the information to control the deformable mirrors. Given a set of guide stars in the field of view, this can be done either using star-oriented or layer-oriented techniques. In the star-oriented measurement each wavefront sensor is coupled to a guide star while in layer-oriented techniques, wavefront sensors are coupled to different layers in the atmosphere and each of them collect light from the whole set of guide stars. This type of measurement is more exactly called optical layer-oriented (OPTLO) as the co-addition of light is done optically. The same information can also be obtained by combining, in a numerical way, star-oriented measurements. This hybrid approach is called numerical layer-oriented (NUMLO). In order to compare their performance, we present an analytical study of the signal to noise ratio (SNR) in the optical and numerical layer-oriented measurements. Optical layer oriented measurements are shown to be more efficient in the regime of faint flux and a large number of guide stars, while low detector noise allows numerical layer-oriented schemes to be more efficient in terms of SNR.
Published: 2003

69. Calibration of NAOS and CONICA static aberrations

Author: Markus Hartung, A. Blanc, Gérard Rousset, Thierry Fusco, and Laurent M. Mugnier
Subjects: Wavefront, Systematic error, Physics, Measure (data warehouse), biology, business.industry, Phase diversity, Experimental data, Astronomy and Astrophysics, Wavefront sensor, Astrophysics, biology.organism_classification, Optics, Space and Planetary Science, Calibration, Conica, business, Algorithm
Abstract: Wedescribe and evaluate the performance of a phase diversity wavefront sensor used to measure the staticaberrations of the VLT instrument NAOS-CONICA. The main limitations of this phase diversity technique are compiled. We investigate the systematic errors due to the experimental implementation and the design restrictions. Further error sources stem from the imperfect knowledge of the system, and from limitations of the algorithm. The influence of these errors on the wavefront estimation is evaluated on numerical and experimental data. This study highlights the essential verifications and calibrations needed to obtain accurate results and gives a practical guideline for the application of a phase diversity wavefront sensor. The comprehensive calibration results and the final gain in optical performance are presented and discussed in a complementary paper (Hartung et al. 2003).
Published: 2003

70. Calibration of NAOS and CONICA static aberrations

Author: Gérard Rousset, Thierry Fusco, Rainer Lenzen, Laurent M. Mugnier, Markus Hartung, A. Blanc, Francois Lacombe, 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, Very Large Telescope, biology, business.industry, Zernike polynomials, Near-infrared spectroscopy, Astrophysics::Instrumentation and Methods for Astrophysics, Physics::Optics, Astronomy and Astrophysics, Wavefront sensor, biology.organism_classification, law.invention, symbols.namesake, Optics, [SDU]Sciences of the Universe [physics], Space and Planetary Science, law, Calibration, symbols, Conica, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Adaptive optics, business, Beam splitter
Abstract: NAOS is the first adaptive optics (AO) system of the Very Large Telescope and will provide CONICA with diffraction-limited images. CONICA is a near infrared camera that offers a variety of imaging and spectroscopic observing modes. A technique will be described to benefit of the AO system to correct not only for atmospheric turbulence but also for the internal optical aberrations of the high-resolution camera and the beam splitters of NAOS. The aberrant optical components in the light path of CONICA as well as the beam splitters are outside of the AO loop and therefore no self-acting correction is possible. Independently of the AO wavefront sensor, a separate measurement of these aberrations using a method called phase diversity allows one to predict for a certain instrument configuration the corresponding aberrations. They are quantified by sets of Zernike coefficients that are rendered to the adaptive optics. This technique turns out to be very flexible and results in a further improvement of the optical overall performance. The application of phase diversity to the instrument is investigated in a preceding paper (Blanc et al. 2003). In the present paper we present in detail the instrumental implementation of phase diversity, the obtained calibration results, and the achieved gain in optical performance.
Published: 2003

71. Analysis of on-sky MOAO performance of CANARY using natural guide stars

Author: Richard M. Myers, Damien Gratadour, Gordon Talbot, Gérard Rousset, O. Martin, Zoltan Hubert, Eddy Younger, Fanny Chemla, Eric Gendron, M. Brangier, Nigel Dipper, Fabrice Vidal, Tim Morris, Alastair Basden, Andy Longmore, David Henry, 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), University of Manchester [Manchester], Department of Physics [Durham University], Durham University, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Laboratoire de l'intégration, du matériau au système (IMS), Université Sciences et Technologies - Bordeaux 1-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS), and Université Sciences et Technologies - Bordeaux 1 (UB)-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS)
Subjects: Wavefront, [PHYS]Physics [physics], media_common.quotation_subject, Strehl ratio, FOS: Physical sciences, Astronomy and Astrophysics, Ranging, Residual, Stars, Space and Planetary Science, Sky, William Herschel Telescope, 14. Life underwater, Adaptive optics, Astrophysics - Instrumentation and Methods for Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Instrumentation and Methods for Astrophysics (astro-ph.IM), ComputingMilieux_MISCELLANEOUS, Mathematics, media_common, Remote sensing
Abstract: The first on-sky results obtained by CANARY, the Multi-Object Adaptive Optics (MOAO) demonstrator, are analysed. The data were recorded at the William Herschel Telescope, at the end of September 2010. We describe the command and calibrations algorithms used during the run and present the observing conditions. The processed data are MOAO-loop engaged or disengaged slope buffers, comprising the synchronised measurements of the four Natural Guide Stars (NGS) wavefront sensors running in parallel, and near Infra-Red (IR) images. We describe the method we use to establish the error budget of CANARY. We are able to evaluate the to- mographic and the open loop errors, having median values around 216 nm and 110 nm respectively. In addition, we identify an unexpected residual quasi-static field aberration term of mean value 110 nm. We present the detailed error budget analysed for three sets of data for three different asterisms. We compare the experimental budgets with the numerically simulated ones and demonstrate a good agreement. We find also a good agreement between the computed error budget from the slope buffers and the measured Strehl ratio on the IR images, ranging between 10% and 20% at 1 530 nm. These results make us confident in our ability to establish the error budget of future MOAO instruments., in press A&A (2014)
Published: 2014

72. High contrast imaging on the THD bench: progress and upgrades

Author: Pierre Baudoz, Kjetil Dohlen, Mamadou N'Diaye, Gérard Rousset, F. Boussaha, A. Caillat, J. Firminy, J. R. Delorme, Raphaël Galicher, Johan Mazoyer, 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), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS), Observatoire de la Côte d'Azur (OCA), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), 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: High contrast imaging, Wavefront, Physics, Total harmonic distortion, business.industry, Exoplanets, High contrast imaging Exoplanets Adaptive optics Coronagraph high angular resolution, Deformable mirror, Exoplanet, law.invention, Coronagraph, Speckle pattern, Amplitude, Optics, law, Monochromatic color, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Adaptive optics, high angular resolution
Abstract: International audience; Direct imaging of exoplanets is very attractive but challenging and specific instruments like Sphere (VLT) or GPI (Gemini) are required to provide contrasts up to 16-17 magnitudes at a fraction of arcsec. To reach higher contrasts and detect fainter exoplanets, more-achromatic coronagraphs and a more-accurate wavefront control are needed. We already demontrated contrasts of ∼ 10 −8 at ∼ 4 λ/D at 635nm using a four quadrant phase mask and a self-coherent camera on our THD bench in laboratory. In this paper, we list the different techniques that were tested on the THD bench in monochromatic and polychromatic lights. Then, we present the upgraded version of the THD bench that includes several deformable mirrors for correcting phase and amplitude simultaneously and obtain a field-of-view covering the complete 360 degrees arouns the star with contrasts down to ∼ 10 −8 − 10 −9 .
Published: 2014

