Study On The Spatial Polarization Distribution Of Light Scattered By Particles Based On Lorenz-Mie Theory

As one of the classical detection methods,particle scattering technology has been widely used in meteorology,oceanography,biomedicine and environmental science.By studying the spatial distribution characteristics of the polarization state of light scattered by particles,we can get more information about the characteristics of particles,which is one of the important development trends of particle scattering theory and practical light scattering technology.The main work of this paper is as follows: two types of scattering scenes,cloud droplets and tiny oil droplets in water,are modeled and calculated,and the influence of each input parameter on the scattering results is discussed.Based on traditional polarization state characterization methods and previous experience in characterizing the polarization state of scattered light,this paper summed up a set of characterization methods for the spatial distribution of polarization states suitable for scattering problems.In addition,in view of the influence of the scattered beam range on the detection result,which is a practical problem that used to be ignored in the field of scattering,this paper introduced the solid angle parameter to measure the range of the scattered beam intercepted by the detection surface and gave the correspondence between the total polarization state obtained by the detection surface and the range of the scattered beam.The numerical calculation method of the total polarization state of the scattered beam is derived and the influence of the range of the scattered beam on the detection result is also discussed.Through the above study on the spatial polarization distribution of particle scattering,we have obtained the following conclusions for the light scattering of spherical particles:(1)When the input parameters are determined,the spatial distribution of the polarization state is determined by the scattering angle and the azimuth angle.The scattering angle plays a leading role in determining the amplitude and phase relationship between the two orthogonal electric vectors of the scattered light,while the azimuth angle plays an auxiliary role in re adjusting the amplitude of the two orthogonal electric vectors,so that the polarization state of the scattered light changes with the change of the spatial position.(2)The change of the long-to-short axis ratio of the ellipsoidal particle will change the curvature distribution of the particle boundary,so that the distribution of the polarization state of the scattered light will change accordingly.The increase in the diameter of the spherical particles will reduce the intensity of the change in the polarization state of the scattered light with the scattering angle.The increase of the refractive index of the spherical particles will increase the non-uniformity of the spatial distribution of the polarization state of the scattered light,and increase the depolarization ratio of the forward scattering zone.Increasing the wavelength of the incident light not only increases the overall intensity of the scattered light,but also weakens the fluctuation of the polarization state of the scattered light in the forward scattering zone.(3)The increase in the range of the scattered light beam intercepted by the detection surface will reduce the fluctuation degree of the four Stokes vector components of the received scattered light with the scattering angle.This means that improper selection of the detection surface will cause part of the characteristic information of the particles to be masked.