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Printer Hardware Science

The Laser Unprinter 168

Posted by samzenpus
from the does-it-work-on-tattoos? dept.
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."
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The Laser Unprinter

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  • Fraud (Score:5, Insightful)

    by TubeSteak (669689) on Wednesday March 14, 2012 @05:53PM (#39358193) Journal

    I wonder what protections the banks will have to put in place to prevent fraud.
    And make sure you have a copy of any contracts you sign. Who knows what shenanigans someone can get up to by modifying the original.

  • by Anonymous Coward on Wednesday March 14, 2012 @05:54PM (#39358197)

    ...is avoiding paper in the first place, and instead using digital methods to distribute information.

  • by ard (115977) on Wednesday March 14, 2012 @05:56PM (#39358227)

    So what is the carbon footprint for powering the laser?

    Ah, electricity from nuclear power. Zero emissions. Unless for the Germans, who are dismantling their nuclear power stations and burn coal instead.

  • Re:Comparisons (Score:3, Insightful)

    by osu-neko (2604) on Wednesday March 14, 2012 @06:03PM (#39358283)

    I would bet that if you compared the carbon foot print of "Laser the sh*t out of it" with "Stuff it in a vat and let the microbes have a party", the current technology would win... it doesn't need much (if any) electricity.

    If you care about which particular microbes party, and that they party the way you want, I'm curious how you accomplish this without the electricity usually required to create and maintain the required controlled environment. I suspect you're vastly underestimating the effort required to do this, as well as vastly overestimating the power requirements of your typical laser.

  • by TarMil (1623915) on Wednesday March 14, 2012 @06:04PM (#39358295)

    Which is why both parties receive a copy of the contract...

  • Re:Comparisons (Score:5, Insightful)

    by MLCT (1148749) on Wednesday March 14, 2012 @06:08PM (#39358343)

    the current technology would win... it doesn't need much (if any) electricity

    Electricity isn't the major factor - total energy is what matters.

    Collecting tonnes of paper and transporting it to recycling centres, pulping, cleaning, processing, re-bleaching (we don't like blue-brown paper, we want white paper) and then transporting the finished paper back to where it is used. Calculate the energy in that.

    At work we almost exclusively use reams of recycled paper. Print something on it and then sometime later (occasionally minutes later) it goes into a recycling bin. That bin is emptied once a week and the paper will travel 20 miles to a local depot. Where it is recycled and turned into new paper I don't know - but what I do know is that the reams of recycled paper we buy will come from at least 400 miles away (and will have travelled that via a circuitous route involving suppliers, buyers and distribution warehouses). Taking the same bit of paper and running it through a unprinter for 20 seconds and then reuse. Energy wise I don't think there will be any contest, but the numbers would have to be crunched to prove it.

  • by Obfuscant (592200) on Wednesday March 14, 2012 @06:17PM (#39358419)
    The standard printer colors are cyan, magenta, yellow, and black. CMYK. CRT/LCD colors are RGB -- red, green, blue.

    The standard laser printer does not put a charge on paper, it puts a charge on a transfer roller that then transfers the toner to the paper. That toner is then melted onto the paper.

    Kodak (and others), used to make dye sublimation printers, where a sheet of plastic with dye on it was whacked with a laser to sublimate the dye directly onto the paper. This had the advantage of being something more than the typical "yes/no" "is there toner there" question, and thus resulted in much better color reproductions. No dithering was required. The major downside, besides cost of supplies, was that you were left with a negative image on the dye sheet, just like the old plastic film typewriters had.

    This system sounds like an incredibly wasteful and complicated process. You have to scan the paper to determine where there is toner and sublimate only those spots. If you miss by just that much, you'll char the paper and miss toner. If you put in a sheet of inkjet-printed paper, you'll burn the paper anyway.

    Making/recycling paper isn't that hard. This is silly.

  • Re:Comparisons (Score:2, Insightful)

    by Obfuscant (592200) on Wednesday March 14, 2012 @06:39PM (#39358597)

    Taking the same bit of paper and running it through a unprinter for 20 seconds and then reuse. Energy wise I don't think there will be any contest,

    Cost of making laser. Cost of maintenance on unprinter to keep the optical system aligned. Cost of "that unprinted paper looks like crap, I want this document reprinted on fresh paper". Cost of recycling entire unprinter when it wears out. Cost of eyepatches for office staff that try to unjam the unprinter. Cost of disability payments to retired office staff who tried to unjam it twice. Cost of fire department that shows up when someone tries to unprint an inkjet page and paper bursts into flame. Cost of disposing of unprinted toner (you can't just let the vapor out into the room, you know.)

  • Re:Fraud (Score:3, Insightful)

    by Em Adespoton (792954) <slashdotonly.1.adespoton@spamgourmet.com> on Wednesday March 14, 2012 @06:49PM (#39358687) Homepage Journal

    It isn't actually regular laser toner, however. Checks are printed with Magnetic Ink Character Recognition (MICR) toner which allows the routing number to be detected by a magnetic scanner.

    I think you mist the GP's point... most companies don't print the MICR -- that's done by their bank. They use a regular laser printer to print the date, value and the recipient. If the unprinter doesn't scrub the magnetic toner, that increases the risk of being able to just re-use someone else's cheques with a new date, value and recipient, but keep the signatures and MICR.

  • by afidel (530433) on Thursday March 15, 2012 @01:27AM (#39361247)
    THIS! Aerosolizing carbon black sounds like a really, really bad idea since it's a known carcinogen (HP got sued by workers in toner plants over exposure). Not to mention I can only imagine the paper jams from trying to use randomly handled paper (brand new reams cause enough problems).

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