Laser Safety in Laser Shows

In a show like this:
Paul van Dyk @ Trance Energy 2009 (lasershow) - YouTube

How is the laser kept at safe levels as it is being shot into the crowd?

Low power output with smoke? High divergence?

bobo99 said:

In a show like this:
Paul van Dyk @ Trance Energy 2009 (lasershow) - YouTube

How is the laser kept at safe levels as it is being shot into the crowd?

Low power output with smoke? High divergence?

Click to expand...

I'm thinking that had to have taken place outside of the US. I believe crowd scanning is illegal in the US; that's why I say that.

Those 532 beams look to be way more than what is acceptable for eye contact ~5mw. Your average laser show projector is 500mw and up. Mine is 1.2W. I have seen up to 5W projectors. People are playing russian roulette with their eyes there.

Maybe they had to sign a waiver. I know I do when I go to LEM's.

Oh yea, I'm pretty sure they are using smoke. That's why the beams look so "fat".

I have wondered the same thing.
Looking back, I am truly amazed how many shows I can remember walking through a green tunnel of light.
Lasers have been in underground (and above) shows right in our faces for many years.
Reminds me of awareness to the dangers of smoking we have taken so long to attain.

Most people just do not know the dangers of a laser beam.

Often it is an eye danger scanning like that...

The ways they can make it safer are:

Expanding beam size through a lens to decrease power densitty
Turning laser power down
Turning up scan speed so the beam is not in any one place for more than a few milliseconds
Failure interlocks to turn off the beam if someting goes wrong

It is illegal most places to do crowd scanning because it's super risky even when done properly and can cause eye strain even if it doesnt cause damage.

Look at all the CCDs wrecked at raves on YouTube.