用于头戴显示的新型耦合光栅结构优化设计与分析

Optimal Design and Analysis of New Coupled Grating Structure for Head-Mounted Display

在头戴显示器中体全息光栅常被用作输入/输出耦合器,其衍射效率的高低将极大影响系统的成像质量。为提高体全息光栅的衍射效率,提出了一种新型耦合光栅结构,该结构由优化后的体全息光栅和闪耀光栅组成。利用严格耦合波分析,对新型耦合光栅结构进行仿真。仿真结果表明,与体全息光栅相比,新型耦合光栅使横电模式光的衍射效率提高了1.5%,横磁模式光的衍射效率提高了9.4%,非偏振光的衍射效率提高了5.3%。此外,相较体全息光栅,新型耦合光栅在不同偏振态(横电模式光、横磁模式光)下,入射角半峰全宽增加了0.2°与0.5°,表明该结构具有更大的视场角。

The volume holographic grating is often used as an input/output coupler in a head-mounted display,and its diffraction efficiency greatly affects the imaging quality of the system.Therefore,a new coupled grating structure is proposed to improve the diffraction efficiency of volume holographic gratings,which is composed of an optimized volume holographic grating and a blazed grating.The rigorous coupled wave analysis is used to simulate the new coupled grating structure.The results reveal that compared with the volume holographic grating,this structure increases the diffraction efficiency of transverse electric mode light by 1.5%,the diffraction efficiency of transverse magnetic mode light by 9.4%,and the diffraction efficiency of unpolarized light by 5.3%.In addition,this structure boasts an increase of 0.2°and 0.5°in the full width at half maximum of the incident angle under different polarization states(transverse electric mode light and transverse magnetic mode light),which indicates that the structure has a larger field of view angle.