Research On Discrimination Method For Morphology Of Particles Based On Polarization Characteristics

Particle field which is the collection of small particles exists widely in daily life.Characterization of particles provides strong and firm support to atmospheric monitoring,microbial study and industrial preparation.The morphology of particles is one of the most important index of the property of particles.In this thesis,particles are divided into homogeneous spherical particles,inhomogeneous spherical particles and homogeneous non-spherical particles.Light scattering models of particles are built based on classical electromagnetic theory and finite element analysis.The relation of morphology of particles and polarization property of light scattered by them is revealed.The change of the polarization state of the light is interpreted by geometric approximation(GOA)model.Considering to the demand of the solution of wave equation and the practical measurement,when linearly polarized light along an arbitrary propagation direction incident to non-spherical particles(take ellipsoid as example)with arbitrary orientation,transformation of the parameters in absolute coordinate system and particle coordinate system is carried out,and the solution methods of the field distribution of light scattered by particles is proposed in absolute coordinate system,which is different from the traditional scattering model.The characteristics of the light scattered by spherical particles,inhomogeneous coated particles and homogeneous ellipsoidal particles are simulated by using those scattering models,and the validity of the scattering models is verified.Comparing the different characteristics of the three different kinds of particles,a method of morphology discrimination for single particle in multi-phase dispersion systems based on the polarization characteristics is proposed.T1.The scattering model of spherical particles is established,the distribution of light scattered by spherical particles is simulated,the results are compared with those of he fringes in the interference particle imaging(IPI)system as reference,the experimental verification of the differences between the polarization characteristics of light scattered by spherical particles and ellipsoidal particles is completed.The work of this thesis is of great significance for the discrimination of the morphology of particles in particle fields.Main work of this thesis is: Mie scattering and the validity of the model is verified.The polarization characteristics of the light scattered by spherical particles is analyzed.2.Taking the coated particles as an example,the polarization characteristics of the light scattered by non-uniform particles are analyzed.The scattering model of coated particles is established,distribution of the light scattered by coated particles is simulated,the results are compared with those of Aden-Kerker scattering,and the validity of the model is verified.3.Taking the ellipsoidal particles as an example,the polarization characteristics of the light scattered by non-spherical particles are analyzed.The polarization characteristics of the light scattered by coated particles is analyzed.The scattering model of the particle coordinate system is established,the distribution of light scattered by the ellipsoid is simulated and the results are compared with those of S.Asano scattering.The transformation of the parameters in absolute coordinate system and particle coordinate system is carried out.4.The ellipsoidal particles is prepared.The polarizing devices are combined with traditional interference particle imaging(IPI)system.The experimental optical system used in the verification of the polarization preserving characteristics of the light scattered by spherical particles and the polarization changing characteristics of the light scattered by non-spherical particles is built.The experiment revealing the difference between the polarization characteristics of light scattered by spherical particles and ellipsoidal ones is completed with the fringes in IPI system as reference.The method of discrimination between spherical particles and ellipsoid particles based on polarization characteristics of the light scattered by them is proposed.The applicability of the method proposed in this thesis used to discriminate the morphological of particles is demonstrated.