Dr. Alain Petit Profile

Dr. Alain Petit

at Commissariat à l'Énergie Atomique

SPIE Involvement:

Author

Publications (14)

Proceedings Article | 28 July 2010 Paper

Setting up ELP-OA: the polychromatic laser guide star demonstrator

N. Meilard, R. Foy, M. Langlois, M. Tallon, E. Thiébaut, A. Petit, A. Blazit, P.-E. Blanc, J. Chombart, O. Fouche, A. Laloge, A. Le Van Suu, X. Regal, J. Schmitt, M. Boër

Proceedings Volume 7736, 77361W (2010) https://doi.org/10.1117/12.858068

KEYWORDS: Projection systems, Adaptive optics, Telescopes, Data modeling, Laser guide stars, Stars, Interferometry, Mesosphere, Sodium, Chemical species

Read Abstract +

Proceedings Article | 10 July 2008 Paper

ELP-OA : status report of the setup of the demonstrator of the polychromatic laser guide star at Observatoire de Haute Provence

Renaud Foy, Pierre-Éric Blanc, Thierry Fusco, Andrée Laloge, Auguste Le Van Suu, Sandrine Perruchot, Alain Petit, Pierre Richaud, Michel Tallon, Éric Thiébaut, Michel Boër

Proceedings Volume 7015, 701517 (2008) https://doi.org/10.1117/12.789287

KEYWORDS: Telescopes, Mesosphere, Sodium, Adaptive optics, Laser guide stars, Mirrors, Projection systems, Wavefronts, Modulation, Dye lasers

Read Abstract +

Proceedings Article | 7 February 2003 Paper

Feasibility study of the polychromatic laser guide star

Renaud Foy, Jean-Paul Pique, Veronique Bellanger, Patrick Chevrou, Alain Petit, Claudia Hogemann, Lothar Noethe, Matthias Schock, Julien Girard, Michel Tallon, Eric Thiebaut, Jerome Vaillant, Francoise-C. Foy, Marcos Van Dam

Proceedings Volume 4839, (2003) https://doi.org/10.1117/12.460080

KEYWORDS: Telescopes, Sodium, Mesosphere, Laser guide stars, Wavefronts, Modulation, Adaptive optics, Doppler effect, Chemical species, Stars

Read Abstract +

Proceedings Article | 29 January 2002 Paper

Laser-sodium interaction for the polychromatic laser guide star project

Veronique Bellanger, Alain Petit

Proceedings Volume 4538, (2002) https://doi.org/10.1117/12.454412

KEYWORDS: Laser guide stars, Palladium, Sodium, Photons, Neodymium, Nd:YAG lasers, Laser energy, Adaptive optics, Atmospheric optics, Atmospheric propagation

Read Abstract +

Proceedings Article | 17 November 2000 Paper

ELP-OA: measuring the wavefront tilt without a natural guide star

Matthias Schoeck, Jean-Paul Pique, Alain Petit, Patrick Chevrou, Vincent Michau, Gilbert Grynberg, Arnold Migus, Nancy Ageorges, Veronique Bellanger, Francois Biraben, Ruy Deron, Hayden Fews, Francoise-Claude Foy, Claudia Hoegemann, Markus Laubscher, Daniel Mueller, Celine d'Orgeville, Olivier Peillet, Mike Redfern, Renaud Foy, Patricia Segonds, Richard Soden, Michel Tallon, Eric Thiebaut, Andrei Tokovinin, Jerome Vaillant, Jean-Marc Weulersse

Proceedings Volume 4125, (2000) https://doi.org/10.1117/12.409304

KEYWORDS: Telescopes, Stars, Sodium, Wavefronts, Adaptive optics, Modulation, Laser guide stars, Oscillators, Astronomy, Chemical species

Read Abstract +

Proceedings Article | 16 August 2000 Paper

Polychromatic guide star: feasibility study

Renaud Foy, Jean-Paul Pique, Alain Petit, Patrick Chevrou, Vincent Michau, Gilbert Grynberg, Arnold Migus, Nancy Ageorges, Veronique Bellanger, Francois Biraben, Ruy Deron, Hayden Fews, Francoise-Claude Foy, Claudia Hoegemann, Markus Laubscher, Daniel Mueller, Celine d'Orgeville, Olivier Peillet, Mike Redfern, Matthias Schoeck, Patricia Segonds, Richard Soden, Michel Tallon, Eric Thiebaut, Andrei Tokovinin, Jerome Vaillant, Jean-Marc Weulersse

