Identification documents employing laser-etched or -engraved features are detailed, together with methods for their manufacture. Tactile effects produced by the laser-processed features may be felt by touch, helping confirm the authenticity of such documents....http://www.google.es/patents/US7661600?utm_source=gb-gplus-sharePatente US7661600 - Laser etched security features for identification documents and methods of making same
Laser etched security features for identification documents and methods of ...
