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Thread: weird waverotator, pbs behavior

  1. #1
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    Default weird waverotator, pbs behavior

    The beam in this illustration I think should go down, not right, "right"?



    Waverotator is from OPTLaser and everything else from techood.

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    Wave plate needs to be able to spin on its axis for final adjustment. It also looks way too thick for a quartz waveplate, which are usually less then a millimeter thick.

    Steve


    Quote Originally Posted by Finale View Post
    The beam in this illustration I think should go down, not right, "right"?



    Waverotator is from OPTLaser and everything else from techood.
    Last edited by mixedgas; 05-23-2017 at 10:56.
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    Sure, but I've been rotating these red and blue circular ones for an hour with no result. I'd expect the beam to gradually shift from one angle (beam angle) to the next one but I see no difference. The rectangular shaped one for the green worked fine and my green module is already usable.

    (The diodes in the illustration photo are NUBM07E not NUGM01, sorry about that)

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    Quote Originally Posted by Finale View Post
    The beam in this illustration I think should go down, not right, "right"?
    I'm not totally clear on what you are asking, and I don't mean to state the obvious, but if you want the opposite laser to be reflected by the PBS cube than the one that is, rotate each diode to the opposite polarization angle (90 degrees assuming it was aligned properly in the first place). You may wish to move your half wave plate to the other diode if you expect the final correction to be opposite to the way it comes out.

    Quote Originally Posted by Finale View Post
    Sure, but I've been rotating these red and blue circular ones for an hour with no result. I'd expect the beam to gradually shift from one angle (beam angle) to the next one but I see no difference. The rectangular shaped one for the green worked fine and my green module is already usable.

    (The diodes in the illustration photo are NUBM07E not NUGM01, sorry about that)
    Oh, so this is a 465nm diode. Are you sure that your cube will work with this wavelength? Most PBS cubes only work with a limited portion of the spectrum. When you run an 'incompatible' wavelength through a PBS cube, it usually just passes the beam through regardless of its polarization. I'm sure Steve or someone else here could explain why this occurs in great detail.

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    Quote Originally Posted by dkumpula View Post
    Are you sure that your cube will work with this wavelength? Most PBS cubes only work with a limited portion of the spectrum.
    I'm not sure, this could be the case. But that wouldn't explain the same problem with the red P73 diode. The PBS for that is advertised as "635-680nm". For the blue it is "405-450nm", but the 450nm diode I know can shift to around 455nm, if this was an issue I'd expect to hear about it from others by now. But I've been absent when the 465nm diode came along so maybe people did talk about this before.

    http://www.ebay.com/itm/Blue-Laser-B...-/261158899714
    http://www.ebay.com/itm/Red-Laser-Be...-/251217446189

    http://optlasers.com/en/43-rotators (they are now all rectangular, blue is "dedicated for 440-473 nm wavelenght")
    Last edited by Finale; 05-22-2017 at 12:42.

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    Uggg, Techhood is not very reliable in my experience. I purchased blues, reds and green PBS cubes from them in the past and I got the wrong cubes from them about half the time (they would most commonly send a cheaper blue cube when I ordered a more expensive green cube). Their blues work OK for 450nm but do not work at all for 405nm despite their range claim. In either case, they don't claim to work with 465nm and likely don't. I would get a blue cube from a more reliable vendor that can show you a high level of efficiency and low reflectivity with this wavelength. Perhaps Edmund Optics would be a good start.

    Regarding the OPT laser wave plates, I haven't purchased their wave plates, but I've been pleased with my other purchases from them.

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    The reflectivity for the green PBS is fine.
    Techood gets things mixed up but I've bought around $2000 worth of stuff from him and most items were fine/as advertised.
    I could buy everything from EO but I'm not making mad money from this, quite the opposite , might start looking for another job at this rate. Yeah, I'm a broke ass.
    Anyway, another possibility is the PBS cube was listed before NUBM07 became available and he's been relisting it without updating any info.

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    The problem is that your rotator plate is not suitable for a 465nm wavelength. I combined in the past a 445nm with a 462nm with the 462nm angled into the pbs with the rotator. The 462nm went partially trough and i ended up with 1600mw/445nm +400mw/462nm instead of 3W total power. The cube works fine with 462nm only you have slightly more losses as its coated for 445nm. But the rotator should be designed for 465nm wich i believe is a 445nm one and that won,t work on a 445nm as its 20nm off.


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    Okay, gotcha. Will just stack them for now, fuck it. Description says "This is a high quality wave rotator plate dedicated for 440-473 nm wavelenght." but whatever I guess.
    What about the red though?

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    edison, where have you gotten your waverotator?
    Because here's an email response I got from OPTLasers:

    They are dedicated to 455nm wavelength and basically +-10nm they work great. They will rotate the polarisation not by 90 by 87 degrees for example so it is not big change and all PBS cubes accept +-5 degrees.

    We switched to the square ones because they are easier to mount, the only reason.

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