73. Adaptive optics simulations for the MICADO SCAO system

Author: Ric Davies, Fabrice Vidal, Gérard Rousset, Damien Gratadour, Yann Clénet, 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: Point spread function, Physics, Aperture, business.industry, Near-infrared spectroscopy, Strehl ratio, law.invention, Telescope, Optics, law, K band, Halo, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Adaptive optics, business
Abstract: We present in this paper the current simulation results of the single-conjugate adaptive optics (SCAO) mode of the wide-field imager MICADO. MICADO is a near-IR camera for the European ELT, featuring a wide field (75"), spectroscopic, and coronagraphic capabilities. It has been chosen by ESO as one of the two first-light instruments. MICADO will be optimized for the multi-conjugate adaptive optics module MAORY and will also work in SCAO mode. This SCAO mode will provide MICADO a high-level, on-axis correction, making use of the adaptive secondary M4 in the telescope. It is shown here that the on-axis compensation level reaches Strehl ratios (SR) of the order of 0.70 in K band under median seeing condition, and quickly degrades with field angle. However, despite the important leak of the light from the core towards the halo, we demonstrate how the point spread function (PSF) remains topped with an Airy-like pattern even at low SR below 0.02. This known effect, due to the large telescope aperture, was already shown in past studies. We show here how dependent from the outer scale value this effect is, and we study how the presence of this peak allows the instrument to preserve astrometric capabilities even far out of the isoplanatic patch domain.
Published: 2014

74. First demo science with MOAO: observations of distant merging galaxies with CANARY

Author: Richard M. Myers, Damien Gratadour, Alastair Basden, Daniel Rouan, L. Grosset, James Osborn, Olivier C. Martin, Eric Gendron, Tim Morris, and Gérard Rousset
Subjects: Physics, Galactic astronomy, Hubble space telescope, Detector, Astronomy, Astrophysics, Galaxy merger
Abstract: During phase B, CANARY, the MOAO demonstrator, has been coupled to a dedicated, high sensitivity, near-IR camera based on a science grade NICMOS detector: CAMICAz. Using this combination, we have observed two distant merging systems at H and K in July 2013, with a resolution better than 150 mas over long exposures (< 1h). In this paper, we present this unique demo science data set, detail the performance achieved in terms of resolution and sensitivity and the first scientific results. Additionally, we provide a comparative study of the scientific output of MOAO with respect to classical LGS AO and HST.
Published: 2014

75. Maximum likelihood approach for the adaptive optics point spread function reconstruction

Author: Damien Gratadour, Gérard Rousset, Laurent M. Mugnier, Yann Clénet, Eric Gendron, 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, 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: Point spread function, Mathematical optimization, Matrix (mathematics), Noise (signal processing), Computer science, Covariance matrix, Maximum likelihood, Wavefront sensor, Covariance, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Residual, Adaptive optics, Algorithm
Abstract: This paper is dedicated to a new PSF reconstruction method based on a maximum likelihood approach (ML)which uses as well the telemetry data of the AO system (see Exposito et al. (2013) 1 ). This approach allows ajoint-estimation of the covariance matrix of the mirror modes of the residual phase, the noise variance and theFried parameter r 0 .In this method, an estimate of the covariance between the parallel residual phase and the orthogonal phaseis required. We developed a recursive approach taking into account the temporal e ect of the AO-loop, so thatthis covariance only depends on the r0, the wind speed and some of the parameters of the system (the gain of theloop, the interaction matrix and the command matrix). With this estimation, the high bandwidth hypothesis isno longer required to reconstruct the PSF with a good accuracy.We present the validation of the method and the results on numerical simulations (on a SCAO system) andshow that our ML method allows an accurate estimation of the PSF in the case of a Shack-Hartmann (SH)wavefront sensor (WFS).Keywords: Adaptive optics, PSF reconstruction, maximum likelihood
Published: 2014

76. A novel fast and accurate pseudo-analytical simulation approach for MOAO

Author: David E. Keyes, Ahmad Abdelfattah, Damien Gratadour, Eric Gendron, Hatem Ltaief, Ali Charara, Carine Morel, Gérard Rousset, Fabrice Vidal, Arnaud Sevin, 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, Minimum mean square error, Tomographic reconstruction, Covariance matrix, business.industry, Computer science, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, Deformable mirror, law.invention, Telescope, law, Aliasing, Computer vision, Tomography, Artificial intelligence, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Adaptive optics, Algorithm
Abstract: Multi-object adaptive optics (MOAO) is a novel adaptive optics (AO) technique for wide-field multi-object spectrographs (MOS). MOAO aims at applying dedicated wavefront corrections to numerous separated tiny patches spread over a large field of view (FOV), limited only by that of the telescope. The control of each deformable mirror (DM) is done individually using a tomographic reconstruction of the phase based on measurements from a number of wavefront sensors (WFS) pointing at natural and artificial guide stars in the field. We have developed a novel hybrid, pseudo-analytical simulation scheme, somewhere in between the end-to- end and purely analytical approaches, that allows us to simulate in detail the tomographic problem as well as noise and aliasing with a high fidelity, and including fitting and bandwidth errors thanks to a Fourier-based code. Our tomographic approach is based on the computation of the minimum mean square error (MMSE) reconstructor, from which we derive numerically the covariance matrix of the tomographic error, including aliasing and propagated noise. We are then able to simulate the point-spread function (PSF) associated to this covariance matrix of the residuals, like in PSF reconstruction algorithms. The advantage of our approach is that we compute the same tomographic reconstructor that would be computed when operating the real instrument, so that our developments open the way for a future on-sky implementation of the tomographic control, plus the joint PSF and performance estimation. The main challenge resides in the computation of the tomographic reconstructor which involves the inversion of a large matrix (typically 40 000 × 40 000 elements). To perform this computation efficiently, we chose an optimized approach based on the use of GPUs as accelerators and using an optimized linear algebra library: MORSE providing a significant speedup against standard CPU oriented libraries such as Intel MKL. Because the covariance matrix is symmetric, several optimization schemes can be envisioned to speedup even further the computation. Optimizing the speed of the reconstructor computation is of major interest not only for the design study of MOAO instruments, but also for future routine operations of the system as the reconstructor has to be updated regularly to cope for atmospheric variability.
Published: 2014

