title: Generalization of the rainbow Airy theory to nonuniform spheres.
abstract: Rainbow techniques permit measurement of refractive indices, and hence the temperatures of liquid droplets through determination of the absolute angular position of a rainbow interference image in space. The Airy theory, which is commonly used to explain the rainbow effect, permits the determination of a unique refractive-index value, even in the presence of nonuniformities in the droplet. An extension of this theory to spheres that exhibit internal refractive-index gradients is proposed. The case of burning droplets is considered as an example of such spheres, and the results obtained are successfully compared with those presented in the literature.
authors.affiliation: Von Karman Institute for Fluid Dynamics, Chaussée de Waterloo 72, B1640 Rhode Saint Genèse, Belgium. vetrano@vki.ac.be
authors.forename: Maria Rosaria
authors.initials: MR
authors.lastname: Vetrano
authors.forename: Jeronimus Petrus Antonius Johannes
authors.initials: JP
authors.lastname: van Beeck
authors.forename: Michel Léon
authors.initials: ML
authors.lastname: Riethmuller