节点文献
液晶光阀及其在大屏幕投影显示中的应用
【作者】 李海峰；
【导师】 唐晋发；
【作者基本信息】 浙江大学 ， 光学工程， 2002， 博士
【摘要】 本论文的研究工作，主要针对光寻址液晶光阀及其在大屏幕投影中的应用展开。光寻址液晶光阀是一种性能优越的空间光调制器，它不仅应用于显示，也广泛应用于光信息处理、光计算以及其他信息系统中。 论文对液晶光阀的电学和光学特性进行了深入的分析和计算。研究结果表明，CdS-CdSe液晶光阀的性能主要取决于二个方面，一是光电导层和光阀其他部分的电学匹配；另一是液晶的工作模式的选取。 在电学匹配方面，我们对光电导材料的暗态电阻、亮暗电导比、厚度以及液晶的厚度等对光阀开关比的影响进行了分析，认为液晶光阀开关能力的提高很大程度上取决于光电导层和液晶层的厚度匹配，以及光电导层的电导变化的区域位置。对液晶光阀的分辨率的分析，主要计算了光阀厚度、电场以及电荷扩散对光阀分辨率的影响，从理论上得到制备的液晶光阀分辨率应大于501p/mm的极限分辨率。 在液晶工作模式方面，计算了反射式液晶器件的参数空间，并选择了适合CdS-CdSe光阀的液晶工作模式。分析计算了633nm以及宽波长下液晶的反射率、对比度以及偏振光的工作角度。获得了用于信息处理以及用于投影显示的液晶工作曲线。 在分析计算的基础上，我们制备了CdS-CdSe液晶光阀，并测试了它的主要性能参数。 为进一步提高反射式液晶光阀的性能，我们研究了带预倾角液晶的垂直定向。论文对摩擦法、斜蒸度法以及光定向法进行了研究。获得了较均匀的定向。在光定向中，我们用非偏振方法实现了带预倾角的均匀的垂直定向，并首次用控制曝光强度的方法，获得了不同的倾角方向的多区域定向。 最后我们用自制的液晶光阀建立了液晶光阀大屏幕投影显示系统，实现了3×4米~2的高分辨率显示。论文对显示系统光能利用效率、对比度等特性进行了充分分析，对Philip棱镜系统以及PBS偏振系统进行了优化和改进，获得了高性能的投影显示。
【Abstract】 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.