77. High-contrast imaging in wide spectral band with a self-coherent camera and achromatic coronagraphs

Author: Mamadou N'Diaye, Raphaël Galicher, Pierre Baudoz, J. R. Delorme, A. Caillat, Kjetil Dohlen, Gérard Rousset, Johan Mazoyer, 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, business.industry, Astronomy, Active optics, law.invention, Telescope, Optics, Spitzer Space Telescope, law, Achromatic lens, Angular resolution, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Adaptive optics, Coronagraph, Image resolution
Abstract: Direct imaging of exoplanets is very attractive but challenging. It requires high angular resolution and veryhigh-contrast imaging. One solution is the use of coronagraphs behind the adaptive optics of large telescopes.Unfortunately, optics of space telescope and ground telescope introduce quasi-static aberrations which stronglylimit the quality of the nal image and a dedicated stage of adaptive optics is required. We proposed a self-coherent camera (SCC) in 2006 and we obtained contrast levels of 2 10 8 at a few 0 =D at 638 nm inlaboratory. In this paper, we explain how to achromatize the SCC. We present laboratory performance in widespectral band 5 10 % bandpass.Keywords: High-contrast imaging { Exoplanets { Adaptive optics { Coronagraph 1. INTRODUCTION Unlike the methods of indirect detection, direct imaging methods can characterize the atmosphere of exoplanetsin the outer part of exoplanetary systems. Some young exoplanets at large separations have already beendetected.
Published: 2014

78. First on-sky results of a neural network based tomographic reconstructor: Carmen on Canary

Author: James Osborn, F. J. de Cos Juez, Alastair Basden, Tim Morris, Richard M. Myers, Damien Gratadour, M. Gomez Victoria, A. Guesalaga, Timothy Butterley, M. L. Sánchez Rodríguez, Eric Gendron, Gérard Rousset, Dani Guzman, F. Sánchez Lasheras, 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, Artificial neural network, Calibration (statistics), Computer science, business.industry, media_common.quotation_subject, law.invention, Telescope, law, Sky, Computer vision, Artificial intelligence, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Adaptive optics, business, media_common
Abstract: We present on-sky results obtained with Carmen, an artificial neural network tomographic reconstructor. It was tested during two nights in July 2013 on Canary, an AO demonstrator on the William Hershel Telescope. Carmen is trained during the day on the Canary calibration bench. This training regime ensures that Carmen is entirely flexible in terms of atmospheric turbulence profile, negating any need to re-optimise the reconstructor in changing atmospheric conditions. Carmen was run in short bursts, interlaced with an optimised Learn and Apply reconstructor. We found the performance of Carmen to be approximately 5% lower than that of Learn and Apply.
Published: 2014

79. Detailed analysis of the Canary on-sky results at the WHT using Rayleigh laser guide stars

Author: Gérard Rousset, James Osborn, O. Martin, Z. Hubert, Eric Gendron, Fabrice Vidal, Tim Morris, Alastair Basden, Richard M. Myers, Damien Gratadour, Fanny Chemla, 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, Tomographic reconstruction, Computer science, media_common.quotation_subject, Perspective (graphical), Near-infrared spectroscopy, Strehl ratio, Covariance, Laser, law.invention, symbols.namesake, law, Sky, symbols, Rayleigh scattering, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Adaptive optics, Remote sensing, media_common
Abstract: CANARY is the multi-object adaptive optics (MOAO) on-sky demonstrator developed by Durham University and LESIA Observatoire de Paris, in the perspective of the E-ELT. Since 2013, CANARY has been operating with 3 off-axis NGS and 4 off-axis Rayleigh LGS and compensating for one on-axis NGS observed with a near IR camera and the Truth Sensor (TS) for diagnostic purpose. In this paper, we present the tomographic performance of CANARY during the runs in 2013. We propose a detailed analysis of the tomographic error leading to the establishment of the CANARY wave-front error budget. In particular we are able to evaluate the tomographic error for each altitude in the atmosphere for a given reconstructor by modelling a set of one-layer covariance matrices. This tool allows us to understand the tradeoffs to be made in the building of the tomographic reconstructor. We present two methods for the wavefront error budget computation. The DTI one uses input system parameters and open loop WFS slopes to estimate the error in a number of independent terms. The DMTS method directly uses the Truth Sensor measurements to estimate the error. We show a good agreement between the two approaches making us confident in our modelling of the instrument. We derive estimations of the Strehl ratio from the error variance and compare them to the recorded IR image Strehl ratio. We find a good agreement between the two, hence validating our wavefront error analysis. Finally we present an on-sky validation of the tomographic reconstruction using LGS based on GLAO and MOAO data. We also quantify the gain brought by the LGS, comparing results obtained in MOAO with 3 NGS and with or without LGS in the wavefront measurements.
Published: 2014

80. CANARY phase B: on-sky open-loop tomographic LGS AO results

Author: M. Cohen, Urban Bitenc, Caroline Kulcsár, Eddy Younger, Andy Longmore, Timothy Butterley, G. Talbot, Richard Wilson, Stephen Todd, Gérard Rousset, Olivier C. Martin, Zoltan Hubert, Henri-François Raynaud, Fabrice Vidal, Eric Gendron, Denis Perret, Colin Dickson, Jean-Michel Huet, Andrew P. Reeves, Alastair Basden, Richard M. Myers, Arnaud Sevin, Damien Gratadour, Tim Morris, Fanny Chemla, James Osborn, Gaetano Sivo, Simon L. Morris, David Henry, Nazim Ali Bharmal, David Atkinson, Jean-Marc Conan, Tom Bailie, Department of Physics [Durham University], Durham University, 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), Laboratoire de l'intégration, du matériau au système (IMS), Université Sciences et Technologies - Bordeaux 1-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS), Laboratoire Charles Fabry / Spim, Laboratoire Charles Fabry (LCF), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS)-Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS), ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), Centre for Medical Imaging, University College London, London, United Kingdom, Ageing Group, Centre for Public Health, Queen's University [Belfast] (QUB), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), University College of London [London] (UCL), 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, Wavefront, business.industry, media_common.quotation_subject, Phase (waves), [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Stars, Optics, Laser guide star, Sky, William Herschel Telescope, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Tomography, business, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing, ComputingMilieux_MISCELLANEOUS, media_common
Abstract: CANARY is an on-sky Laser Guide Star (LGS) tomographic AO demonstrator that has been in operation at the 4.2m William Herschel Telescope (WHT) in La Palma since 2010. In 2013, CANARY was upgraded from its initial configuration that used three off-axis Natural Guide Stars (NGS) through the inclusion of four off-axis Rayleigh LGS and associated wavefront sensing system. Here we present the system and analysis of the on-sky results obtained at the WHT between May and September 2014. Finally we present results from the final ‘Phase C’ CANARY system that aims to recreate the tomographic configuration to emulate the expected tomographic AO configuration of both the AOF at the VLT and E-ELT.
Published: 2014