Proceedings Volume 4065, (2000) https://doi.org/10.1117/12.407359

KEYWORDS: Telescopes, Sodium, Stars, Oscillators, Adaptive optics, Modulation, Wavefronts, Chemical species, Photons, Laser guide stars

Read Abstract +

Adaptive optics at astronomical telescopes aims at correcting in real time the phase corrugations of incoming wavefronts caused by the turbulent atmosphere, as early proposed by Babcock. Measuring the phase errors requires a bright source located within the isoplanatic patch of the program source. The probability that such a reference source exists is a function of the wavelength, of the required image quality (Strehl ratio), of the turbulence optical properties, and of the direction of the observation. It turns out that the sky coverage is disastrously low in particular in the visible wavelength range where, unfortunately, the gain in spatial resolution brought by adaptive optics is the largest. Foy and Labeyrie have proposed to overcome this difficulty by creating an artificial point source in the sky in the direction of the observation relying on the backscattered light due to a laser beam. This laser guide star (hereinafter referred to as LGS) can be bright enough to allow us to accurately measure the wavefront phase errors, except for two modes which are the piston (not relevant in this case) and the tilt. Pilkington has emphasized that the round trip time of the laser beam to the mesosphere, where the LGS is most often formed, is significantly shorter than the typical tilt coherence time; then the inverse-return-of-light principle causes deflections of the outgoing and the ingoing beams to cancel. The apparent direction of the LGS is independent of the tilt. Therefore the tilt cannot be measured only from the LGS. Until now, the way to overcome this difficulty has been to use a natural guide star to sense the tilt. Although the tilt is sensed through the entire telescope pupil, one cannot use a faint source because $APEX 90% of the variance of the phase error is in the tilt. Therefore, correcting the tilt requires a higher accuracy of the measurements than for higher orders of the wavefront. Hence current adaptive optics devices coupled with a LGS face low sky coverage. Several methods have been proposed to get a partial sky coverage for the tilt. The only one providing us with a full sky coverage is the polychromatic LGS (hereafter referred to as PLGS). We present here a progress report of the R&D program Etoile Laser Polychromatique et Optique Adaptative (ELP-OA) carried out in France to develop the PLGS concept. After a short recall of the principles of the PLGS, we will review the goal of ELP-OA and the steps to get over to bring it into play. We finally shortly described the effort in Europe to develop the LGS.

Proceedings Article | 7 July 2000 Paper

ELPOA: toward the tilt measurement from a polychromatic laser guide star

Proceedings Volume 4007, (2000) https://doi.org/10.1117/12.390401

KEYWORDS: Telescopes, Sodium, Oscillators, Adaptive optics, Modulation, Laser guide stars, Photons, Chemical species, Wavefronts, Atmospheric optics

Read Abstract +

Adaptive optics at astronomical telescopes aims at correcting in real time the phase corrugations of incoming wavefronts caused by the turbulent atmosphere, as early proposed by Babcock. Measuring the phase errors requires a bright source, which is located within the isoplanatic patch of the program source. The probability that such a reference source exists is a function of the wavelength of the observation, of the required image quality (Strehl ratio), of the turbulence optical properties, and of the direction of the observation. Several papers have addressed the problem of the sky coverage as a function of these parameters (see e.g.: Le Louarn et al). It turns out that the sky coverage is disastrously low in particular in the short (visible) wavelength range where, unfortunately, the gain in spatial resolution brought by adaptive optics is the largest. Foy and Labeyrie have proposed to overcome this difficulty by creating an artificial point source in the sky in the direction of the observation relying on the backscattered light due to a laser beam. This laser guide star (hereafter referred to as LGS) can be bright enough to allow us to accurately measure the wavefront phase errors, except for two modes which are the piston (which is not relevant in this case) and the tilt. Pilkington has emphasized that the round trip time of the laser beam to the mesosphere, where the LGS is most often formed, is significantly shorter than the typical tilt coherence time; then the inverse-return- of-light principle causes deflections of the outgoing and the ingoing beams to cancel. The apparent direction of the LGS is independent of the tilt. Therefore the tilt cannot be measured only from the LGS. Until now, the way to overcome this difficulty has been to use a natural guide star to sense the tilt. Although the tilt is sensed through the entire telescope pupil, one cannot use a faint source because approximately equals 90% of the variance of the phase error is in the tilt. Therefore, correcting the tilt requires a higher accuracy of the measurements than for higher orders of the wavefront. Hence current adaptive optics devices coupled with a LGS face low sky coverage. Several methods have been proposed to get a partial or total sky coverage for the tilt, such as the dual adaptive optics concept, the elongation perspective method, or the polychromatic LGS (hereafter referred to as PLGS). We present here a progress report of the R&D program Etoile Laser Polychromatique et Optique Adaptative (ELP-OA) carried out in France to develop the PLGS concept. After a short recall of the principles of the PLGS, we will review the goal of ELP-OA and the steps to get over to bring it into play.

