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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 More

The Laser Unprinter

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  • Fraud (Score:5, Insightful)

    by TubeSteak ( 669689 ) on Wednesday March 14, 2012 @04:53PM (#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.

    • Yeah, it's true.

      Use Gamemaker.

    • Re: (Score:1)

      by Anonymous Coward

      How is this any worse than high-precision scanners+photoshop+ high-precision printers?

      • Re:Fraud (Score:5, Informative)

        by realityimpaired ( 1668397 ) on Wednesday March 14, 2012 @05:24PM (#39358489)

        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.

        • 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).

          At this point, the signature on paper is just symbolic [wikipedia.org].

          On May 27, 2011, U.S. President Barack Obama became the first president to use an autopen to sign a bill into law.[4] While visiting France, he authorized the use of an autopen to create his signature which signed into law an extension of three key provisions of the USA PATRIOT Act

        • Okay but seriously, forging a signature really isn't that hard.

          In fact I'm 99.9999% certain you could put together a simple ink plotter style arm that would copy a signature exactly for cheap.

          There's a reason you've *always* been supposed to keep copies of this stuff

          • Re: (Score:2)

            by TheLink ( 130905 )
            It's harder to forge if you sign the stuff with PGP/GPG and print the entire thing out (including the PGP/GPG signature). Make sure you have time and date as part of the document to defend against replay attacks.

            But nobody really cares that much about security AND it isn't a big enough problem in real life. Otherwise a system for creating and checking such documents reliably and efficiently would be more common.

            A possible problem with the PGP/GPG method is if one day your private key is compromised, you're

        • Re: (Score:2)

          by ceoyoyo ( 59147 )

          A signed document that's been faxed is legal, so if you're relying on a signature....

          An unprinted page probably has all sorts of traces left. The hardest part about photoshopping a fax is making it look bad enough.

        • Re: (Score:2)

          by gl4ss ( 559668 )

          signatures are shit crap useless for authentication.

          look, that's the reason why you have witnesses on contracts that are worth a lot. and then, if all the other witnesses want to fraud you then you're fucked anyhow.

          I couldn't tell my signature from a fake anyhow.

      • Re:Fraud (Score:5, Interesting)

        by DittoBox ( 978894 ) on Wednesday March 14, 2012 @05:27PM (#39358509) Homepage

        Infinitely worse.

        Many companies buy check paper (complete with anti-fraud holographs, watermarks etc.), and then print on top of that using a regular laser printer. Being able to remove just the laser overprint.

        That having been said, it wouldn't take long for the check paper companies to begin making check paper that will fail upon being introduced to the green laser field.

        • Re: (Score:2)

          by ahecht ( 567934 )

          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.

          • Re: (Score:3)

            by Dahamma ( 304068 )

            He wasn't talking about the ink used to create the check, he was talking about the ink used to print the name and amount on the check. I'm sure you can see the potential issues with that...

          • Re: (Score:3, Insightful)

            by Em Adespoton ( 792954 )

            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.

          • Re: (Score:2)

            by afidel ( 530433 )
            MICR doesn't really matter these days since the checks are just scanned and sent to the electronic clearinghouse (that's why you can snap a picture of a check with Chase to deposit it, they no longer need the physical check, just an image). For any check in an amount that matters there's already the parallel deposit ledger system in place to void any non-authorized transactions.

        • The paper used for Student Transcripts (the record of achievement) at universities is closely guarded. Even access to live student data is less restricted than access to the paper.

          "Hi Mom and Dad, look, I got straight A's. Can I have that new car now?"

          And the dude on the dorm that offers the unprinting service will be rolling in money. Well, relative to other students anyway.

    • Re: (Score:3)

      by RyoShin ( 610051 )

      I can't see how this would be an issue. You can already modify stuff in Photoshop to change things like terms, this "unprinter" wouldn't change anything. It might be a bit easier to change the terms (assuming the original paper was printed with a laser printer in the first place--this won't work for ye standarde inkjet as far as I know; after actually RTFA, it provides no more or more accurate information than the /. synposis, and the full thing is behind a paywall), but the cost would be expensive even if

      • Re:Fraud (Score:4, Funny)

        by Nutria ( 679911 ) on Wednesday March 14, 2012 @05:30PM (#39358529)

        You can already modify stuff in Photoshop to change things

        Except that you must scan in and then print back out your the document, in which signatures would instantly be detected as fraudulent.

        the cost would be expensive even if they become mainstream

        Like computing power and capacity (and laser printers, for that matter) are as expensive as they were 20 years ago?

        only groups that would need one would be offices that have a laser printer

        ROTFLMAO.

