Transparent film thickness measurement by three-wavelength interference method: An extended application of Global Model Fitting algorithm

Conventional transparent film thickness measurement methods such as spectroscopy are basically capable of measuring a single point at a time, and the spatial resolution is limited. We propose a novel areal film thickness measurement method by extending the Global Model Fitting algorithm developed for three-wavelength interferometric surface profiling. It estimates the film thickness distribution from a color image captured by a color camera with three-wavelength illumination. The validity of the proposed method is demonstrated by computer simulations and actual experiments.