A green laser that “unprints” toner from printed paper

Researchers at the University of Cambridge have developed a laser “unprinter”, a laser configuration that can gently remove toner from a printed sheet of paper enabling its reuse. After the “unprinting” process, the paper remains undamaged – at least for the first three times.

Building up on the work already done in the field, the British researchers tried several laser setups before finding the right one: their testing work with different wavelengths and pulse speeds resulted in a prototype capable of vaporizing toner particles from microscopic layers of the paper substrate.

The Cambridge research, “Toner-print removal from paper by long and ultrashort pulsed lasers” explains that the right configuration for an optimal toner unprinting process uses a laser with a 532 nanometers wavelength – the same of the green-toned visible light – and 4 nanoseconds-long pulses.

The method, however, isn’t perfect: “We have repeated the printing/unprinting process three times on the same piece of paper with good results”, the researchers stated, warning that “the more you do it, the more likely it is for the laser to damage the paper, perhaps yellowing it”.

And yet the already gained results – the chance of reusing a laser-printed sheet of paper for at least three times – encourage the researchers to go on with further testing: developing a “perfect” method for toner unprinting would mean concrete and huge benefits for users, companies and the environment overall.

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I don't see much use for this. Who wants to reuse old wrinkled papers or go through the trouble of "unprinting" them. Paper is a recyclable, renewable resource and is dirt cheap. This whole idea seems stupid and far less green than simply recycling the paper.

ahhell said,
Shady bankers are funding this research.
/s

Al Gore's funding it, so he and the likes can print more shady papers about global bullsh*t warming.

I've been in the photocopier business for 31 years as a tech.
I've been through the transition of copiers from a POS liquid machine that barely made a reproduction you could read on e-stat paper, to the digital world today where the document most of time the copy looks better than the original.
This "green" idea uses more energy than just taking the used paper, shredding it and buying a new ream of paper.
The xerographic process pretty much hasn't changed since Chester Carlson patented the idea in 1946. You put a charge on a photoconductor, expose it to light (or laser), apply toner, transfer the toner to the paper, and then fuse it somehow to the paper. What becomes a problem with today's machines, is they most always use heat & pressure to accomplish this. The paper receives a small charge to the back of the paper to hold the toner in the transfer process. After heat & pressure is applied to the paper, running it back through, even on a copier that has built in duplexing, you can usually see a very small degradation between the image quality on side one and side two, ESPECIALLY on photos copied between side 1 & 2. Yes, this "new" process uses a photosensitive toner, but the xerographic process is the same. Unless they have tackled the process of how the fibers of the paper are changed during fusing, by the time you run this through 4-5 times, you won't have an acceptable copy.
This was patented by Toshiba, and I've worked on that brand for the last 21 years. Anyone familiar with their machines knows sometimes they will release a machine BEFORE it is ready for prime time. If you know anything about the Toshiba E-Studio 4511 series, you'll know what I'm talking about.

Environment friendly as MY HAIRY LOWER BACK! Where does the toner go when it evaporates? Phooosh! In the air! Common inks and toners alone are a health hazard, "per book" requiring well-ventilated rooms. And you inhale it and then get a cancer. Or two. Or if you somehow manage to stay clear, together with energy required to unprint before printing again, it still contributes to pollution.
But, well, slap the "Green" Eco bullsh*t label on a fresh turd and people will kick each other in the nuts to buy it.

Now there's no argument that it isn't useful as such, of course it is. It's just this quasi-green crap that makes my roof fly off.

Phouchg said,
Environment friendly as MY HAIRY LOWER BACK! Where does the toner go when it evaporates? Phooosh! In the air! Common inks and toners alone are a health hazard, "per book" requiring well-ventilated rooms. And you inhale it and then get a cancer. Or two. Or if you somehow manage to stay clear, together with energy required to unprint before printing again, it still contributes to pollution.
But, well, slap the "Green" Eco bullsh*t label on a fresh turd and people will kick each other in the nuts to buy it.

Now there's no argument that it isn't useful as such, of course it is. It's just this quasi-green crap that makes my roof fly off.

"Green" and "Environmentally Friendly" labels don't only apply to those things that cause no environmental harm... The labels apply also to processes that reduce the wasteful output of already harmful chemicals. This is why a "hybrid" card is considered environmentally friendly when compared to a regular car while both still consume gas and output carbon dioxide.

Frazell Thomas said,

And I'm not talking about not causing environmental harm at all. It's impossible. I'm just wondering if one considers:
+ Reduced paper use
vs.
- Increased energy consumption
- Toner vapor

And how does that even out for even remotely reduced impact on environment? It is better for toner to be chemically inert, sticked to paper than floating in air and contributing to greenhouse.

It is good for business and that I reckon. That's it. Slap "monies friendly" sticker on it. Everything "green" in all proportions is shameless false advertising, and people actually believing it are severely deluded subjects that, should it come to self-defense, must be killed with fire. Period.

Phouchg said,

And I'm not talking about not causing environmental harm at all. It's impossible. I'm just wondering if one considers:
+ Reduced paper use
vs.
- Increased energy consumption
- Toner vapor

And how does that even out for even remotely reduced impact on environment? It is better for toner to be chemically inert, sticked to paper than floating in air and contributing to greenhouse.

