Russian laser show 'blinds' revellers

[James Lehman]

Isolated case?? - Huh - here's the 'Darwin Award' for the day: http://www.youtube.com/watch?v=t65_JJrLFZ8

I think I'm gonna' be sick!

That's very upsetting video.

James.

[Alsone]

What an arrogant statement to make. As if I don't know how to properly ensure audience safety. Jerky statement to say the least.
I can do the math, I can buy the meters I can even buy the spendy "safe audience scanning projector" from the big boy's.
I can follow all the same regulations just like everybody else.
I mean how many times in this post is there a direct link to the formulas?
Do you think it is too hard for me to point and click then follow the directions?? WTF??

I think audience scanning is a lame way to wow a crowd by a laser operator who cannot do a really good 3 meter show.
I choose not to do audience scanning as I do not think is is ethical.
I think people do not realize the consequences of their actions. Monkey see monkey do.

SKipp, I apologise if my statement offended you. I was merely trying to say that I understand if you personally don't feel its safe to audience scan and I applaud you taking a stance on that rather than a risk. It came out wrong, I shouldn't have said you didn't know how to ensure audience scan safety but rather that you didn't feel comfortable taking a chance on audience safety. Hope you accept the apology.

Audience scanning I think is not worth the risk. It will be the death of this industry.
Skipp

Here I have to disagree with you. Unsafe audience scanning or a ban on audience scanning will be the death of industry.

I don't know where you are based, maybe the US where its the exception rather than the rule, but in Europe, clubbers enjoy being scanned (safely). They like to play in the beams and they expect to interact with the light. To have a show that doesn't have scanning in it, is unacceptable to most European clubbers. The show I posted a link to above that I attended where I was scanned, at the next show, myself and many others complained afterwards because all of the next show was aerial and we weren't scanned. It just wasn't the same and the event was far less enjoyable.

In Europe scanning is an ingrained part of the club scene and not having that would simply be unnaceptable to most clubbers and as they're the paying customers, the death of most laser shows as there simply isn't a demand for aerial displays in clubs unless a part of a combined scanning program. Or to put it another way, a ban on scanning would see most club laserists out of business.

What the industry needs to do is clean up its act and ensure fair cross border regulation (easy in EU states if done through central legislation) that ensures that all professionals are working to safe standards and that all amateurs have the necessary data provided in a way that provides an easy way calculating and ensuring eye safety.

[dsli_jon]

Hey Kats...

Was doing some 'visual analysis' of the vids online (I seem to have a pretty good 'trigger finger' - remember this damning shot?? ...that are *supposedly* from the Aquamarine rave, there... and I am wondering if this MIGHT have been a Copper-Bromide (like Spectronika makes...)...

Reasons I wonder are somewhat relevant to the question we all wanna know - how could some laserist have been such an IDIOT to have audience-scanned with what most people KNOW is the wrong-type of laser for this type of gig... well, here's my thinking...

First, watch the video (skip to the laser parts, but watch both the day and nite-time segs...), then look at these stills I grabbed, below, then look at this shot from Spectronika...(which, here, uses some sort of grating/prism to break-out the two lines in the CuBr mix, but not seen separately in the rave vids - perhaps they did not have any-such options installed, if in fact, it was a CuBr...)

Now, yes, I fully acknowledge that making color-judgments off a damaged-cell-phone video is not exactly a 'scientific' approach - the colors likely are skewed. But #1: notice how - especially during the day-time video / stills - there is a clear 'YELLOW-tint' to the laser-color - and every time the laser flashed the cel (again, see still below) there is a pronounced yellowish hue, along with the green.

Yes, ok, that COULD be just color-skew / aberrations from cel-video, or the fact that it was half-fried to begin with, then flashed even more during filming, etc - but the point is, this 'green' seems to have a clear 'tint-shift' towards yellow - and the combined lines of a CuBr (511nm and 578nm) make a wierd-sort of 'icey' green (see here), rather than the more unmistakable 'lime' green from 532 (see here) - and yeah, I know - there are differences in photography/colors in these two shots - what I need is a shot of 532 next-to CuBr output, all-lines, but you get the idea - there IS a distinct color-difference, visually, between the two 'greens'...

What's my point?? Before I make it, I wanna take another tack, first - RAW POWER. Ya know, for even a pulsed KTP to do THAT MUCH eye damage to so many - scanning - I THINK (even acknowledging relatively high-peak pulses found in such systems) you'd really need to have been cranking at least like, 30-40W or more. Now, I read, from outside-PL-sources, that it was 'confirmed' (whatever THAT means - still 'word-of-mouth' - I don't think anyone has actually SEEN the laser used...) that it was a "..30W YAG" used...

Hmm. Well, I have done a LOT of shows with 40+W of 532, and the thing I can tell you about that much 532, (heck, even 20W - lookie here) is you always notice the extreme SURPLUS of 'incident' light - ESPECIALLY in such close-quarters...(see install shot below with 36W beams..there are NO OTHER lights on in this dome, but the laser!) If, in fact, this was a '30W YAG' - why is that WHOLE TENT not TOTALLY GREEN??? (Again, especially this close-proximity)...

So my long-winded point is, It seems both 'logical' (deducing from the standpoint that even a relatively IN-experienced 'supposedly-pro' laserist would see 30W coming out, and LIKELY THINK 'damn, maybe this is too much??'), and at least 'visually-plausable' (that video doesn't really look to me to be 30W of green!) - that is MIGHT NOT have been a YAG/KTP.

BUT, if that same in-experienced laserist was only looking at 5-6W coming out of a CuBr - heck, even if it was a 'hot' 8W-model - it seems quite plausible to me, to think that he might not 'SEE anything dangerous' about it. Not likely anyone, there would, for that matter, just that it looked 'bright', and 'cool'...

