双自由曲面大视场头盔显示光学系统设计

Abstract

Field-of-view(FOV) is the key performance indicator to evaluate a head-mounted display (HMD) in areas such as virtual reality. In order to overcome the difficulties of a sharp increase of optical system aberrations with the increased FOV, a wide FOV HMD optical system with double freeform surfaces was proposed. First, the principles of the double ellipsoid HMD which could achieve large FOV and low distortion were analyzed, and the reason of the aberration correction limitations of the double ellipsoid HMD was pointed out. Then wide FOV HMD optical system with double freeform mirrors was proposed. Two free-form mirrors were used by the new optical system which were symmetrical in vertical direction and asymmetrical in horizontal direction to correct off-axis aberrations brought by increasing FOV. The FOV of the new optical system was 106.3(H)80(V). The maximum relative distortion is 6.97%. The exit pupil diameter was 8 mm and the eye clearance distance was 19 mm. Through tilt outside 8 the binocular FOV was 122.3(H)80(V) and the binocular overlapped FOV was 90.3(H)80(V). The IPD is adjustable within 55-71 mm. The analysis of optical performance indicates that image quality is greatly improved, and the relative distortion and FOV can meet the application requirements of the virtual reality.