Near-Field 3D Camera based on microlens array with extended Depth of Field

Abstract

Imaging systems by using microlens arrays (MLAs) is a promising application for the depth estimation sensor, hologram, and the surveillance camera. However, the narrow focusing range (i.e. depth of field) have been hindered for accurate, reliable depth estimation. Multifocal microlens array (Mf-MLAs) is known as a major solution, but fabrication methods are still expensive, and low-throughput from the cause of multiple steps in the photolithography process. Moreover, different numerical aperture (NA) of individual lenses also increase the computational cost. This paper reports the near-field light-field camera (LFC) with the customized optics components (i.e. main lens, MLAs) based on the micro-electromechanical system (MEMS) process for optimized condition. Then, we also provide the fabrication process of Mf-MLAs for the extended depth-offield using single-step photolithography assisted by chemical wet etching. The Mf-MLAs have high-uniform NA via this method. The lens parameter (such as diameter and radius of curvature) of Mf-MLAs are manipulated by the photomask with multi-sized hole and the wet etch time. Comparing with the previous reports, this method has cost-effective and large-area fabrication of Mf-MLAs. We believe the Mf-MLA have the clever candidates for extended depth of field with the integration of conventional camera, microscope, and endoscope imaging systems.