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Proceedings Paper

Measurements of the wavefront outer scale at Paranal: influence of this parameter in interferometry
Author(s): Rodolphe Conan; Aziz Ziad; Julien Borgnino; Francois Martin; Andrei A. Tokovinin
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Paper Abstract

The Generalized Seeing Monitor (GSM) has undertaken a campaign of measurement of the optical turbulent parameters: the Fried's parameter, the outer scale (L0) and the isoplanatic patch, at Paranal, the site of the VLT, in December 1998. The principle aim of this mission was to measure L0 values at Paranal. In a first part, we present the GSM, the results of the mission and particularly the statistics of L0. In a second part, we emphasize the effect of L0 on the optical path difference (OPD) values for the co-phasing of an interferometer. We derive the exact formulation of the OPD for the Von Karman model and we give the expected OPD at Paranal with L0 values measured by the GSM. We give also the expression of the residual OPD at the output of a fringe tracker system as a function of L0, of the exposure time of the fringe sensor and of the frequency of the closed-loop of the system.

Paper Details

Date Published: 5 July 2000
PDF: 11 pages
Proc. SPIE 4006, Interferometry in Optical Astronomy, (5 July 2000); doi: 10.1117/12.390176
Show Author Affiliations
Rodolphe Conan, Univ. de Nice Sophia-Antipolis (Germany)
Aziz Ziad, Univ. de Nice Sophia-Antipolis (France)
Julien Borgnino, Univ. de Nice Sophia-Antipolis (France)
Francois Martin, Univ. de Nice Sophia-Antipolis (France)
Andrei A. Tokovinin, Sternberg Astronomical Institute (Chile)


Published in SPIE Proceedings Vol. 4006:
Interferometry in Optical Astronomy
Pierre J. Lena; Andreas Quirrenbach, Editor(s)

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