Discussion of a physical optics method and its application to absorbing smooth and slightly rough hexagonal prisms

摘要: Abstract Three different mathematical solutions of a physical optics model for far field diffraction by an aperture due to Karczewski and Wolf are discussed. Only one them properly describes can, applying Babinet's principle, be used the corresponding plane obstacle, further approximation, particle. Studying absorbing scatterers allows closer investigation external component because transmission is negligible. The has been improved on two aspects: (i) To apply based two-dimensional apertures more accurately three-dimensional objects, size parameter dependent volume obliquity factor introduced, thus reducing slightly overestimated side scattering computed objects. (ii) compensate simplifications in underlying [26] cross polarisation implemented. It improves reflection small particle facets. 2D patterns P11, –P12/P11 P22/P11 their azimuthal averages rough hexagonal prisms fixed orientation obtained compared with results from discrete dipole approximation. For orientations where shadowing not negligible, phase functions using new method incident beam divided into sub-beams triangular sections. intersection points three sub-beam edges prism define vertices triangle, which treated tracer as incidence-facing facet. This ensures that facing but shadowed crystal facets or regions thereof do contribute functions. captures much fine detail contained DDA. important speckle can characterizing roughness particles such ice crystals.