The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
He Long-qing - One of the best experts on this subject based on the ideXlab platform.
-
Numerical Simulation of Fresnel Diffraction by a Square Aperture with Grating Structure
Journal of Nanjing Xiaozhuang University, 2008Co-Authors: He Long-qingAbstract:The intensity distribution of the Fresnel Diffraction field for square aperture with grating structure is analyzed and simulated by a numerical method.An algorithm of numerical calculations of Fresnel Diffraction by a square aperture with grating structure is presented along with the corresponding MATLAB programs and simulations.The results indicate that the Fresnel Diffraction pattern of a square aperture with sinusoidal amplitude grating structure is an image of grating with features of Diffraction by square aperture,and the image definition is decided by Fresnel number and the number of spatial periods of the grating contained in the aperture.Similar to the Fresnel Diffraction by a boundless sinusoidal amplitude grating,the image has twice the frequency that the original grating does and has reduced the contrast when certain conditions are satisfied.
-
Simulation for Realizing Fresnel Diffraction of Square Aperture Based on Coherence Superposition of Wavelets Algorithm
Electro-Optic Technology Application, 2008Co-Authors: He Long-qingAbstract:The intensity distribution of Fresnel Diffraction field for square aperture are analyzed and simulated through numerical method.A high performance algorithm of numerical calculations for square aperture Diffraction and corresponding MATLAB programs and simulations are presented.The results indicate that the intensity distribution of Diffraction light field is determined by Fresnel Number.And the value of Fresnel Number on transition from Fresnel Diffraction to Fraunhoer Diffraction is discussed.
Tomoyoshi Ito - One of the best experts on this subject based on the ideXlab platform.
-
Aliasing-reduced Fresnel Diffraction with scale and shift operations
Journal of Optics, 2013Co-Authors: Tomoyoshi Shimobaba, Takashi Kakue, Naohisa Okada, Minoru Oikawa, Yumi Yamaguchi, Tomoyoshi ItoAbstract:Numerical simulation of Fresnel Diffraction with fast Fourier transform (FFT) is widely used in optics, especially computer holography. Fresnel Diffraction with FFT cannot set different sampling rates between source and destination planes, while shifted-Fresnel Diffraction can set different rates. However, an aliasing error may be incurred in shifted-Fresnel Diffraction in a short propagation distance, and the aliasing conditions have not been investigated. In this paper, we investigate the aliasing conditions of shifted-Fresnel Diffraction and improve its properties based on the conditions.
-
Arbitrary shape surface Fresnel Diffraction.
Optics express, 2012Co-Authors: Tomoyoshi Shimobaba, Nobuyuki Masuda, Tomoyoshi ItoAbstract:Fresnel Diffraction calculation on an arbitrary shape surface is proposed. This method is capable of calculating Fresnel Diffraction from a source surface with an arbitrary shape to a planar destination surface. Although such calculation can be readily calculated by the direct integral of a Diffraction calculation, the calculation cost is proportional to O(N2) in one dimensional or O(N4) in two dimensional cases, where N is the number of sampling points. However, the calculation cost of the proposed method is O(N log N) in one dimensional or O(N2 log N) in two dimensional cases using non-uniform fast Fourier transform.
Tomoyoshi Shimobaba - One of the best experts on this subject based on the ideXlab platform.
-
Aliasing-reduced Fresnel Diffraction with scale and shift operations
Journal of Optics, 2013Co-Authors: Tomoyoshi Shimobaba, Takashi Kakue, Naohisa Okada, Minoru Oikawa, Yumi Yamaguchi, Tomoyoshi ItoAbstract:Numerical simulation of Fresnel Diffraction with fast Fourier transform (FFT) is widely used in optics, especially computer holography. Fresnel Diffraction with FFT cannot set different sampling rates between source and destination planes, while shifted-Fresnel Diffraction can set different rates. However, an aliasing error may be incurred in shifted-Fresnel Diffraction in a short propagation distance, and the aliasing conditions have not been investigated. In this paper, we investigate the aliasing conditions of shifted-Fresnel Diffraction and improve its properties based on the conditions.
-
Arbitrary shape surface Fresnel Diffraction.
