Liquid crystal lens with a shiftable optical axis

Abstract

A liquid crystal (LC) lens with a laterally shiftable optical axis is proposed and demonstrated. The optical axis of the lens can be driven to shift within the lens aperture without compromising its optical properties. The lens is constructed by two glass substrates with identical interdigitated comb-type finger electrodes on the inner surfaces, and they are oriented at 90° with respect to each other. The distribution of voltage difference between two substrates is determined by eight driving voltages, and is controlled within the linear response region of LC materials, thereby generating a parabolic phase profile. In experiments, an LC lens with an LC layer of 50 µm and an aperture of 2 mm × 2 mm is prepared. The interference fringes and focused spots are recorded and analyzed. As a result, the optical axis can be driven to shift precisely in the lens aperture, and the lens maintains its focusing ability. The experimental results are consistent with the theoretical analysis, and good performance of the LC lens is demonstrated.