It is good for business and that I reckon. That's it. Slap "monies friendly" sticker on it. Everything "green" in all proportions is shameless false advertising, and people actually believing it are severely deluded subjects that, should it come to self-defense, must be killed with fire. Period.

Valid concerns for sure. This, so far, is no more than an academic exercise on if it is even possible. It looks like it is, but no one yet has any idea if it is commercially viable. Maybe in use the energy consumption would be too high and negate any benefits or the risk of vapor, as you suggest, would be too high. Only time will tell if this technology brings benefits large enough to offer changes.

Keep in mind though, they are focusing on the ability to reduce the waste of paper itself as paper is a very environmentally harmful process. If we can reduce the need for new, and even recycled, paper to any serious degree we will have major impact on the environment.

See: http://en.wikipedia.org/wiki/Environmental_impact_of_paper (Just a primer, not an in depth look at this process, but I'm sure you could research more in depth information).

One minor little problem though.
you are NOT supposed to run a paper through a laser printer twice. the heat form the fuser causes the paper to curl and change, a second time around this can cause a paperjam or at best the paper will yellow or discolor.

And since most offices don't believ the support tech or resellers when they tell them to use Laser Printer paper and not copy paper or universal paper, this problem is even worse(on top of the ridiculous amount of paper dust the cheap copy and universal paper leaves behind).

HawkMan said,
One minor little problem though.
you are NOT supposed to run a paper through a laser printer twice. the heat form the fuser causes the paper to curl and change, a second time around this can cause a paperjam or at best the paper will yellow or discolor.

And since most offices don't believ the support tech or resellers when they tell them to use Laser Printer paper and not copy paper or universal paper, this problem is even worse(on top of the ridiculous amount of paper dust the cheap copy and universal paper leaves behind).


I'm sure they've thought about this.

HawkMan said,
Further heat treating th paper is not "thinking" about it.

I'm sure they've thought about it or encountered it in testing. Even if they haven't, it's only a proof of concept device at the minute, and it even mentions in the article that they admit it's "not perfect".

Majesticmerc said,

I'm sure they've thought about it or encountered it in testing. Even if they haven't, it's only a proof of concept device at the minute, and it even mentions in the article that they admit it's "not perfect".

Whatever they do, they can't change the fact that the paper has already been through the fuses once, and that's s may as they're supposed to.

TEX4S said,
Enter the age of "unprinting fraud"

exactly what came to my mind...

unprint papers with executive signatures and print whatever you on 'em.

TEX4S said,
Enter the age of "unprinting fraud"

True. But, I figure, easy to disprove in courts. It might look the same to human eye but few glances with a microscope will definitely reveal that paper's surface has been f* up in very certain places.

bushbrother said,
Also, are we not supposed to be moving to "paperless" ?

Indeed, but some industries just aren't going to be able to for a variety of reasons. Most cases I would agree with you though.

bushbrother said,
Also, are we not supposed to be moving to "paperless" ?

Some stuff remains unbeaten when you can touch and feel it and all that.

Maybe that's just me, but I don't want printing to die.

GS:mac

Kushan said,
I get that it may be good for the environment, but how much energy does such a process use?

Energy can be sourced via green means... whereas ink, paper, chemicals in the recycling process and round trips to the recycle plant and back in the shops is more energy intensive and uses natural resources.

Of course we have to look at not just the use of the machine but also the green credentials of the production of the machine itself.

Kushan said,
I get that it may be good for the environment, but how much energy does such a process use?

The full article reads it uses less energy than recycling paper.

ajua said,
This is great. It can help reduce tons of wasted sheets by erasing and making them reusable.

What would be amazing, would be if they did print masking on with this.

So you have a blank sheet of paper, you print out a document.
A week later, you want to print something else on that sheet, so you feed it in, it gets scanned - what you want to print is masked against what's already on the page, and what will no longer be in use by your new document is removed with the green laser, and the remainder is printed.

End result - less green laser usage, less toner usage, higher level of computations, but if done correctly, would still be very green compared wiping the entire page each time!

JustinN said,

What would be amazing, would be if they did print masking on with this.

So you have a blank sheet of paper, you print out a document.
A week later, you want to print something else on that sheet, so you feed it in, it gets scanned - what you want to print is masked against what's already on the page, and what will no longer be in use by your new document is removed with the green laser, and the remainder is printed.

End result - less green laser usage, less toner usage, higher level of computations, but if done correctly, would still be very green compared wiping the entire page each time!

Seems like that would be a lot slower...

M_Lyons10 said,

Seems like that would be a lot slower...

The process of wiping the paper with the green laser prior to printing in general would be slower. The time to perform the calculation I mentioned is almost instant, the only additional time would be the scan time, and hell, if you want to go green, you'll expect things to be a bit slower.

M_Lyons10 said,

Seems like that would be a lot slower...

unless you develop printers that have a seperate feed for paper to be laser cleaned - the printer could do this when its not printing ready for you to use