title: Influence of small inhomogeneities on the spectral characteristics of single thin films.
abstract: It is well known that the spectral transmittance and reflectance of a thin film can be influenced by even small inhomogeneities or variations in its complex refractive-index profile. Formulas are derived that describe the theoretical variation of the spectral characteristics for small changes in the refractive index and the extinction coefficient of a homogeneous thin film. These formulas, accurate to the first order in the change in the complex refractive index, are compared with exact calculations for a number of different types of inhomogeneities. It is shown that specific qualitative features in the refractive-index profile of a nearly homogeneous thin film frequently can be determined from an examination of the change in the spectral transmittance and reflectance at normal incidence.
authors.forename: A V
authors.initials: AV
authors.lastname: Tikhonravov
authors.forename: M K
authors.initials: MK
authors.lastname: Trubetskov
authors.forename: B T
authors.initials: BT
authors.lastname: Sullivan
authors.forename: J A
authors.initials: JA
authors.lastname: Dobrowolski