基于全色全息透镜的增强现实系统  

Augmented reality system based on full-color holographic optical elements lens

作　　者：杨雨桦 何龙 邓林宵[1,2,3] 朱立全 顾春 许立新 Yang Yu-Hua;He Long;Deng Lin-Xiao;Zhu Li-Quan;Gu Chun;Xu Li-Xin(State Key Laboratory of Particle Detection and Electronics,University of Science and Technology of China,Hefei 230026,China;Department of Optics and Optical Engineering,University of Science and Technology of China,Hefei 230026,China;Advanced Laser Technology Laboratory of Anhui Province,Hefei 230026,China)

机构地区：[1]中国科学技术大学,核探测与核电子学国家重点实验室,合肥230026 [2]中国科学技术大学光学与光学工程系,合肥230026 [3]安徽省先进激光技术实验室,合肥230026

出　　处：《物理学报》2023年第11期204-213,共10页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2021YFF0307804)资助的课题.

摘　　要：全息透镜是一种通过全息波前记录制作的成像元件.由于其形状因子小、波长和角度选择性等优势,在增强现实(augmented reality,AR)领域有着很好的应用前景.全色全息透镜的制作与成像过程分析是当前的难点.通过标量衍射理论推导了离轴全息透镜的共轭成像方程,分析了现有成像系统中的畸变和像散问题.此外,通过k矢量圆和光线追迹相结合的几何光学方法模拟了一个视场角为18°,眼盒为10 mm的AR系统,通过干涉曝光实验制作了全色全息透镜,其平均峰值衍射效率为56.7%,达到国际较高水平.将激光微投与全息透镜相结合,搭建了AR系统原型,得到了系统的畸变和像散效果实验效果,与模拟的情况相一致.并测量了系统的MTF参数,其清晰度基本满足人眼的分辨率需求.对于单色成像,提出了添加柱面透镜的方式,保证子午面和弧矢面的光焦度一致以消除像散;提出了设计自由形式的波前记录方式以消除畸变.对于全色成像,提出了记录过程中预先补偿的方法,以解决3个颜色通道之间图像不重合的问题.Holographic optical element(HOE)lens is an imaging element fabricated through recording wavefront by interference.Because of its advantages of small form factor and wavelength,angle selectivity and arbitrary wavefront formation,it has a good application prospect in augmented reality display.To make the system more compact,the HOE lens is adopted as an off-axis optical element.At the same time,according to diffraction principle,its wavelength response is more sensitive than those of traditional refractive and reflective optical elements.Thus the fabrication and design of a full-color HOE lens is a challenge to optimizing the free-space head-up display system.To systematically analyze the HOE imaging system,the conjugate relation between the object and image is derived by scalar diffraction theory.Then the Gaussian conjugate imaging equation is obtained and the off-axis aberration of distortion and astigmatism in the HOE imaging system are analyzed.In addition,A head-up display with field of view(FOV)of 18°and eyebox of 10 mm is simulated and its imaging process is visualized through the geometric optics method of k-vector diagram and ray-tracing.A full-color HOE lens with high diffraction efficiency is fabricated by interference.Its average peak diffraction efficiency is 56.7%,reaching a high level in the world.A prototype of augmented reality system is established by integrating laser pico-projectior with HOE lens.The experimental results of distortion effect and astigmatism effect of the system are obtained,which are consistent with the simulation results.The modulation transfer function(MTF)parameter of the system is measured,and its definition basically meets the requirements of the human eyes for resolution.The aberration of the system is analyzed and the optimization method is proposed.To optimize the monochromatic image quality,an extra cylindrical lens is added to ensure the same optical power of meridian and sagittal plane to eliminate the astigmatism.Besides,a freeform wavefront is designed by the geome

关 键 词：全息光学元件 激光显示 近眼显示 增强现实 

分 类 号：O438.1[机械工程—光学工程] TP391.9[理学—光学]