81. The high contrast imaging modes of MICADO

Author: Anthony Boccaletti, Michael Hartl, Raphael Galicher, Damien Gratadour, Tristan Buey, Eric Gendron, Richard Davies, Pierre Baudoz, Sylvestre Lacour, Gérard Rousset, Yann Clénet, 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, business.industry, Near-infrared spectroscopy, High contrast imaging, Exoplanet, law.invention, Telescope, Optics, law, Extremely Large Telescope, Detection performance, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Adaptive optics, business, Coronagraph
Abstract: We present in this paper an overview of the high contrast imaging modes of the wide-field imager MICADO. MICADO is a near-IR camera for the European Extremely Large Telescope (E-ELT), featuring a wide field (75”), spectroscopic and coronagraphic capabilities. It has been chosen by ESO as one of the two first-light instruments. MICADO will be optimized for the multi-conjugate adaptive optics module MAORY and will also work in SCAO mode. This SCAO mode will provide MICADO with a high-level, on-axis correction, making use of the M4 adaptive mirror in the telescope. After presenting the scientific interest for high contrast imaging modes in MICADO, we describe the technical choices we are studying. We present the hypotheses chosen for our simulation tools and contrast as well as planet detection performance derived from this tool.
Published: 2014

82. Open loop tomography with artificial neural networks on CANARY : on-sky results

Author: Richard M. Myers, Damien Gratadour, James Osborn, Eric Gendron, Tim Morris, M. L. Sánchez Rodríguez, Timothy Butterley, M. Gomez Victoria, A. Guesalaga, Dani Guzman, Gérard Rousset, Alastair Basden, F. Sánchez Lasheras, F. J. de Cos Juez, Public Health Science, Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome] (UNIROMA), Department of Physics [Durham University], Durham University, 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), Department of Physics, Centre for Advanced Instrumentation, Pontificia Universidad Católica de Chile (UC), Universidad de Oviedo [Oviedo], 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), Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome], Oviedo University, 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: media_common.quotation_subject, FOS: Physical sciences, 02 engineering and technology, 01 natural sciences, adaptive optics. [Instrumentation], 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, William Herschel Telescope, Adaptive optics, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), ComputingMilieux_MISCELLANEOUS, media_common, Physics, [PHYS]Physics [physics], Training set, Artificial neural network, Open-loop controller, Strehl ratio, Astronomy and Astrophysics, Atmospheric effects, Space and Planetary Science, Sky, 020201 artificial intelligence & image processing, Tomography, Astrophysics - Instrumentation and Methods for Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Algorithm
Abstract: We present recent results from the initial testing of an Artificial Neural Network (ANN) based tomographic reconstructor Complex Atmospheric Reconstructor based on Machine lEarNing (CARMEN) on Canary, an Adaptive Optics demonstrator operated on the 4.2m William Herschel Telescope, La Palma. The reconstructor was compared with contemporaneous data using the Learn and Apply (L&A) tomographic reconstructor. We find that the fully optimised L&A tomographic reconstructor outperforms CARMEN by approximately 5% in Strehl ratio or 15nm rms in wavefront error. We also present results for Canary in Ground Layer Adaptive Optics mode to show that the reconstructors are tomographic. The results are comparable and this small deficit is attributed to limitations in the training data used to build the ANN. Laboratory bench tests show that the ANN can out perform L&A under certain conditions, e.g. if the higher layer of a model two layer atmosphere was to change in altitude by ~300~m (equivalent to a shift of approximately one tenth of a subaperture)., 8 pages, 6 figures
Published: 2014

83. Proposal for a field experiment of elongated Na LGS wave-front sensing in the perspective of the E-ELT

Author: Tim Morris, G. Talbot, Eric Gendron, Thomas Pfrommer, Tristan Buey, D. Bonaccini Calia, Alastair Basden, Gérard Rousset, Enrico Marchetti, 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), 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, Computer science, business.industry, Laser, law.invention, symbols.namesake, Optics, Sampling (signal processing), law, symbols, Extremely Large Telescope, Guide star, Rayleigh scattering, Adaptive optics, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Remote sensing
Abstract: Wavefront (WF) sensing using Sodium (Na) Laser Guide Stars (LGS) is a key concern for the design of a number of first generation Extremely Large Telescope (ELT) Adaptive Optics (AO) modules. One of the main challenges is the mitigation of the effects induced by extreme LGS spot elongation on the WF measurements. Before the final design studies of the E-ELT instruments, a Na LGS WF sensing on-sky experiment at the E-ELT scale is mandatory to achieve the full validation of the proposed mitigation strategies and their performance. This experiment will provide unique spatial and temporal WF measurements on a true Na LGS, perturbed by the atmospheric turbulence and mesospheric variability. The fine comparative analysis of such data with synchronously acquired WF measurements on at least one natural guide star (NGS) will be fundamental to test a number of algorithms, configurations for spot sampling and truncation and WF reconstruction schemes including multi-LGS configurations. A global error budget for the whole experiment will be derived with time to feed into the numerical simulation and the design of subsequent E-ELT LGS-AO modules. The data produced will be made available to the E-ELT community. We propose to use CANARY, the Multi-Object AO demonstrator installed at the 4.2m WHT which is a modular AO platform, equipped with several NGS WF Sensor (WFS) and Rayleigh multi-LGS unit and WFS. The transportable 20W Sodium laser unit (WLGSU), developed at ESO, will be positioned at a varying distance from the WHT to provide off-axis launching (up to 40m), simulating the whole range of LGS spot elongations obtained on the E-ELT. In such a case, the WHT pupil will represent an off-axis sub-pupil of the main E-ELT pupil. In addition, this experiment will include a Na layer profiler and the capability for open and closed loop operations. The experiment is scheduled before the end of 2016.
Published: 2014

84. Overview of the MICADO SCAO system

Author: Gérard Rousset, F. Chapron, Pierre Baudoz, Bertrand Le Ruyet, Mathieu Cohen, Richard Davies, Z. Hubert, Tristan Buey, Anthony Boccaletti, Damien Gratadour, Fabrice Vidal, Laurent Jocou, D. Perret, Raphaël Galicher, Sylvain Rochat, Yann Clénet, Eric Gendron, Gael Chauvin, Sylvestre Lacour, Fanny Chemla, Philippe Feautrier, Arnaud Sevin, Patrick Rabou, Eric Stadler, 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, business.industry, Wavefront sensor, High contrast imaging, Wide field, Project organization, Computing systems, law.invention, Telescope, Optics, law, Interfacing, business, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Computer hardware
Abstract: We present in this paper an overview of the single-conjugate adaptive optics (SCAO) module of the wide-field imager MICADO. MICADO is a near-IR camera for the European ELT, featuring a wide field (75"), spectroscopic and coronagraphic capabilities. It has been chosen by ESO as one of the two first-light instruments. MICADO will be optimized for the multi-conjugate adaptive optics module MAORY and will also work in SCAO mode. This SCAO mode will provide MICADO with a high-level, on-axis correction, making use of the M4 adaptive mirror in the telescope. We present first the current design of the different subsystems of the SCAO module (namely the optical relay interfacing MICADO to the telescope in its SCAO mode, the wavefront sensor, the real-time computer and the high contrast imaging). We then present the adaptive optics and coronagraphic simulations. The following section is devoted to the presentation of the project organization. We end with the conclusions and perspectives of the project.
Published: 2014

