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Scratch-resistant Eyeglass Lenses
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It may seem hard to believe, but there was a time when eyeglasses actually were made of glass. Not only were they heavy, but if the person wearing them was hit with something, the lens would shatter and spew tiny, vision-threatening shards of glass. For that reason, in 1972, the U.S. Food and Drug Administration declared that all sunglasses and prescription lenses be shatter-resistant, which essentially compelled lens makers to shift to more durable plastic.

Plastic provided better optics and absorbed ultraviolet light better, but there was one problem: Plastic lenses were frustratingly easy to scratch. That's where NASA scientist Ted Wydeven of the agency's Ames Research Center came in. While working on a water purification system for spacecraft, Wydeven coated a filter with a thin, plastic film, using an electric discharge of an organic vapor. The resulting coating was surprisingly tough, and NASA used the concept to develop an abrasion-resistant coating for space helmet visors and aerospace equipment. In 1983, Foster-Grant, the sunglasses manufacturer, commercialized the scratch-resistant coating, and today, the majority of eyeglasses sold in the United States are outfitted with plastic lenses that last 10 times as long as the old ones [source: Space Foundation ].

Can you guess which NASA invention holds the title as the most licensed technology from the agency as of 2010? Read on to see if you guessed right.

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