laser + coffee = blue?

March 27, 2007 at 10:28 am | | hardware, lab safety, stupid technology, wild web

This guy decided to heat his coffee using a very powerful laser. Stupid, right? Even more stupid, he filmed it and put it on the internets. That’s a good way to get fired. (I’m just jealous.)

[youtube OYvynmK0Slo laser coffee]

My question: How come the light is blue? The safety placard says it’s Nd:YAG (invisible IR 1064 nm) or HeNe (red 633 nm). Even doubled Nd:YAG should be green (532 nm). Strange.

Maybe things looks different at 2 kW.

(Thanks to Geekologie.)


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  1. everydayscientist

    Pingback by — May 11, 2007 #

  2. My only guess woud be that what you see is not the laser light but a thermal radiation of something that’s few thoushand kelvins hot, so it gets the brilliant white-bluish, with some UV component init (like in welding or in pyrotechnics with burning Mg metal)

    Comment by milkshake — March 27, 2007 #

  3. I’ve played with enough 2W 532nm light, and that definitely isn’t 532nm stuff. Anyone know what that whole instrument was for? It looks pretty weird..

    Comment by PhilipJ — March 27, 2007 #

  4. Makes me want coffee.

    Comment by Ψ*Ψ — March 27, 2007 #

  5. Looks like a metal cutting YAG.

    Comment by kendall — March 27, 2007 #

  6. PhilipJ: But have you used 2 kW Nd:YAG? ;)

    Comment by sam — March 27, 2007 #

  7. Oh, *kW*. Hmm, no. :)

    Comment by PhilipJ — March 27, 2007 #

  8. I don’t know anything about the properties of the laser, but the cup of water glowed the same colour. I’m with Milkshake. Maybe it is the ceramic of the cup? The other possibility is that the camera CCD is saturated by the intensity of the light and the colour is an artifact.

    Comment by MartinS — March 28, 2007 #

  9. also, at 2 kW!!!!!, i’m pretty surprised that it actually takes that long to heat the water. maybe we’re being lied to about something here…

    Comment by sam — March 28, 2007 #

  10. It’s really quite easy to saturate a CCD, so I don’t think that’s the case here either.. you also see the same blue colour scattered from steam from the liquid, so I suspect, like Sam, that we are being “lied” to in some fashion.

    Comment by PhilipJ — March 29, 2007 #

  11. I bet it’s a quadrupled YAG. 266 nm is hard to see, but with 2 kW there will be something. Besides, at that power raman scattering may be visible.

    Comment by william — March 29, 2007 #

  12. someone on YouTube questioned if the cofee got radioactive. The answer is, of course, yes, and one becomse a spiderman once on drinks it.

    Comment by runcycelxcski — April 4, 2007 #

  13. […] you work in a lab of sorts. Perhaps you can answer a question posed by this scientist who posted a video of someone using a high-powered laser to heat his coffee, which is apparently a major no-no in the […]

    Pingback by Disease Mongering Engine | Cruel.Com — April 9, 2007 #

  14. Infrared light shows up as that exact same color on several digital cameras I have. (Try pointing a TV remote at the lens and pushing a button)

    Comment by niko — May 8, 2007 #

  15. hey niko, really good point! ccd’s are sensitive in the ir, maybe out to 1064 nm.

    Comment by sam — May 8, 2007 #

  16. If you point an IR remote at your camcorder, I think it looks blue in the video. Maybe the same thing’s happening with the IR laser…


    Comment by randog — May 20, 2007 #

  17. Nice one. I bet it’s a tripled Nd:YAG, i.e. blue, laser. By the way, that IS fast. Try that in your 1.5 kW microwave oven and see how long it takes…

    Comment by Martin — July 26, 2007 #

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