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The laser unprinter

extremetech.com

53 pointscolluphid4226 comments

I don't get the environmentalist angle. The paper industry is a net carbon sink; much more carbon is captured in growing the forests of fast-growth trees they plant and cut down than in manufacturing paper or lumber products from it. Every sheet of paper you buy is that much carbon in your hand that would otherwise be in the atmosphere, and will now stay out of the atmosphere as long as it's not burned.

The Intergovernmental Panel on Climate Change identified exactly this as the most effective man-made carbon sequestration method we have. http://www.ipcc.ch/pdf/assessment-report/ar4/wg3/ar4-wg3-cha...

So, paper is cheap and producing it is a net positive for the environment. What about the coal-burning power plants generating electricity to shoot lasers at the paper so we can reuse it again? Is the electricity cost to blast off the toner going to be less than the cost of a sheet of paper?

The paper industry is a net carbon sink

How is that? Neglecting processing-related effects, isn't this zero-sum since they're planting trees and then turning them into paper which eventually decomposes and releases the carbon? A reduction in paper use would leave the existing trees standing.

The trees that the paper companies plant would remain standing? I think you missed part of the argument.

There's not only the carbon dioxyde that counts. If you have ever been around a paper/cardbox factory you know how much it stinks and how heavily they use chemicals.

I don't have time to read the study but you also have to go beyond first order effects. OK growing the trees might be a carbon sink, but what about the second and plus order: the effect on the soil, heavy use of human machinery, use of pesticide.

Just FYI the energy used by laser is extremely low except if you are talking about CO2 laser or something. I would be more concerned about the making of such a laser.

Sure there's plenty of carbon in paper but mining the kaolite used to make it and the paper plant itself generate quite a bit of CO2. The dioxins and other chlorinated by-products of paper-making are also pretty hard on the environment and humans in general.

On a climate time scale, the paper will decompose into CO2. Paper production just defers CO2 from now until a point only a few hundred years in the future.

In a 300 years at a 2% growth rate, the world will be 400 times richer. Long term carbon sequestration will be a trivial cost, or will be unnecessary.

Reused paper tends to be crumpled and warped, especially if you try to feed it through a (laser) printer multiple times. It's more trouble than it's worth, unless they make printers that can handle less-than-perfect paper.

If you'll just use a sheet of paper once, then there's only so much it makes sense to pay for it. But what if you'll be reusing it 20 times? Perhaps there's an opportunity there. Kind of like how paper plates are generally flimsy, but normal plates are very durable.

True. But there are other trivialities that need to be considered. The first thing I do when I've got 5+ pages is either hole punch or staple them. The second thing I do is scribble on it or highlight things. If I wasn't going to do that, I probably wouldn't have printed it out in the first place (unless it was for record-keeping, in which case the paper will probably never be reused anyway).

If this becomes popular there will be a new industry around non-destructive paper management (more than our current choice of paper clips and highlighters).

But I think the critical factor for success is if the technology development outpaces paper-thin, writable LED displays or even tablets (which have progressed a LOT in the last few years). If you can give your "paper" a WiFi connection is anybody really going to invest in traditional (but reusable) paper?

I think you're right. Something like banknote paper --maybe not the same, but in that direction. In some places, I've heard, banknotes are steamed and pressed as they are recirculated, so they look like new.

So I guess everyone has given up on the paper-free office ideal now?

It seems like only yesterday I had to sit through a two hour meeting to convince us that printing things is a needless expense now we're all supposed to be using laptops and iPads! Wait a second....it was only yesterday!

Might I suggest a job search? I'm not some paper fanatic, I rarely print anything out and I'm physically incapable[1] of making substantial use of a pen or pencil, but any company spending two hours on the subject is one I don't think I want to work for.

It was bad enough the day I sat through a 10 minute speech by a CEO on proper urinal usage...

[1] http://en.wikipedia.org/wiki/Dysgraphia#Motor

I can't help but wonder if the same ultra-short pulses of laser light can be used to vaporize dark pen ink, giving users the ability to erase or alter things like signatures.

Oooh, probably! Guess it depends on how the ink is bonded to the paper. Toner is fused with heat, but ink obviously isn't.

There are other things for removing ink from paper, right? Counterfeiters do it, to forge cheques, I think.

http://en.wikipedia.org/wiki/Check_washing

I could see the laser maybe working on ballpoint ink, which AFAIK stays more on the surface due to its high viscosity, but I think like check washing techniques, it'd have trouble with the more liquid inks, since the paper absorbs them more readily.

I used to work in a integrated circuit debugging lab. We had a pulse laser that we would use to ablate the layer of glass on top of the metallization so we could probe the die.

While goofing around I discovered that I could vaporize the ink of dollar bills. The largest area per pulse was pretty small, 25 microns if I remember right. Maybe 100. So it wasn't very practical, but it worked.

I don't remember if I tried it with pen ink. It might work okay for ball-point as that mostly lays ink on top of the paper. You'd still have the impression in the paper from the pen though.

Ink that didn't soak in but lay on top of the paper would probably stand a good chance of working. Maybe gel ink?

Thank you. That's what I thought: any dark ink that just lays on top of (i.e., isn't absorbed by) the paper could probably be vaporized in similar fashion by a pulse laser.

Anyway, when I wrote that, I had an inkling that someone in HN would know probably something about the subject matter, but I never expected anyone to have real-world experience using pulse lasers to vaporize ink from a piece of paper, let alone dollar bills!

Awesome.

This is why I love HN.

There used to be a scam in England where people would use solvents to wash away the postmark from posted letters, allowing them to sell / re-use the stamps.

I can imagine a group stealing a laser to remove the postmark. Luckily, UK stamps now have other security features.

(http://www.telegraph.co.uk/news/uknews/5400999/Royal-Mail-la...)

What about the fumes and such from the ablation of the toner? Seems like it could be a serious health hazard.

Toshiba is releasing a technology for removing the printer up to 5 times from printed paper, but it uses a special toner

http://www.youtube.com/watch?v=r--y9VvSTyg&feature=playe...

So it's the new eInk but with a refresh rate of a few minutes...

Will you have to unjam the paper first before unprinting?

Very likely. I used to work in the HP printer division, and used paper was the bane of the existence of the mechanical engineers that designed our paper handling systems.

Paper is going the way of the stone tablet with chiseled etchings, it is too heavy and slow, let the paper tech die peacefully next to the stone chisel tech. Don't revive paper tech just as we are getting into cool stuff, getting to the root of why paper exists, to exchange ideas between brains.

What else would a laser unprinter be used for besides sensitive documents? Paper is cheap, wouldn't it be easier to just use a new piece of paper and recycle the old one.

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