Multifocal binary diffraction lens with arbitrary focal lengths and number of foci

Abstract

In this paper, a method is proposed to design a binary multifocal Fresnel zone plate (MFZP) with desirable focal lengths and number of foci. By performing simulations, the focusing characteristics of MFZPs with two, three, and four focal lengths are investigated. The obtained results show that the aspect ratio of focal lengths and the number of foci of MFZPs can be chosen freely. Furthermore, designed MFZPs are displayed on a digital micromirror device, and the focusing properties of the reflected laser beam are investigated. Experimental results support the validity of the method. © 2019 Optical Society of America.