85. First on-sky SCAO validation of full LQG control with vibration mitigation on the CANARY pathfinder

Author: Arnaud Sevin, Fanny Chemla, Nigel Dipper, Colin Dickson, Stephen Todd, Gérard Rousset, Jean-Marc Conan, Zoltan Hubert, Tim Morris, Henri-François Raynaud, Andy Longmore, Denis Perret, Gaetano Sivo, Serge Meimon, Richard M. Myers, Damien Gratadour, Eric Gendron, G. Talbot, Caroline Kulcsár, Cyril Petit, David Atkinson, Alastair Basden, David Henry, Eddy Younger, Fabrice Vidal, Olivier J. F. Martin, Laboratoire Charles Fabry / Spim, Laboratoire Charles Fabry (LCF), Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), Université Paris 13 (UP13), 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), Department of Physics [Durham University], Durham University, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Laboratoire de l'intégration, du matériau au système (IMS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS), Ageing Group, Centre for Public Health, Queen's University [Belfast] (QUB), Medicine Division, University College of London [London] (UCL), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS)-Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS), and Université Sciences et Technologies - Bordeaux 1-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS)
Subjects: Optics and Photonics, Astronomy, Linear-quadratic-Gaussian control, 01 natural sciences, Deformable mirror, [SPI.AUTO]Engineering Sciences [physics]/Automatic, 010309 optics, Optics, 0103 physical sciences, Computer Simulation, Adaptive optics, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Lenses, Wavefront, Physics, [PHYS]Physics [physics], business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Atmospheric correction, Equipment Design, Kalman filter, Models, Theoretical, Atomic and Molecular Physics, and Optics, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Pathfinder, Integrator, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Telescopes
Abstract: Adaptive optics provides real time correction of wavefront disturbances on ground based telescopes. Optimizing control and performance is a key issue for ever more demanding instruments on ever larger telescopes affected not only by atmospheric turbulence, but also by vibrations, windshake and tracking errors. Linear Quadratic Gaussian control achieves optimal correction when provided with a temporal model of the disturbance. We present in this paper the first on-sky results of a Kalman filter based LQG control with vibration mitigation on the CANARY instrument at the Nasmyth platform of the 4.2-m William Herschel Telescope. The results demonstrate a clear improvement of performance for full LQG compared with standard integrator control, and assess the additional improvement brought by vibration filtering with a tip-tilt model identified from on-sky data, thus validating the strategy retained on the instrument SPHERE at the VLT.
Published: 2014

86. COMPASS: an efficient, scalable and versatile numerical platform for the development of ELT AO systems

Author: M. Westphal, Damien Gratadour, J. C. Lambert, Eric Gendron, P. Kestener, Mathieu Puech, T. Gautrais, Christophe Vérinaud, Gérard Rousset, C. Petit, I. Jégouzo, Florian Ferreira, J. L. Beuzit, Marc Ferrari, B. Epinat, Yann Clénet, Sergey Rodionov, Y. Yang, S. Taburet, Francois Hammer, J. Brulé, Michele Paillous, Arnaud Sevin, Benoit Neichel, M. Lainé, Alexis Carlotti, M. Gray, 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), 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: business.industry, Computer science, Scale (chemistry), Plan (drawing), 01 natural sciences, 010309 optics, Software, Development (topology), Computer architecture, Real-time Control System, Embedded system, Compass, 0103 physical sciences, Scalability, [INFO]Computer Science [cs], business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS
Abstract: The main objective of the COMPASS project is to provide a full scale end-to-end AO development platform, able to address the E-ELT scale and designed as a free, open source numerical tool with a long term maintenance plan. The development of this platform is based on a full integration of software with hardware and relies on an optimized implementation on heterogeneous hardware using GPUs as accelerators. In this paper, we present the overall platform, the various work packages of this project, the milestones to be reached, the results already obtained and the first output of the ongoing collaborations.
Published: 2014

87. Real-time optical path difference compensation at the Plateau de Calern I2T interferometer

Author: B. Sorrente, Frédéric Cassaing, Yves Rabbia, Gérard Rousset, and S. Robbe-Dubois
Subjects: Wavefront, Physics, Coherence time, Fried parameter, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Interferometry, Optical path, Optics, Space and Planetary Science, Angle of arrival, business, Optical path length, Coherence (physics)
Abstract: The fringe tracker system of the ASSI (Active Stabilization in Stellar Interferometry) beam combining table at the I2T interferometer is described and its performance evaluated. A new real{time algorithm for the optical path dierence (OPD) measurement is derived and validated. It is based on a sinusoidal phase modulation whose amplitude is optimized. It also allows automatic fringe detection at the beginning of an observation when scanning the OPD. The fringe tracker servo{loop bandwidth is adjusted by a numerical gain and ranges between 20 and 50 Hz in the reported experiments. On stars, fringe{locked sequences are limited to 20 s due to fringe jumps. However, the fringe tracker is able to recover the coherence area after a few seconds. Such a fringe tracker operation can last more than one hour. A fringe tracking accuracy of 85 nm is achieved for visibility ranging between 7 and 24%, a turbulence coherence time of approximately 9 ms at 0.85 m, a Fried parameter of around 14 cm at 0.5 m and an average light level of 100 000 photoevents/s, (typically visual magnitude 2 in the conditions of the experiment). Visibility losses are evaluated and are found to be mainly due to turbulent wavefront fluctuations on the two telescopes and to the static aberrations of the optical train. The measurements of OPD and angle of arrival are reduced to derive turbulence parameters: the coherence time, the average wind speed, the Fried parameter and the outer scale. Our estimations for the outer scale range between 20 and 120 m, with an average value of the order of 40 m. Both OPD and angle of arrival data, obtained on 15 m baseline and a 26 cm telescope diameter respectively, are fully compatible with the same modied Kolmogorov spectrum of the turbulence, taking into account a nite outer scale.
Published: 2001

88. Imaging with multi-aperture optical telescopes and an application

Author: Frédéric Cassaing, Laurent M. Mugnier, Gérard Rousset, and B. Sorrente
Subjects: Point spread function, Earth observation, Computer science, Aperture, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, General Physics and Astronomy, Optical telescope, Optics, Component (UML), Orbit (dynamics), Geostationary orbit, business, Image restoration
Abstract: The two main types of Multi-Aperture Optical Telescopes (MAOTs) (so-called Michelson and Fizeau) and the two possible modes of optical beam combination are reviewed. Wide-field imaging with a Michelson instrument is studied and the constraints are identified. An example of application to Earth observation is given. Then, we address the optimization of the aperture configuration, a key issue in the design of a MAOT. We also stress the image restoration, a necessary component of such an instrument because of the shape of its point spread function. Finally, a MAOT seems to be a promising technical solution for high resolution Earth observation from Space on a high orbit such as a geostationary one.
Published: 2001

