METHOD FOR MARKING A MATERIAL BODY

摘要

The invention relates to a method for the application of a sign under the surface of a body (14), by directing a laser beam (12) to its surface for which the material of which the body (14) is made virtually is not transparent. The energy of the beam (12) absorbed by the material is sufficient to form local strains in the body (14) in a place found under the surface without any perceptible changes on it. The local strains formed are usually invisible for the naked eye, but they can become visible under polarized light. 15 claims, 6 figures