Dynamic Liquid Optics

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The power of tunable optics based on optofluidics stems from the ability to controllably deform liquid interfaces to a desired shape for a refractive surface. Using electrowetting as an actuation technique, tunable liquid lenses, prisms, and scanners have been demonstrated, and recently it has even been shown that surfaces with controlled optical aberrations may be generated. Key to many of these developments has been the use of a tubular fluidic structure with a high density of azimuthally-distributed and individuallyaddressable actuation electrodes. Yet the capabilities of liquid optics for realizing advanced imaging systems can be extended further, and the DynaLO project will attempt to demonstrate an entirely new means for controllably generating arbitrary liquid surface profiles, namely through time-varying surface waves in the lens. With the unique capabilities of the 32-electrode tubular lenses developed by the PI in prior work, the ability to generate precisely-controlled traveling and standing waves across the lens aperture will be analyzed theoretically and experimentally. Inspired by the wave patterns which can be generated in 25 m diameter wave tanks using mechanical actuators, the DynaLO project will translate this concept to a 5 mm liquid lens. It is expected that such dynamic surface waves can be used to generate a wide variety of surface features, also non-circularly-symmetric ones, which cannot be achieved using static actuation. This novel dynamic surface shaping will then be combined with static surface shaping as well as feedback-stabilized interface positioning to allow the generation of an even wider range of optical freeform surfaces. The liquid profile will be monitored in real time and interface variations due to, for example, orientation changes of the lens or system vibrations, will be directly compensated. The ultimate goal will be a liquid lens for which actuation can be instantaneously and continuously adjusted to assure that the desired profile is generated. If successful, the dynamic surface wave approach combined with static interface shaping will open entirely new horizons for tunable liquid optical components.