The Liquid Crystal-Based Visible To IR Dynamic Image Converter (VIDIC)

The Liquid Crystal -Based Visible to IR Dynamic Image Converter (VIDIC)U. Efron, S.T. Wu, P.O. Braatz, J. Grinberg, L.D. HessA.M. Lackner, J.D. Margerum and F.G. YamagishiHughes Research Laboratories3011 Malibu Canyon RoadMalibu, California 90265AbstractThe development of a liquid crystal -based visible -to -IR dynamic image converter isdescribed. Liquid crystal studies in the IR, as well as the structure, operation andpreliminary performance results of a 10.6 um VIDIC are reported.IntroductionExisting infrared simulation systems suffer from low resolution (caused by thermalspread in the image plane), slow response (caused by a large thermal time constant), andlimited dynamic range capabilities (limited by the conflicts between high resolution anddynamic range of a thermal -based target simulation system.) Because of these limitations anew simulation system is needed which can provide a complex, fast changing IR scene with ahigh degree of dynamic range and resolution, and is capable of real -time interaction with acomputer image generation (CIG) system.We believe that one such solution is offered by the liquid crystal light valve (LCLV) -based VIDIC. This device is based on the liquid crystal and semiconductor technologieswhich were developed at Hughes Research Laboratories during the past decade.1,2 The twomain advantages of the LCLV -based VIDIC over existing systems such as the Bly cell are:(1) the generation of a non -thermal image at the focal (target) plane, and (2) theseparation of the output source from the input image. Optical modulation of the IR beamcaused by polarization- rotation effects frees the LCLV -VIDIC system from the severe trade-offs associated with a thermal target projection system. Separation of the output imagefrom the input source allows a compact, low power input image source (e.g., a CRT) to beused without sacrificing the high IR power required at the output. Thus, much higherperformance in resolution, dynamic range and speed is expected from a LCLV -VIDIC system,with the additional advantages of high temperature simulation and compatibility with a CIG