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Thread: combining beams

  1. Default combining beams

    Hey Everyone,
    I just bought an argon laser and i was wondering if it was possible to mix a red diode laser or red dpss laser with the argon beam to make whitelight? Would this be possible...and if yes how could i do it?
    Thanks alot
    -Adam

  2. #2
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    Lightbulb

    Umm... I am suprised by this question. Of course it is possible to mix and argon with a diode laser. That is how we all, well most, have RGB projectors...

    You use a dichroic filter. Little pice of glass that has a film on one side that will pass certain wavelengths and reflect others. You shine one laser through the filter and reflect the other off the other side...

    1st laser |
    V
    2nd laser -> \ -> mixed beam

    You will need a green laser to get white, and another dichro. And some goggles...
    Love, peace, and grease,

    allthat... aka: aaron@pangolin

  3. #3
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    Smile

    There's a bit more to it than Aaron's post would suggest.

    I'm assuming you've got a multi-line Argon laser, Adam... If that's the case, then you're going to need some way to modulate those colors. If you have a PCAOM, that would be the ideal solution. (A PCAOM will give you analog color control of anywhere from 4 to 8 lines, depending on the model you buy, with a loss of 15-20% of total power.)

    You would simply mount the PCAOM in front of the argon laser, and send the output beam from the PCAOM down the beam table to the red dichro. Then you could mix in the red from the diode laser after the PCAOM and use direct modulation of the red diode power supply to control your red. (No sense putting the red through the PCAOM and loosing all that power.) You'd end up with a white light beam that you would have full color control over.

    On the other hand, if you don't have a PCAOM, then you've got a problem. You could use a dichro to split the green wavelengths off from the argon beam, and then use scanner blanking separately on the green and blue beams, but then you'd need another dichro to put the two beams back together again. (And then a third dichro to add in the red at the end.)

    Likewise, you could separate the green and blue lines (using a dichro) and then use separate AOM's on each beam to modulate the intensity, and again recombine them using another dichro before adding the red in last.

    Now, if you have a single line blue argon laser (at 488 nm), then you'd want an AOM or scanner blanking on that blue beam. Then you'd need a DPSS green laser (which you could modulate electrically just like your red diode laser). You would then combine the blue and green with one dicrho, and then add in the red with a second dichro.

    Some more information about the laser you have, the blanking scheme you planned to use, the controller and software you're running, and the intended use of the projector will all help us recommend the best solution for you.

    Adam

  4. Default

    Thanks alot buffo,
    Your advice really helped. It is a multi lined argon laser. Its a coherent innova 90 outputting around 2.5 watts. I do intend on buying a pcaom to do the job, and i am planning to use pangolin software to control it. Its a slow process, step by step cuz of how expensive everything is lol. But thoes are my plans right now.
    Thanks again
    -Adam

  5. Default

    Hey i forgot to ask one more question...does it matter, or would it matter what colour red i used. Like 635nM or 660nM?
    Thanks
    -Adam

  6. #6
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    Cool

    Ok Adam, sounds like you're on the right track then. With regard to wavelength for your red - if you've got a Coherent I-90, you're going to want a *lot* of red to balance it. So you'd be better off with 635 nm vs. 660 nm, simply because 635 nm red appears brighter to the human eye, so you'll need less of it to balance the other colors.

    Still, to get proper color balance, you're going to need a couple *watts* of 635 nm red. That's going to be expensive!

    Adam

  7. #7
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    Default

    Quote Originally Posted by premierlaser View Post
    a coherent innova 90 outputting around 2.5 watts
    Hi Adam,

    Just a thought; it may be worth getting the I90 checked out before deciding on direction for your projector because if 2.5w is quite low output from that multiline beauty...

  8. Default

    Hey,
    yes it is a bit low, its an old tube and it doesn't have much time left. Its all i could afford now so i have to do with. The guy who checked it tho said the cathode is in good shape (for now) however it is a bit over pressure.

    Back to what Adam said about the 635nM and 660nM...is it worth all of that extra money for the 635nm or would 660nm work as well, so i can get more bang for my buck? I dont know much about this but does the 25nm difference make a whole big deal, considering the price difference is big?
    Thanks guys
    -Adam

  9. #9
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    Default

    Adam

    635 looks good but is orange more than red but is pretty visible. 650 is about half as visible as 635 so twice the power will look the same though I think its a nicer red and you can easily combibe 2 650s for more power and get better beams out. My dual DVD based red has a nice tight beam and 350mW (ish) of power - though you will need more than that.
    do you know roughly how much blue and green power the laser is giving?

    Rob
    If you need to ask the question 'whats so good about a laser' - you won't understand the answer.
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  10. #10
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    Default

    hey rob-

    think he said his argon is puttin out approx 2.5W

    i would have to agree with buffo here. to balance out or even come close to balancing out to white you would need a SERIOUS amount of red. i would suggest stickin with 635nm. its going to look TERRIBLE next to the argon beam (635 as we all know has the beam characteristics of a flood light ) but at least the "brightness" can appear better than a 650.

    just quick math here-
    (this is a close approximation. NOT exact figures)

    ~2.5W of green would need ~4.2W of 635 or ~7W of 650!!!!! for a theoretical white balance. obviously, that aint gonna happen. so....my suggestion would be to stick with the 635 and get as much as humanly possible! sell a kidney or something. LOL...

    -Marc

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