Expanded field of view light-field extended-reality displays with metalens array.

Abstract

Extended reality with an immersive visual experience needs to achieve vergence-accommodation-conflict-free (VAC-free) and human-level field of view (FOV) simultaneously. Holography is a dreamlike solution but seriously suffers from both an ultra-narrow diffraction angle and uneliminated coherent laser speckle. Incoherent-based light-field display is an alternative solution, but it still has an inherent issue with off-axis aberration when using a homogeneous microlens array for lightweight applications. Here, we propose a heterogeneous metalens array (MeLA) that integrates VAC-free operation and aberration correction into a slim monolithic component with expanded FOV. Such a large etendue is due to a unique phase profile in the heterogeneous MeLA, each lenslet of which has an identical hyperbolic term cascading a varying linear-tiling term. Nanoimprint lithography is employed to achieve a centimeter-scale MeLA with a feature aspect ratio of 7:1. In this way, we developed a light-field 3D display prototype with monocular focus cues and a FOV of 50°, approximately four times that of the microlens-array case, and fully exploiting the commercial micro-displays. The proposed MeLA system can even be scaled to human stereoscopic vision, with a maximum value of 80°, without compromising other performance metrics such as depth of field, resolution, and compactness. The characteristics of FOV expansion with monocular 3D display capability are demonstrated through experimental videos generated using a real-time elemental image array algorithm dedicated to the proposed MeLA system. This work opens new opportunities for extended reality through VAC-free 3D display and a wide FOV, poised to transform consumer electronics, precision nanofabrication, and healthcare.