Fabrication and Characterization of a Repositionable Liquid Micro Lens System

A novel method to improve both the lateral positioning and focal length tuning accuracy of a liquid lens in a micro lens system, based on the electrowetting on dielectrics (EWOD) principle, is described. This system consists of a device, encapsulated with a packaging technique, fabricated on a transparent substrate featured with an array of electrodes and a structured surface whose periodicity is smaller than the electrode´s dimension. With variable applied voltage signals, the liquid lens is actuated precisely in the lateral position and also tuned dynamically irrespective of the lens position on the substrate. The accuracy of lateral positioning is mainly dependent on the structure of the dielectric surface. Measurements of the focal length tuning range and the positioning accuracy are presented. A first design of reconfigurable micro lens system, which has diverse application as adaptive wave-front sensing, optical tweezers and etc, is demonstrated.