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Thread: Combining RGB DPSS

  1. #1
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    Default Combining RGB DPSS

    Ok, I am trying to combine RGB DPSS, but ran across an interesting problem. First off I have 3 lasers, the green is dpss532, and that is simply passed though two dichros, the red is at 671 and reflected from a dichro and the blue is at 473 and is also reflected, the pass green+blue and reflect red dichro is fine, it reflects >90% of the red beam without a problem, and passes >90% of the green/blue beams, the problem is with the pass green/reflect blue dichro, it seems to be passing 50% of the blue, and reflecting 50% of the blue, whats going on here?
    Thanks

  2. #2
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    Who manufactured the dichros?

    It sounds like the AOI's(Angles-of-Incidence) are way way off, its either that or the "dichro" is actually a non-polarizing beam splitter, but that doesn't sound likely given the lasers already in the pathway are not being split similarly.

  3. #3
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    Question

    Sorry OT here...

    Wow, how big is that 671nm? You gotta throw up some pic, I bet that beast is DEEP...

    Welcome to the forum!
    Love, peace, and grease,

    allthat... aka: aaron@pangolin

  4. #4
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    Default

    671 is 500mW rated making approx 595mW (its a CNI). The Dichros are actually pulls from one of those china made off the shelf RGB lasers, they are definately dichros, and they are colored properly. Like I said the Pass Green/Reflect Red dichro is working properly. The one in question is the pass Green + Red, reflect blue.
    Thanks

  5. #5
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    Lightbulb

    I'm not the expert, I just post a lot... The advice I got here was to go the extra mile for optics. I compromised and got an Edmunds for the blue, reflect blue pass the rest and got a cheaper pass red reflect green from eBay. I still spent $25 on it, so it wasn't THAT cheap... This is a dumb question, but is it facing the correct way... I ask, cause at FLEM... Bill from Pangolin pointed out that my blue optic was backwards... I wasn't losing 50% but still... blue ain't cheap. I seem to get a decent amount of red reflecting off as it "passes" through the green filter. I think I have red to spare though. I'd like to see your red up next to two combined maxyzmodules, just to see how deep 671 is and shits and grins of cource.

  6. #6
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    Quote Originally Posted by illuzion View Post
    Ok, I am trying to combine RGB DPSS, but ran across an interesting problem. First off I have 3 lasers, the green is dpss532, and that is simply passed though two dichros, the red is at 671 and reflected from a dichro and the blue is at 473 and is also reflected, the pass green+blue and reflect red dichro is fine, it reflects >90% of the red beam without a problem, and passes >90% of the green/blue beams, the problem is with the pass green/reflect blue dichro, it seems to be passing 50% of the blue, and reflecting 50% of the blue, whats going on here?
    Thanks
    The question must be the pass green/reflect blue dichroic mirror,Are you place with 45 degree?
    First:
    1\you must check the blue mirror polarization rate.May be s=1:1,this problem is the coating not think the polarization state of the beam.
    2\Though the coating is think the polarization state of the beam, but ceoating process isn't well,the center reflect wavelength excursion to the short wavelength,the best is 473,May it is 450.
    3\The incident degree is same to the coating incident degree?
    All the way,the reflection is only 90% is not well.
    So,My suggestion is:
    1\ You must tell the coating manufacter the polarization of your laser,if you don't know,you can ask your laser manufacter.
    2\Tell him the degree you place,and the degree toleration(+-).
    3\design you own system,because the 473 only 50nm short than 532nm,from you descreption I think the dichroic pass green and reflect red maybe better.
    In one word,the best coating is whatever polarization state your laser is,it can still work well.

  7. #7
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    Thanks bridge, that's very useful information!

  8. #8
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    Talking

    Breee! Breee! Breee! Sarcasm alert! Sarcasm alert! This is a stage 3 sarcasm alert! All hands open your engrish dictionaries immediately and prepare for emergency translation!

    truely funny stuff though, eh Yadda?

  9. #9
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    Default

    I was able to translate most of that, here is my translated copy, feel free to correct any errors,

    1: There is a Polarization Problem
    2: You are using the wrong wavelength dichro
    3(1,2,3): Your pass Red/Green, Relect Blue dicro is a piece of $@&%


    Here is my take on this, as far as a polarization problem goes, it should not be terribly sensitive to that, after all it is not a PCAOM, and people use cube beamsplitter combined beams with dichros all the time, and those are truly random polarization, and you dont hear about 50% losses on that. As far as the wavelength of the dichro goes, it was a pull from a chinese made RGB laser using diodes and dpss modules, and for the price that unit is selling for, believe me they are not using 457nm. The dichro is a piece of junk, is the most likely explaination, the only way to test this is to order a quality dichro from edmund or thorlabs, and test it that way. I should have done that in the first place anyways, kinda silly to spend thousands on lasers to get every available mW dpss technology can offer for the $, and throw away half the power through cheap a$$ optics.

  10. #10
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    Default mistake

    Now is ok
    1\you must check the blue laser polarization state.May be s : p=1:1,this problem is the coating not think the polarization state of the beam.

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