Focus-Tunable Microlens Arrays Fabricated on Spherical Surfaces

We present microlens arrays consisting of multiple focus-tunable microlenses omnidirectionally fabricated on spherical surfaces, to realize large field of view. Thin flexible polymer bridges connecting adjacent microlenses are designed to reduce the wrapping stress and deformation of the microlens array. Each microlens, formed via water-oil interface, is individually tuned by a thermo-responsive hydrogel actuator. The range of the focal length of each microlens in this array varied from millimeters to infinity. A prototype of optical imaging system based on such a microlens array on a spherical surface, including a charged-coupled device camera, a fiber bundle, and a 3-D rotational stage, is demonstrated as well.