Slashdot Mirror
The Laser Unprinter
MrSeb writes "You've heard of laser printers — and now a team of researchers from the University of Cambridge in England has created a laser unprinter that can remove ink without damaging the paper. Despite both methods using lasers, their (un)printing approaches are fundamentally very different. In a laser printer, a laser is used to give individual 'pixels' on a piece of paper a positive charge (a separate heat source is used to fuse toner). In the laser unprinter, picosecond pulses of green laser light are used to vaporize the toner, or ablate in scientific terms. The primary goal of unprinting is to cut down on the carbon footprint of the paper and printing industries. Manufacturing paper is incredibly messy business, with a huge carbon footprint. Recycling paper is a good step in the right direction, but it still pales in comparison to unprinting. In a worst-case scenario, The University of Cambridge unprinting method has half the carbon emissions of recycling; best-case, unprinting is almost 20 times as efficient."
Cyan, Magenta, Yellow and blacK, actually.
If you're going to be pedantic, you have to be right too.
It's fairly easy to tell the difference between a signature that was printed with an inkjet and an actual pen being held by a human (forget using a laser, that's even more obvious). Quite aside from the ink having a different composition for a printer than it does for a pen, there's the actual physical indent on the paper caused by the pen.
If they can take the paper you actually signed, and remove the original printing without affecting your signature, it becomes a lot harder to tell.
one major flawed assumption: that the "unprinted' paper will be used in printers instead of recycled paper. As a professional laser printer repair tech, I can tell you right now that won't happen. Even paper that has just been run through the printer once and left on a neat pile is significantly more likely to cause printer jams than fresh paper that's never been used. Any "savings" (whether carbon footprint, money, or otherwise) over using recyled paper will be quickly consumed by the extra repair trips.
There is no -1 Disagree mod. Slashdot.org/faq defines mod options. USE IT.
Spouse in the forest sciences here,
A minor point, but the huge carbon footprint of paper manufacturing is (at least in Scandinavia) deceptive. While paper factories do burn large amounts of wood to boil the fibres into pulp, the emitted carbon is a part of the natural cycle: it gets picked up again by the trees in the mandatory-by-law reforesting step. As long as the forest is kept at a constant size, the net carbon emission is pretty much zero.
(The sulphite and nitrogen emissions are another story, however.)