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Thread: safety scan lense question

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    Default safety scan lense question

    Okay i have a question about Pangolin safety scan lens.
    Does it just reduce laser power by changing the divergence or make it 'completely' safe (below MPE).

    And how can you attach it to a projector without a mount?

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    Is that a goldenstar laser?
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    It changes the divergence when the beam passes through it. It should be mounted in such a way as to not move, fall off, or otherwise be rendered useless - while still achieving it's design purpose. When it comes to MPE - idiot proof is a myth.
    "There are painters who transform the sun into a yellow spot, but there are others who, with the help of their art and their intelligence, transform a yellow spot into the sun." Pablo Picasso

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    Quote Originally Posted by zorn View Post
    Does it just reduce laser power by changing the divergence or make it 'completely' safe (below MPE).
    .

    Hi Zorn,

    The lens increases divergence, but the safety question is a more complicated combination of the individual laser's beam characteristics, power, the power of the lens, the closest possible the laser is to someone's eyes, etc. etc. The only way to be sure it is "safe" is to be trained on how to measure the beam's power and have the right tools.

    Quote Originally Posted by zorn View Post
    And how can you attach it to a projector without a mount
    You could tape it to the projector but you would lose several features that the proper Pangolin mount provides. The proper mount is quite inexpensive for what it does and it's great build quality. I wouldn't try to save a couple dollars by avoiding the mount if I were you.

    David
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    JD3 - yes it is a GS projector/case.

    Zorn - if you want to see the lenses and mounts, click to my FB page in my sig, there are shots there of both items.
    This weekend I'll be putting the mounts on 2 very similar GS projector cases (the same case but aperture is not central), and I'll probably post some pics to my page.
    Frikkin Lasers
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    You are using Bonetti's defense against me, ah?

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    Get the Pangolin mount. It's ridiculously inexpensive for the amount of machining and precision involved. $29.95 is more than worth it.

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    It sounds like you're talking about the $100 Radiant Electronics X4 power meter, be aware that it is not designed for high speed, low power measurements like you would need to confirm MPE. What country are you based in where you're looking at doing audience scanning?

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    There are 6 different power lenses available dependent on your situation so, each one is going to affect your divergence differently. To do it properly, you need the kit of all six lenses although, my theory was to just get the strongest (6 diopter) to start off with. The power of your lasers and the distance to the audience and your measurements actually dictate the correct lens to use. I doubt you would use number one or number two for example, for anything other than a large stadium/arena situation OR, for a very low powered laser to begin with at closer distances.

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    This is bringing up a question I thought about last night and was going to post a thread about it here. It's specially aimed at people outside the US doing audience scanning shows such as the guys in the UK, etc. What measures are you electing to take on your own when doing an audience scanned show? Are you using PASS? Are you using divergent lenses? Are you using Eye Magics Iris Color Safe? Are you just using BAM in Pangolin software? Are you "honestly" doing anything or just talking a good game? I'm just curious what people are really doing in other countries.

  10. #10
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    It's specially aimed at people outside the US doing audience scanning shows such as the guys in the UK, etc. What measures are you electing to take on your own when doing an audience scanned show? Are you using PASS? Are you using divergent lenses? Are you using Eye Magics Iris Color Safe? Are you just using BAM in Pangolin software? Are you "honestly" doing anything or just talking a good game? I'm just curious what people are really doing in other countries.
    I use -6 diopter lenses pretty much exclusively. I just don't do big enough shows to use the others. In my experience, you always need as much divergence as possible. If I ever get to the point where full power through the lens is too far below MPE, it means I'm not using a big enough projector!!

    I use scanfail, and I measure a static beam at full power through the lens, and basically 'walk it backwards' away from the projector until I find the point where its at MPE. This has an added safety factor built in with an RGB projector, because this is a worst case scenario. Most of the time, all 3 colours won't be on full.

    Clearly I don't do this every gig. Once you know the MPE distance for a given projector, its going to stay fairly constant, even with fluctuating DPSS greens.
    If the room isn't big enough to hit 'safe distance' then I don't crowd scan. Likewise, I don't use BAMs to ensure MPE, as a simple mistake in zoning can blow that out of the water.

    Knowing what MPE is on my meter sensor, I will say that I don't fuss about a mW here or there. I apply some common sense to things. I think that given the sometimes HUUUGE powers people are scanning with uncorrected beams, a well diverged beam that might be 1.005 x MPE is still a pretty safe beam, certainly if it is scanning it is VERY safe. But as has been pointed out before, we aren't doing these calculations for the best case scenario, we're doing it for the worst case scenario! A stopped beam.

    And thats why I find the idea of doing pulse time measurements a bit of a misleading thing with laser safety, as your pulses are pretty much always going to be shorter than the exposure time in the event of a failure, even WITH a very fast scanfail.

    So there you go, there's my methodology, reasoning and logic.

    P.S. notice that I have used the term MPE throughout rather than actual irradiance, and this is because MPE varies depending on what kit you have, predominantly the scanfail, which can modify your worst case exposure time.

    P.P.S. I was seriously considering PASS for my new 8W builds, but then it occurred to me that I'm never going to be in a position to crowd scan with them, so whats the point! It is actually the lower power/cheaper projectors in my arsenal that would benefit most from PASS, but it is an unfortunate reality that the cheaper the projector, the higher the percentage of the total cost PASS will make up. And given that people tend to build the most powerful projector they can afford, the likelihood of them setting aside the $500 for PASS is not great.
    Frikkin Lasers
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    You are using Bonetti's defense against me, ah?

    I thought it fitting, considering the rocky terrain.

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