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Thread: Pushing Argon tube to the limit

  1. #1
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    Default Pushing Argon tube to the limit

    Has anybody cranked up the current on an ar-ion laser to the point of melting or damaging the tube in other ways? Just curious

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    Default Re: Pushing Argon tube to the limit

    Quote Originally Posted by steve-o
    Has anybody cranked up the current on an ar-ion laser to the point of melting or damaging the tube in other ways? Just curious
    I've run one of my Spectra Physics 161 heads at 14 amps tube current for a while, just to see what would happen. What I learned was that you start to get gain saturation at around 11 amps of tube current, and after that no matter how much current you cram down the tube, you don't get any more light out. (But you do generate a shitload more heat!!!)

    There are some stories in the laser FAQ about people overdriving 60X tubes. The results aren't pretty.

    Adam

  3. #3
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    Har!
    Did it hurt it?

    meh..

    didnt mean to laugh. I'd like to get more light out of mine but dont know how. Bigger fan? I might blow it up though. :roll:

  4. #4
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    Hey Steve-o;

    Nah, it didn't hurt it. I only ran it that way for about 10-15 min though.

    It's not good for the tube. You will shorten it's life by increasing the current like that. If you go too high you can really do some damage to the internals. Extra cooling isn't really going to help much, because the plasma will still expand and erode the walls of the bore. (This can deposit all kinds of nasty things on your mirrors.) You might keep it cool enough to save the tube seals, but the internals of the tube can still be ruined.

    Plus, it doesn't give you any more optical output anyway. If you have a power meter you can plot a graph of power vs tube current. If your power supply will go up to 12 amps (or even higher) you can see how the power starts to level off as the current gets up really high. Eventually you'll reach a plateau where more current does not mean more power. (Though your power supply might not be able to force that much current down the tube.)

    Bottom line, if you run high current, you get short tube life. Run it only as high as you need to get the power you want. And if you crank it up and start to see the gain fall off (the graph of power vs current starts to level off), then you are overdriving the tube. Back off on the current. (I never exceed 10 amps now, which means I live with the measly ~38 mw of blue that I get.)

    If you want more light, you'll probably need to get a new tube. (or a whole new laser)

    Adam

  5. #5
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    Thanks Adam. Good info. Yeh I love 488nm, I think its the best color for a laser. I may wait and see how popular the blue-rays get and consequently the diodes may come down in price. Then I'll get one and maybe mix it with a little green.. Meanwhile I'm going to get a couple of maxyzmodules 200mw to continue with the solid state project. Got >200mw 532 already. Hopefully I'll end up with RGB before too long..The money though, uhhh the money

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    Blue-ray isn't going to be as nice as you might think. For one, the diodes are *stupidly* expensive right now, and likely will continue to be that way for a long time. Another problem is that there's no real reason to build one that can make more than 15-20 mw, because that's all they need for the burners. So you won't be able to buy one that makes, say, 200 mw or more for a very long time - if ever.

    But the real reason why Blue-ray is such a non-starter for laser hobbyists is the wavelength. 405 nm is damn close to ultra-violet. Thus, the human eye can't see it very well. (Our sensitivity really starts to fall off around 450nm or so.) Spec and Marconi actually managed to build a Blue-ray laser pointer, and after playing with it for a while, they both agreed that it's more of a "black light laser" than a blue laser. The beam looks cool, but it's not very bright. (Though it will really light up things that would normally glow under a black light...)

    473 nm blue from a DPSS unit is very pretty, although it's expensive. 456 nm blue from a multi-line Argon is downright beautiful, but unfortunately the gain is pretty low on that line. So yeah, 488 nm will give you the most light for your dollar, even if it isn't the best blue to use as far as color spectrum goes.

    And as for the money - well, yeah... That's just the way it is with this hobby. Get used to spending way more than you planned...

    Adam

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    I thought blue-ray was a longer wavelength. What do you think of the Lasever 473s? Good quality?

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    IMHO, i prefer CNI over Lasever
    KVANT Australian projector sales
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    Lasershowparts- Laser Parts at great prices
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  9. #9
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    My lasever: 80 mW 473 nm
    Beamdiameter: ~1mm
    Divergence: < 1 mrad!!!

    Never had problems. I never had a CNI, so I can only tell you how the lasever work. And it work good!

  10. #10
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    Blue ray is 405 nm. There is another direct injection diode (Nichia) that lases at 440 nm, but it's still too close to the UV side of blue. 465 nm would probably be ideal, but the closest we've got to that is 473 nm from a DPSS blue. (Which is pretty good.)

    As for the Lasever blue DPSS units - I've never owned one. However, there are some posts here on PhotonLexicon explaining other member's experiences with these lasers, and from what I've read the general consensus is that they're not quite ready for prime time yet. There are several members that have experienced premature failures, poor beam quality, and other problems with the Lasever blues. (Not everyone, mind you, but a disturbing number of members nonetheless.) This nearly always requires that the unit be sent back to China - sometimes multiple times - to be fixed. (Note that the DPSS greens from Lasever seem to be much more robust.)

    Adam

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