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127 results on '"Michau, V."'

1. PROVIDENCE: toward a 2.5m adaptive telescope for optical space domain awareness (but not only…)

Author

Jackson, Kathryn J., Schmidt, Dirk, Vernet, Elise, Petit, C., Fusco, T., Védrenne, N., Sauvage, J.-F., Leplat, G., Barbon-Dubosc, D., Adami, C., Advani, T., Blanc, P.-E., Bonnefois, A., Basa, S., Cassaing, F., Coiro, E., De La Barrière, F., Dolon, F., Fetick, R., Ferrari, M., Floriot, J., Frederick, Y.-M., Gustave, F., Haensler, P.-E., Heritier, C. T., Hespel, L., Jouve, P., Michau, V., Mugnier, L., Neichel, B., Tricoli, U., and Vernazza, P.

Published
2024
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5. Performance analysis of an adaptive optics based optical feeder link ground station

Author

Védrenne, N., primary, Petit, C., additional, Montmerle-Bonnefois, A., additional, Lim, C. B., additional, Conan, Jean-Marc, additional, Paillier, L., additional, Velluet, M.-T., additional, Caillault, K., additional, Gustave, F., additional, Durecu, A., additional, Michau, V., additional, Cassaing, F., additional, Meimon, S., additional, and Montri, J., additional

Published
2021
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8. Single-mode fiber coupling for satellite-to-ground telecommunication links corrected by adaptive optics

Author

Lim, C B, Petit, C., Saab, K., Fleury, B., Mendez, F., Montri, J., Védrenne, N., Michau, V., DOTA, ONERA, Université Paris Saclay [Châtillon], ONERA-Université Paris-Saclay, DOTA, ONERA, Université Paris Saclay (COmUE) [Châtillon], and Université Paris Saclay (COmUE)-ONERA

Subjects
telecommunication, [PHYS.PHYS]Physics [physics]/Physics [physics], single-mode fiber, coupling, satellite-to-ground, adaptive optics
Abstract

International audience; The need for high data rate communication systems has encouraged the development of new satellite-to-ground optical links using adaptive optics to compensate for atmospheric turbulence, while exploiting existing fiber components to limit their cost. Knowing the statistic distribution of the fading durations of the corrected flux coupled into a single-mode fiber is a cornerstone to design the optical transmission system (coding and interleaving protocols for example). Besides, results on such coupling efficiency statistics are not limited to the telecom applications and could be useful for astronomical applications, such as spectroscopy. In this context, an analytical model was developed at ONERA, along with a compact optical bench (LISA2), we integrated for experimental validation on the sky. Based on a previous study, an injection module was included to LISA2 to maximize the fiber-coupling and minimize the impact of static aberrations. The system integration along with the first results of its functional validation are presented.

Published
2018

9. First Experimental Demonstration of Adaptive Optics Pre-Compensation for GEO Feeder Links in a Relevant Environment

Author

Vedrenne, N., primary, Montri, J., additional, Conan, J. M., additional, Michau, V., additional, Sodnik, Z., additional, Voland, C., additional, Montmerle-Bonnefois, A., additional, Lim, C. B., additional, Petit, C., additional, Sauvage, J. F., additional, Meimon, S., additional, Perrault, P., additional, Mendez, F., additional, and Fleury, B., additional

Published
2019
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13. Adaptive optics precompensation of a GEO feeder link : the FEEDELIO experiment

Author

Montmerle-Bonnefois, A., primary, Petit, C., additional, Lim, C.B., additional, Sauvage, J.-F., additional, Meimon, S., additional, Perrault, P., additional, Mendez, F., additional, Fleury, B., additional, Montri, J., additional, Conan, J.-M., additional, Michau, V., additional, Védrenne, N., additional, Sodnik, Z., additional, and Voland, C., additional

Published
2019
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15. Multiple-aperture optical telescopes: cophasing sensor testbed

Author

Sorrente, B., primary, Cassaing, F., primary, Baron, F., primary, Coudrain, C., primary, Fleury, B., primary, Mendez, F., primary, Mugnier, L., primary, Bentadj-Paris, V., primary, Michau, V., primary, Montri, J., primary, Rousset, G., primary, Rousset-Rouviere, L., primary, and Velluet, M.-T., primary

