Share Email Print

Proceedings Paper

Infrared technique for decoding of invisible laser markings
Author(s): Heinz Haferkamp; Peter Jaeschke; Johannes Stein; Martin Goede
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

Counterfeiting and product piracy continues to be an important issue not only for the Western industry, but also for the society in general. Due to the drastic increase in product imitation and the request for plagiarism protection as well as for reducing thefts there is a high interest in new protection methods providing new security features. The method presented here consists of security markings which are included below paint layers. These markings are invisible for the human eye due to the non-transparency of the upper layers in the visible spectral range. However, the markings can be detected by an infrared technique taking advantage on the partial transparency of the upper paint layers in the IR-region. Metal sheets are marked using laser radiation. The beam of a Nd:YAG-laser provides a modification of the surface structure, resulting in dark markings due to the annealing effect. After coating of the laser-marked material, the markings are invisible for the bare eye. In order to read out the invisible information below the coating, an infrared reflection technique is used. The samples are illuminated with halogen lamps or infrared radiators. Many coating materials (i. e. paints) show a certain transparency in the mid-infrared region, especially between 3 - 5 micrometers . The reflected radiation is detected using an IR-camera with a sensitivity range from 3.4 - 5 micrometers . Due to the different reflection properties between the markings and their surrounding, the information can be detected.

Paper Details

Date Published: 15 March 2002
PDF: 8 pages
Proc. SPIE 4710, Thermosense XXIV, (15 March 2002); doi: 10.1117/12.459560
Show Author Affiliations
Heinz Haferkamp, Laser Zentrum Hannover e.V. (Germany)
Peter Jaeschke, Laser Zentrum Hannover e.V. (Germany)
Johannes Stein, Laser Zentrum Hannover e.V. (Germany)
Martin Goede, Laser Zentrum Hannover e.V. (Germany)

Published in SPIE Proceedings Vol. 4710:
Thermosense XXIV
Xavier P. Maldague; Andres E. Rozlosnik, Editor(s)

© SPIE. Terms of Use
Back to Top