After six decades in which the venerable dollar never changed its look, the US currency has undergone a slew of makeovers. The most amazing is yet to come. A new security thread has been approved for the $100 bill, The Associated Press has learned, 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 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 makes 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 contract to produce the new security threads. Larry Felix, director of the Bureau of Engraving and Printing, confirmed details about the security thread in an AP interview. The redesign of the $100 is about one-third of the way complete. The bill is expected to go into circulation late next year. Starting in 2003, splashes of color have spruced up the $20 bill and other currencies. Those changes followed the addition of a first round of security features in the mid-1990s. Benjamin Franklin's latest makeover was delayed while the government searched for a hi-tech security device that would provide extra protection on the bill. The $100 bill represents more than 70 percent of the $776 billion in currency in circulation, two-thirds of which is held overseas. The new security thread is used on the Swedish 1,000 kroner note and has been selected by the government of Mexico for some higher denomination notes. Felix said many other devices expected to be included in the $100 redesign will be similar to features added over the past four years to the $20, $50 and $10 bills. That means subtle pastel colors on the currency and patches of micro-printing that are difficult to duplicate, along with a touchup on Ben Franklin's portrait. Originally there were no plans to redesign the $5 bill. That decision was reversed once counterfeiters started bleaching $5 bills and printing fake $100 bills over the bleached paper; certain security features were in the same location on both bills. The new $5 design will be made public on September 20 and will go into circulation early next year. "Counterfeiting is becoming highly organized and highly efficient," Felix said. He said some clandestine printing plants in Latin America and Eastern Europe have been caught counterfeiting not only the US currency but other countries' notes. The government says $118.1m. in counterfeit US currency was detected in 2006, an increase of 3.8% from 2005.