Published
2018
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21. The LAM space active optics facility

Author

Falzon, F., primary, Liotard, A., primary, Michau, V., primary, Engel, C., primary, Ferrari, M., primary, Hugot, E., primary, Escolle, C., primary, Bonnefois, A., primary, Bernot, M., primary, Bret-Dibat, T., primary, Carlavan, M., primary, Fusco, T., primary, Laubier, D., primary, and Mugnier, L., primary

Published
2017
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22. Comparative theoretical and experimental study of a Shack-Hartmann and a phase diversity sensor, for high-precision wavefront sensing dedicated to space active optics

Author

Fusco, T., primary, Michau, V., primary, Mugnier, L., primary, Sauvage, J. F., primary, Hugot, E., primary, Liotard, A., primary, Bernot, M., primary, Carlavan, M., primary, Bret-Dibat, T., primary, Laubier, D., primary, Montmerle Bonnefois, A., primary, Meimon, S., primary, Engel, C., primary, Escolle, C., primary, Ferrari, M., primary, and Falzon, F., primary

Published
2017
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27. Cn2 profilometry from Shack-Hartmann data: model and experiment

Author

Voyez, J., Robert, C., Fleury, B., Vedrenne, N., Michau, V., Fusco, T., and Samain, E.

Subjects
ADAPTIVE OPTICS, WAVEFRONT CORRECTORS, REAL-TIME CONTROL, PATHFINDERS, ATMOSPHERIC TURBULENCE, MODELING, POST-PROCESSING, INSTRUMENTS, EXTREMELY LARGE TELESCOPES, WAVEFRONT SENSING, LASER GUIDE STAR SYSTEMS
Abstract

Wide Field Adaptive Optics (WFAO) systems require a precise reconstruction of the turbulent volume. The C2n profile, representing the turbulence strength, becomes a critical parameter for the final tomographic reconstruction performance. We present a new method, CO-SLIDAR (COupled SLope and scIntillation Detection And Ranging), that uses correlations of slopes and scintillation indexes recorded on a Shack-Hartmann (SH), to retrieve the C2n profile. A design is proposed for the instrument. Reconstruction performances are showed in simulation. Tests are carried out on the optical bench, and improvements are suggested. Sensitivity of the method to outer scale is demonstrated.

Published
2011
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28. LGS WFS on ELTs I: Wavefront measurements analysis

Author

Muller, N., Thomas, S., Michau, V., and Fusco, T.

Subjects
ADAPTIVE OPTICS, WAVEFRONT CORRECTORS, REAL-TIME CONTROL, PATHFINDERS, ATMOSPHERIC TURBULENCE, MODELING, POST-PROCESSING, INSTRUMENTS, EXTREMELY LARGE TELESCOPES, WAVEFRONT SENSING, LASER GUIDE STAR SYSTEMS
Abstract

Adaptive Optics relies on a Wave Front Sensor (WFS) to measure properly the perturbations induced by the turbulence. In case of a Shack-Hartmann (SH) WFS, the spot elongation, due to the longitudinal extension of Laser Guide Stars (LGS), affects the quality of the WFS measurements. As the diameter of the telescope increases, non-linearities appear through spot truncation and sampling effects. In addition, the spatial structure of the LGS, set by the Sodium layer density profile, has an impact on the measurements. In this paper we aim at optimizing the design of a SH WFS in the case of a LGS on an ELT. Considering a Gaussian Sodium profile, we show that the impact of the WFS non-linearities can be neglected with regards to the noise. Taking then into account the reconstruction filtering, the impact of the longitudinal extent of the LGS on the WFS measurement accuracy is moderate. Moreover this result is established with a wide range of analytical Sodium profiles, provided that the Sodium density profile is known. The impact of the Sodium layer fluctuations is specifically studied in the second part of this paper, LGS WFS on ELTs II.

Published
2011
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29. Laser Tomographic AO system for an Integral Field Spectrograph on the E-ELT : ATLAS project

Author

Fusco, T., Meimon, S., Clénet, Y., Cohen, M., Schnetler, H., Paufique, J., Michau, V., Thatte, N., Hubin, N., Petit, C., Amans, J. P., Damien Gratadour, Conan, J. -M, and Jagourel, P.

