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Proceedings Paper

First light of the OVLA active mirror with its surface heating system
Author(s): Olivier Lardiere; Luc Arnold; Julien Dejonghe
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Paper Abstract

The Optical Very Large Array (OVLA) project consists in a kilometric-size optical interference of 27 mobile 1.5 m telescopes designed to provide high-resolution IR and visible snap-shot images. An OVLA prototype telescope has been developed at the Observatoire de Haute-Provence. It features a 1.5 m meniscus-shaped f/1.7 primary mirror weighting 200 kg including its active cell with 32 actuators. The mirror blank made of 24 mm-thick ordinary window glass is very cheap but extremely sensitive to temperature variations because of its large CTE (3 times larger than Pyrex). Indeed, the mirror shows a Z11 equals 3150 nm rms wavefront error due to a 0.5 degree(s)C thermal gradient generated between its front and back side by an unbalanced heat dissipation towards the night sky and the ground. This spherical aberration, too large to be corrected by the actuators, is compensated by an uniform electrical current generated through the aluminum coating by 42 peripheral electrodes. We also describe the electrodes control hardware and present some results obtained during the first light of the telescope. Lastly, we propose a possible upgraded surface heating system to adjust thermally other optical aberrations.

Paper Details

Date Published: 20 July 2000
PDF: 10 pages
Proc. SPIE 4003, Optical Design, Materials, Fabrication, and Maintenance, (20 July 2000); doi: 10.1117/12.391533
Show Author Affiliations
Olivier Lardiere, Observatoire de Haute-Provence (France) and College de France (France)
Luc Arnold, Observatoire de Haute-Provence (France)
Julien Dejonghe, College de France (France)

Published in SPIE Proceedings Vol. 4003:
Optical Design, Materials, Fabrication, and Maintenance
Philippe Dierickx, Editor(s)

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