SSS 2012-03-15

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Every year, about 10 million tons of paper winds up in American landfills and incinerators, which is not only wasteful¹ but adds CO2 to the atmosphere. Recycling helps, but even that material has to be repulped and paper-ized before you can use it to print out that recipe you’ll never make. But what if you could wipe the page clean and use it again?

 

Light amplification² by stimulated³ emission⁴ of radiation to the rescue. A new study shows that laser light can erase⁵ the toner from a piece of printed paper. The approach appears in the Proceedings⁶ of the Royal Society A. 

 

Taking a page from the art-restoration handbook, scientists sampled a variety of light sources to see if any could be used to strip the ink from laser-printed documents without damaging or discoloring the paper. UV and infrared⁷ were too harsh. But a bright green laser applied⁸ in 4 nanosecond pulses vaporizes the print, leaving paper that looks as good as new.

 

Such unprinters will probably run about 30,000 bucks⁹, so they probably won’t catch on for home use. But people in the recycling world might find that the green laser fits the bill—for making paper that’s really green.

 

Thanks for the minute, for Scientific American 60 Second Science, I am Karen Hopkin~

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