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Proceedings Paper

Laboratory demonstration of wavefront-based stochastic parallel gradient descent adaptive optics system
Author(s): Mikhail S. Belen'kii; Jeff Barchers; Eric Berg; Don Bruns; Deborah Fung; Richard Gallant; Clay Kirk; Hope Runyeon; Vincent Rye; Josh Voass
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Paper Abstract

A laboratory demonstration of two novel tactical beam control methods for correcting the effects of strong turbulence including Beacon Anisoplanatism, and the combined effects of Beacon Anisoplanatism and Thermal Blooming, respectively, were performed in SAIC's Tactical Beam Control Test-Bed. Both systems were tested with ratio of aperture diameter to Fried parameter, D/r0, of up to 7, and ratio of beam spot size at the target to isoplanatic angle, θBo, of up to 10. The first method was implemented in a Wavefront-based Stochastic Parallel Gradient Decent (WSPGD) adaptive optics (AO) system, which uses an off-axis wavefront sensor (WFS) to provide feedback for a multi-dithering beam control algorithm. The second method was implemented in a Hybrid WSPGD AO system, which incorporates the WSPGD AO system with a conventional Phase Conjugate (PC) AO system. The Hybrid system uses an on-axis WFS to generate initial deformable mirror commands and an off-axis WFS to generate additional commands that account for the high frequency phase components removed from the wavefront of a laser return by Beacon Anisoplanatism. We developed a low speed PC-based WSPGD controller, implemented designs of the WSPGD and Hybrid WSPGD AO systems in SAIC's Test-Bed, and tested both AO systems in static and dynamic turbulence over a wide range of turbulence conditions. A target-plane tracker was used to stabilize the line-of-sight in the AO corrected beam. Test results show that the WSPGD AO system efficiently compensates the effects of Beacon Anisoplanatism for both static and dynamic turbulence, providing a mean performance gain of 1.8 averaged over multiple turbulent realizations. We also found in testing that the Hybrid WSPGD system efficiently compensates for Beacon Anisoplanatism in the presence of Thermal Blooming - providing improved compensation for both Thermal Blooming and turbulence. In the presence of strong Beacon Anisoplanatism with θBo of up to 10, the maximum performance gain is 4.9 and the mean performance gain for multiple turbulence realizations is 2.1.

Paper Details

Date Published: 25 September 2007
PDF: 14 pages
Proc. SPIE 6708, Atmospheric Optics: Models, Measurements, and Target-in-the-Loop Propagation, 67080I (25 September 2007); doi: 10.1117/12.734309
Show Author Affiliations
Mikhail S. Belen'kii, Trex Enterprises Corp. (United States)
Jeff Barchers, Science Applications International Corp. (United States)
Eric Berg, Science Applications International Corp. (United States)
Don Bruns, Trex Enterprises Corp. (United States)
Deborah Fung, Science Applications International Corp. (United States)
Richard Gallant, Science Applications International Corp. (United States)
Clay Kirk, Science Applications International Corp. (United States)
Hope Runyeon, Trex Enterprises Corp. (United States)
Vincent Rye, Trex Enterprises Corp. (United States)
Josh Voass, Pipeline Processing Co. (United States)


Published in SPIE Proceedings Vol. 6708:
Atmospheric Optics: Models, Measurements, and Target-in-the-Loop Propagation
Stephen M. Hammel; Alexander M. J. van Eijk; Michael T. Valley; Mikhail A. Vorontsov, Editor(s)

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