Аннотация:A novel device, the fast-scanning acousto-optic spectrophotometer, was used to measure the in situ reflectance of a thin film during deposition. The reflectance data, which was measured at different film thicknesses and over a wavelength region from 400 to 1100 nm, was used to study the refractive index profile of inhomogeneous ZrO2 films. This data was subsequently analyzed using a homogeneous thin film model to derive an 'effective' refractive index profile.