Design of ultra-compact augmented reality display based on grating waveguide with curved variable-period grating

Abstract

Compact augmented reality (AR) display devices are necessary for the prevalence of AR technology. However, AR devices now usually have bulky size, which is not convenient for daily use. For waveguide AR system, the collimating optical system determines the thickness of the whole system. To address this challenge, we propose a grating waveguide system with curved grating. The function of both collimating lens and in-coupling grating is replaced by a variable-period curved grating, which can reduce the thickness of optical system significantly. We add a conical lens to correct the aberration without significant change of thickness. In our design, the thickness can be reduced by 39.3% compared with conventional grating waveguide system. The structure of grating is designed and optimized, and the average efficiency is over 70%. The stray light is analyzed and will not be seen by human eyes. The diagonal field of view (FOV) of the system reaches 36.6°.