Multifuctional liquid lens for high-performance miniature cameras

This paper presents a novel multifunctional liquid lens (MLL) for miniature cameras. MLL firstly offers concurrent variable-focus and variable-zoom functions in a single lens system using two different actuation schemes: electrowetting-on-dielectric (EWOD) actuation for controlling the lens curvature and electromagnetic actuation for controlling the lens position. Image focus test is firstly carried out using the prototype of MLL. When a target electrical voltage is applied to the EWOD electrode on the inside cylindrical wall of a lens chamber, the curvature of a liquid interface in the lens chamber is modified and the focal length of the lens is simultaneously changed. As a result, an initially blurred check pattern image is clearly focused. The control of the height of a liquid column in a lens chamber is separately investigated using electromagnetic actuation. When an electrical voltage is applied to an electromagnetic system beneath the prototype MLL, a ring-shaped magnet presses an elastic membrane down. As a consequence, the liquid initially residing in the actuation chamber flows into the lens chamber through open walls, and the height of the liquid column rises. The average height of the liquid column is linearly increased from 0 mm to 1.2 mm while the applied voltage is changed from 0 V to 50 V at 5 V increment. The average height variation per volt is about 24 μm. Finally, the image magnification performance of MLL is experimentally validated using both EWOD and electromagnetic actuation. The proposed MLL offers a simple design structure to be easily miniaturized but covers a wide range of variable lens curvatures and positions for high optical performance.