用于CF-LCoS投影偏置LED照明光棒的角度分割原理及其偏振复用系统

Principle of Biased LED Illuminated Light Pipe Angle Segmentation and Polarization Recovery System for CF-LCoS Projection

研究了LED相对光棒中心位置存在偏置时光棒对LED的角度分割与虚像形成原理,籍此计算了不同偏置以及不同尺寸LED的光棒尺寸,再将计算所得的光棒与前端成像透镜、中间像面偏振复用系统、后端积分透镜及偏振分束器等进行综合优化设计,然后根据所得中间像确定不同情况下的偏振复用系统具体结构,确保LED发散角范围内光能的偏振复用,并实现对滤色片式硅基液晶芯片的均匀照明.最后设计了一款以白光LED为光源的滤色片式硅基液晶芯片微型投影光引擎,在1W LED功耗下实现12.8lm投射亮度(114lm/W),均匀性达93%.对比没有应用偏振光复用的微型投影光引擎,在保证均匀性的前提下,提升了微型投影系统的光效率,丰富了光棒偏振复用的内容.

The biased LED illuminated light pipe angle segmentation and its virtual image array forming principle were reserached. The light pipe size was calculated according to the biased LED position and divergence angles, and then optimizated with front imaging lens, intermediate image polarization conversion system, backend integral lens and polarization beam splitter. The polarization conversion system structure was determined by the optimized intermediate image distribution to insure the polarization conversion of luminous energy within the range of LED divergence angle and realize the uniform illumination to color-filter liquid crystal on siliconsize. A color-filter liquid crystal on silicon projection optical engine was finally designed with the white LED, wich can output light flux of 12.8 lumens per watt（the LED efficiency is about 114 lm/W） with 93% irradiance uniformity. Comparing with the optical engine without polarization conversion, the proposed optical engine enhances the light efficiency of the color-filter liquid crystal on silicon micro-projection system and enriches the light pipe applications while maintaining the homogeneity.