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Thread: Safety of high power graphics shows due to reflected light power

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    Default Safety of high power graphics shows due to reflected light power

    With the advent of super ubber powered home projectors, we are getting close to the level of power where the relflected light from the image is dangerous to watch. Has anybody done studies on this or have information as to when bright is bright enough?

    I just went from 300mw to 1.5w of power on a 7x7' screen at 20 feet distance. I noticed some of the images leave an after image for a few seconds and make my eyeballs hurt. Is that a sign of too much power? Can you hurt yourself from watching too much show material at these levels?

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    Quote Originally Posted by kecked View Post
    With the advent of super ubber powered home projectors, we are getting close to the level of power where the relflected light from the image is dangerous to watch. Has anybody done studies on this or have information as to when bright is bright enough?

    I just went from 300mw to 1.5w of power on a 7x7' screen at 20 feet distance. I noticed some of the images leave an after image for a few seconds and make my eyeballs hurt. Is that a sign of too much power? Can you hurt yourself from watching too much show material at these levels?
    Assuming a diffuse cosine scatterer and a 1-2 meter viewing distance, VERY Long term, with daily exposure, yes, probably, with the blue. Short term, other then eye strain/ temporary rhodopsin depletion, no..

    ANSI Z136 sets a limit at 320 uWatts cm^2 for a 8 hour day. To meet that with a steady spot works out to something like a meter back from a 300 mW blue source impacting a average scatterer.

    21 CFR 1040 states that no audience member will be exposed to a AEL greater then class I, and the three meter vertical rule used in public laser shows does a good job of this in most cases.

    PM me and I'll send you some PDFs via email with some calculations and standards. I'm not too far away and have a silicon based power meter that has a low end of scale of microwatts, so if you want some numbers, let me know.

    When all this started the then BRH sent guys out with cases of gear to follow a professional laserist around on tour, and the rules and practices used to date are based on their measurements, those practices were ION laser based, and so may need a little review.

    As LEDs climb in power, you'll start to see studies about the effects of excess blue.

    But for the most part up to say a watt or so, no long term effects if your viewing distance is in meters.


    Steve
    Last edited by mixedgas; 07-29-2010 at 08:47.
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