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Thread: weird waverotator, pbs behavior

  1. #11
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    it was quite a while ago , more then a year or so i think. It was a waveplate not a rotator and i found out that the waveplate wich was designed for 445nm only worked with that specific wavelength. I think it was one from Laserwave. OPT is convinced that its not the rotator so i would order a PBS as then it should solve them problem.


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  2. #12
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    I just sent a message to OPTLasers, Stanwax and techood whether their "445nm PBS" will work with 465nm properly. Honestly, I've only seen "445nm blue" PBS in these shops.
    I don't expect to get a good answer from techood but maybe OPTLasers and Stanwax have tested this.

    THe only real reason I'm skeptical my PBS is bad is because I have the same issue with the red PBS and the read diode I use is the good old P73. This is not only an unusual blue wavelength issue.

  3. #13
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    I got some answers.
    Techood says the 445nm PBS should work up to 470nm. We can be skeptical towards him, but
    Stanwax says 445nm PBS should work with 465nm with about 6% loss and
    OPTLasers says their 445nm cube should work with 465nm with a little loss but don't have exact measurements.
    So I don't think the PBS is the issue and I shouldn't consider getting something from Thorlabs or Edmund yet.

  4. #14
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    You need to be able to spin the "waverotator" which is known as a waveplate, while your adjusting it, with the beam on. The odds of it nearly working without spinning it are roughly 1 in 180. It has either two or four sweet spots, depending on its design.

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  5. #15
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    I find the arrangement odd. May I suggest the following...

    Move the pbs cube so a diode goes straight through. The eliminates a mirror. Make that a fixed axis. Yes this removes adjustability.
    Second turn the diode in the same direction as the first. The eliminates a second mirror. Now put the waveplate in line with the second diode and bounce the result into the pbs cube. You eliminated two bounces of loss and still have adjustability of one beam to align it all. You will most likely have other mirrors down stream to adjust the result of the module to match other modules. This way you maximize the power output by reducing reflection loss. Also each time you bounce you change and in some cases scramble polarization a bit. It adds up. You are already fighting a battle just with the loss of the pbs cube. Why waste more. I think you will save a good 10-20% if make these changes. Plus the module will be smaller. My two cents. If you had something in mind when you did what you did share it so I can maybe learn too. Thanks for reading.

  6. #16
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    The point of the two mirror setup is to make the projector easily upgradable up to 30W.
    https://www.youtube.com/watch?v=IBt8yYApEVo

    I know budget wise I'm far from populating so many diodes but it's not purely a dream either.
    The projector case and modules sizes are made to hold 12 diodes for each color. The holes for the brass parts are already drilled.

    Sure, even with 30W RGB they could be arranged in such a way to avoid a second bounce mirror but that would make one big projector and this is pretty big already.

  7. #17
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    Default Ah

    Quote Originally Posted by Finale View Post
    The point of the two mirror setup is to make the projector easily upgradable up to 30W.
    https://www.youtube.com/watch?v=IBt8yYApEVo

    I know budget wise I'm far from populating so many diodes but it's not purely a dream either.
    The projector case and modules sizes are made to hold 12 diodes for each color. The holes for the brass parts are already drilled.

    Sure, even with 30W RGB they could be arranged in such a way to avoid a second bounce mirror but that would make one big projector and this is pretty big already.
    Ah I get it. I was just looking at what was posted. Holly crap. All I would do with something that size is hurt myself🙀

  8. #18
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    You mean by the weight of the case or so many beams? because I just use a tripmot to lower power while aligning beams.

    Oh and I still can't find that sweet spot. Too much of the beam that had passed the waveplate still goes right through instead of reflecting.

  9. #19
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    I was thinking 30w on the wall in my living room would burn my eyes out just by reflection!

  10. #20
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    See this, might help understanding adjusting your waveplate.
    My mentor in optics was DR. Shaoul's PhD student.
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    https://www.youtube.com/watch?v=_sUVXHfUVsY
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    Steve
    Last edited by mixedgas; 05-30-2017 at 17:49.
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