Pupil-Adaptive Retina Projection Augment Reality Displays With Switchable Ultra-Dense Viewpoints.

Multi-viewpoint retina projection displays (RPD) with an expanded visible range have been utilized in recent augmented reality (AR) systems to address the vergence-accommodation conflict (VAC) by providing a long depth of field (DOF). However, these fixed multi-viewpoint RPD systems still face a common critical challenge of imaging overlap or discontinuity when eyes rotate or under varying ambient light. To address this, an RPD AR system featuring switchable ultra-dense viewpoints is presented, enabled by a photo-alignment liquid crystal Dammann grating (p-LCDG). The number of viewpoints reaches 49, which forms an ultra-high density of diffraction lattice in front of the pupil with a record high rotation precision of 1.28°/viewpoint, allowing for a substantial range of 36 mm2. More importantly, the spacing of adjacent viewpoints is 0.532 mm, much smaller than the minimum radius of the pupil (≈1 mm). To facilitate viewpoint switching, a light selector is implemented, ensuring that only the light from a specific viewpoint reaches the eye, which effectively eliminates the image missing or discontinuity. By combining eye tracking technology, the viewer can consistently perceive a singular and clear image from the proposed RPD system, achieving seamless switching of viewpoints. This innovative design paves the way for high-performance RPDs in AR applications.