Quantitative evaluation of scattering properties of surface defects

摘要

The surface is scanned in two dimensions using a laser spot of defined size and intensity distribution. The scan raster point distance is smaller than the spot dia. Regularly reflected laser light is absorbed by a light trap. An optical scattered light collection system with large aperture feeds the light scattered at a surface or vol. defect to a receiver. The scattered light measurement values (4) for each defect produced by the receiver are summed at least one-dimensionally to yield a scattered light measurement value sum, depending on defined threshold conditions allowing only measurement values corresp. to a defect typical signal characteristic, and with a sufficient number of summands, to be summed.