Improved stability of electroactive elastomer tunable lenses using focal length estimation

Abstract

We proposed a tunable liquid lens composed of silicone oil and a Dielectric Elastomer Actuator (DEA). The lens is composed of dielectric elastomer films, silicone oil, and acrylic frames. When a voltage is applied to the DEA, Maxwell stress occurs, and the area of the DEA increases. The force generated by the area change of the DEA causes a change in the radius of curvature of the lens, which varies a focal length. However, DEA’s viscoelastic properties are nonlinear, and only voltage control cannot control focal length accurately. Therefore we established a self-sensing system to control the DEA’s nonlinear properties. We measured the capacitance of DEA by using LabVIEW software and a parallel circuit composed of several capacitors and resistors to control the DEA’s strain and shape of the lens. The stability of the DEA shape change can maintain a constant lens’s focal length. The developed tunable liquid lens with a simple structure will be helpful in optical systems.