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MICROPATTERN ANTI-COUNTERFEITING IMAGES
Chris Neuzil writes: I saw a story in the July 25, 2013 issue of Nature that mentions the use of optical science against counterfeiting of paper money and labels on high-end products. The way things are going, PCGS may want to use it in their slabs. Microscopic markings that are too small to be reproduced by standard printers can give rise to optical illusions, and could be used to mark authentic banknotes or luxury-brand goods. Jürgen Brugger, Victor Cadarso and their group at the Swiss Federal Institute of Technology in Lausanne fabricated microscopic lines in rows or spirals (pictured, left) by patterning pixels in gold using ultraviolet light. When an array of tiny cylindrical lenses is laid over the lines, interference patterns produce images (pictured, right) of letters and other symbols. Copying these patterns, or moirés, would be difficult, the researchers say, because even micrometre-sized blemishes visibly distort the illusion.
Another journal I came across has an article on this study, and it includes a nice video of the images in action. Check it out.
-Editor
To read the complete article, see:
Micro-optical method thwarts counterfeiting
(www.rdmag.com/news/2013/07/micro-optical-method-thwarts-counterfeiting?et_cid=3399527&et_rid=472507257&type=cta)
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