Liquid Crystal Spatial Light Modulator for Multispot Beam Steering

Jay Stockley, Steve Serati, Xiaodong Xun, Robert Cohn

Published in SPIE Proceedings Volume 5160, Free-Space Laser Communication and Active Laser Illumination III; (2004)


The advantages of laser communications including high bandwidth, resistance to jamming and secure links have made it a key technology for current and future C4ISR capabilities. Laser Communications between space/air/ground/sea-based assets may require multiple links. One advantage of this redundancy is that the signal is more likely to reach the intended receiver even if the environmental conditions are poor for laser transmission. In addition, multiple links provide simultaneous receipt of information to various assets engaged in activities that may need to be coordinated. That is, multibeam laser communication mimics the "broadcast" advantage of RF communications but with less likelihood of jamming or intercept. Liquid Crystal spatial light modulators are a versatile optical head that can be used for multispot beam steering applications. One advantage of the liquid crystal approach to multibeam laser communication is that the device is a modulator in addition to a mirror, so that one could conceivably send different signal amplitudes to different locations simultaneously. This paper discusses recent improvements to a 512x512 spatial light modulator that is specifically implemented as a multispot beamsteerer. This will include characterization of the device, analysis of its performance, and what improvements should be incorporated into the next generation device.

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