Preliminary closed-loop results from an adaptive optics system using a sodium resonance guide star

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

doi:10.1117/12.176070

31 May 1994 Preliminary closed-loop results from an adaptive optics system using a sodium resonance guide star

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

Author Affiliations +

Proceedings Volume 2201, Adaptive Optics in Astronomy; (1994) https://doi.org/10.1117/12.176070
Event: 1994 Symposium on Astronomical Telescopes and Instrumentation for the 21st Century, 1994, Kailua, Kona, HI, United States

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.

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Michael Lloyd-Hart, James Roger P. Angel, Bruce P. Jacobsen, David M. Wittman, Donald W. McCarthy Jr., Edward J. Kibblewhite, Barbara Carter, and Walter J. Wild "Preliminary closed-loop results from an adaptive optics system using a sodium resonance guide star", Proc. SPIE 2201, Adaptive Optics in Astronomy, (31 May 1994); https://doi.org/10.1117/12.176070

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