Methods are described for determining the refractive indices of dielectric films and substrates and the thickness of the film. The determination makes use of a single measured distribution of monochromatic, specular reflectance as a function of incidence angle. The methods are based on certain properties of the reflectance maxima and minima, which properties are deduced from electromagnetic theory. Either perpendicular-polarized or parallel-polarized light may be employed; the latter has some advantage, in that it provides a cross check on one of the results and also facilitates the treatment of very thin films.
M. RUIZ-URBIETA, E. M. SPARROW, and E. R. G. ECKERT, "Film Thickness and Refractive Indices of Dielectric Films on Dielectric Substrates," J. Opt. Soc. Am. 61, 1392-1396 (1971)