双球粒子对任意入射单波束及双波束的散射

基于广义Lorenz-Mie理论,研究了双介质球粒子对任意角度入射波束的散射.将入射波束用球矢量波函数展开,推导了双介质球形粒子对任意入射单波束的散射方程;将该方法进一步推广,研究了双波束任意入射时的情况.以Gauss波束为例,对以上理论进行了数值验证,比较分析了单波束及双波束任意入射时散射特性随入射方向、球心距等参数的变化关系.     

双球粒子对任意入射单波束及双波束的散射

基于广义Lorenz-Mie理论,研究了双介质球粒子对任意角度入射波束的散射.将入射波束用球矢量波函数展开,推导了双介质球形粒子对任意入射单波束的散射方程;将该方法进一步推广,研究了双波束任意入射时的情况.以Gauss波束为例,对以上理论进行了数值验证,比较分析了单波束及双波束任意入射时散射特性随入射方向、球心距等参数的变化关系. 关键词： 广义波束因子 双球粒子 Gauss波束     

Scattering of shaped beam by a conducting infinite cylinder with dielectric coating

Based on the generalized Lorenz–Mie theory (GLMT), which provides the general framework and expansion of the incident shaped beam in terms of cylindrical vector wave functions, an analytic solution to the electromagnetic scattering by coated infinite cylinders is constructed for arbitrary incidence of a shaped beam. As an example, for a tightly focused Gaussian beam propagating perpendicularly to the cylinder axis, the scattering characteristics that obviously demonstrate the three-dimensional nature are described in detail, and numerical results of the normalized differential scattering cross section are evaluated.     

Gaussian beam scattering by a chiral sphere

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.     

离心球对高斯波束的光散射及应用

基于广义米氏理论研究了在轴离心球对高斯波束光散射特性.入射高斯波束的波束因子用积分区域近似法计算,散射场的展开系数由矢量球面波函数的加法定理并求解边界条件得到.以离心球为模型研究了单核生物细胞对高斯波束的散射特性并给出了相关数值模拟,讨论了离心距、波束的束腰半径和核的大小对散射强度角分布和散射、消光系数的影响.     

任意形状凸粗糙物体高斯光束相干散射研究

研究了任意形状凸粗糙物体对高斯光束的相干散射特性。由平面波谱展开法推导出粗糙面高斯波束散射场表达式．并根据物理光学近似和稳相法原理得到相干散射截面的理论公式。与平面波解不同的是,在公式中引入了波束因子这一表征波束作用的重要参量,该参量与束腰半径、束腰中心与物体中心距离和物体照射面积以及入射、散射方向有关。最后数值计算了1．06μm激光波束对粗糙球的散射,分析了波束因子．介电常量和极化状态对红外激光相干散射截面的影响,重点讨论了波束因子的变化规律。分析表明．当波束半径远大于物体尺寸时,波束入射的结果可退化到平面波情况。     

理论模拟有核细胞对高斯光束偏振散射特性的影响

利用双层球形粒子模拟了有核细胞;根据广义米理论(GLMT),对入射激光束(高斯光束)利用矢量球谐函数进行展开;利用分离变量法研究了有核细胞对高斯光束的散射特性的影响.数值计算了高斯光束正入射时,斯托克斯散射矩阵中各元素的角分布,并与平面波入射情况进行了比较.     

粗糙体目标激光束散射场的互相关函数统计特征

依据高斯波束体目标散射特征,研究了粗糙体目标高斯波束散射场量的互相关函数统计特征。在激光波束入射下,通过数值方法讨论圆球类目标、不同半径、不同材料、不同入射波束极化等条件下,散射场量的互相关函数随散射角变化情况。数值计算结果表明:金属薄膜材料比非金属镀漆材料互相关函数量值要大,金属材料球体目标的后向散射互相关函数值较大,而非金属镀漆材料球体互相关函数值较小。材料表面的粗糙度和目标尺寸对互相关函数影响较大,而入射光的极化方式对相关函数有影响但影响较小。     

Calculations of Infrared Laser Beam Scattering from Rough Dielectric Objects

The coherent and incoherent scattering cross sections of Infrared Laser Gaussian beam scattering from arbitrarily shaped convex dielectric objects with rough surfaces are investigated by using plane wave spectrum method and physical optics approximation. In the paper, the infrared laser scattering cross sections of rough sphere are calculated at 10.6 m , and the influence of the beam size, permittivity, and polarization as well as roughness parameters is analyzed numerically. When the beam size is much larger than the size of object, the results in the paper can reduce to those of an incident plane wave. On the other hand, for the case of roughness statistical parameter close to zero, only the forward scattering has a parent difference compared with the result of gaussian beam scattering from smooth sphere.     

