This process of “unphotocopying” the ink involves the use of short laser pulses to erase words and images by heating the printed material to the point of vaporisation.
The unprinting approach used by laser device is fundamentally very different from typical laser printers. In a laser printer, a laser is used to give individual “pixels” on a piece of paper a positive charge. Negatively-charged toner particles stick to these positive regions, and a heat source then fuses the toner to the paper.
On the other hand, the laser unprinter uses very short pulses of laser light – on the order of picoseconds; (there are one billion picoseconds in a millisecond), which are then used to vaporise the toner, or “ablate” in scientific terms. The trick to erase the toner ink without damaging the paper is applied by using green laser light that is readily absorbed by dark toner, but which passes harmlessly through cellulose fibers in paper.
The researchers have told that the process is workable with commonly used papers and toner inks and is more eco-friendly than recycling. However, there is said to be a need of advance research to bring a formally introduce the product into the market.
This study has been published in the Proceedings of ‘The Royal Society A’ journal and reported by New Scientist, the engineers have acknowledged that they are pioneer to think of this idea. But they also have indicated that the others who have initially tried it found to have either damaged or discolored the paper or both in the mean process.
Toshiba already markets a laser printer able to erase ink, but it has been noted that the device is dependent on its own “e-blue” ink to function.
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