Topic
Fresnel zone
About: Fresnel zone is a research topic. Over the lifetime, 2337 publications have been published within this topic receiving 37650 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this paper, the effects of contrast in the Fresnel zone plate on the amplitude in the focal point due to a normally incident plane wave are obtained by direct evaluation of the FK diffraction integral.
Abstract: The effects of contrast in the Fresnel zone plate on the amplitude in the focal point due to a normally incident plane wave are obtained by direct evaluation of the Fresnel–Kirchhoff diffraction integral. The change in focal-point amplitude due to smoothing the ordinary, discontinuous, “square-wave” transmission function into a continuous, “sine-wave” function is also calculated. Finally, an expression is derived for the amplitude in the point image due to a plane wave impinging on the zone plate at a small angle of incidence.
31 citations
TL;DR: In this article, the amplitude and phase factor for finite cylinder lengths were derived for straight and bent cylinders and the results showed that the amplitude is proportional to the length of the cylinder for lengths much less than the Fresnel zone diameter.
Abstract: The normal mode solution for sound backscattered by a finite fluid (gas)‐filled cylinder in water is replaced by a Kirchhoff approximation for ka>0.15 and the normal mode solution for ka<0.15 where a is cylinder radius and k is the wave number. The composite solution was tested for density and sound‐speed ratios g and h in the ranges of 0.0012
31 citations
TL;DR: Nonuniform sampled ASM and Fresnel diffraction is developed to improve the problem using the nonuniform FFT.
Abstract: Scalar diffraction calculations, such as the angular spectrum method (ASM) and Fresnel diffraction, are widely used in the research fields of optics, x rays, electron beams, and ultrasonics. It is possible to accelerate the calculation using fast Fourier transform (FFT); unfortunately, acceleration of the calculation of nonuniform sampled planes is limited due to the property of the FFT that imposes uniform sampling. In addition, it gives rise to wasteful sampling data if we calculate a plane having locally low and high spatial frequencies. In this Letter, we developed nonuniform sampled ASM and Fresnel diffraction to improve the problem using the nonuniform FFT.
31 citations
Patent•
18 Apr 2006TL;DR: In this paper, a Fresnel zone plate having a complex irradiation function capable of improving resolution even when the outermost opaque band width cannot be reduced and an X-ray microscope using the Fresnel plate was presented.
Abstract: [Object] To provide a Fresnel zone plate having a complex irradiation function capable of improving resolution even when the outermost opaque band width cannot be reduced and an X-ray microscope using the Fresnel zone plate. [Solution] A Fresnel zone plate 1 having a complex irradiation function according to the present invention has opaque bands 3 and transparent bands 4 arranged alternately in the radial direction from the center on a flat transparent substrate 2 , and a transmission window 7 formed such that a portion of a plane wave vertically applied onto the upper surface vertically enters directly a sample 6 disposed below the Fresnel zone plate 1.
31 citations
TL;DR: Compound photon sieves for hard-x-ray nanofocusing in the high-energy region above 20 keV can provide not only slightly better resolution compared to CZPs, but also it can significantly suppress the sidelobes, leading to a high signal-to-noise ratio.
Abstract: Combining the advantages of photon sieves (PSs) and compound Fresnel zone plates (CZPs), we designed compound photon sieves (CPSs) for hard-x-ray nanofocusing. A CPS consists of an inner PS using the first-order diffraction surrounded by an outer zone plate using the third-order diffraction. A robust digital prolate spheroidal window was used as an apodization window for the inner PS, making CPSs more flexible than CZPs. CPSs can provide not only slightly better resolution compared to CZPs, but also it can significantly suppress the sidelobes, leading to a high signal-to-noise ratio. Further improvement of the high-aspect-ratio metal nanostructure process will allow CPSs to be a promising candidate for hard-x-ray nanofocusing in the high-energy region above 20keV.
31 citations