Topic
Fresnel zone
About: Fresnel zone is a research topic. Over the lifetime, 2337 publications have been published within this topic receiving 37650 citations.
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TL;DR: In this paper, a binary Fresnel Zone Axilens (FZA) is designed for the infinite conjugate mode and the phase profile of a refractive axicon is combined with it to generate a composite Diffractive Optical Element (DOE).
Abstract: A binary Fresnel Zone Axilens (FZA) is designed for the infinite conjugate mode and the phase profile of a refractive axicon is combined with it to generate a composite Diffractive Optical Element (DOE). The FZA designed for two focal lengths generates a line focus along the propagation direction extending between the two focal planes. The ring pattern generated by the axicon is focused through this distance and the radius of the ring depends on the propagation distance. Hence, the radius of the focused ring pattern can be tuned, during the design process, within the two focal planes. The integration of the two functions was carried out by shifting the location of zones of FZA with respect to the phase profile of the refractive axicon resulting in a binary composite DOE. The FZAs and axicons were designed for different focal depth values and base angles respectively, in order to achieve different ring radii within the focal depth of each element. The elements were simulated using scalar diffraction formula and their focusing characteristics were analyzed. The DOEs were fabricated using electron beam direct writing and evaluated using a fiber coupled diode laser. The tunable ring patterns generated by the DOEs have prospective applications in microdrilling as well as microfabrication of circular diffractive and refractive optical elements.
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TL;DR: In this paper, a hollow chain-like beam has been experimentally generated as a result of the first order Bessel beam diffraction by zone plate with the first and the ninth open Fresnel zones.
Abstract: To generate hollow chain-like beams the diffraction of the first order Bessel beam by zone plate with two odd open Fresnel zone has been investigated. It has been shown that the capsules size is influenced by the number of the second odd open Fresnel zone and by the zone plate focal length. A hollow chain-like beam has been experimentally generated as a result of the first order Bessel beam diffraction by zone plate with the first and the ninth open Fresnel zones. The orbital angular momentum presence has been proved experimentally. The main features of the beam have been investigated. Sufficiently good agreement between experimental and numerically calculated results has been demonstrated.
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TL;DR: Based on scalar diffraction optics theory, a new type of mm-wave antenna(diffraction antenna) phase-correcting Fresnel zone plate with continuous structure is described in this paper.
Abstract: Based on scalar diffraction optics theory, a new type of mm-wave antenna(diffraction antenna) phase-correcting Fresnel zone plate with continuous structure is described in this paper. It has the advantages of thinner thickness, lighter weight and design flexibility. The design theory and space shadow are discussed in details, and the measured results are presented. The results show that the properties of this kind of antenna is closed to paraboloid reflector.
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13 Jul 2014TL;DR: In this paper, parallel stochastic gradient search optimization was used to optimize and improve degraded beam quality in a holographic beam steering experiment for various steering angles for different steering angles.
Abstract: Parallel Stochastic Gradient Search optimization is used to optimize and improve degraded beam quality in a holographic beam steering experiment for various steering angles.
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TL;DR: In this article, a cross-like Fresnel zone plate is introduced and the focusing properties of the element are compared to a classic and square Fresnel plate and it is shown that the focusing of the elements is well corrected in comparison to a square and rectangular Fresnel Zone plate, resolution is noticeably increased, DC noise is substantially reduced and also secondary maxima have been suppressed.
Abstract: Cross like Fresnel zone plate is introduced This element is composed of two perpendicular linear Fresnel zone plates Focusing properties of the element is studied and it is compared to a classic and square Fresnel zone plate Analysis clarify that focusing of the elements is well corrected in comparison to square Fresnel zone plate Resolution is noticeably increased, DC noise is substantially reduced and also secondary maxima have been evidently suppressed Theoretical results have been completely verified by experiment