Modeling and Optical Simulation of Varifocal Diffraction Alvarez Lenses Based on Phase Plates

Varifocal lenses have received extraordinary attention owing to their varifocal property, which offers the ability to image targets at different distances. Compact and wide varifocal lenses could find usage in many application fields such as biomedical engineering, industrial imaging, and beam manipulation. The model and optical simulation of varifocal Alvarez lenses, which include two thin phase diffraction plates are carried out in this paper. The proposed varifocal Alvarez lenses can achieve a wide and continuous varifocal range at a small lateral displacement between these two phase plates. The results show that when the lateral displacement of the phase plates varies from 0 mm to 1 mm, the focal length of the proposed varifocal diffraction Alvarez lenses changes from 25 mm to 125 mm, which indicates that the varifocal ratio is 5×. The proposed varifocal lenses demonstrate an excellent application prospect in varifocal imaging fields.