二维高斯波束对多层球粒子电磁散射的解析解

基于矢量波函数在球和柱坐标系中表达式之间的转换关系,提出了一种求解球坐标系中二维高斯波束波形因子的方法,得到了二维高斯波束波形因子在球坐标系中的解析公式.结合广义米理论推导了在轴二维高斯波束入射多层球粒子的电磁散射的解析解,并对散射强度随散射角的分布进行了数值模拟,结果与平面波入射情况进行了比较. 关键词： 矢量波函数 波形因子 电磁散射 广义米理论     

Scattering of on-axis polarized Gaussian light beam by spheroidal water coating aerosol particle

Small particle light scattering can produce light with polarization characteristics different from those of the incident beam. An analytical solution to the scattering by a spheroid with inclusion for an on-axis polarized Gaussian beam incidence is provided within the generalized Lorenz-Mie theory framework. The shapes of the inclusion can be spherical, confocal spheroid, or non-confocal spheroid. The Muller scattering matrix elements are computed for plane wave incidence or Gaussian light beam incidence. The effect of the size and shape of the inclusion or the coating on the polarized Oaussian light scattering characteristics by a spheroidal water coating aerosol Darticle are commlted and a,nalvzed.     

Scattering of shaped beam by an arbitrarily oriented spheroid having layers with non-confocal boundaries

An approach to express an incident shaped beam with respect to an arbitrarily oriented spheroidal particle having layers with non-confocal boundaries is presented. To overcome the difficulty of non-confocal boundary conditions connected with different spheroidal coordinate systems, a theoretical procedure is developed to deal with the non-confocal boundary conditions by virtue of a transformation for vector wave functions. The unknown coefficients of scattered and internal electromagnetic fields are determined by solving a system of linear equations derived from the boundary conditions and relations between the spheroidal vector wave functions and spherical ones. Numerical results of the normalized scattering cross section for a two-layered non-confocal prolate spheroid are evaluated. PACS 42.25.Fx; 42.25.Bs     

The scattering fields for a spherical target irradiated by a plane electromagnetic wave in an arbitrary direction

The relation between corresponding trigonometric functions in two rotating coordinate systems is presented. The transformation formula for a vector in the two rotating spherical coordinate systems is obtained. The scattering fields for a spherical target irradiated by a plane electromagnetic wave in an arbitrary direction are derived. These fields in a particular case retrogress to those available in the literature. The obtained results have great potential in practical applications.     

Scattering from a Multi-Layered Sphere Located in a High-Order Hermite-Gaussian Beam

Scattering of a high-order Hermite-Gaussian beam by a multi-layered sphere is analyzed. The incident high- order Hermite-Gaussian beam field is expressed by the complex-source-point method and expanded in terms of spherical vector wave functions. The beam shape coefficients of the Hermite-Gaussian beam are obtained. Under electromagnetic field boundary conditions, coefficients in the expressions of scattering fields are derived. Results of the numerical calculation of scattering intensity are presented. The effects of the particle parameters and beam parameters on scattering intensity are discussed in detail.     

Gaussian beam scattering from arbitrarily shaped objects with rough surfaces

The scattered field of Gaussian beam scattering from arbitrarily shaped dielectric objects with rough surfaces is investigated for optical and infrared frequencies by using the plane wave spectrum method and the Kirchhoff approximation, and the formulae for the coherent and incoherent scattering cross sections are obtained theoretically based on geometrical optics and tangent plane approximations. The infrared laser scattering cross sections of a rough sphere are calculated at 1.06 μm, and the influence of the beam size is analysed numerically. It is shown that when the beam size is much larger than the size of the object, the results in this paper will be close to those of an incident plane wave.     

离轴多层球对高斯波束的光散射

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。     

Gaussian beam scattering from arbitrarily shaped objects with rough surfaces

Abstract

The scattered field of Gaussian beam scattering from arbitrarily shaped dielectric objects with rough surfaces is investigated for optical and infrared frequencies by using the plane wave spectrum method and the Kirchhoff approximation, and the formulae for the coherent and incoherent scattering cross sections are obtained theoretically based on geometrical optics and tangent plane approximations. The infrared laser scattering cross sections of a rough sphere are calculated at 1.06 μm, and the influence of the beam size is analysed numerically. It is shown that when the beam size is much larger than the size of the object, the results in this paper will be close to those of an incident plane wave.     

对称型闪耀光栅的矢量模态理论

本文将满足均匀矢量亥姆霍兹方程的标准矢量波函数作为基矢对对称型闪耀光栅槽内、外的电磁场分别进行矢量模式和矢量平面波展开。然后通过在槽内外分界面上的场耦合条件得到一组振幅系数方程组。从方程组中求解出相应的振幅系数,就可研究光栅的衍射场分布。该方法适用于对称型闪耀光栅对任意入射方向、任意偏振态入射场衍射问题的研究。在K_2=0入射情况下,其振幅方程组与已发表的文献[6]相同。