Santarsiero, MassimoPiquero Sanz, Gemma MaríaDe Sande, J. C. G.Korotkova, O.Martínez Herrero, RosarioGori, Franco2023-06-222023-06-222022-05-010146-959210.1364/OL.458764https://hdl.handle.net/20.500.14352/71557© Copyright 2022, Optica Publishing Group. Fundings. Ministerio de Economía y Competitividad (PID2019-104268GB-C21).The degree of coherence and the intensity distribution on the axis of the beam radiated by a planar partially coherent source of the Schell-model type are investigated. We present an expression for the on-axis cross-spectral density which is valid for a very general Schell-model source, with the only constraint that the intensity distribution across the source is Gaussian. Furthermore, we show that such an expression takes very simple analytical forms for several commonly used degrees of coherence of the source.engjournal articlehttp://dx.doi.org/10.1364/OL.458764https://opg.optica.orgopen access535Longitudinal spatial coherenceLengthÓptica (Física)2209.19 Óptica Física