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Proceedings Paper

A prototype phasing camera for the Giant Magellan Telescope
Author(s): Srikrishna Kanneganti; Brian A. McLeod; Mark P. Ordway; John B. Roll; Stephen A. Shectman; Antonin H. Bouchez; Johanan Codona; Roger Eng; Thomas M. Gauron; Felix Handte; Timothy J. Norton; Phil Streechon; David Weaver
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Paper Abstract

Achieving the diffraction limit with the adaptive optics system of the 25m Giant Magellan Telescope will require that the 7 pairs of mirror segments be in phase. Phasing the GMT is made difficult because of the 30-40cm gaps between the primary mirror segments. These large gaps result in atmospheric induced phase errors making optical phasing difficult at visible wavelengths. The large gaps between the borosilicate mirror segments also make an edge sensing system prone to thermally induced instability. We describe an optical method that uses twelve 1.5-m square subapertures that span the segment boundaries. The light from each subaperture is mapped onto a MEMS mirror segment and then a lenslet array which are used to stabilize the atmospherically induced image motion. Centroids for stabilization are measured at 700nm. The piston error is measured from the fringes visible in each of the 12 stabilized images at 2.2 microns. By dispersing the fringes we can resolve 2π phase ambiguities. We are constructing a prototype camera to be deployed at the 6.5m Magellan Clay telescope.

Paper Details

Date Published: 13 September 2012
PDF: 10 pages
Proc. SPIE 8447, Adaptive Optics Systems III, 844752 (13 September 2012); doi: 10.1117/12.926517
Show Author Affiliations
Srikrishna Kanneganti, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Brian A. McLeod, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Mark P. Ordway, Harvard-Smithsonian Ctr. for Astrophysics (United States)
John B. Roll, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Stephen A. Shectman, Giant Magellan Telescope Organization Corp. (United States)
Antonin H. Bouchez, Giant Magellan Telescope Organization Corp. (United States)
Johanan Codona, Steward Observatory, The Univ. of Arizona (United States)
Roger Eng, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Thomas M. Gauron, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Felix Handte, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Timothy J. Norton, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Phil Streechon, Harvard-Smithsonian Ctr. for Astrophysics (United States)
David Weaver, Harvard-Smithsonian Ctr. for Astrophysics (United States)


Published in SPIE Proceedings Vol. 8447:
Adaptive Optics Systems III
Brent L. Ellerbroek; Enrico Marchetti; Jean-Pierre Véran, Editor(s)

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