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Contrôle longitudinal et caractérisation optique du détecteur Virgo

Abstract : The Virgo detector aims at direct detection of the gravitational waves emitted by astropysical objects. Essentially, it is a Michelson interferometer with arms constituted by 3 km long Fabry-Perot cavities which use the recycling technique.
To reach the required sensitivity, the instrument must be maintained at its working point using both angular and longitudinal controls. This thesis covers my work on the algorithm implemented in the Global Control to control the four characteristics lengths of the interferometer within a few nanometers, as part of locking process.
To achieves this result, we use the Pound-Drever technique, which provides for an optical cavity a signal sensitive to its length compared to the resonance position. Two algorithms has been tested. The first one is inspired by the algorithm developped by LIGO. We control sequentially the different lengths of Virgo. But, the difference between Virgo and LIGO has been the reason of the failure of this algorithm. The other algorithm brings simulatneously the four lengths on the half fringe of the Michelson interferometer. Our deterministic algorithm brings the instrument to its working point in a few minutes.
Another part of this work deals with in situ measurements of optical parameters critical to an interpretation of the behaviour of the instrument. These allowed us to tune the Virgo simulation and prepare the lock acquisition algorithm.
Finally, we will interest on the coupling between the angular control and the longitudinal control techniques. We show the mechanism and we evaluate his impact on the locking of Virgo.
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-00012159
Contributor : Stephane Kreckelbergh <>
Submitted on : Tuesday, April 18, 2006 - 8:07:44 PM
Last modification on : Wednesday, September 16, 2020 - 4:24:27 PM
Long-term archiving on: : Saturday, April 3, 2010 - 9:04:56 PM

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  • HAL Id : tel-00012159, version 1

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Citation

Stephane Kreckelbergh. Contrôle longitudinal et caractérisation optique du détecteur Virgo. Cosmologie et astrophysique extra-galactique [astro-ph.CO]. Université Paris Sud - Paris XI, 2005. Français. ⟨tel-00012159⟩

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