We report a liquid lens with a liquid-membrane-liquid structure in order to realize a variable-focus lens with a large optical aperture. We studied a typical liquid lens with a liquid-liquid structure and examined its physical limitation, namely, the capillary length, restricting the design of a larger-aperture liquid lens. We propose using elastic force instead of surface tension to acquire a much longer capillary length. We demonstrated that this approach can achieve sufficiently long capillary length when external pressure is loaded. A prototype lens with 30 mm aperture was constructed, and a resolution of 8.00 lp/mm was realized. V C 2013 American Institute of Physics.
We report on a method to fabricate a varifocal microlens array that employs a dielectric elastomer (DE) sandwiched between two electrodes as the lens material. The microlens array is patterned on the electrode plates, and when the electrodes are subjected to a controllable operating voltage, the DE material is "squeezed" by the Maxwell force to deform the lens array pattern, thus resulting in curvature deformation yielding a tunable lens profile. The tunable focal length performance ranges from 950 mm to infinity. When compared with liquid-filled lenses, solid-based varifocal lenses are more robust to thermal expansion, gravity, and vibrational motion. Our approach can be utilized in applications such as machine vision systems.
We report an improved method of fabricating a variable focus lens in which an in-plane pretension force is applied to a membrane. This method realized a lens with a large optical aperture and high performance in a low-optical-power region. The method was verified by comparing membranes in a simulation using the finite element method. A prototype with a 26 mm-diameter aperture was fabricated, and the wavefront behavior was measured by using a Shack-Hartmann sensor. Thanks to the in-plane pretension force, the lens achieved an infinite focal length with a wavefront error of 105.1 nm root mean square.
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