Expressions are developed for the dielectric-needle limit for scattering by dielectric cylinders, and the domain of validity of these expressions (2% and 10% error contour diagrams) over the refractive-index—size-parameter (m—α) domain is elucidated.
M. KERKER, D. D. COOKE, and J. M. CARLIN, "Light Scattering from Infinite Cylinders. The Dielectric-Needle Limit," J. Opt. Soc. Am. 60, 1236-1239 (1970)