Analysis of Optical System Combined with Expander and Output Grat-ing for Improving Field of View of Augmented Reality Device

摘要

Augmented reality (AR) is the significant technology of head-mounted-display (HMD) which is one of the next-generation displays, and has received great attention in recent years.[1] AR displays have been studied for a long time with folded freeform optics in optical design. Recently, diffraction optics based flat plate integrated optics technol-ogy has been introduced to dramatically reduce the form factor of optical systems.The diffractive optical element(DOE) based AR display system consists of combiners with three different gratings in three areas. The three areas are composed of input, ex-pander, and output grating structures, and the user can ob-serve the AR image through the specific functions generat-ed by the three grating structures. In such an optical system, the field of view (FOV) is greatly influenced by the inci-dence angle of the input grating structure. When the angle of the incidence bundle rays increase, the angle of the out-put bundle rays from the output grating structure increase and the FOV also increases. However, when the angle of the incidence bundle rays increase, the area of the expander grating structure widens accordingly. As a result, the size of the combiner is increased, it significantly decreases the characteristics of the head mounted display (HMD).In this paper, we have suggested an optical system that combines an expander grating and an output grating as part of a study on improving FOV of AR display.