Reflection energy from a linear reflector comes from an integrant over an aperture often described by the Fresnel zone. Within the Fresnel zone, the diffraction energy constructively builds the reflection energy. This paper uses diffraction theory to explain the reflector edge effect on amplitude and the amplitude variation within the Fresnel zone. Thus, discuss the Fresnel zone effect for AVO ...

A simple method to make a switchable liquid crystal (LC) Fresnel lens with high diffraction efficiency and a low driving voltage was proposed based on the photo-induced surface modification of the vertical alignment layer. UV illumination alters the pretilt angle of alignment layers, a Fresnel zone-distribution hybrid alignment in the homeotropic LC cell can be straightforwardly achieved throug...

This paper describes the concepts of diffraction, diffraction gain, diffraction loss, field strength at receiver due to knife-edge obstacles between the propagation path of the signal i.e. b/w transmitter and receiver. This paper also present the complete idea of identifying the position of obstacle in a Fresnel zone, diffraction loss, position of obstacle with varying distances b/w source and ...

Diffraction and interference are optical phenomena which split light into its component wavelengths, hence producing a full spectrum of iridescent colors. This paper develops comput er graphics models for iridescent colors produced by diffractive media. Diffraction gratings, certain animal skins and the crystal structure of some precious stones are known to produce diffraction. Several techniqu...

We compare the Fresnel diffraction pattern of a thin circular disk with that of a square obstacle, specifically evaluating the on-axis field strength. Photographs of the diffraction patterns reveal some curious features for the square obstacle. Second, the precise electric and magnetic fields behind a conducting circular disk are evaluated without invoking the Fresnel approximation and contrast...

2014 The paper describes the principles and theoretical models of new X-ray optical elements based on the behaviour of Bragg-Fresnel diffraction. The use of volume diffraction permits one to achieve better spatial resolution compared with conventional plane optics and bending mirrors. The construction of Bragg-Fresnel elements combines the advantages of high-resolution Fresnel optics with stabi...

This study investigates a voltage-controllable liquid crystals lens with a Fresnel zone electrode. When applying a proper voltage on the liquid crystal cell, a Fresnel-zone-distributed electric field is induced to direct liquid crystals aligned in a concentric structure. Owing to the concentrically aligned liquid crystals, a Fresnel lens is formed. We probe the Fresnel liquid crystal lens using...

Tomographic coherent imaging requires the reconstruction of a series of two-dimensional projections of the object. We show that using the solution for the image of one projection as the starting point for the reconstruction of the next projection offers a reliable and rapid approach to the image reconstruction. The method is demonstrated on simulated and experimental data. This technique also s...

Modified volume Fresnel zone plates (MVFZPs) fabricated with laser direct writing were optimized for higher diffraction efficiencies. The Fresnel radii in each layer of a volume zone plate were iteratively adjusted by a simulation-based direct search optimization. The results show that optimization is effective but depends strongly on the starting diffraction efficiencies determined by the MVFZ...