A METHOD AND APPARATUS FOR DETERMINING DISTANCE BETWEEN TWO SPACED APART SURFACES

摘要

A method for determining distance between two spaced apart surfaces comprises: sampling values of an interference spectrum produced by reflections of frequency components of white light from the respective surfaces to produce a first array of sampled values of intensity of the interference spectrum and corresponding values of wavelengths of the reflected frequency components of the white light, computing an approximate value of the optical distance do between the surfaces as a function of the wavelengths of two of the reflected frequency components of the white light from the first array transforming the first array into a second array of the sampled values of intensity of the interference spectrum and values of the inverse of the wavelengths of the corresponding reflected frequency components of the white light, and computing at least one further approximate value of the optical distance between the surfaces.