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Thread: Help with mega green

  1. #1
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    Default Help with mega green

    Is there a way to combine two green beams with a dichro? What I want to do is install a high power 532nm unit into the completed projector and retain the optical train that is present now. One unit for high power single color and opt out this unit {simply alternate power between laser PSU's}and still use the lower powered unit employed for RGB. Trying to figure out how to get this type of setup without a total rebuild. I have a combiner cube but I am not sure of it's limits. This will function as an attention getting device in daylight or similar settings. Then the functionality of the RGB setup is not disturbed.....easy swicth from the two regimes of operation. Let me know if this just a crazy idea....I think it can be done. The final result would be a great advantage for me.
    You are the only one that can make your dreams come true....and the only one that can stop them...A.M. Dietrich

  2. #2
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    Short anser: no. You can't use a dichro. But the concept is doable, if a bit involved...

    The best way to do this would probably be to put the 2 green lasers FIRST in your beam path, and then use a polarizing cube beam splitter to combine the two green beams into a single green beam. Then that beam would continue on to the two dichros where you would add in the red and the blue. (Come to think of it though, there's no real reason why the greens would need to be first, apart from the fact that green photons are cheap, while red and blue ones are both precious and worth saving... You can afford to lose a few percent of green across each dichro.)

    There's no way you're going to combine two beams of the same color using a dichro though... Dichros reflect one color and pass others. If you have the same wavelength in both beams they will be equally reflected or passed, depending on the dichro's coatings. (This is why you need the polarizing cube beam splitter to combine the beams.) Also, you have to have the two lasers adjusted so that the beam polarizations are perpendicular to each other.

    Now, if you had 514 nm green from an argon, then if you found a dichro with *really* good coatings it would be possible to mix in the 532 nm green from a DPSS unit in with that 514 nm green from the Argon without resorting to a beam-splitter... But that doesn't really apply to your situation.

    What about simply installing the larger laser in your projector in place of the small one and then dialing back the drive current when you want a balanced whitelight beam? Surely the power supply for the larger DPSS unit supports analog blanking, yes? Just add a small bias circuit that holds the analog intensity low enough that you get good color balance, and switch off the bias circuit whenever you want full green to grab attention in daylight. That simplifies your projector and still gives you both whitelight balance and death-ray green...

    Adam

  3. #3
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    one caveat:

    Polarization ratios on green lasers can be as low as 10:1, average is 18:1. You can order higher at a higher cost, obviously.

    But like buffo said: green is really really cheap power/price wise so the losses are almost a non issue.

  4. #4
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    If your not going to use any other beam but the high power green at the same time, you could just opt for a mirror to replace the beam from the RGB unit with the high power beam. No need to combine them at all then.
    You know, I have one simple request. And that is to have sharks with frickin' laser beams attached to their heads!

  5. #5
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    Default mega green

    Going to install the big green in to aim at the trichro. Software supports intensity so I will experiment befor trying to align all the beam paths. Is there any concern of a reflection killing the diodes....wouldn't think so on blue or green. Seems the optical train in the laser head itself would suppress any worry of this happening. Taken care of red unit......no reflections back at all. I managed to kill the TTL circuit of the greeny........doesn't like quite so much modulation. Replacement inbound. Thanks Spec.......if there are any of the big blue units left ........PM me w/price and maybe we can work out something...........I can always sell the one I have now.Low hours....maybe 10 or 12 at the most.
    You are the only one that can make your dreams come true....and the only one that can stop them...A.M. Dietrich

  6. #6
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    Default Re: mega green

    Quote Originally Posted by MechEng3
    Going to install the big green in to aim at the trichro. Software supports intensity so I will experiment befor trying to align all the beam paths. Is there any concern of a reflection killing the diodes....wouldn't think so on blue or green. Seems the optical train in the laser head itself would suppress any worry of this happening.
    Yea, the crystals eat/filter that out nicely. Did have one weird issue where the laser had lots of 808/1064 in the beam and when it was sent back through the optical train the beam would modulate in power... kind of like a sputtering neon tube... weird trick, but it goes to show that they are not completely impervious.

    Taken care of red unit......no reflections back at all. I managed to kill the TTL circuit of the greeny........doesn't like quite so much modulation. Replacement inbound. Thanks Spec.......if there are any of the big blue units left ........PM me w/price and maybe we can work out something...........I can always sell the one I have now.Low hours....maybe 10 or 12 at the most.
    With the trichros here ive noticed that its a lot easier to offset the angle 5 some odd degrees and align everything using the dot that shows up on the housing. Trichros are great

    Still have all three units. (go figure). Will send a PM in about 10 minutes.

  7. #7
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    Default mega green

    sorry ..............I just read your PM befor looking at this. A rebuild is absolute at this point. I have sent you a note....let me sort a few things and I will get with you on a deal. I have to kick off a lot of work and will be free this Sunday night.
    You are the only one that can make your dreams come true....and the only one that can stop them...A.M. Dietrich

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