Integral imaging 3D display using triple-focal microlens arrays for near-eye display with enhanced depth of field

Abstract

As the entrance to the metaverse, the near-eye display (NED) technology based on naked eye three-dimensional (3D) display can transform how people interact with digital information as a possible next-generation display. Depth of field (DoF) is an essential indicator for viewers to explore 3D display scenarios, but traditional devices for improving the DoF of integral imaging (II) naked eye 3D display cannot be well incorporated with a high-integrated NED. To improve II’s DoF for NED, we propose triple-focal-length microlens array (TFL-MLA) with a honeycomb layout. The TFL-MLA is fabricated utilizing multilayer photolithography and thermal reflow. Microlenses with varying focal lengths are achieved on a single glass wafer using three photomasks with alignment marks. The results indicate that multi-layer microlenses can be precisely positioned with alignment marks. Furthermore, altering the thickness of the photoresist enables height control in the TFL-MLA. The prepared TFL-MLA has good morphology, with a diameter of approximately 208.3 ± 2.6 µm and three heights of 28.8 ± 0.7 µm, 23.1 ± 0.6 µm, and 13.7 ± 0.3 µm. The TFL-MLA provides excellent focusing and imaging in three focal planes (focal lengths of 368.8 μm, 441.1 μm, and 701.6 μm). As a proof-of-concept, a DoF-enhanced NED system based on II utilizing the TFL-MLA is implemented, allowing a clear presentation of 3D objects in various center depth planes. The proposed NED’s DoF has increased from 154 mm to 541.8 mm. This TFL-MLA is anticipated to promote the evolution of NED with diverse DoF, boosting the development of the metaverse.