基于二维扩展的高效率透视型波导近眼显示器设计

Design of a High Optical Efficiency Waveguide See-through Near to Eye Display Base on Two-dimensional Expansion

为了改善全息波导器件的衍射效率,提出了一种结合了几何波导和全息波导的二维扩展的新型近眼显示器。几何波导对目镜出瞳进行垂直扩展,全息波导对目镜出瞳进行水平扩展,从而得到更大的窥视窗。为了提高耦合过程中光学效率,重点分析了目镜的出瞳位置和耦入光栅的长度和周期。对耦出光栅阶梯状的衍射效率分布拟合得到连续的衍射效率曲线,使窥视窗处的所有视场亮度均匀。经过仿真,该系统实现了30°(水平)×40°(垂直)的视场和30 mm(水平)×22 mm(垂直)的窥视窗。仿真得到的系统在不考虑误差的情况下零视场的光学效率达到88.36%,边缘视场的最小光学效率达到53%。

In order to improve the optical efficiency of holographic waveguide,a novel see-through near to eye display,combining with geometric waveguide and holographic waveguide is proposed.The exit pupil of the eyepiece is expanded vertically by the geometric waveguide;and the exit pupil of the eyepiece is expanded horizontally by the holographic waveguide to obtain a larger eye box.The exit position of the eyepiece and the length of the input-coupling grating are analyzed to improve optical efficiency during the coupling process.A continuous diffraction efficiency curve is obtained by fitting the step-like diffraction efficiency distribution of the out-coupled grating to achieve uniform brightness of all FOV at the eye box.After simulation,this system has a field of view(FOV)of 30°horizontal(H)×40°vertical(V)and an eye box of 30 mm(H)×22 mm(V).The optical efficiency of 0°FOV in the simulated system reaches 88.36%without considering the error,and the minimum optical efficiency of edge FOV reaches 53%.