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Thread: New Thought on Crowd Scanning??

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    Default New Thought on Crowd Scanning??

    Last night after much caffeine and the "outside the box" brain working overtime, I started pondering something. We all know that the magic is really being in the "cone" and that seeing a show as designed, is the way lasers should be viewed. There is such an issue, whether here in the US or the UK or other places about the safety of doing that. It can be done but...requires special, expensive measuring equipment, a math degree and maybe even a bit of luck convincing officials you know what you're doing and giving approval. So, the brain gets to wondering...

    We always bitch how much is lost with optics in the projector and work to find the best mirrors, best dichros, best PBS, to minimize those losses. Therefore, that tells me that optics can also be used to reduce power.

    Some of you into photography may be familiar with the Cokin system of special effects filters. The basic idea was a square filter holder screwed onto the front of your camera lens and had slots to slip up to three filters in to alter your photographs. The filter holder and filters were all one size but, you bought different adapter rings that matched the size of your lens thread and held the filter holder. There were the standard things like sunlight filters but also gradient filters of various colors, star filters, pinhole shapes, prisms, even one where you smeared colored vaseline onto the filter and gave your photos an odd swirling eclectic look. There was one that, similar to a beam block, covered half the lens and blocked it completely for odd double exposure shots. You could even add a rainbow to a picture where there wasn'tone by inserting the rainbow filter. Kinda like using Photoshop IN your camera before there was such a thing as Photoshop. So I get to thinking... why couldn't you have something similar to the Cokin filter holder that could be adapted to fit the aperture window and have a series of glass filters coated with SOMETHING that would reduce laser power on a measurable scale on the bottom half and be clear on top. Or, just half moon shaped filter. It could be slid up or down much in the way a beam block might be during show setup but, rather than block beams entirely, allow a safe but visible amount to come through. A set of filters could be possibly be created that covered a "range" of milliwatts and you use the one that matches the power of your projector.

    For example, say a "+1" filter reduces 50-100 milliwatts to safe levels, a "+2" reduces 100-150 milliwatts, a "+3" reduces 150-200 milliwatts or something along those lines. Kinda like sunglasses (Or, laser safety glasses if you prefer) for the lower portion of the projectors output. You'd just get a filter or couple of filters that reduces your 1.7 watt RGB down to a still visible but safe 4.95 or whatever.

    I'm certain there is a multitude of reasons I don't understand as to why it might not work and, I'm sure someone has thought of it and maybe experimented but, thought I'd throw it out there for discussion. (Slow day at work )

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    Beam Attenuation Map... Something else I can show you at SELEM. There are also a couple of products out there that do this or something similar. I think "IRIS" is one, and Pangolin is working on a Beam Brush that uses lenses to expand the beams divergence to make is safe for audience scanning.
    Love, peace, and grease,

    allthat... aka: aaron@pangolin

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    IIRC Pangolin was also working on a beam attenuation filter, that had a "horizon" and attenuated the lower you went

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    Pangolin has those bifocal lenses that diverge the beam in the lower half of the scan window. They make the beam much
    bigger so its more comfortable for the eye to view and leave the upper half alone.

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    That's along the lines of what I was thinking about.

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    you can use a neutral density filter to reduce brightness (much like sunglasses, only with know and measurable properties) or use a lens of some sort to increase divergence. still, if you go multiwatt, this does not look sufficient

    it has to be a combination of divergence, distance, scanning speed and reduced power
    "its called character briggs..."

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    I am surprised with the cheap galvos out now, people have not build projectors just for audience scanning.

    People will not notice the quality of scanned beams at them. So use lasers that are low power just for that purpose.

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    Quote Originally Posted by PhantomRage View Post
    I am surprised with the cheap galvos out now, people have not build projectors just for audience scanning.

    People will not notice the quality of scanned beams at them. So use lasers that are low power just for that purpose.
    What's safe at one venue/for one show may not be safe for another. Alternatively if the power's are safe for all venues/shows then it's unlikely bright enough to see the scanned beams. Also, having attenuated beams for crowd scanning and full power beams for overheads is preferable.

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    meh, a 5mW 532nm projector with a lot of fog can look pretty ok

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    Quote Originally Posted by PhantomRage View Post
    I am surprised with the cheap galvos out now, people have not build projectors just for audience scanning.
    I must admit I'm surprised that projectors haven't separated out into graphic and beam projectors along the lines of tight beams for graphics and wide beams for beam projectors.

    One of the problems with lenses is they tend to make the beams look fuzzy whereas if the beam is fat straight out of the laser it still looks quite crisp and with the development of faster galvos over the last few years, I would have thought larger mirrors would have been employable to prevent mirror losses thus making projectors for designed for beam shows alone viable using say 5x5mm lasers instead of the 2.5x3 that's quite common now.

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