Scattering Of Anisotropic Particle System From Plane Wave/Gaussian Beam

Due to wide application in the areas of grain size analysis, biomedical engineering,environmental testing and so on, the interactions of electromagnetic (light) wave withregular and irregular particles have always been an important and hot internationalresearch topic. Recently, the scattering problems of a plane wave by single anisotropicdielectric spherical particle and multiple isotropic dielectric spherical particles havebeen diffusely reported. However, the scattering characteristics of two or multipleuniaxial anisotropic spherical particles and other shaped anisotropic particlesilluminated by an electromagnetic (light) wave are still new and merit problems andneed further research.In this thesis, we principally investigated scattering properties of single uniaxialanisotropic dielectric sphere, spheroid, multiple uniaxial anisotropic dielectric sphericalparticles illuminated by a plane wave (arbitrary incident direction); and the radiationforce and torque exerted on a uniaxial anisotropic dielectric spherical particle by anarbitrary direction incident Gaussian beam. The main contributions and results of thethesis are as follows:1. The expansion formats and expansion coefficients of two polarization modelsplane wave with an arbitrary propagating direction are derived. The angulardistributions of radar cross section (RCS) of larger particle size parameter are analyzednumerically when the plane wave incident along the primary optical axis. The effects ofpermittivity and permeability tensor elements, lossy and lossless dielectric, incidentangle and azimuth angle on the RCS of a uniaxial anisotropic sphere illuminated by anarbitrary direction incident plane wave are numerically analyzed in detail.2. Scattering of an off-axis Gaussian beam by a uniaxial anisotropic sphere isstudied. Applying orthogonal and recursive relationships of associated Legendrefunction and trigonometric function, analytical expressions of the transverse and axialradiation forces exerted on a uniaxial anisotropic dielectric spherical particle by anoff-axis incident Gaussian beam are derived. The effects of permittivity tensor elementson axis radiation forces are numerically analyzed by an on-axis Gaussian beam. Theinfluences of the anisotropic absorbing dielectric, sphere radius, beam waist width,distance between sphere center and beam waist center on the axial and transverseradiation forces exerted on a uniaxial anisotropic dielectric sphere by an off-axisGaussian beam are discussed in detail.3. Using spherical vector wave functions (SVWFs) and their coordinate rotation theory, the field of a Gaussian beam with an arbitrary propagating direction expanded interms of the SVWFs is derived. The beam shape coefficients and its convergenceproperty are discussed in detail. Analytical expressions of the transverse and axialradiation forces exerted on a uniaxial anisotropic dielectric spherical particle by anoff-axis obliquely incident Gaussian beam are derived. The changes of axial, transverseand resultant radiation forces with the incident angle and azimuth angle are numericallyanalyzed. Applying orthogonal and recursive relationships of associated Legendrefunction and trigonometric function, analytical expressions of the transverse and axialradiation torque exerted on a uniaxial anisotropic dielectric spherical particle by anoff-axis obliquely incident Gaussian beam are derived. The effects of location of beamcenter and incident angle on the radiation torque exerted on a uniaxial anisotropic by anoff-axis obliquely incident Gaussian beam are numerically discussed.4. Based on generalized multi-spheres Mie theory (GMM), scattering of anarbitrary direction incident plane wave and Gaussian beam by a random aggregate ofhomogeneous isotropic spherical particles is investigated. The interactive scatteringcoefficients and total scattering coefficients are derived by using the addition theorem ofSVWFs. The angular distributions of total scattering intensity of several kinds ofaggregate spherical particles with different configurations are calculated. The effects ofbeam waist width, sphere separation distance, sphere number, beam center positioningand incident angle for a Gaussian beam with two polarization models incident onvarious shaped clusters spherical particles are numerically analyzed. The scatteringcharacteristics of two kinds of shaped red blood cells and soot aggregation particlesilluminated by an arbitrary direction incident Gaussian beam with two polarizationmodels are numerically discussed in detail.5. The scattering of two interacting homogeneous uniaxial anisotropic spheres withparallel primary optical axes illuminated by a plane wave propagating parallel to theoptical axes is investigated. The analytical expressions of scattering coefficients arederived through the continuous boundary conditions on which the interaction of thebispheres is considered. The effects of the size parameter, the uniaxial anisotropicabsorbing dielectric and the sphere separation distance on the scattering characteristicare numerically analyzed. Based on scattering results of uniaxial anisotropic bispheres,an exact analytical solution is obtained for the scattering of a plane wave with arbitrarypropagation directions by a random aggregate of interacting homogeneous uniaxialanisotropic spherical particles with parallel primary optical axes. The interactivescattering coefficients and total scattering coefficients are derived. The effects of the incident angle and azimuth angle on RCSs of several types of collective uniaxialanisotropic spheres are numerically analyzed in detail. The characteristics of theforward and backward RCSs in relation to the incident wavelength are also numericallystudied.6. The scattering of a uniaxial anisotropic rotation dielectric spheroid illuminatedby a plane wave propagating parallel to the primary optical axis is firstly investigated intheory. Utilizing the expansion method of internal fields of a uniaxial anisotropic spherein terms of SVWFs and complete relationship of SVWFs and spheroidal vector wavefunctions, the expansion formats of the electromagnetic fields in a uniaxial anisotropicprolate rotation spheroid in terms of prolate spheroidal vector wave functions arederived. The corresponding expansion coefficients of internal fields are given.Expansion formats and coefficients of the incident plane wave field in terms of prolatespheroidal vector wave functions are also derived by using the expansion of a planewave field in terms of SVWFs and the relationship of SVWFs and spheroidal vectorwave functions. Applying a smart method dealing with boundary condition of spheroidwhich is proposed by Asano et al., the equation set on the scattering coefficients andunknown expansion coefficient are obtained. The analytical expressions of thescattering coefficients are derived by solving this equation set.