Proceedings Article | 7 July 2000 Paper

PASS-2: quantitative photometric measurements of the polychromatic laser guide star

Matthias Schoeck, Renaud Foy, Jean-Paul Pique, Patrick Chevrou, Nancy Ageorges, Alain Petit, Veronique Bellanger, Hayden Fews, Francoise-Claude Foy, Claudia Hoegemann, Markus Laubscher, Olivier Peillet, Patricia Segonds, Michel Tallon, Jean-Marc Weulersse

Proceedings Volume 4007, (2000) https://doi.org/10.1117/12.390338

KEYWORDS: Laser guide stars, Telescopes, Sodium, Stars, Global system for mobile communications, Oscillators, Wavefronts, Adaptive optics, Calibration, Photometry

Read Abstract +

Proceedings Article | 14 July 1999 Paper

Comparison of measured and modeled BRDF of natural targets

Yannick Boucher, Helene Cosnefroy, Alain Petit, Gerard Serrot, Xavier Briottet

Proceedings Volume 3699, (1999) https://doi.org/10.1117/12.352945

KEYWORDS: Bidirectional reflectance transmission function, Data modeling, Mathematical modeling, Performance modeling, Sensors, Head, Calibration, Spectral resolution, Lamps, Spectroscopy

Read Abstract +

Proceedings Article | 14 September 1998 Paper

Polychromatic guide star

Renaud Foy, Michel Tallon, Herbert Friedman, Andre Baranne, Francois Biraben, Gilbert Grynberg, Miska Le Louarn, Alain Petit, Jean-Marc Weulersse, Arnold Migus, Jean-Pierre Gex

Proceedings Volume 3343, (1998) https://doi.org/10.1117/12.321566

KEYWORDS: Telescopes, Adaptive optics, Stars, Laser guide stars, Sodium, Atmospheric optics, Wavefronts, Diffraction, Wavefront sensors, Mesosphere

Read Abstract +

Proceedings Article | 3 March 1995 Paper

Selective laser photolysis of organic molecules in complex matrices

Christophe Moulin, Alain Petit

Proceedings Volume 2374, (1995) https://doi.org/10.1117/12.205022

KEYWORDS: Photolysis, Molecules, Absorption, Molecular lasers, Excimer lasers, Chromatography, Matrices, Biochemistry, Spectrophotometry, Gas lasers

Read Abstract +

Proceedings Article | 28 May 1993 Paper

Ionization yield in a three-step photoionization process of an optically thick atomic column: numerical modelization and experiments in atomic thulium

Philippe Kupecek, M. Comte, Jacques De Lamare, Alain Petit

Proceedings Volume 1859, (1993) https://doi.org/10.1117/12.145512

KEYWORDS: Ionization, Thulium, Isotope separation, Ions, Absorption, Diffraction, Laser processing, Chemical species, Laser beam propagation, Dye lasers

Read Abstract +

Proceedings Article | 28 May 1993 Paper

Hyperfine structure in the configuration F³DS² of uranium

R. Avril, A. Ginibre, Alain Petit

Proceedings Volume 1859, (1993) https://doi.org/10.1117/12.145486

KEYWORDS: Uranium, Isotope separation, Magnetism, Laser induced fluorescence, Information operations, Matrices, Luminescence, Chemical species, Collimation, Tunable lasers

Read Abstract +

Proceedings Article | 28 May 1993 Paper

Spectroscopy of uranium within the SILVA program

R. Avril, Alain Petit, J. Radwan, E. Vors

Proceedings Volume 1859, (1993) https://doi.org/10.1117/12.145508

KEYWORDS: Spectroscopy, Uranium, Oscillators, Isotope separation, Laser induced plasma spectroscopy, Ions, Laser induced fluorescence, Pulsed laser operation, Laser energy, Luminescence

Read Abstract +

Showing 5 of 14 publications

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years