Lasing CO2 from human breath


YouTube user magx1’s CO2 laser looks like it’s taking over his living room…

“Look Mom; I Lased my Breath” … Seriously, though – by exhaling into my ‘supply’ balloon, I was able to get pretty good results considering! Unlike a ‘proper’ laser mix of CO2, N2, and He; the ‘breath’ trick appears to have a much narrower pressure range over which lasing will occur. But I like it anyway – it doesn’t get much more DIY than this!

Also see the project’s Flickr set. [Thanks, Bill!]

4 thoughts on “Lasing CO2 from human breath

  1. jdoege says:

    If results differ based on how long you hold your breath before exhaling.

  2. Simon says:

    Very cool! Is that based on the old 10W Scientific American CO2 laser? Oddly enough I was talking about that on another blog the other week.

    I made the Scientific American CO2 laser back when I as at university. Not as part of my study, more as a hobby. I got some glass tube from the chemistry lab glass blowers and the technicians in the particle accelerator lab let me set up there behind the accelerator and do my ‘experiments’. They already knew me from helping me out when I was a school kid with some superconductors I made for a science fair but that’s another story.

    The end pieces of the laser were made of brass plate and for the flexible bellows I pulled apart some old air conditioning thermostats and removed the copper bellows from them. The bellows were soldered between the two brass plates of the end pieces. A brass pipe fitting was soldered to that. The glass discharge tube slid into the pipe fitting and was selaed in place and a brass hose barb was soldered into the side of it for the gas inlet/outlets.

    Unfortunately I didn’t have a way to get a proper gold coated mirror back then. No Internet to just order things like that. I had a lens made with the right curvature then had it sputter coated by the chaps in the engineering school who used to gold coat electron microscope samples that way.

    The technicians found me an old vacuum pump minus it’s motor so I found an old washing machine or dryer motor and got it working with that.

    The laser was water cooled and run from a neon sign transformer. I didn’t have the proper mixture of gases so was only using nitrogen (from liquid nitrogen) and CO2. The output mirror was polished copper with a hole drilled in it sealed with a clear salt crystal I got from the chemistry lab technicians. These crystals were output windows in some instrument they had. The windows would break and and I was able to get the broken bits and use them.

    Everything was aligned with a HeNe laser (I still have several of those at home). No laser diodes easily available back then. The HeNe laser might have been one I got from a barcode scanner company as a free reject too.

    Yes, I was VERY good at scrounging and getting help on my inventions back in those days.

    I only ran the laser once. And it only ran for a few seconds before the gold literally evaporated off the mirror before my eyes.

    But I did get, on a piece of thermal fax paper positioned a short distance away from the output, a very faint darker spot the same diameter as the output hole.

    Perhaps it was only heat but I like to think that, just for a second, the thing actually worked. That was the end of my CO2 laser experiments though. This was back in about 1992 I think.

    I still have the actual laser assembly tucked up in the attic of my parents house I think unless my dad cleaned it out!


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My interests include writing, electronics, RPGs, scifi, hackers & hackerspaces, 3D printing, building sets & toys. @johnbaichtal

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