超短焦偏振折反射虚拟现实镜头设计方法  

Design Method of Ultrashort Focal Polarization Catadioptric Virtual Reality Lenses

作　　者：程德文[1,2] 黄逸伦 李阳 侯起超[1,2] 李丹阳 张甜 陈海龙 王涌天 Cheng Dewen;Huang Yilun;Li Yang;Hou Qichao;Li Danyang;Zhang Tian;Chen Hailong;Wang Yongtian(School of Optics and Photonics,Beijing Institute of Technology,Beijing 100081,China;Beijing Engineering Research Center of Mixed Reality and Advanced Display,Beijing 100081,China)

机构地区：[1]北京理工大学光电学院,北京100081 [2]北京市混合现实与新型显示工程技术研究中心,北京100081

出　　处：《光学学报》2023年第15期303-317,共15页Acta Optica Sinica

基　　金：国家重点研发计划(2021YFB2802100);北京市科学技术委员会和中关村科技园区管理委员会资助项目(Z221100006722011)。

摘　　要：超短焦偏振折反射虚拟现实(VR)镜头是新兴的近眼显示光学解决方案,能满足用户对大视场、大出瞳和高清晰度的需求。本文详述了超短焦偏振折反射VR镜头的光路原理,说明了偏振折反射VR光学方案相较于传统VR光学方案的优势,并研究了低应力镜片的设计方法。为增加设计自由度,提出将非球面转化为环形拼接非球面,并介绍了拼接非球面的数学描述与优化策略。针对不同视场的像质差异问题,引入了像质自动平衡优化算法。采用上述方法先后设计了47°视场角和96°视场角的两款超短焦偏振折反射VR镜头,在像质平衡优化后,全视场调制传递函数值较采用普通非球面的系统提升了0.35以上。研究结果证明了环形拼接非球面在VR镜头设计中的可行性与高自由度优势,并体现了像质平衡优化算法的实用性。介绍了超短焦偏振折反射VR镜头的研发流程,原理样机的测试结果验证了该光学系统的良好显示性能。本文提出的设计方法对VR近眼显示设备的高清化与轻量化发展具有指导意义。Objective Virtual reality head-mounted displays(VR-HMDs)are experiencing increasing demands for improved imaging performance and enhanced user comfort.This has led to the popularity of VR lenses that offer a wide field of view(FOV),large pupil size,and compact form factor.However,achieving these desired properties simultaneously presents significant challenges.Three generations of VR optical solutions have been developed,each with its own limitations.The earlier smooth aspherical VR lenses,while capable of providing a wide FOV,are bulky and fall short in terms of image quality.Fresnel VR lens offers a larger FOV and reduced weight,but it suffers from"ring artifacts"that result in low contrast and poor resolution.A more recent solution,an ultrashort focal polarization catadioptric VR lens,takes advantage of polarized light transmission to fold the optical path three times within a short physical length.This design reduces the thickness of the catadioptric optical module to approximately half that of the Fresnel lens,alleviates focusing challenges,and enables smoother optical surfaces.As a result,ultrashort focal polarization catadioptric VR lenses have become the mainstream optical solution for VR-HMDs,offering significant benefits such as a large FOV,large exit pupil,ultra-thin structure,and high resolution.However,despite their advantages,most of these lenses employ aspherical surfaces,and the theoretical model and design process of the system have not been extensively elaborated upon,nor has the image quality of the system been thoroughly explored.Consequently,there is an urgent need for new optimization design methods to guide the development of ultrashort focal polarization catadioptric VR lenses.These methods will not only contribute to the design process but also facilitate the high-definition,lightweight,and market-oriented evolution of VR-HMDs.Methods A mathematical model is established to describe the ultrashort focal polarization catadioptric VR lens,demonstrating its structural and imaging advantages c

关 键 词：光学设计 虚拟现实 近眼显示 拼接非球面 超短焦偏振折反射镜头 

分 类 号：O435[机械工程—光学工程]