RESUMO
Laser surface authentication (LSA) is a technique for authenticating optically rough surfaces based on the intensity of diffusely scattered light. The degradation in the LSA signature over linear and rotational displacement is examined. Randomly roughened glass surfaces with roughness amplitudes ranging from 0.4 microm to 3 microm and correlation lengths from 16 microm to 45 microm are examined experimentally, showing that the average size of the surface feature has a negligible impact on the rate of LSA signature degradation. The average size of the surface features is shown to have a greater effect on the fractional intensity of the variations in diffuse light and on the quality of LSA signature match.
RESUMO
We have found that almost all paper documents, plastic cards and product packaging contain a unique physical identity code formed from microscopic imperfections in the surface. This covert 'fingerprint' is intrinsic and virtually impossible to modify controllably. It can be rapidly read using a low-cost portable laser scanner. Most forms of document and branded-product fraud could be rendered obsolete by use of this code.
