Wavelength correction for thin film measurement in a microscopic white light spectral interferometer

A film measuring method based on a new data model using a home-made microscopic white light spectral interferometer is proposed. It can improve the measuring accuracy of the thin film thickness at different OPDs. The influence of the effective thickness caused by the beam splitter prism in a Michelson interferometric objective is analysed and found not to be negligible while calculating the thin-film thickness. The linear relationship between the effective thickness and the optical path difference (OPD) can be removed by introducing a wavelength correction which made the effective thickness measurement more accurate. Some experiments on the film standard with calibrated film thickness showed that introducing a wavelength correction made the film thickness measurement more accurate at different OPDs.