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Proceedings Paper

Preliminary closed-loop results from an adaptive optics system using a sodium resonance guide star
Author(s): Michael Lloyd-Hart; James Roger P. Angel; Bruce P. Jacobsen; David M. Wittman; Donald W. McCarthy Jr.; Edward J. Kibblewhite; Barbara Carter; Walter J. Wild
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Paper Abstract

A sodium guide star has been used to sense and correct atmospheric aberration during two runs at the Multiple Mirror Telescope (MMT). For the first run in 1993 May, the artificial star was created by a 0.5 W beam from a continuous- wave dye laser tuned to the D2 resonance line, projected from a telescope centered and coaxial with the main array of six 1.8 m mirrors. Scattering by the mesospheric sodium layer produced an artificial beacon equivalent in brightness to a natural star of visual magnitude 12.5, and of angular extent 1'.2 full width at half maximum (FWHM). During the second run in 1994 February, a 1.7 W dye laser was used to generate an artificial guide star of visual magnitude 10.4, and 1'.1 FWHM. In each case, the beacon was used by the MMT adaptive optics system to compensate in real time for atmospherically- induced differential image motion between the six mirror elements, at correction rates of up to 76 Hz. In the latter experiment, global wavefront tilt correction using a natural reference star was added, giving complete adaptive control. Simultaneously recorded images of a natural star coincident with the laser beacon show significantly reduced width and an increase in Strehl ratio of almost a factor of two.

Paper Details

Date Published: 31 May 1994
PDF: 9 pages
Proc. SPIE 2201, Adaptive Optics in Astronomy, (31 May 1994); doi: 10.1117/12.176070
Show Author Affiliations
Michael Lloyd-Hart, Univ. of Arizona Steward Observatory (United States)
James Roger P. Angel, Univ. of Arizona Steward Observatory (United States)
Bruce P. Jacobsen, Univ. of Arizona Steward Observatory (United States)
David M. Wittman, Univ. of Arizona Steward Observatory (United States)
Donald W. McCarthy Jr., Univ. of Arizona Steward Observatory (United States)
Edward J. Kibblewhite, Univ. of Chicago (United States)
Barbara Carter, Univ. of Chicago (United States)
Walter J. Wild, Univ. of Chicago (United States)

Published in SPIE Proceedings Vol. 2201:
Adaptive Optics in Astronomy
Mark A. Ealey; Fritz Merkle, Editor(s)

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