Fabrication of polymeric lenses using magnetic liquid molds

Abstract

Traditional molding and casting processes in optical manufacturing require sophisticated and expensive molds and molding equipment. In this work, magnetic liquid droplets were used as soft and deformable molds. The magnetic drop within an immiscible polymeric resin forms a conical shape at the interface due to the equilibrium of magnetostatic force and surface tension, which results in a plano-concave lens after curing. An apparatus was assembled to control the amplitude and gradient of the magnetic field. A Shack-Hartmann sensor was employed to measure the focal length of the formed polydimethylsiloxane lenses. The effects of magnetic field intensity, gradient of the magnetic field, and magnetic susceptibility were investigated. This technique is low cost, rapid, and straightforward and can be used for forming lenses with different sizes and shapes.