DETERMINATION OF THE OPTICAL-CONSTANTS OF AN INHOMOGENEOUS TRANSPARENT LAF3 THIN-FILM ON A TRANSPARENT SUBSTRATE BY SPECTROSCOPIC ELLIPSOMETRY

The optical constants of a thin inhomogeneous transparent film of LaF3 on a transparent vitreous silica substrate have been determined by spectroscopic ellipsometry. To overcome the lack of accuracy in the spectroscopic-ellipsometry measurements of transparent samples, an achromatic compensator was used with a rotating-analyzer ellipsometer. As a result, we were able to determine the depth profile of the film and also determine the refractive index of LaF3 and its dispersion in the near-UV-visible region to the third decimal place, even though the film thickness was only lambda/4 (almost-equal-to 150 nm).