Optical film thickness measuring device for measuring two-layer film thicknesses using spectral reflectance

摘要

The optical film thickness measuring device comprises a spectral reflectance measuring device for measuring spectral reflectance of two layers of a two-layer optical film, a memory device for storing, as reflectance data theoretical values of optical thickness and refractive index of each layer of the two-layer optical film as well as those of reflectance of the two-layer optical film, a data selecting device for selectively reading out the reflectance data corresponding to the measuring wavelengths for measured values of spectral reflectance and a film thickness deciding means for determining thickness of each layer of the two-layer optical film on the basis of the selected reflectance data and the measured spectral reflectance. This optical film thickness measuring device is capable of quickly and accurately measuring thickness of each layer of two-layer optical films.