Hybrid method in light scattering by an arbitrary particle.

A hybrid method for light scattering by an arbitrary particle using the scattering-order formulation of the coupled dipole method is described. An arbitrary particle is divided into two or more segments, and the field scattered by the particle is obtained from the fields scattered by each segment together with the field due to interactions among segments. An exact or approximate theory is used to calculate the scattered field from each segment, and interactions are included using the scattering-order formulation of the coupled dipole method. Calculations show that for certain particles, this hybrid approach can require fewer computations and give more accurate results than the scattering-order method.

Theoretical factors in modeling polarized light scattering by arbitrary particles.

The coupled dipole method has been used to model the S(34) scattering matrix element for particles of arbitrary shape. Comparison of the results of the approximate method with the exact theory for a sphere shows that the size of the units required for S(34) is much smaller than the size required for calculating S(11) with similar accuracy. Model calculations for chiral particles show that the S(34) matrix element depends sensitively on the exact shape, size and optical properties of the scatterer.

Light scattering by an arbitrary particle: the scattering-order formulation of the coupled-dipole method.

The field scattered by an arbitrary particle modeled as an array of coupled dipoles can be expressed as an infinite series in terms of scattering orders. The fields of a given scattering order can be calculated from those of the previous order. When the series converge, the approximate method agrees well with the exact theory for a sphere. The maximum size of the dipolar array that can be used with the method as well as the number of terms required for convergence depends on the relative refractive index and the shape of the particle.

Light scattering by an arbitrary particle: a physical reformulation of the coupled dipole method.

The coupled dipole model of scattering by an arbitrary particle has been reformulated in terms of internal scattering processes of all orders. This formalism readily permits physical interpretation of observables and provides a rational basis for making computations more efficient. The calculation of scattering parameters can be simplified by appropriately terminating the infinite series at any order as well as by restricting the summations over the dipolar interaction terms within each order. Large particles can be partitioned into segments so that the scattered field is a superposition of the fields from the segments together with fields due to interactions among dipoles in different segments.