Abstract
Unlike electrowetting lens, a tunable liquid lens driven by dielectric force was demonstrated and it was analyzed its optical performance experimentally. The lens consisted of two liquids, a high dielectric liquid and a low dielectric liquid, sealed in one chamber with an iso-density. The dielectric force was induced by the difference of dielectric constants and it acted on the interface of two liquids to deform a droplet’s profile. Such a deformation causes a lensing effect by the difference of refractive index of the two immiscible liquids. In the liquid lens, the deformation of a droplet was actuated by forces such as surface tension, adhesion, gravitation and dielectric force. Theoretical models were developed to calculate the deformation of a liquid droplet’s profile and to evaluate the spherical aberration of the lens. In addition, a circuit model was used to understand the frequency response while the lens is actuated. Three centering mechanisms were proposed to reduce angular misalignment of the optical axis of the liquid lens. Finally, a convex liquid lens with a thickness of 4mm was demonstrated. This lens was analyzed its optical performance experimentally and theoretically. Contact angle hysteresis and contact angle retardation appeared while the droplet was actuated in the lens. The interfacial reflection in the lens module reduced the optical resolution that was estimated by software ASAP. Microbubbles and ITO erosion that were induced by high electric conductivity were observed. This lens had a triple change of focal length in the range of applied voltage of 0-200V. The maximum of the angular misalignment was measured to be about 1.3°.