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Thread: lowest useful output power?

  1. #1
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    Default lowest useful output power?

    I was just wondering with all the drama about the inevitability of these going into pointers, whats the lowest output power you can realistically get out of these diodes, can you run them at like 5~10mW and still get lasing?

    I was thinking of putting one of these in my stand-alone lumia projector but 1W would be waaayyyyyy too much blue...

  2. #2
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    I doubt they can go quite as low as 5mw since their threshold is around 200mA. I would imagine when they pop to life and start lasing it's already at 50-100mW of output.

  3. #3

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    ..interesting question! the modes maybe will be different as well. add a lens which clips most of the outer part, and we may have a relatively safe and well-collimated pointer which deserves this name! :-) manuel

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    The lowest I can run mine and get a real beam not just blue led is about 15mw.

    Forgot to mention down this low power is really temp dependent.

    chad
    Last edited by chad; 06-07-2010 at 14:09.


    When the going gets weird, the weird turn pro.


  5. #5
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    ^ That is actually a problem then. 15mw is not low enough for proper fading using analog modulation.

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    Quote Originally Posted by JohnYayas View Post
    ^ That is actually a problem then. 15mw is not low enough for proper fading using analog modulation.
    That rather depends how big your projection target is.

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    Mostly home use where even 5-10mw is visible and usable. Perhaps after the losses due to optics the power will be low enough.

    I never thought I would be hoping for some blue power to be lost.

  8. #8

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    (Hi PhotonLexicon! This is my first post here.) I'm thinking about the idea of modulating it as fast as a Blu-Ray LASORB will go, and taking the duty cycle down by a decent factor, and using telescopic or prismatic beam expanding optics for a fat and theoretically safe beam. Does that sound good? Is there any reason there'd be trouble modulating it that fast at the minimum lasing current?

    Or (defeating most of the purpose of it being a laser) what about just using divergent optics directly in front of the diode to get a nice monochromatic flashlight?

    Of course, those just looking for a safe way to get a bunch of monochromatic 445nm photons could just leave the diodes in the Casio projector, but it would be nice to have a one-diode-at-a-time solution.

  9. #9
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    Quote Originally Posted by Ike View Post
    I'm thinking about the idea of modulating it as fast as a Blu-Ray LASORB will go
    Hmmm, I'm not sure I get the intent behind modulating a LASORB. Could you state what you intend to achieve regardless of how you might achieve it?

  10. #10

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    Quote Originally Posted by taggalucci View Post
    Hmmm, I'm not sure I get the intent behind modulating a LASORB. Could you state what you intend to achieve regardless of how you might achieve it?
    Well, I hope I'm not threadjacking here, but the intention is an enclosed one-diode system that is at least as eye-safe or safer than the 445nm output of the Casio XJ-A130 projector itself. (It's probably a very bad idea to put your eye up to the exit aperture of any 2000 lumen projector.)

    One way to do this would be to just throw away the majority of the output power so that you're only left with 1mW or so shining out of the system, but if you're getting about 200mW of radiant power just above the lasing threshold, that's another 200mW you've got to heat sink in the build, and it seems a shame to just throw all of those photons away.

    The LASORB would be there to protect the diode from ESD, because even if the diode only costs <$50, we might as well keep it safe too. I imagine beam-expansion or divergent optics are probably the better and more foolproof idea, but the intention behind as-fast-as-possible modulation is to do PWM dimming, where the pulses are short enough (and perhaps far enough apart) that no single pulse has a dangerous energy, if that is a good way to help ensure eye-safety. And having a LASORB on the diode affects, to some extent, how fast the diode can be modulated, according to the LASORB-L44-833-X.pdf datasheet from http://www.lasorb.com/12_datasheets.htm

    Does any of this make sense, and should the topic of "Eye-safe 445nm build" be a separate thread? Is there anything I've got egregiously wrong here?

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