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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21 Jun 1998
TL;DR: In this article, the double-layer FZP lens was proposed to enhance the aperture efficiency by using an improved full-wave analysis, and the results showed that the double layer lens was more efficient than the single layer FZp lens.
Abstract: Owing to its low cost, light weight, and easy fabrication, the Fresnel zone plate (FZP) antenna is becoming an important candidate for such applications as DBS reception and mobile communication. Compared with the FZP reflector, the FZP lens has no feed blockage, so it is more attractive to study. The printed FZP lens, in which the concentric zones are alternatively transparent and opaque, is discussed in this paper. However, the single-layer FZP has a rather low efficiency, for about half of the incident energy is reflected backward, so the double-layer FZP lens had been proposed to enhance the aperture efficiency. By using an improved full-wave analysis the double-layer FZP lens is studied.
4 citations
4 citations
01 Jan 1988
TL;DR: The finest soft x-ray probes generated so far have been produced by modified fresnel zone plates [1,2,3] as discussed by the authors, which are used to demagnify a source of x rays.
Abstract: Image formation in scanning x-ray microscopy is achieved by rastering a semi transparent specimen across a small x-ray probe and counting the number of photons transmitted by the specimen at position of the scan. The finest soft x-ray probes generated so far have been produced by modified fresnel zone plates [1,2]. In scanning x-ray microscopy a zone plate is used to demagnify a source of x rays. The dimensions of the probe are primarily determined by the width of the finest zone (dr) of the zone plate. If the zone plate has been fabricated with sufficient accuracy and is illuminated with x-rays which are both spatially and temporally coherent then the probe shape will resemble an airy pattern which has a full width at half maximum (FWHM) which is very nearly equal to the finest zone.
4 citations
TL;DR: In this paper, the effects of transverse coherence in time domain nuclear resonant scattering experiments using synchrotron radiation were discussed and the importance of source and detector sizes, as well as the Fresnel zone size of the sample are described.
Abstract: We discuss the effects of transverse coherence in time domain nuclear resonant scattering experiments using synchrotron radiation. The importance of source and detector sizes, as well as the Fresnel zone size of the sample are described. These effects are demonstrated in experiments using a rotating stainless-steel foil [1]. The emphasis of the text is to provide simple physical explanations while mathematical details are discussed in the appendix.
4 citations
TL;DR: In this paper, an analysis of the Fresnel fringe contrast in defocused bright-field images of a Si-SiO2 interface imaged parallel to the beam is carried out with contrast simulations.
Abstract: An analysis of the Fresnel fringe contrast in defocused bright-field images of a Si-SiO2 interface imaged parallel to the beam is carried out with contrast simulations. The drop in the mean potential across the interface is assumed to be continuous and of error function type. The width of the potential drop is shown to have a strong influence on the visibility of the Fresnel fringes for different values of the defocus.
4 citations