Waveguide‐Based Retinal Projection Near‐Eye Display with Bidirectional Eyebox Expansion

Based on the mechanism of human visual imaging, retinal projection display (RPD) directly projects images onto the retina, achieving sharp images without relying on the focal adjustment of human eye. However, the physiological phenomenon of eye movements makes it difficult to align the convergence point of image lights with the human pupil, especially when the viewer needs to wear a pair of vision‐corrected frame glasses, resulting in blurred images. To accommodate the movements of human eye, herein, a waveguide‐based RPD system with bidirectional extended eyebox is proposed, in which two‐layer holographic optical elements (HOEs) are designed as the image combiner to generate different eye reliefs along the visual axis of the human eye. Each layer of HOEs generates two horizontally arranged viewpoints, thus, achieving bidirectional eyebox expansion. Experimental results show that the proposed RPD system provides two sets of viewpoints with the eye reliefs of 11 and 12 mm, respectively, and obtains a 2 × 2 viewpoint array distributed horizontally and axially. Additionally, two sets of viewpoints can be switched to accommodate the different eyewear habits of viewers. The proposed RPD system enhances the adaptability of near‐eye display device to the human eye through the bidirectional eyebox expansion.