Scattering Properties And Applications Of Complex Particle Systems Illuminated By Shaped Beam

Electromagnetic(optical) scattering of shaped beams by particles is an important international research topic, and widely applied in the areas of grain size analysis, biomedical engineering, environmental testing, and remote sensing of the universe. The scattering characteristics of an isotropic sphere and an isotropic infinite cylinder illustrated by a plane wave and a three dimension(3D) Gaussian beam have been vastly reported. However, the scattering characteristics of other shaped beams, and the anisotropic media as well, still require further discussion.Regarding the topic of the scattering properties of shaped beam by complex particle systems has great value and wide application, some work in this paper is done. The main work and results are as follows:1. The scattering coefficient formulas of Debye series of an infinite multi-layered cylinder in a 2D Gaussian beam are derived. With the recurrence relations of the Bessel functions and applying induction, the consistency between our results by Debye series and those by GLMT is proved. Numerical calculations are given. The effects of particle and beam parameters on the scattering intensities, and the relationship between Debye series and twin primary rainbow of a two-layered cylinder are discussed.2. Starting with the transform relations of spherical vector wave functions and cylindrical vector wave functions, based on the beam shape coefficients of a 2D Gaussian beam in the cylindrical coordinates, the on-axis and off-axis beam shape coefficients are deduced respectively. The method we provide avoids the complex integral calculation and greatly improves the computational efficiency. The incident, internal and scattering fields are all expanded in terms of the spherical vector wave functions. Combining with boundary conditions, scattering coefficients are obtained. Taking a droplet and a cell as examples, numerical calculations are given. The effects of the beam and particle parameters on the scattering properties are studied.3. The scattering characteristics of a Gaussian beam by an anisotropic sphere are explored. Based on the Fourier transform and spherical vector wave functions, the scattering and internal fields are expressed. Using the boundary condition, both the scattering and internal field coefficients are derived. Numerical calculations are presented for both on-axis and off-axis Gaussian beams respectively. The angular distributions of the scattering intensities are calculated and the effects of beam parameters and dielectric constant on the scattering properties are analyzed. The internal and near-surface field components are also discussed in detail. On the basis of this method, the scattering characteristics of a plasma-coated conducting sphere are analyzed as well.4. The scattering characteristics of a multi-layered sphere and a multi-layered cylinder are developed, respectively. The derivation of the relationship between the paraxial wave equation and the complex source points is given and proved. Based on the complex source points expressions of the multi-mode Gaussian beam field, with the spherical and cylindrical vector wave functions, the beam shape coefficients of the 2D and 3D Hermite Gaussian beams are obtained, and the scattering properties of a multi-layered sphere and a multi-layered cylinder are studied. The effects of particle and beam parameters on the angular distributions of scattering intensities in multi-mode Gaussian beam field are analyzed.5. On the basis of spherical vector wave functions and Monto Carlo(MC) method, the characteristics of scattering and transmission by a single charged sphere and multiple charged spheres are involved. The scattering coefficients of a single charged sphere are deduced. And with spherical vector wave functions and addition theorem, the scattering coefficients of multiple charged and uncharged spheres are derived. The sampling method of simulating a Gaussian beam in use of MC is provided. As an application, scattering characteristics of charged Carbon particles and ice crystals are calculated, and the effects of the charge quantity on the properties of scattering and transmission are discussed.