89. Characterization of adaptive optics point spread function for anisoplanatic imaging. Application to stellar field deconvolution

Author: Vincent Michau, T. Fusco, Laurent M. Mugnier, Gérard Rousset, and Jean-Marc Conan
Subjects: Point spread function, Physics, Optics, Field (physics), business.industry, General Physics and Astronomy, A priori and a posteriori, Field of view, Deconvolution, Astrometry, business, Adaptive optics, Characterization (materials science)
Abstract: The point spread function (PSF) of an adaptive optics system evolves in the Field Of View (FOV). This variation strongly limits the conventional deconvolution methods for the processing of wide FOV images. A theo- retical expression of this PSF variation is derived. This ex- pression is both validated on simulations and experimental data. It is then applied to the a posteriori processing of stellar elds. Using the available prior information about the object (point-like sources), this technique allows the restoration of the star parameters (positions and intensi- ties) with a precision much better than the conventional methods, in a FOV much larger than the isoplanatic eld.
Published: 2000

90. Performance of the angle of arrival correction system of the I2T + ASSI stellar interferometer

Author: S. Robbe, Yves Rabbia, Frédéric Cassaing, Gérard Rousset, and B. Sorrente
Subjects: Wavefront, Physics, Interferometry, Coherence time, Optics, business.industry, Angle of arrival, General Physics and Astronomy, Table (information), business, Tracking (particle physics), Spectral line, Line (formation)
Abstract: The Active Stabilization in Stellar Inter- ferometry (ASSI) recombining table, developed at Oce National d'Etudes et de Recherches A erospatiales (ONERA), France, was implemented on the two-Telescope Interferometer (I2T) of the Observatoire de la C^ ote d'Azur (OCA) in 1993, compensating for the atmospheric tur- bulence wavefront fluctuations. Initial fringe observations were made in June 1994 with a 11 m North-South base- line. In this paper, we report the performance of the ASSI table servo system for correction of the angle of arrival. Tracking accuracy of about0:24 arcsec was achieved in typical seeing conditions (r0 10 cm) and on mv =2 sources. Collected data allows to compare theoretical with observed temporal power spectra of the angle of arrival fluctuations, using Kolmogorov model. Spatio-temporal seeing parameters met during observations (Fried param- eter r0 and coherence time t0) are estimated.
Published: 1997

91. Les développements de l'optique adaptative en astronomie

Author: Gérard Rousset
Subjects: General Engineering, General Earth and Planetary Sciences, General Materials Science, General Environmental Science
Abstract: Resume L'optique adaptative consiste a corriger en temps reel les perturbations de front d'onde resultant de la traversee de l'atmosphere. Les deux composants cles en sont le miroir deformable et l'analyseur de front d'onde. Deux classes de systemes d'optique adaptative sont utilisees en astronomie: les systemes fondes sur l'analyseur de front d'onde de Shack-Hartmann et les systemes fondes sur une idee originale de Francois Roddier, concernant la mesure de la courbure du front d'onde. Les performances de ces deux types de systemes sont comparees et leur domaine d'application est donne.
Published: 1997

92. [Untitled]

Author: Francois Lacombe, Norbert Hubin, Frank Eisenhauer, P. Gigan, D. Rabaud, Gérard Rousset, Laurent Demailly, E. Prieto, Reiner Hofmann, D. Bonaccini, Jean-Luc Beuzit, Frederic Chazallet, Eric Gendron, Daniel Rouan, and P. Y. Madec
Subjects: Physics, User Friendly, Adonis, biology, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Artificial intelligence software, Astrophysics::Cosmology and Extragalactic Astrophysics, biology.organism_classification, law.invention, Telescope, Space and Planetary Science, law, Computer graphics (images), Metre, Astrophysics::Earth and Planetary Astrophysics, Adaptive optics, Astrophysics::Galaxy Astrophysics, Remote sensing
Abstract: ADONIS is an adaptive optics (AO) user friendly instrument offered to the European astronomical community on the ESO 3.6-m telescope at La Silla. It is an upgraded version of COME-ON-PLUS, the VLT AO prototype, which already produced significative astrophysical results in a wide range of fields, from planetology to extragalactic astrophysics. ADONIS is now allowing the astronomer to use adaptive optics as a common user instrument thanks to the implementation of an open artificial intelligence software that handles the large number of parameters needed to optimise the AO correction. We will describe the ADONIS system, including the two dedicated infrared cameras, summarize its performances and discuss the observing procedures.
Published: 1997

93. High-contrast imaging with a self-coherent camera

Author: Raphael Galicher, Gérard Rousset, Pierre Baudoz, Johan Mazoyer, 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, business.industry, Deformable mirror, law.invention, Speckle pattern, Optics, Achromatic lens, law, A priori and a posteriori, Contrast ratio, Computer vision, Monochromatic color, Artificial intelligence, business, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Coronagraph
Abstract: Direct imaging of exoplanets is very challenging because the planet is 104 to 1010 fainter than the star at a separation of a fraction of arcsec. Several coronagraphs have been proposed to reduce the contrast ratio but their performance strongly depends on the level of phase and amplitude aberrations that induce speckles in the science image. An active control of the aberrations and a posteriori calibration are thus required to reach very high contrasts. Classical adaptive optics are not sufficient for this purpose because of non-common path aberrations. Our team proposed a self-coherent camera that spatially modulates the speckles in the science image. It is then possible to both actively control a deformable mirror and calibrate the residuals a posteriori. The current paper is an overview of the developments we have been working on for 7 years. We present the principle of the self-coherent camera, laboratory performance obtained in monochromatic light, and upgrades of the technique to make it achromatic.
Published: 2013

94. Full LQG control with vibration mitigation: from theory to first on-sky validation on the CANARY MOAO demonstrator

Author: Gérard Rousset, Zoltan Hubert, Serge Meimon, Alastair Basden, Richard M. Myers, Damien Gratadour, Tim Morris, Caroline Kulcsár, Gaetano Sivo, Olivier J. F. Martin, Eric Gendron, Jean-Marc Conan, G. Talbot, Henri-François Raynaud, Fabrice Vidal, Cyril Petit, Nigel Dipper, Eddy Younger, Laboratoire Charles Fabry / Spim, Laboratoire Charles Fabry (LCF), Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), DOTA, ONERA, Université Paris Saclay (COmUE) [Châtillon], ONERA-Université Paris Saclay (COmUE), 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), 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, Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), DOTA, ONERA, Université Paris Saclay [Châtillon], ONERA-Université Paris-Saclay, Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), and PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, media_common.quotation_subject, 02 engineering and technology, Vibration mitigation, 021001 nanoscience & nanotechnology, Linear-quadratic-Gaussian control, 01 natural sciences, Deformable mirror, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], [SPI.AUTO]Engineering Sciences [physics]/Automatic, 010309 optics, Control theory, Sky, 0103 physical sciences, William Herschel Telescope, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Atmospheric turbulence, 0210 nano-technology, Adaptive optics, ComputingMilieux_MISCELLANEOUS, Remote sensing, media_common
Abstract: Full LQG adaptive optics (AO) control is validated for the first time on sky for classical AO and multi-object AO with 3 natural guide stars (GSs) and a Rayleigh laser GS, including vibration mitigation, on the Canary demonstrator (William Herschel Telescope, Spain).
Published: 2013