      • > It might be a bit easier to change the terms
        Well photoshopping (and printing back on the original, i guess?) can only add, this can subtract, it's a huge step forward. I guess the ablated portions will be detectable though.

        The big thing will be intelligent toner nanoparticles :)

    • Re: (Score:2)

      by geekoid ( 135745 )

      you mean, just like you have to now?

    • So what you're saying is this changes nothing with respect to the security of printed documents.

    • Who knows what shenanigans someone can get up to by modifying the original.

      This happens now. And before. The technology doesn't matter.
      Two perfectly modified copies to both appear authentic won't do either of you much good in court. If nothing else it's another great way for lawyers to get rich and get you out of a contract.

    • I wonder what protections the banks will have to put in place to prevent fraud.

      Check paper will likely be pre-printed with ink (not toner) which turns black when hit with the green laser. In fact, things like cashiers checks may already have it -- removing the toner might be an attack known to security people (and criminals)

      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.

      You should always have a copy of any contract you sig

    • Time to go digital with documents PGP signed (or similar). Hell my digital signature would be a hell of a lot more fraud proof than the scrawl that is my real signature.

  • Even more efficient (Score:2, Insightful)

    by Anonymous Coward

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

    • Re: (Score:1)

      by osu-neko ( 2604 )
      I doubt that this is always the case. It's not like digital distribution methods have no carbon footprint -- they often have much greater power requirements.

    • Re: (Score:1)

      by Anonymous Coward

      Yes, the day man first put stylus to papyrus our environment was almost doomed. Thank heavens for the industrial and electronic revolutions, bringing us lower energy usage than ever.

  • 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.

    • Well, I guess power from those coal plants is the worst case that produces 50% less CO2 than produciong new paper.

    • Re:Carbon footprint of green laser? (Score:4, Interesting)

      by HyperQuantum ( 1032422 ) on Wednesday March 14, 2012 @05:09PM (#39358349) Homepage

      What about the environmental impact of vaporizing toner? Isn't that some kind of air pollution?

    • Re: (Score:2)

      by geekoid ( 135745 )

      That's the wrong question.

      This is the correct question:

      So what is the carbon footprint for powering the laser compared to recycling or throwing out the paper?

      And it will be less.

      • Re: (Score:3, Interesting)

        by roc97007 ( 608802 )

        Does that include the carbon footprint of building and maintaining the laser unprinters?

        • Re: (Score:2)

          by rtaylor ( 70602 )

          Still has to be less than transporting waste paper, recycling (large cities will have multiple plants; unprinters may mean fewer plants), transporting to a store, then delivery to the office.

          • Your mileage may vary, but there is an effort at my company to capture non-private documents and print on the other side. I wonder how that enters into the equation.

    • Re: (Score:2)

      by jd ( 1658 )

      Fission does generate emissions, although most are indirect. (Moving fuel rods in and out, for example.) Fusion would not, but governments are adverse to funding real power systems.

    • Re: (Score:2)

      by Nemyst ( 1383049 )

      I can already tell you that picosecond flashes of a green laser that could be used in household appliances takes less power than the heavy duty recycling machines required for taking the paper, removing the ink and recreating new recycled paper from it. The environmental impact should also be lower since you're not using rather dangerous chemicals to remove the ink from the paper paste.

      Remember, you'd need one trillion pulses lasting one picosecond each from a 1W laser to expend one Joule.

  • This may work well for office paper. What about the spam mail I get in the mailbox every day? If it works for that, AND it becomes expected that we 'unprint' all paper, what do we do with all the excess household paper? (no, did not RTFA)

    • This may work well for office paper. What about the spam mail I get in the mailbox every day? If it works for that, AND it becomes expected that we 'unprint' all paper, what do we do with all the excess household paper?

      This question is based on an absurd assumption. Why would you need to unprint everything? If you have no use for your junk mail just recycle it. Same as always.

      • This question is based on an absurd assumption. Why would you need to unprint everything? If you have no use for your junk mail just recycle it. Same as always.

