共查询到18条相似文献,搜索用时 413 毫秒
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提出了一种将任意入射波束因子用矢量波函数展开的方法,根据波束在球坐标系中的展开形式,以及球谐矢量函数与非球坐标系的波矢量函数之间的关系,推导出任意入射波束在相应坐标系中的波束因子的理论表述形式.以椭球坐标系为例,介绍了将离轴的入射波束,用椭球矢量波函数展开的波束因子求解方法,此方法还可应用于柱坐标、椭柱坐标系中波束因子的求解,为研究粒子对任意入射波束的散射打下了基础.
关键词:
波束因子
广义米理论
光散射 相似文献
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基于面积分方程的矩量法及其快速算法研究了复杂含核粒子对任意入射贝塞尔波束的散射特性.将零阶贝塞尔束的矢量解和坐标系旋转理论相结合,推导出任意入射贝塞尔波束电磁场分量的数学表达式.根据等效原理,建立了求解具有任意形状和复杂内部结构含核粒子散射问题的面积分方程.对贝塞尔波束任意入射下一些复杂含核粒子的散射进行了数值模拟,结果表明:贝塞尔波束入射时的微分散射截面要小于平面波入射时的微分散射截面,且随着半锥角的减小而增大;当波束中心的位置远离粒子中心时,微分散射截面会减小;微分散射截面对波束的入射角非常敏感.这为激光对微粒的探测、诊断以及操纵技术提供有益帮助. 相似文献
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离轴多层球对高斯波束的光散射 总被引:2,自引:2,他引:0
根据广义米氏理论,将入射的高斯波束按矢量球谐函数展开,获得了波束因子(展开系数)gmn,TM和gmn,TE的一般表达式。应用gmn的局域近结果和散射系数anm和bnm的迭代公式与算法,研究了多层有耗介质球的光散射。讨论了波束宽度与球形粒子的尺寸和位置对散射系数和散射强度角分布的影响。 相似文献
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非球形大气粒子对任意波束的电磁散射特性 总被引:9,自引:6,他引:3
研究大气中变形球状的气象粒子对电磁波以及激光的散射特性,采用广义米氏(Mie)理论,精确地求解在任意波束中大气粒子的散射强度,数值计算激光束腰位置对散射强度分布的影响,分析彩虹强度和散射角与变形球状粒子偏心率的关系,研究随着长短轴比例增加,彩虹强度峰值的偏移。计算结果表明雨滴在下降过程中,它在各个方向的光散射强度逐步减弱,即随着雨滴偏心率的增大,散射强度减少,彩虹角变大。对于激光入射,当粒子距离波束中心位置越远,粒子的散射就越弱,并且随尺寸参量增加,后向散射振荡的频率要大于前向散射,当束腰位置矢径的大小增加时,后向散射和前向散射强度均变小。 相似文献
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根据广义Mie理论,研究了具有轨道角动量拉盖尔-高斯光束(LGB)的空间传输特性以及单粒子散射特性.在单体球粒子对高斯光束散射研究的基础上,分析了在自由空间不同传输距离LGB光束的光强分布情况,在不考虑散射和波束相移关系的情况下,将LGB作为入射高斯光束,通过对波束入射时的散射衰减截面求解得到波束因子,利用矢量球谐函数对入射高斯波束进行展开,从而研究了单球粒子在在轴条件下对具轨道角动量高斯波束入射的散射问题.通过数值计算,讨论了散射强度及角分布在不同波束宽度情况下对其散射特性的影响,并与平面波的情况做了对比.结果表明,当波束束腰半径较小时,束腰半径对衰减率的影响较大,而当束腰半径远大于粒子半径时,接近于平面波的情况.
