Determining refractive index and thickness of thin films from wavelength measurements only

The dispersive refractive index n(λ) and thickness d of thin films are usually determined from measurements of both transmission and wavelength values. Many factors can influence transmission values, leading to large errors in the calculated values of n(λ) and d. A method is presented to determine n(λ) and d in the region where k2 ≪ n2 from wavelength values only. This entails obtaining two spectra, one at normal incidence and another at oblique incidence. The method yields values of n(λ) and d to an accuracy better than 1%.