Authentication by Laser

Mark Henderson, Document "DNA" can outfox forgers, Times Newspapers Limited (July 28, 2005):

British scientists have found that a laser scanner can read microscopic imperfections on paper or plastic surfaces that are almost impossible to modify or forge. These provide a signature when exposed to the laser, say researchers at Imperial College London, Durham University and the University of Sheffield. It remains recognisable even when scrubbed in water, scorched or scribbled on, making it a suitable way to confirm that documentation, from passports to credit cards, is genuine.

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Details are published in the journal Nature today.