Washington, August 27:

After six decades in which the venerable dollar never changed its look, the US currency has undergone a slew of makeovers. The m-ost amazing is yet to come.

A new security thread has been approved for the $100 bill, and the change will cause double-takes. The new look is part of an effort to thwart counterfeiters who are armed with ever-more sophisticated computers, scanners and color copiers.

The $100 bill (worth about euro73) features the likeness of Benjamin Franklin and is the most frequent target of counterfeiters operating outside the US. The operation of the new security thread looks like something straight out of the Hogwarts School of Witchcraft and Wizardry. This magic, however, relies on innovations produced from decades of development.

It combines micro-printing with tiny lenses — 650,000 for a single $100 bill. The lenses magnify the micro-printing in a truly remarkable way. Move the bill side to side and the image appears to move up and down. Move the bill up and down and the image appears to move from side to side. “It is a really complex optical structure on a microscopic scale. It ma-kes for a very compelling high security device,” said Douglas Crane, a vice-president at Crane & Co.

The Dalton, Massachusetts-based company has a $46 million (euro34 million) contract to produce the new security threads.

Larry Felix, director of the Bureau of Engraving and Printing, confirmed details about the security thread.

The redesign of the $100 is about one-third of the way complete.