Method of detecting flaws on the surface of metal

摘要

A method of detecting minute flaws on the surface of a metal material is provided, which is constituted by the steps of directing a laser beam onto the surface of the metal material, reflecting a component of the beam directly reflected by the surface of the material by a reflector having a rough surface, and measuring the change in the quantity of light in the beam reflected by said reflector. Alternatively, a component of the laser beam directly reflected by the surface of the material and a component of the laser beam scattered by the metal surface are passed through a semitransparent filter having a rough surface, and the change in the quantity of light in the beam passed through the filter is measured.