Sector-based Fresnel zone plate with extended depth of focus

Abstract

A Sector-based Fresnel zone plate consists of a binary diffractive lens composed of a mosaic of sectors of Fresnel zone plates with different focal distances. When these focal distances are linearly distributed within the sectors, dual focus is obtained. Besides, we explore the possibility to generate an extended depth-of-focus lens by using a cubic distribution of the focal distances assigned to the sectors and optimizing the weight factors given to the terms of the cubic polynomial. Finally, numerical simulations based on the Rayleigh-Sommerfeld approach are carried out and experimental verifications by using a Spatial Light Modulator are performed, showing high agreement. The proposed kind of zone plate has potential applications in different research fields such as microscopy, lithography, data storage, or imaging.