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Proceedings Paper

Comparing woofer-tweeter control methods through deep turbulence: A simulation (Conference Presentation)
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Paper Abstract

Laser propagation through deep turbulence requires adaptive optic systems capable of correcting wavefront distortions with large phase shifts. The large phase shifts, can be overcome by using dual deformable mirrors in a woofer-tweeter configuration. In this configuration the woofer corrects low spatial-frequency aberrations and the tweeter corrects higher order distortions. In this work, we perform a simulated side-by-side comparison of various control methods for woofer-tweeter adaptive optics systems. Attention is focused on the deep turbulence regime, where the wavefront distortions contain discontinuities. Our simulated wavefronts originate from a cooperative point-like beacon placed at the target plane. The light from the beacon propagates horizontally through multiple kilometers of turbulent atmosphere to the receiving aperture. At the receiver, the wavefronts are interfered with a local reference wave to produce a hologram. Through digital holographic processing, we recover the complex wave field at the receiver, in which the phase contains both branch cuts and branch points. These discontinuities pose a challenging problem for continuous surface mirrors required for high-energy applications. Our study explores the ability of previously published control methods to correct wavefronts with branch points and cuts. Various control methods for woofer-tweeter systems, including zonal and modal methods, are compared using the Strehl ratio and stroke efficiency as performance metrics. The investigation of these control methods will enable future applications to maximize the the stroke of dual deformable mirror adaptive optics systems leading to better energy on target in deep turbulence conditions.

Paper Details

Date Published: 18 September 2018
Proc. SPIE 10770, Laser Communication and Propagation through the Atmosphere and Oceans VII, 107700S (18 September 2018); doi: 10.1117/12.2322381
Show Author Affiliations
Abbie Tippie Watnik, U.S. Naval Research Lab. (United States)
Dennis F. Gardner Jr., U.S. Naval Research Lab. (United States)
Mark F. Spencer, Air Force Research Lab. (United States)

Published in SPIE Proceedings Vol. 10770:
Laser Communication and Propagation through the Atmosphere and Oceans VII
Jeremy P. Bos; Alexander M. J. van Eijk; Stephen Hammel, Editor(s)

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