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Thread: Dicro order?

  1. #1
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    Default Dicro order?

    I'm thinking of trying to build a RGB laser sometime in the future as I happen to have the major components (Red, green and blue lasers ). For this i will need to use dicro mirrors but I'm new to this. What setup will loose most power - pass thru or reflecting a beam? Passing thru two mirrors or reflecting on one?

  2. #2
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    Quote Originally Posted by Danny View Post
    I'm thinking of trying to build a RGB laser sometime in the future as I happen to have the major components (Red, green and blue lasers ). For this i will need to use dicro mirrors but I'm new to this. What setup will loose most power - pass thru or reflecting a beam? Passing thru two mirrors or reflecting on one?
    It all depends on the spec of the dichro. In general passing through will lose more power than reflecting. Usually green is abundant and is passed through two dichro's. Choose which is the weakest, red or blue? Let that one reflect of the second dichro and the other pass through.

  3. #3
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    yep like zoof said.

    some people like the red closest and some people like the blue closest but almost every time the green is furthest.

    most common is blue since it is the more expensive one
    -Josh

  4. #4
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    Thanks! Of course my blue is the weakest so I will place it closest to the combined output (first or second mirror depending on where you start the count ) reflecting on one mirror. Then I'll place my red reflecting on one and passing thru one. Last goes the green passing thru two mirrors. My blue is really cyan, but at least it's almost blue

  5. #5
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    Oh, almost forgot to ask this. What about beam diameter? Does the beam diameter have to be the same on all lasers to achieve a good mix?

  6. #6
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    Beam diameter is hard to control as is divergence. If possible pick lasers with equal divergence. In practice you'll find red will be fatter than blue and green. Try to keep the red small by choice. Near field and far field alignment are much more important (this really means: make sure the beams follow exactly the same path, from dichro to wall)
    What kind of laser are you using, you mentioned using cyan (488 argon??) instead of blue.

  7. #7
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    Nope no argon, it's a solid state lasing at 488nm made by Picarro. I got it for free and it's used and in unknown functional state. I only got the laser head and I can't find ANY information at all about it, so I need to do some reverse engineering and build a driver for it. Hence the "I'm THINKING of TRYING to build an RGB laser SOMETIME" It is clearly not a lasershow laser. It's been used for DNA analysis or something like that. I'm gonna make something more fun out of it someday . Or I may just make something out of a blueray diode...

    Thank's for your tip on dicros. I also got some mirror mounts with unknown dicros. I probably can't use them but at least I got some really nice mirror mounts... I take it as the beam diameter isn't that important. I just have to align all beams very accurate?

  8. #8
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    Quote Originally Posted by Danny View Post
    I take it as the beam diameter isn't that important. I just have to align all beams very accurate?
    Don't worry about it too much. Build with the stuff you have and tinker with it. Then you can judge for yourself what is important to you. The ting is you don;t have much of a choice when it comes to beam diameters / divergence. The two are inherently coupled, The smaller the beam diameter, the larger the divergence. Sounds like you have a high end cyan dpss. What is your green? If it is low end (very cheap chinese) its divergence will be slightly larger. If it is the better quality chinese (e.g., CNI) it will be pretty good as well.

    The red laser usually suck when it comes to divergence. Beams are usually kept fat to limit the divergence (smaller diameter will give larger divergence) and as such give problems. Often they are to fat to fit on the galvo mirrors but essentially we have to live with it. Not much we can do about it but wait for the technology to advance.

    You have some choice when it comes to red. I believe the bright 635nm lasers are fatter / worse divergence than the less bright 650-660nm reds. For lower power projectors the 200mW 650-660nm reds can be fine.

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