title: Generalization of the geometric description of a light beam in radiometry and photometry.
abstract: Radiometric and photometric quantities rely on a geometric description of the beam subtended by a source and a receptor. In this paper, a generalization of this description is proposed as the product of the apparent size of the source times the receptor angular extent, whatever the natures of these elements: point, line, surface, or volume. The obtained flux density per geometric extent expressions are then applied to the determination of the irradiances induced in the near field and far field by a rectilinear source represented as a point source, a line source, and a surface source.
authors.affiliation: Material Physics and Mechanics Department, Prime Institute, University of Poitiers, CNRS UPR 3346, Poitiers, France. lionel.simonot@univ‑poitiers.fr
authors.forename: Lionel
authors.initials: L
authors.lastname: Simonot
authors.forename: Pierre
authors.initials: P
authors.lastname: Boulenguez