Expanded description of electromagnetic arbitrary shaped beams in spheroidal coordinates, for use in light scattering theories: A review

During the last decade, a strong effort has been devoted to the development of a generalized Lorenz-Mie theory for spheroids illuminated by Gaussian beams, and more generally by arbitrary shaped beams. An important issue in such a framework concerns the expanded description of the illuminating beam, and particularly the evaluation of beam shape coefficients. Unfortunately, the effort in this field is located at the bridge of three streams, each one with different conventions and notations, making the access to the literature inconveniently difficult. The aim of the present paper is to review the different approaches published, and to establish in a clear way the relationships between them. Beside being a help to the newcomer, this paper also aims to set milestones for future works, particularly concerning the development, under current investigation, of a localized beam model in spheroidal coordinates.

► Expressions for beam shape coefficients in spheroidal coordinates are established. ► Relationships between expressions from several authors are provided. ► The paper is intended to facilitate the newcomer to enter the field of laser scattering by spheroids. ► Opportunity is taken to provide a few errata.