95. Point spread function reconstruction validated using on-sky CANARY data in multiobject adaptive optics mode

Author: O. Martin, Fabrice Vidal, Tim Morris, Benoit Neichel, Richard M. Myers, Carlos Correia, Damien Gratadour, Eric Gendron, Alastair Basden, Gérard Rousset, Thierry Fusco, 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), 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), Department of Physics, Centre for Advanced Instrumentation, Durham University, ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), 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: THERMOGRAPHY, Point spread function, TELESCOPE, CANARY, media_common.quotation_subject, OPTIQUE ADAPTATIVE, WIDE-FIELD ADAPTIVE OPTICS, 01 natural sciences, POINT SPREAD FUNCTION RECONSTRUCTION, law.invention, MULTIOBJECT ADAPTIVE OPTICS, Telescope, Optics, law, 0103 physical sciences, EUROPEAN-EXTREMELY LARGE TELESCOPE, RECONSTRUCTION, TOMOGRAPHIE, Adaptive optics, 010303 astronomy & astrophysics, Instrumentation, Remote sensing, media_common, ADAPTIVE OPTICS, Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, business.industry, Mechanical Engineering, Strehl ratio, Astronomy and Astrophysics, Reconstruction algorithm, MOSAIC, Electronic, Optical and Magnetic Materials, Laser guide star, FONCTION ETALEMENT POINT, Space and Planetary Science, Control and Systems Engineering, Sky, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Guide star, business
Abstract: International audience; In preparation of future multiobject spectrographs (MOS) whose one of the major role is to provide an extensive statistical studies of high redshifted galaxies surveyed, the demonstrator CANARY has been designed to tackle technical challenges related to open-loop adaptive optics (AO) control with jointed Natural Guide Star and Laser Guide Star tomography. We have developed a point spread function (PSF) reconstruction algorithm dedicated to multiobject adaptive optics systems using system telemetry to estimate the PSF potentially anywhere in the observed field, a prerequisite to postprocess AO-corrected observations in integral field spectroscopy. We show how to handle off-axis data to estimate the PSF using atmospheric tomography and compare it to a classical approach that uses on-axis residual phase from a truth sensor observing a natural bright source. We have reconstructed over 450 on-sky CANARY PSFs and we get bias/1-sigma standard-deviation (std) of 1.3/4.8 on the H-band Strehl ratio (SR) with 92.3% of correlation between reconstructed and sky SR. On the full-width at half-maximum, we get, respectively, 2.94 mas, 19.9 mas, and 88.3% for the bias, std, and correlation. The reference method achieves 0.4/3.5/95% on the SR and 2.71 mas/14.9 mas/92.5% on the FWHM for the bias/std/correlation.
Published: 2016

96. Discovery of concentric broken rings at sub-arcsec separations in the HD 141569A gas-rich, debris disk with VLT/SPHERE

Author: Mickael Bonnefoy, A-L. Maire, Dino Mesa, J. Lannier, Wolfgang Brandner, Esther Buenzli, Antonio Garufi, Arnaud Sevin, David Mouillet, C. Perrot, Anthony Boccaletti, M. Carle, Valentin Christiaens, Pierre Baudoz, Johan Olofsson, J. L. Beuzit, O. Moeller-Nilsson, Raffaele Gratton, J. Péricaud, Arthur Vigan, Myriam Benisty, R. Galicher, Eric Pantin, Gael Chauvin, Julien Milli, Johan Mazoyer, Gérard Rousset, Sascha P. Quanz, Norbert Hubin, A-M. Lagrange, Anne Dutrey, Thierry Fusco, S. Peretti, Markus Feldt, E. Sissa, Enrico Giro, Jean-Charles Augereau, Julien Girard, Simon Casassus, J. de Boer, Silvano Desidera, E. Di Folco, P. Blanchard, François Ménard, Maud Langlois, D. Maurel, Graeme Salter, L. Weber, 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), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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 Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, 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), AMOR 2016, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Mathématiques de Marseille (I2M), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), European Synchrotron Radiation Facility (ESRF), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), 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), Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), Unité de Catalyse et de Chimie du Solide - Site Artois (UCCS Artois), Université d'Artois (UA)-Université de Lille, Sciences et Technologies-Ecole Centrale de Lille-Ecole Nationale Supérieure de Chimie de Lille (ENSCL)-Centre National de la Recherche Scientifique (CNRS), ONERA, 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), GBR, Unité de Catalyse et Chimie du Solide - Equipes du Site Artois (UCCS Artois), Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), and Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Lille (ENSCL)-Ecole Centrale de Lille-Université d'Artois (UA)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Lille (ENSCL)-Ecole Centrale de Lille-Université d'Artois (UA)
Subjects: Brightness, 010504 meteorology & atmospheric sciences, [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], media_common.quotation_subject, Population, Phase (waves), FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Asymmetry, Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, education, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, media_common, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Debris disk, education.field_of_study, Spiral galaxy, Astronomy and Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, Jupiter mass, Astrophysics - Earth and Planetary Astrophysics
Abstract: Transition disks correspond to a short stage between the young protoplanetary phase and older debris phase. Along this evolutionary sequence, the gas component disappears leaving room for a dust-dominated environment where already-formed planets signpost their gravitational perturbations. We endeavor to study the very inner region of the well-known and complex debris, but still gas-rich disk, around HD 141569A using the exquisite high-contrast capability of SPHERE at the VLT. Recent near-infrared (IR) images suggest a relatively depleted cavity within ~200 au, while former mid-IR data indicate the presence of dust at separations shorter than ~100 au. We obtained multi-wavelength images in the near-IR in J, H2, H3 and Ks bands with the IRDIS camera and a 0.95-1.35 micrometers spectral data cube with the IFS. Data were acquired in pupil-tracking mode, thus allowing for angular differential imaging. We discovered several new structures inside 1", of which the most prominent is a bright ring with sharp edges (semi-major axis: 0.4") featuring a strong north-south brightness asymmetry. Other faint structures are also detected from 0.4" to 1" in the form of concentric ringlets and at least one spiral arm. Finally, the VISIR data at 8.6 micrometers suggests the presence of an additional dust population closer in. Besides, we do not detect companions more massive than 1-3 mass of Jupiter. The performance of SPHERE allows us to resolve the extended dust component, which was previously detected at thermal and visible wavelengths, into very complex patterns with strong asymmetries ; the nature of these asymmetries remains to be understood. Scenarios involving shepherding by planets or dust-gas interactions will have to be tested against these observations., Accepted by A&A. 10 pages, 8 figures
Published: 2016