        The absurd question is why would you want to unprint anything? If you've already got to deal with recycling junk mail that is printed using any of a number of different processes that aren't laser printing, why not just throw in the laser printed sheets?

  • No more damn toner! Just change the paper. And, presumably, any paper that is standard size would work in one of these printers, there wouldn't be any propriatary paper. You'd be able to keep using the same printer until it mechanically fails, could probably keep using the same printer for a decade.

    • I've been using the same printer for a decade. It's not that hard as long as you don't buy an Ink Jet. My previous printer, a laserjet 6L, also lasted 10 years.

      • Re: (Score:2)

        by afidel ( 530433 )
        Yeah, my dad's company uses some ~20 year old LJ 4's. You can still get refurb kits and toner for them so for the jobs where the slower print speed isn't an issue why not?

  • Even more efficient (Score:3)

    by theycallmeB ( 606963 ) on Wednesday March 14, 2012 @05:00PM (#39358257)
    Unless they also developed a way to make paper that can not be unprinted without damage, I imagine that unprinting a signed contract that is just a little too fair and replacing everything but the signature with something more to your liking will be far more efficient than regular forgery.

    • Re:Even more efficient (Score:4, Insightful)

      by TarMil ( 1623915 ) on Wednesday March 14, 2012 @05:04PM (#39358295)

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

      • Which means it becomes a case of one printed, signed and dated document and another printed, signed and dated document. It is just like having two differing files with the same checksum and same digital signature. But I bet buying an unprinter won't require as smart a crook as producing a good MD5 hash collision.

        Unless there is a clear way to tell which has been unprinted and then reprinted it simply devolves into a case of who has more lawyers on speed dial.

        And to build on another poster's reply to m

        • When you sign the document, make sure you cross over the printed line. If toner underneath the ink is vaporised, it will affect what you wrote. If it isn't, then it will be there underneath what you wrote, visible to forensic examination.

  • Toxic vapor? (Score:5, Interesting)

    by jimshatt ( 1002452 ) on Wednesday March 14, 2012 @05:05PM (#39358305)
    So, how unhealthy would the vaporized toner be? I really don't know. Somebody care to enlighten me?

    • So, how unhealthy would the vaporized toner be? I really don't know. Somebody care to enlighten me?

      Probably just as safe/toxic as the ozone made when the original was laser printed...

      • It's not about ozone. However unhealthy ozone may be if you inhale it, it's easily dealt with. It's about micro-particles containing cancerous substances. As anybody in the toner-industry can tell you, it's incredibly unhealthy to breath in toner dust. Laser printers come with a plethora of particle filters (at least the professional ones do) so you can actually use them in an office without being exposed to levels of danger anywhere near the average tobacco smoking addict or worse. As long as the proper pr

    • If it can be collected an put back into a toner cartridge - not terribly

  • Comment removed based on user account deletion

    • No, the problem clearly is that all the non-nerds are so obsessed with cleanness. If all people just stopped bathing and showering, the water consumption would go down considerably! :-)

    • Thermal power stations use vast amounts of water, as fresh as available, for cooling. However none of it is actually "destroyed", not much is evaporated, and what is used either goes back through a loop again or goes downstream to be used again for something else.

  • I can not (Score:3)

    by geekoid ( 135745 ) <{moc.oohay} {ta} {dnaltropnidad}> on Wednesday March 14, 2012 @05:08PM (#39358341) Homepage Journal

    wait for this to be built into printers. It detected text, zaps it, then prints.

    The real issue is wrinkled papers.

    • I can, actually.

      The big supposed value behind this is supposed to be that it will cut down on paper use. But it would be far more efficient to use e-paper for that. Not to mention less time-consuming, and regular paper suffers from wear and tear.

      It's nice to see people researching conservation technologies, but unless this has other applications as well I really can't see much value in it compared to what we already have. Perhaps it could be used to scan-and-remove graffiti? (amusing visual of someone w

    • I just recently went through a license contract negotiation, which went back and forth with many different versions of the contract before we got one we could sign.

      I can't wait for this to be built into printers either. No need to negotiate ahead of time, we could alter the contract *after* we signed it.

      • Re: (Score:2)

        by rtaylor ( 70602 )

        [b]we could alter the contract *after* we signed it.[/b]

        This is done now. Take page 23 from the final copy with signatures and a modified page 21 from an earlier copy when you submit it to the judge.