HOWEVER - did you notice the SPECS for the pulsed energy of a CuBr sys????? They are a TRUE pulsed-laser, kicking out 'relatively-long' peak-pulses of up to 8.8kW!!! (Uh, I believe that's 88,000 WATTS, correct??? Even if for 'only' 30ns at 20kHz, still- HOLY SHIII!!!) That's like, going to a nuclear-powered tanning booth, where they never told you to shut your eyes, and you go in and STARE at the 'pretty bulbs', not-knowing you're actually BAKING your retinas - but in THIS case, it's not UV, but 8.8kW peaks of the practically PEAK-brightest wavelengths our eyes are sensitive to - at close range - AND with likely HUGELY dialated pupils from xtc, etc - and whattaya got???!!! Bad news, man. Bad, bad news...

But bottom line here, is, even if the clearly in-experienced laserist was 'innocently' / ignorantly using only a CuBr in this gig, still the WAY WRONG laser to be using for audience-scanning, especially in such close-proximity.

Message?? EDUCATION, PEOPLE, EDUCATION!! And then bloody FOLLOW the rules / established standards!

Again, hope all turns out ok for those kids. And hope the ignorant cuss laserist gets his hide tanned with his own laser - whatever it was...

Any CuBr experts (cause I am NOT one...) in the house wanna correct my 'thesis', here? Thoughts? Discussion? Rotten tomatoes?

peace...
J

[Alsone]

Interesting...

John, as an aside to this thread itself, don't you think that you should contact ebay about the lasers you found for sale and point out that YAG / KTP / Medical lasers can never be safe for laser shows if there's any eye contact involved and that these products should not be allowed to be marketed for "entertainment purposes" on ebay as there's a clear danger that they will be bought by people who don't understand the dangers of pulsed light and the distinction between these and normal CW lasers.

[trwalters001]

Not that this makes any difference at all...
8.8kW = 8,800 watts

[mccarrot]

Can someone tell me the advantage of using pulsed lasers (YAG) compared to CW lasers?

[trwalters001]

Pulsed lasers produce very high power pulses. As dsli_jon pointed out, each pulse of that laser is 8800 watts. If you produce pulses fast enough, the laser looks like it's on continuously. Pulsed lasers aren't any good for graphics because the beam is going on and off (albeit very quickly). They are typically used for beam shows. The power of pulsed lasers is usually given as an average power produced over time. That laser that dsli_jon was talking about produced those 8800 watt pulses at 20khz, but they were only 30ns long. The specs on that laser say that the average power is 5 watts.

Years ago, I worked on the development team for the laser rangefinder for the M1 tank. It was far infrared and you couldn't see it. The beam coud be focused through a lens and air would ionize in a bright flash at the focal point. It would pop holes in Kleenex. You could put that same focal point on your hand and you couldn't feel a thing because the pulses were in the nanosecond range. It WOULD pop holes in your retinas, however... just a piece of old-guy trivia...

[mccarrot]

so with the High power DPSS laser we can get today there is no reason to use pulsed lasers anymore?

[trwalters001]

The brightness of an 8800 watt peak power pulsed laser is WAY WAY more than the highest power DPSS you can get.

[dsli_jon]

Hey Alsone -

Interesting...

John, as an aside to this thread itself, don't you think that you should contact ebay about the lasers you found for sale and point out that YAG / KTP / Medical lasers can never be safe for laser shows if there's any eye contact involved and that these products should not be allowed to be marketed for "entertainment purposes" on ebay as there's a clear danger that they will be bought by people who don't understand the dangers of pulsed light and the distinction between these and normal CW lasers.

Been there, done that... and alerted the FDA as well, too, via here - any effort are best focused at the sellers, but #1, no one, let alone me, has time to 'police' all eBay sellers, and #2, it is far from the only arena for selling these things - the issue is education - those sellers need to be educated about what they are selling, and I am sure they'd listen better if the comms are direct from FDA, rather than nobody-ol-me. If FDA does nothing, well, what else can ya do...

Not that this makes any difference at all...
8.8kW = 8,800 watts

Uh, yeah...that's what I meant... that's what I get for posting at 4:30 am - ya just get 'sucked-in', ya know?

so with the High power DPSS laser we can get today there is no reason to use pulsed lasers anymore?

Yes and no - YAG/KTP systems have their 'place' (ie: see below) provided they are converted properly (to certified-standards) and any shows are done in compliance with CDRH regs (or international ones, as-may be the case) and FAA, etc - but that 'place' is NOT in such a small room with a low-ceiling and NEVER EVER EVER EVER for audience scanning - the last pic is an example of what you DON'T DO with a pulsed laser - especially-so, Copper-Vapors...

But bottom line, again, is safety / doing it right, whether using DPSS or ion or YAG/KTP or whatever - it's like the whole argument about guns - yes, if they did not exist, people could not use them to kill with, but guns in-and-of-themselves don't kill - people do - whether intentionally or accidentally due to their irresponsibility (leave them unlocked, etc, etc..)

Similarly, it's not so much the laser used (ie: does it really matter whether you are irresponsible and shoot someone with a .22 or .44?? - you're gonna HURT THEM, that's the point...) - but the use of the laser - IF, say, that laserist had gone ahead and USED a CuBr at the rave, (due to the un-planned covering with the tent) BUT had STRICTLY kept it ABOVE the crowd, well, it might have not been the 'best' laser to use for an indoor rave, but at least he might have avoided injuring people.

BTW - look at the 3rd and 4th pic below - the mall-side and the billboard - see what I mean about the SURPLUS of light from 30-40W of 532?? (look at the cars and ground below in each example) - another reason I am skeptical that was actually 30W in that tent...

Anyhoo, 'solo mis dos centavos'
peace..

J