Research Of Phase-Only Liquid Crystal Spatial Light Modulator

Liquid crystal spatial light modulators (LCSLMs) are very important components in the processing of optical information. Optical transfer and information processing can be done by using their modulation characteristics. Image can be reconstructed by a phase-only LCSLM instead of a holography, and optical phase conjugate can be realized by a phase-only LCSLM, and a phase-only LCSLM can be also used as digital optical computer and so on. Based on the broad application of phase-only LCSLM, the main points researched in this thesis are as follows.The development of liquid crystal and the research on spatial light modulator in the past are introduced briefly. Then, the modulating principle of electrical addressing SLM is analyzed. The theory of Jones Matrix which demonstrates the feasibility to use liquid crystal as phase-only SLM in theory is introduced chiefly.A LCD (Liquid Crystal Display) which fits for SLM is chosen. Based on the research of former researcher, the driver circuit is modified, the values in registers are set and the module of video signal processing is added in terms of the driving structure and the optical properties of the LCD, the voltage on the molecule of the LCD is limited in the period which can achieve phase-only modulating. The structure of power supply which is modified make the signal processing more stable. The size of PCB is smaller and it is operated more conveniently by modulation of MCU and Serial Interface Control.After the driver circuit board designed, the phase modulation characteristic and the intensity modulation characteristic of this LCSLM are investigated. Firstly, the chart of light route and the measuring principle are introduced separately and the interferogram captured by CCD is treated in order to extract the phase modulation information. Then, the components are adjusted during measuring and the phase modulation characteristic and the intensity modulation characteristic are gained in different modes. So, the mode of phase-only modulation is gained. It's that, the maximum phase modulation depth reaches 2πnearly and there is no intensity modulation. The advantages of the LCSLM in the thesis are also demonstrated in comparison with the LCSLMs which exist in our lab.Finally, this phase-only LCSLM is used as a phase grating. And the diffractive characteristics of vertical grating and horizontal grating are analyzed, which demonstrates the potential application of diffractive optical components in the future.