Infrared optical constant determination of weakly absorbing dielectric thin films.

Simple approximate relations are given for the reflectance of a weakly absorbing dielectric layer deposited as a quarter wave or a half-wave upon transparent and metallic substrates. These approximated relations are used in the infrared to calculate the optical constants n and k and the inhomogeneity partial differentialn of the index n of a material deposited as a thin film. A high degree of accuracy is sought for k. Two examples are given for ZnS and ThF(4) in the 3-11-microm spectral range.