| Because of liquid crystal (LC)'s unique optical characters people have been researching liquid crystal for its possibility in optical applications since it is found. In twenty years liquid crystal technology is developed much further not only in flat plate display but also in optical information process and communication. Liquid crystal is broadly used in optical systems for transmission, modulation, grating switching and etc. Spatial light modulator (SLM) based on LC film especially active matrix pixel LC devices has merits in modulating phase and amplitude of light which other types of modulators doesn't. LC SLM is real-time tunable, independent pixel control in modulation surface which makes any part of illumination area is adjustable, and able to switch in different modulation modes for special demand without any mechanical modification. We analyze the working principle and modes of LC SLM and construct a LC SLM system based on a liquid crystal on silicon (LCOS). To choosing its initial working point for amplitude modulation mode, we use Jones matrix and parameters space method in modes optimizing, comparing the common modes used in display recently and find two new amplitude modulation modes which are fit for SLM. We also give the experiment results and measured modulation quality. For higher efficient and more applied phase modulation, we have performed some try in using phase modulation in different kinds of optical applications after research phase modulation character of the LCOS SLM. Based on light steering and focusing function of phase SLM, a tunable LC lens array is formed. It is high flexible for tuning the columns and lines of the array, the gap, radius and focal length of the lens and converging/diverging switching even tuning any part of the whole array real-timely. In another experiment, we give a new light energy allocation method using present light phase modulation, with this method we form multi-in/multi-out allocation system, which is freely capable of changing light beam intensity of multiple input and guiding the modulated beams to multiple receiving ports located in specified positions. Both two experiments have their own worth of originality and utility in researching LC devices' application possibility in optical systems. In this paper we give the experiment results and discuss the theory and analyze the results in detail. In final section we demonstrate a digital stereo video system based on light switching technology of LC film. It is digitalized in capturing, editing, storage and replay, and shows real 3D feeling when watching the video with LC glasses. These works mentioned above accumulate foundation and experience for our further researching in theory and practice of LC devices in optical technology and entertainment. |
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