Piquero Sanz, Gemma MaríaMejías Arias, Pedro MiguelMartínez Herrero, María Rosario2023-06-202023-06-201995-03-150030-401810.1016/0030-4018(95)00012-Whttps://hdl.handle.net/20.500.14352/58853© 1995 Elsevier Science B .V. The research work leading to this paper was supported by the Comisión Interministerial de Ciencia y Tecnología of Spain, under Project No. TAP93-211. We thank José Aranda for his valuable suggestions concerning the conditions for the number of extremals of four-order polynomials. We also thank an anonymous referee for pointing out to us some misleading aspects concerning the classification scheme in the former version of this paper.The behaviour of the kurtosis parameter of a partially coherent beam that freely propagates is investigated. A general classification scheme of light beams is given in terms of the number of extremals of the kurtosis in free space. Propagation through ABCD optical systems is also considered and a number of general properties of the kurtosis parameter are provided concerning the relationship between the extremals of the kurtosis and the position of the beam waist.engjournal articlehttp://dx.doi.org/10.1016/0030-4018(95)00012-Whttp://www.sciencedirect.comopen access535Wigner Distribution FunctionFirst-Order Optical-SystemsABCD-LawMomentsLightÓptica (Física)2209.19 Óptica Física