        Having watched this, I've become much better at ensuring my files are complete and keep offsite copies when warranted.

        • Right, but the counter-argument might be that with malice aforethought, you altered *your* copy before putting it in offsite storage.

          I wonder if we eventually see some kind of sealed (either electronic or physical) container approach, overseen by a notary.

          • Re: (Score:2)

            by afidel ( 530433 )
            Yeah, it's called a signed pdf, I did all of the paperwork for my refi using them except the final loan documents that the archaic process in my state still requires be done on paper using a notary.

        • Re: (Score:2)

          by Whibla ( 210729 )

          This is done now. Take page 23 from the final copy with signatures and a modified page 21 from an earlier copy when you submit it to the judge.

          Nice to see that your people have worked out how to fully utilise the marvels of headers and footers and version numbering in your important documentation...

  • Money (Score:4, Funny)

    by NEDHead ( 1651195 ) on Wednesday March 14, 2012 @05:19PM (#39358433)

    Unprint $1 bills, print $100's

  • *hands in 20 stapled blank pages* (Score:4, Funny)

    by DSS11Q13 ( 1853164 ) on Wednesday March 14, 2012 @05:31PM (#39358537)

    Professor, I totally had my paper finished but I accidentally unprinted it!

  • Ablation (Score:3)

    by KhabaLox ( 1906148 ) on Wednesday March 14, 2012 @05:38PM (#39358585)

    picosecond pulses of green laser light are used to vaporize the toner, or ablate in scientific terms

    So all that toner gets vaporized and is now floating around in the air of your office? What could go wrong?

  • Except it's based on... (Score:5, Informative)

    by Endo13 ( 1000782 ) on Wednesday March 14, 2012 @05:47PM (#39358665)

    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.

  • Carbon footprint (Score:4, Informative)

    by Anonymous Coward on Wednesday March 14, 2012 @06:28PM (#39359021)

    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.)

    • Re: (Score:2)

      by ceoyoyo ( 59147 )

      Yes, but we're talking about recycling paper, which is an entirely different furnace.

  • Generic spelling Nazi complaint (Score:3)

    by Samantha Wright ( 1324923 ) on Wednesday March 14, 2012 @06:36PM (#39359117) Homepage Journal
    "Unprint" violates the phonotactic constraints of Latin. Unpossible! Clearly, the antonym of "print" should be "imprint". (Wait. Oh noooooo...)

    • Re: (Score:2)

      by ceoyoyo ( 59147 )

      Just burn it. I hear paper is very... inflammable.

    • Well, since the opposite of wind, is rewind, then they can reprint.

    • Re: (Score:2)

      by selven ( 1556643 )

      Your phonotactic complaints are very umproductive.

      • Perhaps—but they're certainly conductive!

        (Also, I looked it up. 'improduco' is totally a Latin word. As weird as it may sound, we actually should be saying improductive. Obviously that's not the case, but reality has never diminished the appeal of idealistic purism, and it's not about to start!)

  • Just wondering, maybe it will pay for itself in avoided sewage costs.

  • Can these be used to "unprint" those pesky yellow dot patterns in colour laser printers?

  • I bought a second paper tray for my laser printer ($50) and print on the back side of pages already printed for another purpose. It seems I get enough paper heading for the trash or recycling to have enough to print on the second side. It works better than the proposed solution although not as exciting.

  • Why was a laser "eraser" not a perfectly adequate word for it ?

  • That is not how a laser printer works (Score:3)

    by fearofcarpet ( 654438 ) on Thursday March 15, 2012 @02:08AM (#39361589)

    Laser printers don't use lasers to charge paper, they use them to selectively discharge an image transfer drum, which is then covered in toner and pressed against a piece of paper. The toner and paper are on opposite ends of the triboelectric series [wikipedia.org] and spontaneously develop opposite charges when brought into contact with each other.

    As for the toxicity of the toner vapor, the composition is of course proprietary, but black toner historically has comprised mainly oxides of selenium. In small quantities it's probably harmless, but long-term exposure is almost certainly bad for you.

  • If this works on tattoos, then there's a hundred of million dollar industry about to erupt. The tattoo industry is exploding right now, which means that in about 5-10 years, tattoo removal will be almost as big. Where can I license this technology?
  • By the inventors of the laser no less. Check http://www.youtube.com/v/CoGsoH2UtMM [youtube.com] at 17:18.

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