نتایج جستجو برای: kirchhoff integral

تعداد نتایج: 117367  

Journal: :Applied optics 2001
M Martínez-Corral L Muñoz-Escrivá A Pons

The scalar field in the focal volume of nontelecentric apodized focusing systems cannot be accurately described by the Debye integral representation. By use of the Fresnel-Kirchhoff diffraction formula it is found that, if the aperture stop is axially displaced, the focal-volume structure is tuned. We analyze the influence of the apodizing function and find that, whereas axially superresolving ...

2015
Y. T. Tsai M. R. Haberman J. Zhu

A transient analytical solution is presented to predict the pressure responses along the axis of a parabolic reflector for normally incident plane waves. The solution was derived using geometrical acoustics and the Kirchhoff-Helmholtz integral. Results of the analytical solution were compared to the numerical simulation results, and good agreements were obtained. The numerical simulation visual...

2003
Klaus D. Mielenz

The accuracy and physical significance of the classical Rayleigh-Sommerfeld and Kirchhoff diffraction integrals are assessed in the context of Sommerfeld's rigorous theory of half-plane diffraction and Maxwell's equations. It is shown that the Rayleigh-Sommerfeld integrals are in satisfactory agreement with Sommerfeld's theory in most of the positive near zone, except at sub-wavelength distance...

2013
Jianfeng Ma X. J. Xin

In this paper, the meshless integral method based on the regularized boundary integral equation [1] has been extended to analyze the large deformation of elastoplastic materials. The updated Lagrangian governing integral equation is obtained from the weak form of elastoplasticity based on Green-Naghdi’s theory over a local sub-domain, and the moving least-squares approximation is used for meshl...

2016
M. Darmon R. Raillon V. Dorval

Simulation is helpful for evaluating the performances of inspection techniques and requires the modeling of waves scattering from defects. Two classical flaw scattering models have been previously evaluated and implemented in the CIVA platform developed by CEA/LIST to deal with planar defects: the geometrical theory of diffraction (GTD) and the Kirchhoff approximation (KA). These two approaches...

2007
Norman Bleistein

We collect recent ideas on transforming integral operators for imaging/inversion that use quotients of wave fields into operators that use products of wave fields; that is, transforming deconvolution-type operators into correlation-type operators. The transformation avoids evaluation of extremely large or extremely small numbers; hence, the designation “computer-friendly.” For this author, “inv...

2014
J. Bahrdt U. Flechsig W. Grizolli F. Siewert

The current status of the software package PHASE for the propagation of coherent light pulses along a synchrotron radiation beamline is presented. PHASE is based on an asymptotic expansion of the Fresnel-Kirchhoff integral (stationary phase approximation) which is usually truncated at the 2 order. The limits of this approximation as well as possible extensions to higher orders are discussed. Th...

2012
F. Ticconi N. Pierdicca

Models for scattering of electromagnetic waves from random rough surfaces have been developed during the last two centuries and the scientific interest in the problem remains strong also today due to the importance of this phenomenon in diverse areas of science, such as measurements in optics, geophysics, communications and remote sensing of the Earth. Such models can be categorised into empiri...

1991
D. C. Bertilone

The first and second Rayleigh-Sommerfeld diffraction theories, together with the Kirchhoff diffraction theory, are widely used in the formulation of optical diffraction problems [ 1 ]. They arise in the context of the half-space boundary-value problem of scalar wave theory; all sources of the optical field are assumed to be located in the Z~< 0 half-space, and the Z > 0 half-space is taken to b...

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