Patent ID: 6731380
Filing Date: 2004-05-04
Classification: G01B,G01N

Abstract:
A method for the simultaneous determination of a sample thickness L and index of refraction n, the method comprising:a) forming said sample with a first and a second surfaces, wherein the first and second surfaces are substantially locally flat; b) forming a radiation beam and impinging said radiation beam onto said sample at a first incidence angle A1 relative to an axis perpendicular to said first surface; c) reflecting said impinged radiation beam from said first and said second surfaces of said sample forming a first and a second reflected radiation beams; d) impinging said first and second reflected radiation beams on a detection device; e) measuring a distance d1 on said detection device between an impingement point of said first reflected beam and an impingement point of said second reflected radiation beam; f) altering said first incidence angle to a second incidence angle A2 and again measuring a distance d2 between an impingement point of a third reflected beam and an impingement point of a fourth reflected beam on said detection device; g) obtaining the sample thickness L and sample index of refraction n from the following equations: d1=[2.L/n].[sinA1/(1âˆ’(sin2A1)/n2)1/2] and d2=[2.L/n].[sinA2/(1âˆ’(sin2A2)/n2)1/2].