Finite-depth and vari-focal head-mounted displays based on geometrical lightguides

Abstract

Existing waveguides and lightguides in optical see-through augmented reality (AR) displays usually guide collimated light, which results in a fixed image depth at optical infinity. In this paper, we explore the feasibility of integrating a lightguide with a varifocal optics engine to provide correct focus cues and solve the vergence-accommodation conflict in lightguide-based AR displays. The image performance and the cause of artifacts in a lightguide-based AR display with a varifocal optics engine are systematically analyzed. A non-sequential ray tracing method was developed to simulate the retinal image and quantify the effects of image focal depth on the image performance and artifacts for a vari-focal display engine of different depths. A prototype with varying image depths from 0 to 3 diopters was built and the experimental results validate the proposed system. A digital correction method is also proposed to correct the primary image artifact caused by the physical structure of the lightguide. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement