FIELD: marking of objects. SUBSTANCE: method involves directing laser beam 12 to surface of object 14 made from opaque material. Energy of beam absorbed by object surface is sufficient to develop localized stresses in object at points spaced from object surface without evident changes on this surface. Localized stresses are normally invisible by naked eye, but may become visible in polarized illumination. It is unlikely that marking applied by mentioned method will be detected or imitated or removed by potential violator. EFFECT: increased efficiency and simplified method. 23 cl, 6 dwg
