Nonspherical particles with reflectance symmetry with respect to the scattering plane (particle is identical to its mirror image) have a diagonal scattering matrix and consequently do not depolarize an incoming linearly polarized plane electromagnetic wave with electric vector either parallel or perpendicular to the scattering plane. They behave like a sphere as far as the depolarization is concerned, and consequently they cannot be distinguished from spheres using usual remote sensing depolarization techniques.
© 1977 the Optical Society of America
Petr Chýlek , "Depolarization of electromagnetic radiation scattered by nonspherical particles," J. Opt. Soc. Am. 67, 175-178 (1977)