One-lens camera using a biologically based artificial compound eye with multiple focal lengths

Abstract

This work presents the fabrication of a one-lens camera using a biologically inspired artificial compound eye with multiple focal lengths. Traditional camera designs that consist of many separated lenses are difficult to assemble due to tight tolerance. The one-lens camera design is demonstrated experimentally in this work to avoid tolerance buildups. This structure is based on the principles of both the human eye as well as an insect’s compound eye. The artificial compound eye is a curved hexagonal microlens array, like an ommatidial array, wherein each artificial ommatidium collects light with a small angular acceptance. The ommatidia, in a typical hexagonal arrangement of 37 lenses, are arranged across a hemispherical photopolymer dome. The curved hexagonal array helps us to achieve a compact and wide field-of-view camera module. The fabrication process for the curved array is divided into two parts: creation of a planar hexagonal multi-lens array, and a replication process. To create the planar array, we use inkjet printing technology with the hydrophilic confinement effect to establish microlens shapes with different profiles. Next, the replication process converts the planar array into a curved shape. The spherical configuration of the hexagonal array is accomplished by applying the template architecture to a reconfigurable surface shape, that is, a photopolymer duplication using a deformed elastomer membrane with the hexagonal array pattern. In our experimental demonstration, microlenses in four rings with different focal lengths are fabricated on a single hemispherical lens with radius of curvature of 2.4 mm. The thickness of our proposed system is 3.04 mm, the f-number is 1.68, and the diagonal field of view is 92.6 deg. Above all, our presented camera module system uses a single one-piece lens.