Subjects
ADAPTIVE OPTICS, WAVEFRONT CORRECTORS, REAL-TIME CONTROL, PATHFINDERS, ATMOSPHERIC TURBULENCE, MODELING, POST-PROCESSING, INSTRUMENTS, EXTREMELY LARGE TELESCOPES, WAVEFRONT SENSING, LASER GUIDE STAR SYSTEMS
Abstract

ATLAS is a generic Laser Tomographic AO (LTAO) system for the E-ELT. Based on modular, relatively simple, and yet innovative concepts, it aims at providing diffraction limited images in the near infra-red for a close to 100 percent sky coverage.

Published
2011
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30. LGS WFS on ELTs II:Impact if the sodium layer fluctuations

Author

Thomas, S., Muller, N., Michau, V., and Fusco, T.

Subjects
ADAPTIVE OPTICS, WAVEFRONT CORRECTORS, REAL-TIME CONTROL, PATHFINDERS, ATMOSPHERIC TURBULENCE, MODELING, POST-PROCESSING, INSTRUMENTS, EXTREMELY LARGE TELESCOPES, WAVEFRONT SENSING, LASER GUIDE STAR SYSTEMS
Abstract

The application of laser guide stars to large aperture telescopes has spurred many new studies in wavefront sensing. For the particular case of the Shack-HartmannWFS, wavefront sensing is prone to new sources of errors not previously considered. The primary source of error is spot elongation resulting from the resolution of the finite thickness of the sodium layer. The elongation spreads the signal over several pixels, resulting in a decrease of the signal to noise ratio and an increase of non-linearity. Also, the SHWFS performance becomes sensitive to temporal and spatial variations of the density of the sodium atoms. Among the different centroid algorithms to be used with this WFS, the most powerful methods (correlation, matched filter, WCoG) require a reference. Although straightforward for a point source, the use of a resolved laser guide star is more cumbersome because the sodium layer variations affect their performance. In this paper we look at the impact of the sodium layer fluctuations and the reference choice on the performance of the WFS, considering real as well as analytical non-symmetric profiles, and investigating both the subaperture level and the wavefront reconstruction level. We conclude on the compromise between the use of the best possible reference versus the difficulty of implementation.

Published
2011
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31. Adaptive optics results with SOTA

Author

Petit, C., primary, Vedrenne, N., additional, Michau, V., additional, Artaud, G., additional, Issler, J.-L., additional, Samain, E., additional, Toyoshima, M., additional, Akioka, M., additional, Kolev, D., additional, Munemasa, Y., additional, Takenaka, H., additional, and Iwakiri, N., additional

Published
2015
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35. The LAM space active optics facility

Author

Sodnik, Zoran, Karafolas, Nikos, Cugny, Bruno, Engel, C., Ferrari, M., Hugot, E., Escolle, C., Bonnefois, A., Bernot, M., Bret-Dibat, T., Carlavan, M., Falzon, F., Fusco, T., Laubier, D., Liotard, A., Michau, V., and Mugnier, L.

Published
2017
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37. ATLAS: the Laser Tomographic Adaptive Optics module for the E-ELT

Author

Fusco, T., primary, Clénet, Y., additional, Meimon, S., additional, Cohen, M., additional, Paufique, J., additional, Petit, C., additional, Gratadour, D., additional, Michau, V., additional, Amans, J.-P., additional, Dournaux, J.-L., additional, Jagourel, P., additional, Schnetler, H., additional, Conan, J.-M., additional, Robert, C., additional, Gendron, E., additional, Rousset, G., additional, and Hubin, N., additional

Published
2010
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42. Femtosecond filamentation in turbulent air

Author

Houard, A., primary, Franco, M., additional, Prade, B., additional, Durécu, A., additional, Lombard, L., additional, Bourdon, P., additional, Vasseur, O., additional, Fleury, B., additional, Robert, C., additional, Michau, V., additional, Couairon, A., additional, and Mysyrowicz, A., additional

Published
2008
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