关键词:
广义Mie理论
轨道角动量
Laguerre-Gauss光束
单球粒子 相似文献
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Based on spherical vector wave functions and their coordinate rotation theory,the field of a Gaussian beam in terms of the spherical vector wave functions in an arbitrary unparallel Cartesian coordinate system is expanded.The beam shape coefficient and its convergence property are discussed in detail.Scattering of an arbitrary direction Gaussian beam by multiple homogeneous isotropic spheres is investigated.The effects of beam waist width,sphere separation distance,sphere number,beam centre positioning,and incident angle for a Gaussian beam with two polarization modes incident on various shaped sphere clusters are numerically studied.Moreover,the scattering characteristics of two kinds of shaped red blood cells illuminated by an arbitrary direction incident Gaussian beam with two polarization modes are investigated.Our results are expected to provide useful insights into particle sizing and the measurement of the scattering characteristics of blood corpuscle particles with laser diagnostic techniques. 相似文献
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Y.P. Han Z.W. Cui G. Gouesbet 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(13):1719-1727
An efficient numerical method based on the surface integral equations is introduced to simulate the scattering of Gaussian beam by complex particles that consist of an arbitrarily shaped host particle and multiple internal inclusions of arbitrary shape. In particular, the incident focused Gaussian beam is described by the Davis fifth-order approximate expressions in combination with rotation defined by Euler angles. The established surface integral equations are discretized with the method of moments, where the unknown equivalent electric and magnetic currents induced on the surfaces of the host particle and the internal inclusions are expanded using the Rao–Wilton–Glisson (RWG) basis functions. The resultant matrix equations are solved by using the parallel conjugate gradient method. The proposed numerical method is validated and its capability illustrated in several characteristic examples. 相似文献
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Xiaoping Zhu Tongqing Liao Huayong Zhang Rongqing Hui 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(15):1946-1950
Based on the generalized Lorenz–Mie theory that provides the general framework, an analytic solution to Gaussian beam scattering by a chiral sphere is constructed, by expanding the incident Gaussian beam, scattered fields and internal fields in terms of spherical vector wave functions. The unknown expansion coefficients are determined by a system of equations derived from the boundary conditions. For a localized beam model, numerical results of the normalized differential scattering cross section are presented. 相似文献
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U.K. Krieger P. Meier 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(11):1761-1765
We use single bi-sphere particles levitated in an electrodynamic balance to record two-dimensional angular scattering patterns at different angles of the coordinate system of the aggregate relative to the incident laser beam. Due to Brownian motion the particle covers the whole set of possible angles with time and allows to select patterns with high symmetry for analysis. These are qualitatively compared to numerical calculations. A small cluster of four spheres shows complex scattering patterns, comparison with computations suggest a low compactness for these clusters. An experimental procedure is proposed for studying restructuring effects occurring in mixed particles upon evaporation. 相似文献
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A.B. Evlyukhin S.I. Bozhevolnyi A.L. Stepanov J.R. Krenn 《Applied physics. B, Lasers and optics》2006,84(1-2):29-34
The operation of a micro-optical beam splitter for surface plasmon polaritons (SPP’s) formed by lined up scatterers is modeled
and studied in the framework of a vectorial dipolar approach for multiple SPP scattering by equivalent non-spherical nanoparticles.
It is shown that the inclusion of anisotropic polarizability of individual scatterer in the vectorial dipolar model of multiple
SPP scattering allows one to obtain, in some cases, quantitative agreement between modeling and experimental results. As an
example, we apply this approach to model an SPP beam-splitter formed by a chain of spheroidal particles. The dependencies
of the splitting efficiency on the shape of particles, the incidence angle and the waist of an incident SPP Gaussian beam
are considered. It is found that the efficiency is very sensitive to the shape of scatterers and the angle of SPP beam incidence.
Comparison of numerical results with experimental data shows good agreement with respect to the particle shape and incident
angular dependences.
PACS 02.70.-c; 71.36.+c; 78.68.+m 相似文献
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The study of light scattering by various particles is an active and important subject of research with myriad practical applications. During the years the scattering of plane wave by various particles has been investigated extensively. In recent years, with the development of laser sources and the tremendous expansion of their application, there has been a growing interest in the study of light scattering by various particles illuminated by a focused Gaussian beam. Since the analytical methods are only suitable for the analysis of Gaussian beam scattering by some regular particles, for complex particles with arbitrary shape and structure, one has to resort to the numerical methods. In this article, we review the recent numerical investigation on the scattering of Gaussian beam by systems of complex particles, including arbitrarily shaped conducting particles, dielectric particles, composite particles with inclusions, as well as random discrete particles and fractal soot aggregates. The essential formulations of the proposed numerical methods are outlined and the numerical results for some complex particles are also presented. This review is expected to provide useful help for the study of the interaction between the laser beams and the complex particles. 相似文献
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Stephen RA 《The Journal of the Acoustical Society of America》2000,107(3):1095-1102
Gaussian beams provide a useful insonifying field for surface or interface scattering problems such as encountered in electromagnetics, acoustics and seismology. Gaussian beams have these advantages: (i) They give a finite size for the scattering region on the interface. (ii) The incident energy is restricted to a small range of grazing angles. (iii) They do not have side lobes. (iv) They have a convenient mathematical expression. The major disadvantages are: (i) Insonification of an interface is nonuniform. The scattered field will depend on the location of the scatterers within the beam. (ii) The beams spread, so that propagation becomes an integral component of the scattering problem. A standard beam parameterization is proposed which keeps propagation effects uniform among various models so that the effects of scattering only can be compared. In continuous wave problems, for a given angle of incidence and incident amplitude threshold, there will be an optimum Gaussian beam which keeps the insonified area as small as possible. For numerical solutions of pulse beams, these standard parameters provide an estimate of the smallest truncated domain necessary for a physically meaningful result. 相似文献