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Proceedings Paper

Design and analysis for interferometric measurements of the GMT primary mirror segments
Author(s): J. H. Burge; L. B. Kot; H. M. Martin; R. Zehnder; C. Zhao
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Paper Abstract

The Giant Magellan Telescope (GMT) uses seven 8.4-m diameter segments to create a giant primary mirror, 25 meters across with focal ratio f /0.7. The off-axis segments will be difficult to measure accurately, as they have 14.5 mm departure from the nearest fitting sphere! The test configuration adopted uses a large 3.75-m powered mirror to fold the light path and provide most of the aspheric correction, with a smaller mirror and computer generated hologram (CGH) providing the additional correction. These optics will be aligned to a vibration-insensitive interferometer using a combination of optical references created by the CGH and metrology with a laser tracker. Some key challenges for this system are presented here including, the system alignment, the large fold mirror, and the mechanical structure. Analysis of the optical test shows that it will meet GMT specifications, including the difficult requirement that the separate segments have matching radius of curvature. Additional corroborative testing will be performed to assure that the mirror segments are correctly figured.

Paper Details

Date Published: 6 July 2006
PDF: 12 pages
Proc. SPIE 6273, Optomechanical Technologies for Astronomy, 62730M (6 July 2006); doi: 10.1117/12.672484
Show Author Affiliations
J. H. Burge, Steward Observatory, Univ. of Arizona (United States)
College of Optical Sciences, Univ. of Arizona (United States)
L. B. Kot, Steward Observatory, Univ. of Arizona (United States)
H. M. Martin, Steward Observatory, Univ. of Arizona (United States)
R. Zehnder, College of Optical Sciences, Univ. of Arizona (United States)
C. Zhao, College of Optical Sciences, Univ. of Arizona (United States)

Published in SPIE Proceedings Vol. 6273:
Optomechanical Technologies for Astronomy
Eli Atad-Ettedgui; Joseph Antebi; Dietrich Lemke, Editor(s)

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