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Proceedings Paper

Phasing metrology system for the GMT
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Paper Abstract

The Giant Magellan Telescope (GMT) is a 25.4 m diameter ground-based segmented Gregorian telescope, composed of 7 8.4 meter diameter primary mirror segments, and 7 1 meter diameter adaptive secondary mirror segments. Co-phasing of the integrated optical system will be partially achieved by making real-time measurements of the wavefront of an offaxis guide star. However, slowly varying aberrations due to thermal and gravitational effects, as well as wind buffeting, will make it difficult to maintain alignment using real-time optical measurements alone. Consequently, we are proposing internal metrology systems to maintain the relative alignment of the optical elements. In this paper we describe a differential capacitive edge sensing system to maintain the relative alignment of the adaptive secondary mirror reference bodies. We also propose an interferometric system for sensing of the relative displacements of primary mirror segments.

Paper Details

Date Published: 17 September 2012
PDF: 10 pages
Proc. SPIE 8444, Ground-based and Airborne Telescopes IV, 844423 (17 September 2012); doi: 10.1117/12.925012
Show Author Affiliations
D. Scott Acton, Ball Aerospace & Technologies Corp. (United States)
Antonin Bouchez, Giant Magellan Telescope Project (United States)

Published in SPIE Proceedings Vol. 8444:
Ground-based and Airborne Telescopes IV
Larry M. Stepp; Roberto Gilmozzi; Helen J. Hall, Editor(s)

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