Patent ID: 8553231
Filing Date: 2013-10-08
Classification: G01B

Abstract:
1. A method for determining the height of a number of spatial positions on a sample defining a height map of a surface through white light interferometry with a broadband light source, comprising for each spatial position: obtaining a correlogram during scanning of the surface through a focal plane of an objective using white light interferometry; and estimating the point of the correlogram where an amplitude of the correlogram is at its maximum, thus determining an approximation of the height of the spatial position on the sample represented by said correlogram, wherein estimating the point of the correlogram where the amplitude of the correlogram is at its maximum comprises: subjecting the correlogram to a Fourier transform; subjecting the Fourier transformed signal to a filter; subjecting the filtered signal to an inverse Fourier transform; and calculating the location of the centre of mass of the inversed filtered Fourier transformed signal.