The Characteristics Of Liquid-crystal Spatial Light Modulator And Its Application In Holographic Measurement

The characteristics of Liquid Crystal Spatial Light Modulator (LC-SLM) and its application in holographic measurement are investigated in this thesis. Especially investigated are the characteristics of LC-SLM when the readout light is in normal incidence or oblique incidence. A new calculation method when incident readout light is oblique is proposed. Two holographic interference application systems by using LC-SLM are also put forward.Based on the elastic continuum theory and the common concept of liquid crystal, the detailed formulas for calculating the director alignment of phase-only LC-SLM are given. The Light dissemination in liquid crystal and the electrically controlled birefringence (ECB) of the liquid crystal are also theoretically analyzed.In normal incidence, high diffraction efficiency and the high phase modulation depth at various voltage and frequency were obtained. Using a high-speed camera system, the response time of three types of LC-SLM in several temperatures are studied. The distinctive feature of this system is the whole SLM can be divided into 128 X 128 lattices, then lattices can be studied separately. That means response time in 2-dimensional plane can be studied. By using this measurement, the fast changes of response can be obtained, which cannot be considered by conventional measurement.A new calculation method is proposed for studying the phase modulation when the incident readout light is oblique. The theoretical model is established, and the simulative results are quite match with experimental results.We proposed two real-time holographic interference systems to measure the vibration object, in which LC-SLM is employed as a recorder. Using time average holographic interference technique, we established a system for measuring vibrated aluminium foil that fixed on a speaker by theoretical analysis, simulation and experiments. Using the Fabry-Perot interferometer and LC-SLM, the holographic shear interference is realized, and the result is theoretically analyzed. The character of these two systems is that the dynamic change process can be obtained.The experimental researching of this thesis is accomplished in the No.4 laboratory of Central Research Labortory, Hamamatsu Photonics K.K.