ABSTRACT
The Fresnel-zone plate (FZP) is a quasi-optical component that provides the functions of a lens (or a reflective antenna when the zone plate is backed by a mirror). The zone plate has the advantages of simplicity of design and construction, planar configuration, low loss, low weight, and low cost, while giving performance comparable to a lens (sometimes better). The zone plate produces lens-like focusing and imaging of electromagnetic waves by means of diffraction, rather than refraction. Thus the field is often referred to as diffraction optics. The zone plate transforms a normally incident plane wave into a converging wave, concentrating the radiation field to a small focal region. Much of the material that follows has been adapted from the author’s papers in the list of references.
