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Thread: Safety rgb laser with ND filters

  1. #1
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    Default Safety rgb laser with ND filters

    Hi

    I would like to know if someone already use ND filter in front of a 1w laser output for audience scanning or just testing shows at home.

    If yes what kind of filter is best suited for it and what were the specs of the filter

    something like this

    https://www.amazon.com/66-011356-Neu.../dp/B000A1SX76

    Thanks
    Last edited by bgnt44; 07-26-2017 at 08:01.

  2. #2
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    No matter what you do you still have to measure the result and calculate the mpe. So the nd might cut it back but it doesn't change the amount of work you need to do. Turn the current down is a better way to do it if you can.

  3. #3
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
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    You still need a laser power meter to do that safely, and you cant trust the filter to be what is specified on the label. Low cost Optical coatings and commercial grade filters are rarely checked at the factory for performance, let alone performance across 3 wavelengths. They might do twenty coating runs of sixty pieces before they stop and take a witness sample for measurement.. Did I mention that many coated filters can be angle sensitive?
    !
    I've seen "one watt" RGB lasers ship at two point four watts, too.. You cannot assume you have roughly one Watt of Laser Power.
    ~
    It is best to turn down the diode drive. Then obtain a proper power meter and measure the results. You only have one set of eyes, and they are not replaceable.
    ~
    There is a good reason that no one uses ND filters for audience scanning commercially.
    !
    I'll put a plug in here for Pangolin's "Safety Scan" calibrated lenses to increase your divergence, too. While one lens will not make you "safe" at very short distances, it will go a long way towards reducing your MPE.
    !
    YOU HAVE TO MEASURE THE MPE BEFORE YOU SCAN YOURSELF OR OTHERS.
    ~
    Steve
    Qui habet Christos, habet Vitam!
    I should have rented the space under my name for advertising.
    When I still could have...

  4. #4
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    I like the increase divergence route a lot. It's a good way to spread the core energy out to lower exposure. Please don't mess around. I have a nice black dot that follows me around from guessing....

  5. #5
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    Thanks everybody ! i totally understand what u mean and moreover i read a lot from ILDA website regarding safety.

    I reduce power through software cause diodes are analog ... but dont want trust that.

    never though about reducing it through hardware im def gonna see if thoses diode came with power adjustements

    i receive a set of ND filter which visibly reduce the power but still no measure so no safety (but the dimming is really obvious)

    Quote Originally Posted by mixedgas View Post
    There is a good reason that no one uses ND filters for audience scanning commercially.
    commercially its usually way more than 1W total , and nd filter heat up or reflect the rays that's reason enought for not using them

    But scientist use them on bench to reduce laser power , so that's what my idea came from .

    BUT YOU RE RIGHT , nd filter value cant be used for MPE reduction calcul, ... altought if the laser is barely visible , obvioulsy its irradiance is low (its still visible light after all)

    Actually it would be reasonnable for example to say that "a ND1024 filter of good quality make a 1W RGB laser safe ()" , cause its just optics properties ...
    (i volontary took ND1024 which reduce light by 1000 => 1 w max )

    Moreover, I don't plan to do it commercially , i'm more into developing software for laser shows but thoses days a cheap RGB laser is 350$
    and i cant imagine that people wont use that in a bad way.

    ILDA and pro laserist know very well how dangerous it can be, but when you read forum, the way to make it safer are way more expensive than the laser itself.

    Truth is if u want analog diode and more than 15kpps cheap laser , you re dealing with a least 1W. and if you put 350 in your laser, its only for learning ... or house parties ...

    But for my own case, do you know if there is any "cheap but trustable" illuminance/irradiance meter available (sellable in canada)

    Thanks

    EDIT : ok ..... that ND filter kit was shit, it melt a bit while displaying a constant shape at max power ... ok you guys saved my life ...

    Now i need to find a way to really turn that lasers down , like 10 times .. .and gonna buy a LPM (probably hyperion)
    Last edited by bgnt44; 07-28-2017 at 13:56.

  6. #6
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    Is it possible to reduce each laser output power in the projector ? (hardware not software)

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