Design and fabrication of tunable aspherical lens for spherical compound eye

Abstract

A structural design of spherical compound eye is proposed. Aspherical lenses are fabricated on a spherical shell substrate and serve as channel lenses of the spherical compound eye. Each channel lens incepts lights of certain field of view (FOV) and focuses on a planar photodetector. The spherical compound eye can achieve a large FOV with merits of compact configuration, free assemblage and high capacity usage ratio. However, in this design the focal lengths of different channel lenses are nonuniform. To fabricate tunable channel lens, a method of fabricating tunable aspherical lenses based on shape manipulation by electrostatic field is proposed. The channel lens is fabricated by dropping Ultra- Violet (UV) curable polymer onto a double-concave glass substrate lens. An electrostatic field is employed to manipulate the shape of the liquid lens. The lens shape can be distorted from initial spherical to aspherical. The focal length of the aspherical lens varies as its shape being manipulated. When the in-situ measured focal length and focal spot images satisfy the requirement of a certain channel lens, the liquid aspherical lens can be cured to solid lens and can be used as the channel lens. The experiment results shows that by manipulating the shape of the liquid lens and controlling the liquid volume, the focal length of the lens can be manipulated between 5.5mm and 46.9mm, and keep small optical aberration. These indicate that the aspherical lenses fabricated by this method are tunable and are suitable as channel lenses for the spherical compound eye designed. And it is useful for fabricating spherical compound eye with large FOV.