Reciprocity Relations And Equivalence Theorem Of Light Waves On Weak Scattering

The theory of light waves on weak scattering,which discusses the relationship between the structural characteristics of a scattering medium and the statistical optical properties of its scattered field,has attracted substantial attention of foreign and domestic researchers due to its potential applications in areas such as remote sensing,detection,and medical diagnosis.Over the last decade,great progresses have been made in the study of this theory.For example,the scatterers have been generalized from the quasi-homogeneous medium to a variety of media,including the multi-particle system medium,the anisotropic medium,the semisoft boundary medium and so on;the incident light waves have been generalized from the general plane wave to various common light beams,such as stochastic electromagnetic beams,partially coherent beams,plane wave pulse beams and so on.These studies have greatly promoted the development of the theory of light waves on weak scattering.In this dissertation,the far-zone optical properties of light waves on scattering from media,including the reciprocity relations and the equivalence theorem,are investigated within the accuracy of the first-order Born approximation and the far field approximation.The chapters of this dissertation are arranged as follows:In Chapter 1,the introduction of this dissertation is presented.Firstly,the research background and the current situation of this topic are briefly introduced.Then,by introducing the four parts of the research process of light waves on weak scattering,the research goal and the significance of this dissertation are further presented.In Chapter 2,the theoretical basis of this dissertation is presented,including the scattering theory of scalar light wave,the common scattering media models and the description of their scattered fields,and the scattering theory of vector light wave.In Chapter 3,the reciprocity relations of an electromagnetic light wave on scattering from a quasi-homogeneous anisotropic medium are investigated.Firstly,mathematical expressions of the far field of vector light wave on scattering from quasi-homogeneous anisotropic medium arederived theoretically.Then,by making use of the relation of Fourier transform pair of normalized correlation coefficient,two reciprocity relations between the scattered field in the far zone and the scattering medium are obtained.After that,by assuming that both the strength function and the normalized correlation coefficient of the quasi-homogeneous anisotropic medium obey the Gaussian distributions,the distribution characteristics of the normalized spectral density and that of the spectral degree of coherence of the scattered field in the far zone of the medium are numerically simulated under the condition that the degree of polarization of incident vector light wave is a constant.In Chapter 4,the equivalence theorem of scalar light waves on scattering from different media is investigated.Firstly,the possibility for two different multi-particle system media to produce scattered field with identical optical properties is investigated.By taking the collection of identical determinate Gaussian-centered particles with quasi-homogeneous distribution as an example,specific conditions for these two different multi-particle system media to produce scattered field with identical normalized spectral density or with identical spectral degree of coherence are presented.Then,the possibility for two media with different types to produce scattered fields with identical optical properties is investigated.Through the analysis of far-zone behaviors of light waves scattered from a Gaussian-centered quasi-homogeneous medium and from a collection of identical determinate Gaussian-centered particles with quasi-homogeneous distribution,specific conditions for these two media with different types to produce scattered fields with identical normalized spectral density or with identical spectral degree of coherence are presented.In Chapter 5,the work of this dissertation is summarized.Firstly,the research conclusions and the innovations of this dissertation are presented.Then,the plans for prospect work are put forward.