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 article, the authors presented the first results of high-spatial resolution x-ray imaging studies with an upgraded version of the scanning photoemission multiple application undulator microscope, which is a multilayer coated Schwarzschild objective that focuses undulator radiation onto the sample.
Abstract: We present the first results of high‐spatial resolution x‐ray imaging studies with an upgraded version of the scanning photoemission multiple application x‐ray imaging undulator microscope. The microscope is a multilayer coated Schwarzschild objective that focuses undulator radiation onto the sample. The recent upgrade improved the spatial resolution by a factor six reaching a full width at half maximum value of 0.5 μm. Highly polished mirrors reduced the diffuse background by almost two orders of magnitude and drastically improved the contrast. The improved microscope was used to perform a series of tests on microgrids and reverse Fresnel zone plates. The microscope capability to detect chemical and topological contrast was verified by using patterned metal overlayers on Si and GaAs substrates. Further improvements to increase the flux and the spatial resolution are underway; this includes the installation of a new undulator beamline.
43 citations
TL;DR: In this paper, a local linear grating model was proposed to estimate the diffraction efficiency of high-numerical-aperture two-dimensional circular lenses with one-dimensional rigorous coupled-wave analysis.
Abstract: We describe a local linear grating model that permits estimation of the diffraction efficiency of high-numerical-aperture two-dimensional circular lenses with one-dimensional rigorous coupled-wave analysis. The model is self-consistent and is consistent with the scalar theory that results for low-numerical-aperture lenses. The accuracy of the model increases with the number of Fresnel zones of the lens. On the basis of this model we optimize the discrete phase profile of the lens for the maximum diffraction efficiency, using the random search method. The TE and the TM modes are optimized simultaneously. Their phase variations as functions of local grating periods are removed by cyclic shifts of the grating profiles, resulting in constructive summation at the focus and high diffraction efficiency.
43 citations
43 citations
TL;DR: In this article, a modified computer-generated Fresnel zone plane with the zone distribution determined by a Fermat spiral is proposed for performing generalized Hankel transforms, which is of special interest from the point of view of alignment applications.
43 citations
TL;DR: In this article, high-resolution and large diameter condenser Fresnel zone plates were fabricated in a 0.35-μm-thick Ta layer on an SiN membrane, where sub-field length and position are randamized in order to supress the evolution of small figures at pattern divided parts such as subfield boundaries.
43 citations