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Laser that can burn

  1. Jun 4, 2009 #1
    My friend once said that we can make a laser which can produce fire by taking out a normal laser from a damaged DVD player and "cutting some wire on the laser" ...is that true..?
    Is it possible to make a real laser that can scorch the things like the ones shown in movies..?
  2. jcsd
  3. Jun 4, 2009 #2
    I'm not sure, but it doesn't sound very probable that a DVD laser is capable of scorching a lot of things, otherwise it would also be able to fry your DVDs.
  4. Jun 4, 2009 #3


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    No, not with a DVD laser. You may be able to blind yourself with one, though. Or cause permanent eye damage.

    Don't play around with lasers. Period. You only get one pair of eyes, for life.
  5. Jun 4, 2009 #4
    I've done it before, but it's not like the movies. We were using a CO2 laser to make microspheres. This lazer is in the infra red, so you can't even see it. When we first got it mounted and started to take up the power, the wood on the wall behind the beam began to char. Paper placed in the focus of the beam would light straight away at %10 power or so.

    But again, to chance doing this with your CD laser
  6. Jun 4, 2009 #5
    I'm not sure about a player, but a laser from a "burner" (ie:writer) certainly can scorch and burn paper.

  7. Jun 5, 2009 #6
    wow..thats hot..thanks..
  8. Jun 5, 2009 #7
    With your CD/DVD laser, you probably will not be able to fry your egg tomorrow morning. This laser is not design with a large photon rate.

    YES. Nothing stops you from desgning a laser with an incredible photon rate, like in the movies.

    A few years ago, I had the chance to help develop such a laser, that could make a hole in 2m of concrete in less than a minute. It was very impressive. But there, you have other dangers than damaging your eyes.
  9. Jun 5, 2009 #8


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    Don't you "just" need a lens that focuses down to a very tight focus? Probably not enough to really damage anything (it's still only a few milliWatts), but that should be enough to, say, start a piece of paper on fire, or at least locally darken it a bit, no?
  10. Jun 5, 2009 #9
    Absolutely. I guess, we all played with a magnifying lense as kids. That exactly what you need. The effect is simple, you just concentrate energy into one point.

    Ok, I'll give it to you that a laser is a bit more complicated than that, with the monochromatic wavelentgh. But the idea behind it is the same, the bigger the photon rate, the more "powerful" the laser.

  11. Jun 5, 2009 #10
    I have a 40 mW HeCd laser I used to play around with for holography. Considering how large the power supply was, and that my laser couldn't burn diddly, I would doubt a laser for a dvd player could do much either.
  12. Jun 5, 2009 #11
    You can even launch your own satellite using a laser:


  13. Jun 8, 2009 #12


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    I've seen someone perform modifications to handheld red pointers to make the burn wood. But you would need a very sturdy one as it's electronics might get fried after some time. About the CD/DVD lasers... might be true, but considering the economical down-scaling of it's internal electronics, I think they will fry at very small power scale-ups.
  14. Jun 8, 2009 #13
  15. Jun 8, 2009 #14
    As several posters have mentioned: BE CAREFUL

    Besides the obvious risk to nearby people/animals and to one's self, the laser beam has a very long reach--you might not even realize that someone is there. Also remember the danger of reflective surfaces.

    Here in the USofA, even a green laser pointer can get you in trouble if you point it at a flying aircraft (at night?). These can dazzle a pilot causing temporary inability to see properly.

  16. Jun 8, 2009 #15
    A better option is to buy a few ultra bright white LED and a magnifying lens.

    It's cheaper than buying a DVD burner and safer because the DVD lasers are outside of the visible range so they are more difficult to control.
  17. Jun 17, 2009 #16
    By all means play with lasers. All this wining about things dangerous to you is killing peoples engineering spirit.

    No. or well yes but not how you think. Lasers have gaussian beam propagation. It is not just a parallel beam that you can bundle like the sun. To make a very small spot you need to actually widen it first before you can focus.

    All fear mongering with little information. The important part is this: You do not realize that your eyes have been damaged by a laser. Your brain fills up the gaps that are missing from your field of vision, just like with the blind spot that you have in your eye, which you don't notice, so don't assume nothing has happened just because you didn't notice.

    If you are planning to use mirrors or lenses maybe laser safety goggles or at least sunglasses might be good.

    Your CD/DVD Player or Burner has a solid state laser diode, if you run it at a higher voltage you should be able to extract more laser power, but these things are build so weak, that I am sure that you will burn (overheat) it, before you reach laser power high enough to burn anything.
  18. Jun 17, 2009 #17
    I wasn't trying to cause fear---- just hoping to prevent injury.

    Sorry, where did this come from? As a child (unsupervised) I looked at the sun with no protection (saw the sunspots). I had a blind spot with the brain NOT filling the gaps; now, 50 years later, there is still a moderate seeing deficiency in that eye at that spot.

    Laser safety goggles, yes; sunglasses, where did this come from? Unless they fit closely to the head, they may even be more dangerous---relecting a laser beam into the eye from the side. Depending on the attenuation of intensity, and blocking of laser 'color', sunglasses may be false security.

  19. Jun 18, 2009 #18
    AFAIK it takes a few days and you do not notice the damage anymore even for larger spots. Although your vision is obviously impaired.

    The laser pointer class lasers in dvd players are not that dangerous. Glass absorbs IR. sunglasses absorb visible light, the angle from which you can hit the iris is reduced even if you open a few new reflection paths. If you cannot see the laser you can check if you see it with a digital camera, those can see in the IR range remote controls look cool in digicams.
  20. Jun 18, 2009 #19
    If something does happen to your eyes, you should immediately go to the doctor. In some cases cortisone injections into the eye may help.
  21. Jun 19, 2009 #20
    The fovea or high-resolution part of the eye is surpassingly small. You can actually do an experiment to demonstrate this. Stare in the mirror with one eye closed. Stare directly into your pupil. When you're done freaking out about staring into your own pupil, have someone else bring some text in from the side. You won't be able to accurately recognize any letters until they are very close to your eye line. And don't cheat!! When we did this experiment, we had a frame holding the experimenter's head still, so I'm not sure how it will work in free space.

    Yes, staring at the sun will damage the fovea. I think what the earlier poster was suggesting is as long as you're not staring down the laser, a random reflection is more likely to strike somewhere on the retina other than the fovea.
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