METHOD AND DEVICE FOR MARKING AN OBJECT, METHOD AND DEVICE FOR DETECTING A MARKING ON AN OBJECT AND A DATA CARRIER

摘要

A method for applying a marking to an object. The object has an object surface, a first layer and at least one second layer. The second layer lies beneath the first layer. The method comprises: irradiating a first portion of the object surface with a first laser beam with a first wavelength; irradiating a second portion of the object surface with a second laser beam with a second wavelength different from the first wavelength. For at least one of said first and second wavelength the absorption of at least one of said layers differs such that said layers are differently marked with respect to each other.