全息波导显示中输出扩展光栅的衍射效率分布分析  

Analysis on diffraction efficiency distribution of output extended grating in holographic waveguide display system

作　　者：张攀[1] 杨德兴[1] 徐健[1] 郭钰宁[1] 

机构地区：[1]西北工业大学理学院陕西省光信息技术重点实验室,陕西西安710072

出　　处：《液晶与显示》2014年第5期703-708,共6页Chinese Journal of Liquid Crystals and Displays

摘　　要：对于全息波导显示系统,为获得连续的输出光瞳而引入的半透半反膜,会在波导中形成阶跃形光强分布,与阶跃形强度分布相匹配的输出光栅衍射效率须为阶跃形分布,这样才能获得均匀的衍射输出强度。为保证衍射角带宽内所有光线均有较佳的输出强度均匀性,提出了一种连续递增的衍射效率分布光栅模型。建立了基于对阶跃形衍射效率分布的分段加权平均和二次曲线拟合的优化计算模型,计算得到了衍射效率分布曲线,并由衍射效率分布曲线计算得到衍射角带宽内不同视场光束的输出光强分布。结果表明,输出光强位置均匀性最小为52.4%,出瞳内角度均匀性达到84.9%。随着分束膜层数的增加,波导阶跃形光强差将会减小,可获得更好的输出强度均匀性。For holographic waveguide display system, the beam splitting membrane, adopted for obtaining continuous output pupil, can form step-shaped light intensity distribution, and only when the diffraction efficiency of output grating is step-shaped distribution, can the uniform diffraction output intensity be obtained. To guarantee the output intensity uniformity of light within the diffraction angle bandwidth, a grating model which owns continuous increasing diffraction efficiency is established. Based on segmentation weighted average and quadratic curve fitting of the step-shaped distribution, the calculation model is optimized and curve of diffraction efficiency distribution is obtained. In addition, the output intensity distributions of various fields are calculated from the diffraction efficiency distribution curve. The results show that the minimum position uniformity of output area is 52.4% and angle uniformity within the whole exit pupil could reach to 84.9~. And analysis demonstrates that with the increase number of the beam splitting membrane, the intensity difference between the non-overlap and overlap region would be reduced and better image uniformity obtained.

关 键 词：全息波导显示 图像均匀性 出瞳连续 衍射效率分布 分束膜 

分 类 号：O439[机械工程—光学工程]