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Proceedings Paper

Wide field astronomical image compensation with multiple laser-guided adaptive optics
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Paper Abstract

We report closed-loop results obtained from the first adaptive optics system to deploy multiple laser guide beacons. The system is mounted on the 6.5 m MMT telescope in Arizona, and is designed to explore advanced altitude-conjugated techniques for wide-field image compensation. Five beacons are made by Rayleigh scattering of laser beams at 532 nm integrated over a range from 20 to 29 km by dynamic refocus of the telescope optics. The return light is analyzed by a unique Shack-Hartmann sensor that places all five beacons on a single detector, with electronic shuttering to implement the beacon range gate. Wavefront correction is applied with the telescope's unique deformable secondary mirror. The system has now begun operations as a tool for astronomical science, in a mode in which the boundary-layer turbulence, close to the telescope, is compensated. Image quality of 0.2-0.3 arc sec is routinely delivered in the near infrared bands from 1.2-2.5 μm over a field of view of 2 arc min. Although it does not reach the diffraction limit, this represents a 3 to 4-fold improvement in resolution over the natural seeing, and a field of view an order of magnitude larger than conventional adaptive optics systems deliver. We present performance metrics including images of the core of the globular cluster M3 where correction is almost uniform across the full field. We describe plans underway to develop the technology further on the twin 8.4 m Large Binocular Telescope and the future 25 m Giant Magellan Telescope.

Paper Details

Date Published: 1 September 2009
PDF: 11 pages
Proc. SPIE 7468, Adaptive Coded Aperture Imaging, Non-Imaging, and Unconventional Imaging Sensor Systems, 74680L (1 September 2009); doi: 10.1117/12.827301
Show Author Affiliations
Michael Hart, The Univ. of Arizona (United States)
N. Mark Milton, The Univ. of Arizona (United States)
Christoph Baranec, California Institute of Technology (United States)
Thomas Stalcup, The Univ. of Arizona (United States)
Keith Powell, The Univ. of Arizona (United States)
Eduardo Bendek, The Univ. of Arizona (United States)
Don McCarthy, The Univ. of Arizona (United States)
Craig Kulesa, The Univ. of Arizona (United States)

Published in SPIE Proceedings Vol. 7468:
Adaptive Coded Aperture Imaging, Non-Imaging, and Unconventional Imaging Sensor Systems
David P. Casasent; Jean J. Dolne; Stanley Rogers; Thomas J. Karr; Victor L. Gamiz, Editor(s)

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