Automatic testing system for smooth surfaces - has limited surface field illuminated by imaging illuminated diaphragm onto surface

摘要

The light reflected by the surface according to the law of reflection does not fall into the observation optical system, but is absorbed by a light trap. The light-scattering structures within the illuminated field of the surface are imaged by means of an observation optical system and the resultant contrasting image of the surface is decoded by conventional optoelectrical methods. Several illuminating beam paths (1, 2, 3, 4) illuminate the same field of the surface at different azimuth and height angles. The surface image is converted into electrical signals and faulty points are detected by a threshold discriminator.