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How come laser shows are not a danger to the audience? (newbie)

IceFireForce

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Hello,

I am a newbie to lasers in general and on this precious forum. I did use the search bar for "laser shows" and "laser show safety", but didn't seem to find that explained. How come laser shows are not a danger to the audience? I see and have been to such ones that scan over the audience with the lasers like so:


And if anything above 500 mw is classified as Class 4 and Dangerous, does that mean all lasers here are under 500 mw? This does not seem possible seeing their power output... What is the thing I don't know here?
 



steve001

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Hello,

I am a newbie to lasers in general and on this precious forum. I did use the search bar for "laser shows" and "laser show safety", but didn't seem to find that explained. How come laser shows are not a danger to the audience? I see and have been to such ones that scan over the audience with the lasers like so:


And if anything above 500 mw is classified as Class 4 and Dangerous, does that mean all lasers here are under 500 mw? This does not seem possible seeing their power output... What is the thing I don't know here?
There are not enough binary bits to list what you don't know.
 

IceFireForce

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I did. It talks about not using lasers above 500 mw as they are Class 3b or 4 (but doesn't explain how those low wattage lasers cover a stadium); and also speaks about pulsed and continuous lasers, but this doesn't seem to be related to the class, and at the end it gets a mess and I don't understand the simple short one-sentenced answer that I'm looking for. I am not ready to learn everything about lasers in order to understand the simple concept as of how stage lasers are safe, so I asked here...
 

logsquared

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Its very complicated and can't be explained in one sentence. Audience scanning shows are set-up by highly trained individuals. They use lots of measuring, testing, math and electronic hardware to make the show safe by keeping the power of the laser under safe limits as it scans the crowd.
 

LSRFAQ

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We use Zones in hardware and software that reduce the power below the "zero" or horizon line. Scan Failure Safeguards (Required in the US) Wickedly expensive hardware, we own calibrated laser power meters, oscilloscopes, fast photodiodes set up to mimic the eye, years of training, legal certification, have a laser safety officer check our work etc. We don't share the hard won information on how to construct safe audience scanning frames and animations with just anyone who asks. Why? Because of the risk that some idiot will argue that info should be "free" and then publish a simplified "APP" for a cell phone, distribute it, and the math will end up wrong. Then another idiot will publish the frames, some one will do a show without meeting all the required pre-existing conditions, and some one will get blinded.

Also we stand down range and view our own effects. This tends to make one make sure we have done it right. This is so we can sleep at night, as lasers are dangerous.

Hint: Increasing the repetition rate of the scan actually increases the exposure time.

There is an internationally approved concept called "Maximum Permissible Exposure" and we stay below the cumulative MPE for an eight hour day.


Requires massive amounts of math, and in the US is quite illegal, without a document allowing you to break the 2 and 3 meter rules.
2 Meters horizontal Separation and 3 meters vertical Separation from the highest accessible audience point is the norm for a conventional laser show. Very few people make it to the level where they are allowed to do that in the US. I've taken the classes over the years, been in the audience many times, can do it, but choose not to do it.

Every single part of every single effect gets checked and measured on a second by second basis when your doing it right, and for a typical four minute song, that is a LOT of work.

Now you know a tiny bit. Don't try it, because even at the MPE, it's more then bright enough that it hurts. We have to dial it down even further.

If your asking the question, or reading this to find out how to do it, and have not taken the classes offered by a few consultants, and passed the LSO exam, you don't have a clue and should NOT try it.

Massive amounts of quality control procedures are used, before, during, and after.


The example once explained to me by a Di*ney chief safety officer was this: You have an experienced Brain Surgeon in your audience. Even though you didn't harm them, and can probably be reasonably sure you did not, after doing all the math and quality control checks, he/she files a claim anyways. Can you really afford to pay 450,000$ a year in legal payments plus punitive and cumulative damages for the rest of her/his career? In other words, if you screw up, your basically bankrupt for the rest of your life.

The scan failure safeguard is required to act 100% of the time in 200 nanoseconds or less, that is NOT easy to engineer. Did I mention the 3200$ special laser power meter for pulsed exposures?

nough said.

Steve
 
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steve001

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Thank you for the very informative reply and for letting me know I am dumb for not knowing everything in the world and for daring to ask.
I was joking. I have only a small clue to what all is involved. The other two posters explained in brief detail how complicated a laser show is to put together.
 
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IceFireForce

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Steve,

That is an amazingly well written, beautifully informative reply that I would think should be linked up in a special section with commonly asked questions and perfectly composed answers to them. Now I know everything someone who is not looking to try it himself needs to know.

And no, I don’t see myself doing any laser show in any way. In fact, prior to purchasing my first 1W 445 laser and realizing immediately that I have to read a ton and be careful to the extreme, I had been fantasizing about making a small laser show followed by fireworks, say for a new years eve for friends vewing. Not anymore am I even daring to think that this is anywhere near a good idea.
 

LSRFAQ

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I have a peer judged award, 3rd place internationally, for ONE audience scanning show, done with a former partner. I can legally view my own show in Canada, but not in the US. That was back in the late 1990s. My CANADIAN mentors checked and rechecked that piece before it was screened. A committee of professionals checked the hardware, and a professional LSO checked it again before the judging. Even I nearly stood up and yelled "Terminate" due to the brightness during the contest. In fact I did stand up to start to shout and a peer pulled me down and stopped me. He heard me say "Too Bright" before I stood. So if anyone asks about the validity of that post, I do have the knowledge, but not the hardware.

Steve 001, was sort of right, not enough bits.

HAQ,/Artic Dude, You can sticky my thread posts in this thread, if you wish.

Steve
 
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paul1598419

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I recall the first concert I went where the audience was laser scanned. It was a "Yes" concert in Houston, TX back in 1976. They used what I thought was an argon laser from the beams' color and it was totally eye safe for the nearly four hour show. I have seen "Yes" in concert many times and one thing I can say about them...........they always play much longer than you wish to listen.
 

LSRFAQ

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When a friend went and got his audience scanning package together over the past year, the largest number of variances he could read online, for Aud Scanning were issued to Mega Churches. Followed by a few amusement parks. They at least have the funding, large enough venue, lawyers, insurance, and a pro staff in most cases. Also because churches generally don't tick the "confidential and proprietary" box on the form, which legally buries the "How To" data in the Federal Register. There are only a handful of legal users out there, in the US.

Steve
 
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ArcticDude

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I have a peer judged award, 3rd place internationally, for ONE audience scanning show, done with a former partner. I can legally view my own show in Canada, but not in the US. That was back in the late 1990s. My CANADIAN mentors checked and rechecked that piece before it was screened. A committee of professionals checked the hardware, and a professional LSO checked it again before the judging. Even I nearly stood up and yelled "Terminate" due to the brightness during the contest. In fact I did stand up to start to shout and a peer pulled me down and stopped me. He heard me say "Too Bright" before I stood. So if anyone asks about the validity of that post, I do have the knowledge, but not the hardware.

Steve 001, was sort of right, not enough bits.

HAQ,/Artic Dude, You can sticky my thread posts in this thread, if you wish.

Steve
Uhmm..
I can only sticky whole thread if thats ok?
 




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