Patent ID: 7973931

Claim:
A method for determining a position of an edge bead removal line of a disk-like object having an edge area and an alignment mark on the edge area, comprising the following steps: imaging the edge area on a line-by-line basis, where it is assumed that said edge area comprises at least the edge bead removal line, wherein a detector line of a camera is used to determine an intensity profile I on a line-by-line basis of the imaged edge area comprising the edge bead removal line; detecting the edge area; detecting the alignment mark; plotting a local intensity maxima I′ max of the intensity profile I as points in a diagram having an x axis, on which a relative position of an individual point imaged with the detector line of the camera is plotted within an associated image line of the detector line, and having a y axis, on which a line number of the associate image line is plotted for each point; forming segments in the diagram, wherein each segment comprises a set of points, and intensities of the points of the segments are within a predetermined interval, wherein the x coordinates of the set of points of each segment are within a predetermined other interval; combining at least some of the segments into at least one segment set wherein the x coordinates of the points of the segments for the respective segment set are within an interval, and wherein segments remaining after the combining of the at least some of the segments form one-element segment sets; fitting each segment set into one respective ellipse; and determining a quality criterion q ges for each ellipse, so as to determine whether or not each ellipse in question belongs to the edge bead removal line.