Fresnel zone

About: Fresnel zone is a research topic. Over the lifetime, 2337 publications have been published within this topic receiving 37650 citations.

Diffraction Separation Based on the Projected First Fresnel Zone

Abstract: Summary Medium to small-scale structural details and heterogeneities of a medium, e.g., faults, pinch-outs, thin lenses, fracturing etc. are of crucial importance for prospecting and development of fractured reservoirs. Such details and heterogeneities are a source of scattered waves (e.g., diffractions), carrying information about scattering objects. In this work, we develop a new diffraction weighting function based on the projected (first) Fresnel zone to enhance diffraction separation and imaging. The difference in the width of the projected (first) Fresnel zone for reflections and diffractions appeared to be very consistent and thus it can be a reliable diffraction indicator. We use the common-reflection-surface (commonly known as CRS) technique to extract the kinematic wavefield attributes and the width of projected Fresnel zone. Applications to a simple gradient as well as complex synthetic data set reveal high potential of the new diffraction weight.

Characterisation and modelling of obstructed line-of-sight millimetre wave mobile radio signals

Abstract: The objective of the study is to characterise and model the propagation channel of obstructed line-of-sight millimetre wave radio signals in an indoor environment. Experimental results are compared with theoretical predictions obtained from a model based on geometric optics and Fresnel diffraction. Measured and predicted results are given for an experiment undertaken in a bending corridor at 60.4 GHz where the direct component prevailed for a short distance, and was then blocked as the mobile receiver moved into the shadow region.

Holder frame for x-ray optical element

Abstract: PURPOSE:To improve reliability of an X-ray optical element system and to size it down by providing a window through which visible radiation permeates, at periphery of a holder part of the X-ray optical element. CONSTITUTION:A base plate W consists of a square silicon plate 0.2mm thick and each of which sides is 14mm long, for instance, and, at its central part, a square hole P each of which sides is 0.2mm long and is covered by a thin film N, is formed as a permeating part of a soft X-ray and also, on the thin film N, a Fresnel zone pattern is drawn. Also, in circumference of the hole P, 5mm by 55mm passing-through windows T1 to T4 of visible radiation are formed and, widths of length and breadth beam parts K1 to K4 are different in the surfaces or the backs as their cross-sectional shapes are trapezoid. An objective zone plate R2 is monolithically formed by the Fresnel zone pattern part and the visible radiation windows T1 to T4, on one single silicon plate. Accordingly, positional accuracy during the Fresnel zone pattern is being formed, affects directly to accuracy of an optical alignment during the plate R2 is being positioned, and moreover the plate R2 does not move after being fixed in an X-ray microscope, and therefore an optical system can be easily assembled and an initial accuracy of the optical alignment can be always maintained.

Periodic Filamentation and Supercontinuum Interference

Abstract: In this chapter, supercontinuum (SC) generation and filamentation in BK7 glass were controlled by Fresnel diffraction from a circular aperture or a straight edge. We demonstrated the salient coherent property of multiple SC sources by the periodic filamentation.