97. Dark hole and planet detection: laboratory results using the self-coherent camera

Author: Gérard Rousset, Raphaël Galicher, Pierre Baudoz, Johan Mazoyer, 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), 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), and National Research Council of Canada (NRC)
Subjects: Extremely Large Telescopes, High contrast imaging, Optical telescopes, Reference image, Astronomy, Deformable mirrors, Post processing, Focal Plane, Deformable mirror, law.invention, Telescope, Speckle pattern, Scientific applications, Optics, Image processing, Spitzer Space Telescope, law, Direct imaging, Angular separation, Laser pulses, Coronagraph, Wavefront, Physics, business.industry, High contrast, Speckle noise, Wavefront correction, Astrophysics::Instrumentation and Methods for Astrophysics, Cameras, Planet finders, Exoplanet, Ground based, Cardinal point, Wavefront quality, Near-IR, Optical defects, Planet detection, Astrophysics::Earth and Planetary Astrophysics, Extra solar planets, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Active correction, Coronagraphy
Abstract: Direct imaging and low-resolution spectroscopy of extrasolar planets are exciting but challenging scientific applications of coronagraphy. While the angular separation is well within the reach of actual telescope in the near IR or visible, the planet-star contrast (from 10-6 to 10-10) requires wavefront quality and stability hard to reach even with a well-polished space telescope. Several solutions have been proposed to tackle the speckle noise introduced by the residual optical defects. While some concepts rely only on active wavefront correction using deformable mirror, other techniques are based on post-processing and subtract a reference image recorded sometimes simultaneously with the science image. One interesting solution is to choose a concept that allows both active correction and post-processing of high contrast coronagraphic images. This is the case of the Self Coherent Camera (SCC), which has been proposed for the project of space coronagraph SPICES and for the ground-based planet finder EPICS studied for the European Extremely Large Telescope. After recalling the SCC principle, we present both monochromatic and modest bandwidth (2%) experimental results of Dark Hole in the focal plane using a SCC. Example of a post-processing result with SCC is also given to emphasize the interest of combining it with active correction. © 2012 SPIE., Ground-Based and Airborne Instrumentation for Astronomy IV, July 1-6, 2012, Amsterdam, The Netherlands, Series: Proceedings of SPIE; no. 8446
Published: 2012

98. Experimental results on wavefront correction using the self-coherent camera

Author: M. Mas, Johan Mazoyer, Raphaël Galicher, Gérard Rousset, 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, 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: High contrast imaging, Wavefronts, Astronomy, Deformable mirror, law.invention, Speckle pattern, Optics, Speckle, law, High angular resolutions, Adaptive optics, Instrumentation, Coronagraph, Focusing, Wavefront, Physics, Lyot stop, business.industry, Wavefront correction, Detectors, Wavefront sensor, Computer simulation, Cameras, Aberrations, Cardinal point, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Coronagraphy
Abstract: The Self-Coherent Camera is dedicated to the direct detection of exoplanets. This instrument can be used as a focal plane wavefront sensor to measure static aberrations that induce speckles on the detector, which prevents the detection of faint companions. The Self-Coherent Camera creates a reference beam in the Lyot stop pupil plane in order to spatially modulate the speckle pattern with Fizeau fringes. We can then estimate for wavefront aberrations upstream of the coronagraphic mask and correct for them using a deformable mirror. Currently, the Self-Coherent Camera is combined with a deformable mirror located in the pupil plane upstream of a Four-Quadrant Phase Mask Coronagraph. In this paper, we present the formalism that explains how the Self-Coherent Camera encodes speckles and how we estimate the wavefront aberrations directly from the science image. We present numerical simulation results on speckle suppression in the focal plane. Then, we give experimental results on wavefront correction on our optical bench using a 32x32 actuators deformable mirror. We show that we can improve the contrast in the focal plane by a factor of more than 100 in the PSF wings up to 12λ/D. © 2012 SPIE., Ground-Based and Airborne Instrumentation for Astronomy IV, July 1-6, 2012, Amsterdam, The Netherlands, Series: Proceedings of SPIE; no. 8446
Published: 2012

99. Temporal analysis of aliasing in Shack-Hartmann wave-front sensing

Author: 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), 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, Computer science, business.industry, Filter (signal processing), Wavefront sensor, ComputerSystemsOrganization_PROCESSORARCHITECTURES, Optics, Aliasing, Nyquist frequency, Spatial frequency, Aliasing (computing), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Adaptive optics, Anti-aliasing filter
Abstract: International audience; A Shack-Hartmann wavefront sensor samples the wavefront in the pupil. The wavefront shape will be undersam pled, since although the wavefront average spatial spectrum is a rapidly decreasing function of spatial frequency, it contains frequencies higher than the Nyquist limit : this well-known phenomenon is known as aliasing. The impact of aliasing in adaptive optics is difficult to estimate. Some methods have been proposed, that aim at optically filter out high wavefront frequencies ; some authors gave an estimate of this error, but most of the time these estimations are based on Monte-Carlo simulations of wavefront sensor. We propose in this paper an analytical study of the aliasing effect, and study how the aliasing error distributes over temporal frequencies. An analytical expression of the temporal spectrum of the aliasing error maybe of importance for system modeling or performance prediction in adaptive optics.
Published: 2012

100. Toward an on-sky ELT-scale sodium LGS wavefront sensing experiment

Author: Richard M. Myers, Gérard Rousset, Damien Gratadour, Thomas Pfrommer, Eric Gendron, Tim Morris, Olivier Fauvarque, Domenico Bonaccini Calia, 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), European Southern Observatory (ESO), and Duke University [Durham]
Subjects: Wavefront, business.industry, Computer science, First light, Laser, law.invention, symbols.namesake, Laser guide star, Optics, law, Extremely Large Telescope, symbols, Guide star, Rayleigh scattering, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Adaptive optics, business, Remote sensing
Abstract: The two first light adaptive optics (AO) instruments for the European Extremely Large Telescope (E-ELT) will both rely on several Sodium Laser Guide Stars (LGS). In using this technology, the E-ELT diameter comes with new challenges mainly raised by spot elongation. Before the final design studies of the E-ELT instruments, a Sodium LGS wavefront sensing (WFS) on-sky experiment at this scale is mandatory to provide meaningful spatial and temporal measurement error and performance evaluation. For this purpose, we propose to use CANARY, the Multi-Object AO demonstrator installed at the WHT (4.2m). CANARY is now undergoing a Rayleigh LGS upgrade and also provides natural guide star WFS. It could easily be adapted to the Sodium LGS case. Additionally, a transportable laser system, such as the one developed at ESO, positioned at a varying distance from the WHT could be used to provide off-axis launching (up to 40m), simulating the whole range of spot elongations that will be obtained on the E-ELT. Full scale simulations of a Sodium LGS WFS on the E-ELT have guided us in the definition of the experiment we are proposing. Previous simulation results in the literature have stressed that an estimate of the Sodium profile is necessary to reduce measurement error to an affordable level. Hence parallel Sodium profiling is mandatory in the proposed experiment. In this paper, we present the simulation results as well as the specifications for both the Sodium LGS WFS and profiler to be used on Canary.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Published: 2012

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