大视场二维扩瞳全息光栅波导设计与加工  

Design and Fabrication of 2D Exit Pupil Expansion Holographic Grating Waveguide with Large Field of View

作　　者：程德文[1,2] 倪栋伟 吕鑫 王永东 杨通 王涌天 Cheng Dewen;Ni Dongwei;LüXin;Wang Yongdong;Yang Tong;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》2024年第2期264-271,共8页Acta Optica Sinica

基　　金：国家重点研发计划(2021YFB2802100);北京市自然科学基金(1222026)。

摘　　要：为扩大体全息光栅波导的出瞳直径和视场,提出了二维扩瞳和视场扩展的两重体全息光栅波导设计方法。该波导结构的出耦合光栅由两个两重体全息光栅构成,用于实现二维扩瞳。将入射视场分为两条路径传播,每条路径负责一半的视场,最后将两部分视场拼接形成完整视场。该方法不仅扩大了出瞳直径,还有利于增大全息波导系统的视场角。介绍了二维扩瞳视场扩展的光学原理和设计方法,最终实现的系统水平视场为48°,垂直视场为27°,出瞳尺寸为16 mm×13 mm。实验结果验证了所提方法的可行性。该方法在扩瞳的同时有助于扩展视场角,为头戴近眼显示设备提供了具有前景的有效方案。Objective Augmented reality(AR)head-mounted near-eye display technology combines virtual image information with real environment,and it is the next generation of interactive display technology with potential applications in education,military,medical,consumption,and other fields.The optical waveguide scheme is a promising technology due to its thinness,compactness,and eyeglass shape,which can realize true wearability and all-day utilization.A volume holographic grating(VHG)has a good wavefront reconstruction function and can be fabricated by the laser exposure method.The process is controllable at a low cost,which is a potential AR solution.Although holographic waveguide display technology develops rapidly,its exit pupil size and field of view(FOV)are still important factors affecting the optical performance of volume holographic waveguide.VHG waveguides are difficult to achieve large FOV due to the restrictions of refractive index and angular bandwidth of holographic materials.How to ensure a large FOV display of VHG waveguide under the premise of a large exit pupil is a difficult research point,which requires a breakthrough from the design method of exit pupil expansion(EPE).Thus,we propose a design method of double VHG waveguide with twodimensional(2D)EPE and FOV expansion.Methods To enlarge the exit pupil diameter and FOV of the VHG waveguide,we put forward a design method of double VHG waveguide with 2D-EPE and FOV expansion.The out-coupling grating of the waveguide structure is composed of double VHGs.By changing the light transmission direction in the waveguide through the structure of double VHGs,the beam is converted from one-dimensional propagation to 2D propagation for realizing the 2D-EPE of the system.We divide the incident FOV into two propagating paths,each path is responsible for half of the FOV,and the two parts of the FOV are finally spliced together to form a complete FOV.The optical principle and design method of 2D-EPE and FOV expansion are introduced in detail.Two non-coherent double grating

关 键 词：全息 两重体全息光栅波导 二维扩瞳 视场扩展 

分 类 号：O438.1[机械工程—光学工程]