Liquid Crystal Light Valve And Its Large-screen Projection Display Applications

In this dissertation,the photo-addressed CdS-CdSe liquid crystal light valve and its application in large screen projection displays are studied. The photo-addressed light crystal light valve(LCLV) is a high performance spatial light modulator. It is not only used in displays,but also widely used in optical information processing,optical computing and other information systems.The dissertation gives the detail analyze and calculation of the characteristics of the LCLV. Results show that the performance of the LCLV is mainly dependent on the match of the electrical parameters of all the function layers in LCLV and the working mode of the liquid crystal.In the LCLV,the most important parameter,switching ratio of the LCLV,is analyzed. It is mainly influenced by the dark-conductivity,ratio of light- to dark-conductivity,thickness of the photoconductor and the thickness of the liquid crystal. It is concluded that the switching ratio can be improved by matching the thickness of the liquid crystal and the photoconductpr,and the proper change region of the light conductivity of the photoconductor. We have also calculated the resolution of the LCLV according to the electrical field and the electron diffusion theory. It shows that the limiting resolution of 501p/mm can be obtained in our LCLV.On the other hand,the reflective liquid crystal working mode is calculated. According to the switching ability of the LCLV,a suitable working point was selected in the liquid crystal parameter space. The reflection,contrast ratio and polarization direction are calculated in the wavelength of 633nm and in wide band wavelength,which represent the applications in the optical information process and the projection display.Based on these studies above,we successfully fabricate the high performance CdS-CdSe LCLV. The characteristics of the LCLV are measured in the thesis.In order to improve the performance of the LCLV further,the perpendicular alignment of liquid crystal with proper pre-tilt angle was studied. The alignment method include rubbing on PI,inclined evaporation and photo induced alignment. The uniform inclined perpendicular alignment was successfully obtained by inclined evaporation method and using unpolarized UV light method. It is the first time to observe the tilt direction changes in photo-induced alignment when the exposure UV energy increases. We successfully obtain multi domain alignment with different tilt direction in one exposure processing.At last,the LCLV large screen projection system is setup with self made LCLV,producing 3X4m2 high-resolution picture. In the thesis,the efficiency of the optical energy and contrast of the system are discussed. The traditional Philip prism and the PBS are improved in order to suit our projection system.