Development and Optimization of Light Field Head-Mounted Displays

Abstract

Conventional stereoscopic 3D displays, which present a pair of stereoscopic images on a single plane at a fixed distance, lack the capability of correctly rendering focus cues and may lead to a well-known issue referred to as vergence-accommodation conflict. Various visual artifacts associated with such a conflict in conventional stereoscopic 3D displays have been reported, jeopardizing the viewing experience of users and consequently limiting the applicability of these displays for many demanding applications that require extended periods of usage or accurate visual perception. Light field displays are considered as one of the most promising methods for solving the vergence-accommodation conflict. They allow the reconstruction of a 3D scene by reproducing the directional light rays apparently emitted by the target 3D scene either in horizontal direction only or in both horizontal and vertical directions, and therefore are potentially capable of rendering correct or nearly-correct focus cues similar to those of viewing natural 3D scenes. In this dissertation, a generalized framework to model the image formation process of light field displays was proposed, based on which the perceived retinal image quality and accommodation response of viewing a light field display were further simulated and characterized. Following the framework and targeting for rendering high-quality 3D contents, fundamental design methods and considerations of light field displays were proposed. Based on an integral-imaging (InI) method, a novel architecture of a light field head-mounted-display system was proposed to overcome the performance limitations of a conventional InI based 3D display method, and a high-performance optical see-through InI based light field head-mounted-display enabled by state-of-the-art freeform optics was developed. The prototype system is capable of rendering nearly-correct focus cues for a large volume of 3D space extending into a depth range of more than 3 diopters. By incorporating freeform optics, the prototype not only achieves high quality imagery for the display path but also maintains decent visual resolution of the see-through view, covering a large see-through field of view. The optical design, implementation and experimental validation of the display were presented and discussed in detail.