Phase matrix and cross sections for single scattering by circular cylinders: a comparison of ray optics and wave theory.

The phase matrix and several quantities for single scattering by an arbitrarily oriented circular cylinder are formulated by using the approximation of ray optics, which includes geometrical reflection and refraction plus Fraunhofer diffraction; then the effects of polarization are considered. Computations were made using electromagnetic wave theory and ray optics approximations for m = 1.31-0.0i and 1.31-0.li. Results by these methods approach one another as the ratio of the cylinder's circumference to the incident wavelength increases. One of two ray optics approximations proposed requires less computation time than wave theory. The applicability of the ray optics approximation is dependent on the orientation of the cylinder relative to the incident light as well as the size parameter and, moreover, dependent on what quantity for single scattering is compared.