Optics express, 2012Co-Authors: Tomoyoshi Shimobaba, Nobuyuki Masuda, Tomoyoshi ItoAbstract:Fresnel Diffraction calculation on an arbitrary shape surface is proposed. This method is capable of calculating Fresnel Diffraction from a source surface with an arbitrary shape to a planar destination surface. Although such calculation can be readily calculated by the direct integral of a Diffraction calculation, the calculation cost is proportional to O(N2) in one dimensional or O(N4) in two dimensional cases, where N is the number of sampling points. However, the calculation cost of the proposed method is O(N log N) in one dimensional or O(N2 log N) in two dimensional cases using non-uniform fast Fourier transform.
M. Taghi Tavassoly - One of the best experts on this subject based on the ideXlab platform.
-
Fresnel Diffraction from a step in the general case
Journal of the Optical Society of America. A Optics image science and vision, 2017Co-Authors: Hamid Salvdari, M. Taghi Tavassoly, S. R. HosseiniAbstract:Recently, Fresnel Diffraction from phase steps with parallel plates has been studied in detail, and the subject has led to many interesting metrological applications. In this report we formulate Fresnel Diffraction from a physical step with arbitrarily oriented plates in reflection mode. We simulate the Diffraction patterns for different orientations of the plates and develop the required procedure for determining the involved angles by analysis of the Diffraction pattern. In the experimental part of the report we arrange a setup to form Diffraction patterns in different orientations of the step plates and test the derived formulations. Also, we briefly review the application potentials of the subject.
-
nanometer displacement measurement using Fresnel Diffraction
Applied Optics, 2012Co-Authors: Ali Akbar Khorshad, Khosrow Hassani, M. Taghi TavassolyAbstract:We introduce a relatively simple and efficient optical technique to measure nanoscale displacement based on visibility variations of the Fresnel Diffraction fringes from a two-dimensional phase step. In this paper we use our technique to measure electromechanical expansions by a thin piezoelectric ceramic and also thermal changes in the diameter of a tungsten wire. Early results provide convincing evidence that sensitivity up to a few nanometers can be achieved, and our technique has the potential to be used as a nanodisplacement probe.
-
Determination of refractive indices of liquids by Fresnel Diffraction
Optics & Laser Technology, 2009Co-Authors: Arash Sabatyan, M. Taghi TavassolyAbstract:We demonstrate an easy, reliable, applicable, and sensitive method to measure refractive index of liquids by using Fresnel Diffraction. In this method a cylindrical glass rod, in general, or an optical fiber in special case, is immersed into a liquid. Physical parameters of the rod, like radius and refractive index, should be well known. Then, the normalized intensity distribution on the Fresnel Diffraction pattern of a plane wave diffracted from the immersed fiber is measured. Thereafter, refractive index of the liquid is evolved by the least-square method. This method applied to determine the refractive index of four liquids; pure water, 2-propanol (isopropanol), acetone and methanol. Index of refraction of each one has been acquired for four visible wavelengths. A theoretical approach and experimental results is presented.
-
Applications of Fresnel Diffraction from phase objects
Optical Measurement Systems for Industrial Inspection II: Applications in Production Engineering, 2001Co-Authors: M. Taghi Tavassoly, Ahmad Darudi, Hamid Reza Khalesifard, S.m.r. Sadat HosseiniAbstract:It is shown that when a part of a wave-front bears a sharp change in its phase, the Fresnel Diffraction becomes noticeable. To change the phase sharply, one can reflect the wave-front from a step or transmit it through a transparent medium having a sharp change in its thickness or refractive index. The visibility of the corresponding Diffraction fringes depends on the amount of phase change and can be varied from zero to one. Since the phase change can be accomplished by various means, the effect renders to measure phase change, refractive index change, displacement, and so on. Here, the change of visibility is the measurement criterion, therefore the fluctuations of the source intensity do not affect the measurement precision. In this paper Fresnel Diffraction from one dimensional step, circular step, and single strip are studied, and some of its applications are briefly discussed.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Vincent Vlaminck - One of the best experts on this subject based on the ideXlab platform.
-
Fresnel Diffraction of spin waves
Physical Review B, 2018Co-Authors: Nicolas Loayza, M. B. Jungfleisch, Axel Hoffmann, M. Bailleul, Vincent VlaminckAbstract:The propagation of magnetostatic forward volume waves excited by a constricted coplanar waveg-uide is studied via inductive spectroscopy techniques. A series of devices consisting of pairs of sub-micrometer size antennae is used to perform a discrete mapping of the spin wave amplitude in the plane of a 30-nm thin YIG film. We found that the spin wave propagation remains well focused in a beam shape of width comparable to the constriction length and that the amplitude within the constriction displays oscillations, two features which are explained in terms of near-field Fresnel Diffraction theory.
