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Proceedings Paper

Liquid crystal on silicon (LCOS) wavefront corrector and beam steerer
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Paper Abstract

A spatial light modulator, which is capable of high-resolution wavefront compensation and high accuracy beam steering, has been demonstrated using a Liquid Crystal On Silicon (LCOS) microdisplay with 1024×768 XGA resolution. When the device is used as a wavefront corrector, about 18.7 waves (peak-to-valley at 632.8nm) of aberration in the optical system is corrected to a residual of 1/9 wave (peak to valley) or 1/30 wave rms. Measurement of the far field beam profile confirmed the strehl ratio improved from 0.006 with the wavefront correction off, to a strehl ratio of 0.83 after correction. An additional linear phase ramp was added to the correction phase ramp to simultaneously correct and steer the laser beam. We demonstrated we can steer the beam continuously in the range of ±4 mrad in X-Y plane, with a steering accuracy better than 10μrad, or about 1/10 the diffraction limited beam divergence. The quality of the steered beam remains very high during the steering as the ellipticity of beam is smaller than 1±0.04, focused beam waist is 1.3x the diffraction limited beam waist and strehl ratio remains higher than 0.66. The 1-D beam steering efficiency is 80% at the maximum steering angle of 4 mrad, which agrees very well with our Finite Difference Time Domain (FDTD) simulation result of diffraction efficiency 86% at maximum steering angle. These results suggest that an LCOS device can be used to achieve very high-resolution wavefront control at very high efficiency.

Paper Details

Date Published: 11 December 2003
PDF: 8 pages
Proc. SPIE 5162, Advanced Wavefront Control: Methods, Devices, and Applications, (11 December 2003); doi: 10.1117/12.511504
Show Author Affiliations
Xinghua Wang, Kent State Univ. (United States)
Bin Wang, Kent State Univ. (United States)
John Pouch, NASA Glenn Research Ctr. (United States)
Felix Miranda, NASA Glenn Research Ctr. (United States)
Michael Fisch, Kent State Univ. (United States)
James E. Anderson, Hana Microdisplay Technologies, Inc. (United States)
Vassili Sergan, California State Univ./Sacramento (United States)
Philip J. Bos, Kent State Univ. (United States)

Published in SPIE Proceedings Vol. 5162:
Advanced Wavefront Control: Methods, Devices, and Applications
John D. Gonglewski; Mikhail A. Vorontsov; Mark T. Gruneisen, Editor(s)

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