Light Scattering by an Arbitrary Oriented Cylinder in the Wentzel-Kramers-Brillouin Approximation: 1. Extinction and Absorption Efficiency Factors

摘要

Formulas for the extinction and absorption efficiency factors of an optically "soft" (|m – 1| 1, where m = n + iΧ is the relative refractive index of the cylinder) circular finite-length circular cylinder irradiated by arbitrarily polarized light for incident arbitrary polarized light in the direction at any angle to the cylinder symmetry axis are derived in the Wentzel–Kramers–Brillouin (WKB) approximation. It is shown analytically that the expressions for the extinction efficiency factor of an arbitrary-shape homogeneous particle in the scalar form of the WKB approximation and in the anomalous-diffraction (AD) approximation are identical with an accuracy of up to the sign of Χ. It is noted that the expression for the absorption efficiency factor of an arbitrary-shape homogeneous particle in the scalar WKB approximation reduces to the corresponding formula in the AD approximation only if the particle optical softness is significant (|m – 11→0).