A paper describes the basic design and concepts of tunable liquid-crystal polarization gratings with a nematic liquid crystal (LC) optical phase plate, with a large, continuous in- plane gradient that is variable, and its application to a beam steering device with high efficiency. To improve the important issue of tuning speed, there is a discussion of the dynamics of discrete changes in the phase profile, and also continuous changes in the phase profile through acquired data and numerical modeling. It is shown that a design based on liquid crystals whose dielectric anisotropy can change sign (as a function of frequency) allows continuous tuning with reasonable response times.

The liquid-crystal-based electronically controlled lens is also described. With this technique, one is able to replace the con- ventional eyeglass with a non-mechanical, electrically con- trolled LC lens, also with the capability of different focal length.

This work was done by Lei Shi and Philip Bos of Kent State University for the Air Force Research Laboratory. For more informa- tion, download the Technical Support Package (free white paper) at www.defensetechbriefs.com/tsp under the Physical Sciences category. AFRL-0147

This Brief includes a Technical Support Package (TSP).
Liquid-Crystal-Based Optical Phased Array for Steering Lasers

(reference AFRL-0147) is currently available for download from the TSP library.

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This article first appeared in the April, 2010 issue of Defense Tech Briefs Magazine.

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