Design and performance evaluation of a large-aperture variable-focus lens with a liquid-membrane-liquid structure

Interest in variable-focus lenses is growing due to their dynamic optical power control and reduced spatial demands for focusing and/or zooming functions. Most variable-focus lenses are limited to small apertures (&lt; 10<i>mm</i>), limiting their application scenarios. In this work, we designed and fabricated a 42<i>mm</i> large-aperture variable-focus lens based on a liquid-membrane-liquid (LML) structure. This design surpasses the typical limitations of small aperture sizes in variable-focus lenses. Experiments show that the prototype achieves consistent optical power actuation range in [−3<i>D</i>, +3<i>D</i>], high repeatability during the actuation process, and 82.1622&percnt; transmittance using a ~630<i>nm</i> laser beam. After constructing an imaging system incorporating the proposed prototype, the imaging tests yield average modulation transfer function (MTF) values of 0.7904 at 17.204<i>lp/mm</i> spacial frequency and 0.5439 at 34.409<i>lp/mm</i> in the region where no obvious distortion occurs. The prototype demonstrates potential applications in fields requiring large aperture and high-quality imaging capabilities, such as wearable devices and machine vision.