Outsmarting Counterfeiters With High-Tech Bills

George, for 68 years we knew ye. It didn't matter whether the economy was overheating or plummeting; you, Abe, Alexander, and the rest of the guys were always there, gracing our bills steadfastly, unchanged.

Well, no longer.

Later this month, Federal Reserve Banks will begin distributing redesigned $100 bills. Next year, a redesigned $50 bill is expected to appear, then the $20 bill roughly a year after that, and so on. The new money represents the first major overhaul of American currency since 1928. But the change isn't driven by aesthetics; it's driven by technology.

Color copiers, color scanners, and computer printers are getting so good the federal government is worried that counterfeiters will have a field day. ''We attempt to stay ahead of improvements in technology,'' says Larry Felix, spokesman for the Bureau of Engraving and Printing in Washington, D.C. ''At the speed with which technology is advancing, it is clear that the Department of the Treasury will be changing its currency designs much more frequently.''

The new $100 bill incorporates a number of new security features that should make American currency much harder to counterfeit. The Bureau of Engraving and Printing is eager to make some of these features known, partly to educate the public, partly to discourage the bad guys. Other security features the bureau is keeping to itself. The cost of printing today's notes is 3.7 cents apiece; the security features will add a fraction of a cent to the cost.

The most obvious change in the new $100 bill is Benjamin Franklin's portrait. It's slightly off-center and nearly twice the size of the old one. The background of the portrait uses concentric fine-line printing - curved lines so small that they're difficult for a scanner or color copier to reproduce.

A similar technique - called microprinting - has been added. Within the numeral ''100'' in the lower left-hand corner of the bill, ''USA 100'' is printed in tiny, tiny letters. Ben Franklin's lapel will also contain the words ''United States of America.'' The microprint is extremely difficult to copy without blurring.

That's a problem with today's copying and scanning technology. It's still fuzzy at the finest levels of detail. Presumably, the machines' resolution will improve. Fortunately, the bureau is using a ''layered'' defense in the new bills. This means that even if counterfeiters crack the resolution problem, they still face other obstacles.

One of them is a security thread made of a special polymer that runs vertically through the bill. The thread is engineered to glow red when put under ultraviolet light, but a color copy of the bill won't glow at all. The new bill also includes a watermark on the right hand side of the bill. It can easily be seen when held up to light, but it doesn't reproduce on scanners or copiers.

My favorite feature is the color-shifting ink used on the bill's lower right-hand numeral ''100.'' Viewed straight on, the ''100'' looks green; at an angle, it changes to black. Cashiers should be able to detect a fake if the color on the bill doesn't change.

Soon, machines may do the job for them. This summer, The Standard Register Company in Dayton, Ohio, will introduce new machines able to verify documents quickly. Standard Register is a leading document-security firm. Using its technology, cashiers could run checks, gift certificates, and other documents through a machine that would immediately determine their validity.

Although the first-generation machines won't handle cash, Standard Register isn't ruling out the option for later versions.

So one day, a counterfeiter might not even be able to buy lunch without getting caught. George, I can almost see ye smirking.

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