Processing and Recognition of Two-Coordinate Reference Marks Images in Scanning Probe Microscopy

The article is devoted to the problem of automatic positioning of a scanning probe microscope to a studied region after probe replacement, sample surface treatment, etc. As an auxiliary tool for positioning, it is proposed to use reference marks indicating directions of the probe displacement to the investigated region. The considered pattern of reference marks is a cross. A method of detection of reference marks in the image by analyzing the surface curvature is described. An algorithm of recognition of reference marks based on the structural analysis of positions of singular points (local extrema of curvature) is proposed. Analysis is performed for selected pairs of singular points with specific length and angle of inclination. For selected pairs, parallel transfer parameters are calculated. If reference marks are present in the frame, these parameters are ordered along a straight line, which is a qualitative criterion of recognition of reference marks.