US Patent 7209858 Precision position determining method

A method for generating a surface profile of a microstructure. The profile is processed to determine positions of at least two edges and an approximate center point of the profiled surface. Segments of points on the determined profile are fit to a straight line centered at the approximate center point. A standard deviation of the fitted points is measured. The length and position of the segment are varied until a minimum standard deviation is determined and the process is repeated for segments having different lengths. The point is determined from the longest segment having a standard deviation approximately equal to the minimum standard deviation of all of the segment lengths.