title: Rough Fresnel zone plates over metallic surfaces.
abstract: We analyze the focusing properties of Fresnel zone plates fabricated over steel tapes using laser ablation. Our intention is to implement the use of micro-optical elements when the use of conventional chrome-glass elements is not indicated. Because of the manufacture process, the surface presents a certain anisotropic roughness, which reduces the focusing properties. First, we develop numerical simulations by means of the Rayleigh-Sommerfeld approach, showing how roughness in both levels of the Fresnel zone plate affects the focalization of the lens. We also manufacture Fresnel zone plates over steel tape, and perform experimental verification that corroborates the numerical results.
authors.affiliation: Applied Optics Complutense Group, Optics Department, Universidad Complutense de Madrid, Facultad de Ciencias Físicas, Ciudad Universitaria s.n., 28040 Madrid, Spain. fjsalgado@fis.ucm.es
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Salgado-Remacha
authors.forename: Luis Miguel
authors.initials: LM
authors.lastname: Sanchez-Brea
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Alvarez-Rios
authors.forename: Eusebio
authors.initials: E
authors.lastname: Bernabeu