Can a laser show blind you?

[SubrosaNJ]

Sorry if this seems like a silly question, but I really am curious. Still trying to reach out and grab all the info I can as am still pretty new to lasers. My question I guess is more along the line of.. are laser shows ever dangerous? I have never been to one so I dont know the specifics. Does the audience wear protection glasses? Or is there no chance of beam reflection? I would assume that most show lasers are of very high power, how do they not damage a viewers eye?

Thanks for any info on the subject.

 

[Eudaimonium]

Only one of your questions is rather "silly", which is about audience wearing goggles.

Have you ever seen proper laser safety goggles? Have you seen that the laser is invisible through them? So how can you view a lasershow when you're not seeing anything?

Lasershows are having very powerful lasers inside, yes.

However, they are not always driven at maximum power, there is this thing called modulation. Basically, when beams are passing near the audience, power levels go very low, since angle of beam is very low and it's very visible.

Next, the beams are moving incredibly fast... it's just that you can't see it. So that one beam that appears there, is actually pulsed at some frequency.

Finally, beams themselves are not focused tightly, they are around 1-3 cm wide when they are near the audience. Combine that with low power, and you're pretty much safe.

On a more uhh... logical note, you see, lasershows are beautiful to behold and everything. A lot of people pay a lot of money to construct them and see them.
Do you think people would continue to visit them if they blind everybody in the room?

Events which cause some permanent damage to the audience tend to get very poor reputation and number of people visiting them

This is the first to come to mind on the subject:
Audience scanning - Wikipedia, the free encyclopedia

For more professional read, try visiting PhotonLexicon. Not sure but I think I saw something on that topic there.

 

[Bionic-Badger]

The short answer: yes, this is what laser show safety regulations are for.

 

[Eudaimonium]

The short answer: yes, this is what laser show safety regulations are for.

Indeed, the shortest possible answer. I was trying to focus more on preventing it.
@OP
Oh also, there are usually some sort of "safe zones" defined within the software so beams will automatically drop to safe power level when in safe zone, so you are even more safe that way.

Every lasershow is carefully constructed and pre-sighted for such things. You don't want a hundred lawsuits filed against you

 

[SubrosaNJ]

Thanks for the replies. Yeah I know it would be dumb to have a show in which people would be blinded, I guess I was looking more for the answer of why it doesnt blind. But you explained that very well thanks again!

 

[Cyparagon]

In practice, the only reported injuries have been from pulsed lasers (such as copper vapor and q-switched YAG)

 

[Benm]

Still, i suppose sticking to the MPE levels would be a good idea when any crowd is involved.

Not all injuries would be noted in any case. Its a bit like getting ear damage from music that plays too loud - you get the ringing sound for a bit, but consider that to be a normal morning after effect. The same coud be true for seeing spots as a result of laser exposure beyond recognized safety limits.

 

[Flaminpyro]

Are laser shows allowed to hit the crowd ? I thought that
they had to keep the beams above peoples heads.
I'll bet EF knows the answer to that one !

 

[aryntha]

Are laser shows allowed to hit the crowd ? I thought that
they had to keep the beams above peoples heads.
I'll bet EF knows the answer to that one !

Yes, EF would know better but: this is called "Crowd scanning". It does happen, sometimes intentionally. More often in Europe than the US. It's also the source of some controversy, to a degree.

I'm sure EF could explain more.

 

[ElektroFreak]

You folks already have this well in hand.. not much left to say.

Crowd scanning CAN be done safely. As long as the person doing the show takes the proper measurements using calibrated test equipment and determines beyond all doubt that the show will be safe under all of it's programmed perameters, then it can be done safely and legally with gov't approval. Much of what is seen in Europe is done this way, but also there are a lot of European shows that aren't measured. The operators that don't measure rely mostly on what Cyparagon stated above: that there are very few, if any, publically confirmed reports of injury to audience members by CW lasers of any power level commonly found at laser shows, which is up to around 7-8W in most cases. Pulsed lasers are far more dangerous. Even though the pulse is short, the peak intensity is FAR higher (it's very common to see peak powers in the kW range) and a few kW of instantaneous power can do a lot of damage in not a lot of time.

Generally speaking, in the US crowd-scanning is avoided. I believe this is due more to the operator's fear of litigation than actual danger to the audience myself.

 

[hakzaw1]

IIRC bunch of folks got seriuosly eye zapped at a Lasershow in Moscow a while back. Things are way diff. here than elsewhere. Best place to see a great show with audience scanning in the USA is at a LEM. Lawsuits have made most crowd scanning a thing of the past here. Easy to sue- hard to defend the lawsuit.

SELEM Rocks!!!! Aug- 19 to 21 2011- NEWTON NC-

 

[vk2fro]

There is another way a laser show can blind you. Most laser show projectors are protected against this however, and its a situation where the galvos (the gadgets that move the laser beams around really fast) fail.

This situation is called a "Scanfail" and results in a high powered static beam. However feedback loops in good projectors shut off the laser the instant a scanfail occurs. The protecter for this event is funnily enough, called a scanfail circuit.

Without one, a member of the audiance may not be blinded but if the laser is powerful enough and as we know audiance members like to put there hands into the laser beams, they could get a nasty burn from the laser.

