Null-field method with distributed

In the following analysis we summarize the basic concepts of the null-field method with distributed sources. The distributed vector spherical wave functions are defined as... 

The use of distributed vector spherical wave functions improves the numerical stability of the null-field method for highly elongated and flattened layered particles. Although the above formalism is valid for nonaxisymmetric particles, the method is most effective for axisymmetric particles, in which case the 2 -axis of the particle coordinate system is the axis of rotation. Applications of the null-field method with distributed sources to axisymmetric layered spheroids with large aspect ratios have been given by Doicu and Wriedt [50]. 

The null-field method is used to compute the T matrix of each individual particle and the T-matrix formalism is employed to analyze systems of particles. For homogeneous, composite and layered, axisymmetric particles, the null-field method with discrete sources is applied to improve the munerical stability of the conventional method. Evanescent wave scattering and scattering by a half-space with randomly distributed particles are also discussed. To extend the domain of applicability of the method, plane waves and Gaussian laser beams are considered as external excitations. 

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