Design of a compact waveguide eyeglass with high efficiency by joining freeform surfaces and volume holographic gratings

In this paper, a compact waveguide eyeglass integrating freeform surfaces and volume holographic gratings (VHGs) is proposed for full-color display with high energy utilization. The in-coupler with four freeform surfaces collimates the light emitting from the micro image source (MIS) and couples them into the waveguide. The six-layer VHGs as an outcoupler are designed to modulate the light propagating toward the user's eye. The chromatic aberrations and aberrations are well optimized and compensated by the in-coupler. The diffraction angular bandwidth of the gratings matches the angular range of the light propagating in the waveguide. The simulation results show that our proposed eyeglass achieves a diagonal field of view (FOV) of 39.5 degrees, the average diffraction efficiency of the outcoupler achieves 95.22%, and the diffraction uniformity is about 0.95. Because of the integrated designs and compact stable structures, the optimized display system is expected to be flexibly used in various applications. (C) 2020 Optical Society of America

Automated summary

The compact waveguide eyeglass integrating freeform surfaces and volume holographic gratings is proposed for full-color display with high energy utilization. The eyeglass features optimized modulation and coupling of light, achieving a diagonal field of view of 39.5 degrees and an average diffraction efficiency of 95.22% with high diffraction uniformity.