Zoom liquid lens employing a multifocal Fresnel zone plate.

We propose a zoom liquid lens employing a multifocal Fresnel zone plate. The proposed lens has two optical surfaces: liquid-liquid interface and Fresnel zone plate. The Fresnel zone plate is designed to have a multifocal point and an increased depth of focus. Therefore, the proposed lens has two obvious advantages. Due to increased depth of focus, the proposed lens can realize zooming using only one tunable liquid-liquid interface, which is not available for conventional liquid lens. Thus, it is possible to remove conventional zooming mechanisms from cameras. Besides, the focal length tuning range is also increased, and a lens system based on the proposed lens can simultaneously collect two images with different magnifications. We present the design, fabrication and characterization of the proposed lens. The shortest positive and negative focal length are ∼17.5mm and ∼-34.5mm and the diameter is 5mm. The zoom ratio of the proposed lens reaches ∼1.48×. Our results confirm that the proposed lens has widespread applications in imaging system.