 

[Bionic-Badger]

IIRC bunch of folks got seriuosly eye zapped at a Lasershow in Moscow a while back. Things are way diff. here than elsewhere. Best place to see a great show with audience scanning in the USA is at a LEM. Lawsuits have made most crowd scanning a thing of the past here. Easy to sue- hard to defend the lawsuit.

SELEM Rocks!!!! Aug- 19 to 21 2011- NEWTON NC-

Yeah, it was in 2008.

 

[flecom]

Sorry if this seems like a silly question, but I really am curious. Still trying to reach out and grab all the info I can as am still pretty new to lasers.

thats fine, you learn by asking...

are laser shows ever dangerous?

if done improperly: yes

I have never been to one so I dont know the specifics. Does the audience wear protection glasses?

no

Or is there no chance of beam reflection?

there should be no chance of beams going into the audience in a properly done show (without audience scanning)

I would assume that most show lasers are of very high power, how do they not damage a viewers eye?

only way to guarantee you will not cause any damage (noticable or not) is by simply not letting the lasers enter the audience, so it never enters their eyes, no damage done!

Are laser shows allowed to hit the crowd ? I thought that
they had to keep the beams above peoples heads.
I'll bet EF knows the answer to that one !

this varies by country

Crowd scanning CAN be done safely. As long as the person doing the show takes the proper measurements using calibrated test equipment and determines beyond all doubt that the show will be safe under all of it's programmed perameters,

sounds about right

then it can be done safely and legally with gov't approval.

if you are in the US you ABSOLUTELY better have CDRH variance for the audience scanning, and I guarantee you it WILL get you a visit before they approve it...

Much of what is seen in Europe is done this way, but also there are a lot of European shows that aren't measured. The operators that don't measure rely mostly on what Cyparagon stated above: that there are very few, if any, publically confirmed reports of injury to audience members by CW lasers of any power level commonly found at laser shows, which is up to around 7-8W in most cases.

yikes, just becuase there are no reported injuries does not mean there are no injuries... remember non dramatic eye damage is usually unnoticable, your mind "fills" the gaps usually... its only when there is dramatic damage that it goes reported like when we talk about...

Pulsed lasers are far more dangerous. Even though the pulse is short, the peak intensity is FAR higher (it's very common to see peak powers in the kW range) and a few kW of instantaneous power can do a lot of damage in not a lot of time.

pulsed lasers should never NEVER >>NEVER<< be aimed at an audience...

Generally speaking, in the US crowd-scanning is avoided. I believe this is due more to the operator's fear of litigation than actual danger to the audience myself.

no, in the US crowd scanning is avoided becuase it requires a lot of paperwork AND cannot exceed Class I power levels (like .39mW) in the audience... so the effect is kind of lame anyway

There is another way a laser show can blind you. Most laser show projectors are protected against this however, and its a situation where the galvos (the gadgets that move the laser beams around really fast) fail.

This situation is called a "Scanfail" and results in a high powered static beam. However feedback loops in good projectors shut off the laser the instant a scanfail occurs. The protecter for this event is funnily enough, called a scanfail circuit.

Without one, a member of the audiance may not be blinded but if the laser is powerful enough and as we know audiance members like to put there hands into the laser beams, they could get a nasty burn from the laser.

if you setup your projector to be compliant with CDRH requirements you would not need a scanfail because you would have a physical beam block that even if there was a small explosion inside your case, theres NO way for the projector to scan below your set level (normally 3m above audience for example)

 

[ElektroFreak]

Re: my above quotes

I agree with you for the most part Flecom.. My own personal opinion regarding vision damage from laser shows is that unless you've got some SERIOUS legal representation and a whole bunch of money, DON'T audience scan.. but that's just me. As far as reported injuries, the reason I take the stance that I have on that is that I honestly believe that there is such a thing as making a mountain out of a molehill.. generally speaking, unless there is evidence of a problem, there is no problem as far as I'm concerned and I think that's more than fair. Even though I feel a certain way myself, it's just an opinion not necessarily fact and consequently I don't use or recommend unsafe practices myself and I would never allow any of my associates to do so. None of us could afford a lawsuit if someone were to get hurt, and since being of a certain opinion isn't the same as knowing with 100% certainty it's not worth the risk. Those are my thoughts on it.

 

[flecom]

Re: my above quotes

I agree with you for the most part Flecom.. My own personal opinion regarding vision damage from laser shows is that unless you've got some SERIOUS legal representation and a whole bunch of money, DON'T audience scan.. but that's just me. As far as reported injuries, the reason I take the stance that I have on that is that I honestly believe that there is such a thing as making a mountain out of a molehill.. generally speaking, unless there is evidence of a problem, there is no problem as far as I'm concerned and I think that's more than fair. Even though I feel a certain way myself, it's just an opinion not necessarily fact and consequently I don't use or recommend unsafe practices myself and I would never allow any of my associates to do so. None of us could afford a lawsuit if someone were to get hurt, and since being of a certain opinion isn't the same as knowing with 100% certainty it's not worth the risk. Those are my thoughts on it.

looking at the "real world" picture your absolutely right

problem is even if you do *EVERYTHING* right when it comes to your audience scanning, all it takes is this guy to show up



and mess everything up with his super cool arctic... then the next day when they have blurry vision, they wont think of the jerk off with the pointer, the lawyers will say "well wasn't there some dude running lasers?? sue him!"