Dr. Claudia Karin Hoegemann Profile

Dr. Claudia Karin Hoegemann

Astrophysicist at Instituto de Astrofísica de Canarias

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Author

Publications (14)

Proceedings Article | 1 November 2007 Paper

The hybrid Shack-Hartmann/G-SCIDAR instrument

M. A. C. Rodriguez Hernandez, Jesús Jimenez Fuensalida, Begoña García-Lorenzo, José Delgado, Elvio Hernandez, C. Hoegemann, Héctor Vazquez Ramio

Proceedings Volume 6747, 67470W (2007) https://doi.org/10.1117/12.738065

KEYWORDS: Turbulence, Scintillation, Wavefront sensors, Sensors, Telescopes, Stars, Observatories, Atmospheric turbulence, Atmospheric optics, Phase measurement

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Proceedings Article | 29 October 2007 Paper

Dome-seeing subtraction from G-SCIDAR measurements

J. Fuensalida, B. García-Lorenzo, C. Hoegemann

Proceedings Volume 6747, 67470U (2007) https://doi.org/10.1117/12.737752

KEYWORDS: Turbulence, Scintillation, Telescopes, Atmospheric turbulence, Stars, Algorithm development, Observatories, Domes, Adaptive optics, Atmospheric optics

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Proceedings Article | 11 November 2004 Paper

Statistics of atmospheric parameters for multiconjugated adaptive optics for the Observatorio del Roque del los Muchachos

Jesus Fuensalida, Begona Garcia-Lorenzo, Julio Castro, Sergio Chueca, Jose Miguel Delgado, Jose Gonzalez-Rodriguez, Claudia Hoegemann, Marcos Reyes, Manuel Verde, Jean Vernin

Proceedings Volume 5572, (2004) https://doi.org/10.1117/12.565558

KEYWORDS: Turbulence, Observatories, Adaptive optics, Atmospheric optics, Telescopes, Mirrors, Deformable mirrors, Lanthanum, Astronomy, Atmospheric turbulence

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Proceedings Article | 11 November 2004 Paper

Hybrid instrument for turbulence detection: wavefront sensing and scintillation detection in a fully automatic device

Claudia Hoegemann, Jose Delgado, Jesus Fuensalida, Elvio Hernandez, Angeles Rodriguez, Manuel Verde

Proceedings Volume 5572, (2004) https://doi.org/10.1117/12.565555

KEYWORDS: Turbulence, Wavefront sensors, Scintillation, Adaptive optics, Sensors, Telescopes, Observatories, Atmospheric turbulence, Lanthanum, Calibration

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Proceedings Article | 25 October 2004 Paper

Cute SCIDAR: presentation of the new Canarian instrument and first observational results

Claudia Hoegemann, Sergio Chueca, Jose Delgado, Jesus Fuensalida, Begona Garcia-Lorenzo, Esteban Mendizabal, Marcos Reyes, Manuel Verde, Jean Vernin

Proceedings Volume 5490, (2004) https://doi.org/10.1117/12.551795

KEYWORDS: Telescopes, Cameras, Prototyping, Lanthanum, Stars, Control systems, Turbulence, Binary data, Iris recognition, Observatories

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Proceedings Article | 25 October 2004 Paper

Vertical structure of the turbulence above the observatories of the Canary Islands: parameters and statistics for adaptive optics

Jesus Fuensalida, Sergio Chueca, Jose Delgado, Begona Garcia-Lorenzo, Jose Rodriguez-Gonzalez, Claudia Hoegemann, Esteban Mendizabal, Marcos Reyes, Manuel Verde, Jean Vernin

Proceedings Volume 5490, (2004) https://doi.org/10.1117/12.552031

KEYWORDS: Turbulence, Observatories, Adaptive optics, Solids, Deformable mirrors, Lanthanum, Telescopes, Statistical analysis, Mirrors, Databases

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Proceedings Article | 7 July 2004 Paper

An automatically controlled SCIDAR instrument for Roque de los Muchachos Observatory

Jesus Fuensalida, Jose Delgado, Begona Garcia-Lorenzo, Claudia Hoegemann, Marcos Reyes, Manuel Verde, Jean Vernin

Proceedings Volume 5382, (2004) https://doi.org/10.1117/12.566373

KEYWORDS: Turbulence, Observatories, Telescopes, Cameras, Prototyping, Stars, Data acquisition, Atmospheric optics, Atmospheric turbulence, Automatic control

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Proceedings Article | 7 July 2004 Paper

Turbulence profiles in the observatories of the Canary Islands: preliminary statistics for adaptive optics

Jesus Fuensalida, Sergio Chueca, Jose Delgado, Begona Garcia-Lorenzo, Jose Gonzalez-Rodriguez, Claudia Hoegemann, Esteban Mendizabal, Marcos Reyes, Manuel Verde, Jean Vernin

Proceedings Volume 5382, (2004) https://doi.org/10.1117/12.566324

KEYWORDS: Turbulence, Observatories, Adaptive optics, Databases, Meteorology, Solids, Statistical analysis, Satellites, Reliability, Prototyping

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Proceedings Article | 6 February 2004 Paper

Experimental test of laser beam propagation with simultaneous measurements of turbulence profiles

Sergio Chueca, Angel Alonso, Marcos Reyes, Jesus Fuensalida, Claudia Hoegmann, Begona Garcia-Lorenzo, Esteban Mendizabal

Proceedings Volume 5237, (2004) https://doi.org/10.1117/12.511563

KEYWORDS: Turbulence, Telescopes, Atmospheric propagation, Laser beam propagation, Rayleigh scattering, Observatories, Optical communications, Atmospheric optics, Gaussian beams, Scintillation

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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

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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

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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

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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

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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

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Showing 5 of 14 publications

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