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Thread: Laser power meter (UK based)

  1. #1
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    Default Laser power meter (UK based)

    I am looking for a laser power meter to calculate MPE when setting up laser display shows. Can anyone recommend a model that would be suitable for use with 2W 532 nm DPSS lasers. I am UK based so something available in the UK would be good.

    Thanks

  2. #2
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    Default powermeter

    Hi, i have a LaserBee Deluxe (up to 2.1W), also capable of datalogging with a pc, up for sale, see the buy/sell section. I bought two, one for myself and one for a friend who had to decline afterwards so i have one spare ;-)
    Michel
    Utrecht
    Netherlands

  3. #3
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    It really needs to be a photodiode meter for this application, not a thermopile.

    Regards, Dan.

  4. #4
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    It really needs to be a photodiode meter for this application, not a thermopile.
    No it doesn't, it depends how you want to measure and calculate.

    If you know the max CW power, beam diameter at aperture and divergence you can calculate MPE at any distance, based on a worst case scenario.

  5. #5
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    If it's for calculating MPE's it's important that you have a current calibration certificate with the meter, otherwise how can you prove beyond reasonable doubt that your readings are correct?

    If you do commercial shows you really need a rock solid trail of paperwork to show the test equipment you're using is reliable. I suggest looking at maufaturer's such as Thorlabs, Newport or Melles Griot.

    Cheers

    Jem
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.... Douglas Adams 1952 - 2001

  6. #6
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    Quote Originally Posted by norty303 View Post
    No it doesn't, it depends how you want to measure and calculate.

    If you know the max CW power, beam diameter at aperture and divergence you can calculate MPE at any distance, based on a worst case scenario.
    Sure, for static beams, but what about scanned effects?

    I was always led to believe that thermopile's just weren't fast enough and a fast silicon based photodiode was essential.
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.... Douglas Adams 1952 - 2001

  7. #7
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    Well, (really quick answer, because I'm at work and have limited time to quote references etc)..

    if you know how powerful a static beam is, its easy enough to then apply the calculations for a scanned beam, applying blink reflex time, no of passes per second, etc based on a worst case scenario as I said. So for an RGB projector you would calculate everything assuming all lasers fully on, in reality it would be unlikely to happen all the time like that (I'm referring to 'live' busked shows, not pre-programmed shows)

    Check out an application called Lasersafe PC, which has a demo version restricted to just 532nm (but for laser display purposes fits the bill, as 400-700 can all be treated the same anyway) and you can plug in the numbers and play with the variables.

    re: your comments about certificates and calibration, I'm not so sure you have to be so pinpoint accurate as in my experience, even quite large changes in power (>100mW) don't seem to have too much impact on whether something is over or under MPE. The big factors are divergence and the associated distance to hazard.

    Personally, I don't like the fact that we have this hard line of 0.999 MPE is ok, and 1.000001MPE is suddenly life threatening!

  8. #8
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    The 'nut holding the wheel' has got to be important too.

    What's worse, a user that has a laser that is slightly under MPE but has finger beams in the audience's faces all night or one that has a slightly over MPE projector and a just passes a few sweeping wide fans over the course of the event?
    http://img62.imageshack.us/img62/3985/laser.gif

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