Patent ID: 6392756
Filing Date: 2002-05-21
Classification: G01B

Abstract:
A method for optically determining a physical parameter of a thin film, said method comprising the following steps:a) providing a test beam; b) selecting a wavelength range &Dgr;&lgr; for said test beam; c) providing a complex substrate having at least two layers and a non-monotonic and appreciably variable substrate optical response over said wavelength range &Dgr;&lgr;; d) measuring said substrate optical response; e) depositing said thin film on said complex substrate; f) illuminating said thin film on said complex substrate with said test beam to obtain a total optical response comprising said substrate optical response and an optical response difference due to the presence of said thin film, wherein said complex substrate renders said optical response difference non-zero, non-monotonic and appreciably variable over said wavelength range &Dgr;&lgr;; and g) determining said physical parameter from said total optical response.