We use the T-matrix method, as described by Mishchenko [Appl. Opt. 32,
4652 (1993)], to compute rigorously light scattering by finite circul
ar cylinders in random orientation. First we discuss numerical aspects
of T-matrix computations specific for finite cylinders and present re
sults of benchmark computations for a simple cylinder model. Then we r
eport results of extensive computations for polydisperse, randomly ori
ented cylinders with a refractive index of 1.53 + 0.008i, diameter-to-
length ratios of 1/2, 1/1.4, 1, 1.4, and 2, and effective size paramet
ers ranging from 0 to 25. These computations parallel our recent study
of Light scattering by polydisperse, randomly oriented spheroids and
are used to compare scattering properties of the two classes of simple
convex particles. Despite the significant difference in shape between
the two particle types (entirely smooth surface for spheroids and sha
rp rectangular edges for cylinders), the comparison shows rather small
differences in the integral photometric characteristics (total optica
l cross sections, single-scattering albedo, and asymmetry parameter of
the phase function) and the phase function. The general patterns of t
he other elements of the scattering matrix for cylinders and aspect-ra
tio-equivalent spheroids are also qualitatively similar, although noti
ceable quantitative differences can be found in some particular cases.
In general, cylinders demonstrate much less shape dependence of the e
lements of the scattering matrix than do spheroids. Our computations s
how that, like spheroids and bispheres, cylinders with surface-equival
ent radii smaller than a wavelength can strongly depolarize backscatte
red light, thus suggesting that backscattering depolarization for nons
pherical particles cannot be universally explained by using only geome
tric-optics considerations. (C) 1996 Optical Society of America