Device for detection of blemishes in the surface of symmetrical planar objects

摘要: In a detector of blemishes in the surface planar object, or web, which is symmetrical about an axis plane beam radiation from laser scanning station focussed onto and caused to scan transversely while object move past parallel symmetry. The arranged be located such that crosses it at predetermined time into scan, datum signal generated. During each when leading edge surface, between half taken for traverse so can calculated used turn off before trailing crossed by beam.