Varifocal diffractive lens based on microfluidics

Conventional flat diffractive lenses possess compact dimensions and exhibit exceptional optical performance. However, the focal length can hardly be adjusted adaptively. In this paper, we demonstrate a novel diffractive lens that achieves switchable focal length based on microfluidic. A multi-level diffractive lens (MDL) is designed and optimized. By filling liquid materials into the tiny gaps between the MDL, the proposed lens operates in different states with switchable focal length. Experimental results demonstrate that the proposed lens enables focal length tuning without mechanical movement, allowing for switching between different focal lengths. The proposed lens is polarization-independent and does not require complex driving mechanisms. The core imaging component has dimensions of only 1.5 mm × 1.5 mm × 0.6 mm. The proposed lens enhances the adjustability of diffractive lenses, showcasing the advantages of liquid materials in diffractive lens design. It holds great potential for applications in compact zoom imaging systems.