Simulation and Application of Light Scattering Properties for Scatterers with Large Aspect Ratios

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2014-12-02

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Abstract

For scatterers with axial or N-fold rotational symmetry, the T-matrix is one of the most efficient techniques to obtain the scattering properties. Extended boundary condition method (EBCM) and invariant imbedding T-matrix method (II-TM) are currently two of the most effective realizations of the T-matrix. The T-matrix of the scatterers with the rotational symmetry will be fully or partially decoupled between different azimuthal components, which can dramatically increase calculation efficiencies.

However, the ill-conditioned problem will occur for the EBCM whereas memory requirements and time consumption will be exponentially increased for the II-TM when scatterers have large aspect ratios (the ratios of the heights to the characteristic widths of the scatterers). The many-body iterative T-matrix method (MBIT), which uses the T-matrix and many-body techniques, is developed and generalized to target the homogeneous and inhomogeneous scatterers with large aspect ratios.

For infinite scatterers with one dimension periodicity, a semi-analytical solution instead of the iterative technique has been obtained by extending the application of the MBIT method to infinite number of sub-units. The semi-analytical solution of a scatterer with 1-D periodicity can be treated as an proxy and the limit of the corresponding finite scatterer with extreme large aspect ratios. For oceanic diatom scatterers, which have chain structures in preferential orientations, the MBIT method is applied to get the scattering properties, which can be the indicators of scatterer orientations, compositions, and shapes.

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