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Proceedings Paper

Tulip-form variable-curvature mirrors: interferometry and field compensation
Author(s): Gerard R. Lemaitre; Silvio P. Mazzanti; Marc Ferrari
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Paper Abstract

Active Optics methods are now capable to provide variable curvature mirrors (VCMs) having controlled sags in the focal range from f/∞to f/2.5. Those development have been carried out by the authors for the optical path equalizer dedicated to each Mersenne focus of the VLTI. The basic principle is to use VCMs as cat's eye mirrors in each delay line in order to achieve field compensations at the recombined Mersenne focii. During the VLTI development phase, cycloid form VCMs controlled by air pressure have been performed with a 10-4 mirror sag resolution. The cycloid form has been selected for the VLTi delay lines. However, other analytical solutions from circular plates elasticity theory have been found. Two thickness distributions lead to tulip form VCMs controlled by a central force. One of them, using a lineic reaction at the edge is the object of this paper. Active optics design, construction features, test and experimental He-Ne interferograms obtained with 16mm boundary aperture and 10mm clear aperture are presented. The mean aspect-ratio of the tulip from VCM is d/t0.5 approximately equals 60, providing a focal zoom range from f/∞ to f/2.5. The experiment is carried out form f/∞ to f/5.

Paper Details

Date Published: 24 July 1998
PDF: 7 pages
Proc. SPIE 3350, Astronomical Interferometry, (24 July 1998); doi: 10.1117/12.317099
Show Author Affiliations
Gerard R. Lemaitre, Observatoire de Marseille (France)
Silvio P. Mazzanti, Observatoire de Marseille (France)
Marc Ferrari, European Southern Observatory (France)

Published in SPIE Proceedings Vol. 3350:
Astronomical Interferometry
Robert D. Reasenberg, Editor(s)

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