The Research Of Space Variant Volume Holographic Grating Waveguide Coupler In Augmented Reality Head Mounted Display System

Augmented reality is a recent research focus due to its extensive usage scenarios This paper analyzes the different technical routes of existing head-mounted augmented reality display solutions,and finds that they have the same shortcomings of small field of view angle and low display efficiency.In order to solve these problems,this paper designs and develops a space-variant volume holographic grating(SVVHG)as the outgoing coupler of waveguide display,and proposes large viewing angle and high diffraction efficiency waveguide display system in a small volume.In addition,a solution for preparing one-step exposure of the SVVHG is designed,which reduces the production time of the SVVHG,improves the manufacturing efficiency,and provides a basis for mass productionIn this paper,based on the Kogelnik coupled wave theory,a simulation algorithm of the volumetric holographic grating diffraction efficiency with different variables for the augmented reality use scenario is proposed.In this paper,the design algorithm of continuous variant volume holographic grating is proposed,which optimizes the modulation of the diffraction efficiency of the SVVHG,further increases the angle of view,and improves the quality of the SVVHG.In order to solve the mechanical vibration and error caused by the multiple times exposure,the free-form lens and prism group are used as the wavefront modulation device for recording light of the SVVHG In this paper,a generation algorithm for free-form lens and prism surface is designed And the feasibility of the proposal is verified by software simulation.Three holographic recording materials are used,and customized optical devices are processed according to different schemes.Two sets of exposure experiment platforms are built to carry out exposure producing experiments of SVVHG.After the exposure is completed,the curve between diffraction efficiency and FOV angle of the SVVHG is measured,and the results are collated to verify the degree of diffraction efficiency modulation.A waveguide projection platform coupled with a SVVHG is built to show the display effect and imaging quality of augmented reality under actual use.In this paper,the effectiveness of SVVHG is verified through three aspects:algorithm,simulation,and experiment.The field of view of the grating is successfully increased from 4° to 24°,and the lowest diffraction efficiency in the full field of view reaches 55%of the central.