Far-zone Behavior Of Light Waves On Weak Scattering From Media

Light scattering,which investigates the interaction between light waves and media,has always been one of the important research topics.Considering its potential applications in the fields such as remote sensing,detecting,and medical diagnostics,the relationship between the statistical property of the scattered field and the structural characteristic of the scattering medium has long been attracted much attention.In this dissertation,the far-zone behavior of the scattered field has been discussed within the validness of the first-order Born approximation and the far field approximation.Furthermore,the spectral density,the spectral degree of coherence,and the correlation between intensity fluctuations of the scattered field have been investigated in detail.The dissertation could be elaborated on the following parts.In Chapter 1,the research background and research status of this dissertation have been introduced.Based on previous research work,the motivation and the significance of this dissertation are illustrated.Finally,content and structure of this dissertation are presented.In Chapter 2,there is some basic information for light waves scattering.It contains the scattering theory of scalar light waves,the scattering theory of electromagnetic light waves,several scattering media,and the correlation between intensity fluctuations.In Chapter 3,the far-zone behavior of scalar light waves on scattering from an anisotropic semisoft boundary quasi-homogeneous medium has been discussed.At first,a new model of scattering medium,named anisotropic semisoft boundary quasi-homogeneous medium,has been constructed.Later,the spectral density and the spectral degree of coherence of the scattered field have been studied.Based on the theory,some numerical results of spectral density and spectral degree of coherence have been given.It is shown that the spectral density of the scattered field is influenced by the boundary properties of the scattering medium,while the spectral degree of coherence of the scattered field is independent of the boundary properties of the scattering medium.However,both the spectral density and the spectral degree of coherence of the scattered field are influenced by the anisotropy of the scattering medium.In Chapter 4,spectral changes of scalar light waves on scattering from an isotropic medium with spectral dependence have been discussed.At first,the influence of the incident light waves on the refractive index of the scattering medium has been discussed.Then,the function of scattering potential of such kind of scattering medium has been produced,and the expression for spectral density of the scattered field has also been derived.Finally,the influence of different parameters of scattering medium on the spectral shifts and spectral switches has been investigated.It is shown that parameters of the scattering medium play an important role in the direction at which the spectral switch occurs.In Chapter 5,the HB-T effect of scalar light waves on scattering from a collection of particles is discussed.Firstly,the mathematical expression of correlation between intensity fluctuations in the scattered field has been derived.Next,the distribution of normalized correlation between intensity fluctuations in the scattered field is numerically simulated.It is shown that the correlation between intensity fluctuations in the scattered field is affected by structural characteristics of the scatterer.In Chapter 6,the correlation between intensity fluctuations of electromagnetic light waves on scattering from a collection of particles is investigated.The mathematical expression of correlation between intensity fluctuations in the scattered field is calculated in theory.And one can find that the normalized correlation between intensity fluctuations could be decomposed into two independent parts: One is only governed by polarization properties of the incident field,the other is only governed by structural characteristics of scattering medium.Then two special media,i.e.quasi-homogeneous-distributed particles collection and deterministic-distributed particles collection,are discussed.It is shown that,when particles have quasi-homogeneous distribution,its correlation between intensity fluctuations is not only affected by polarization properties of the incident field but also affected by structural characteristics of the scattering medium.However,when particles have deterministic distribution,its correlation between intensity fluctuations is only affected by polarization properties of the incident field.In Chapter 7,a brief summary of this dissertation is given.The main conclusions and innovations of this dissertation are presented.And some possible work is discussed.