Now I've got something to show!

[buffo]

MTV awards did it with Muse. Noone said a word when someone posted it here.

Actually, a few people did comment that the show looked unsafe on the YouTube video. However, MTV isn't a member of PhotonLexicon, so it's pointless to try to talk safety with them. They're not going to answer.

suddenly when new member does it. Everybody waves their arms around.

One of the topics that come up with new members is safety. Sometimes right away, sometimes later on. But it's an important topic. Jerome happened to post some pictures that got the discussion started rather quickly.

No one is waving their arms. The first question that was asked (by Lasermad) was simply, "Did you do any MPE calculations?"

Now where do you get "everyone waving their arms" from that question?

After it was clear that the calculations were not performed, yes, a few others (myself included) joined in and asked more questions. But that's hardly "everyone".

It sounds to me like you feel threatened by this topic, Doc... What do you have at stake?

I've started reading documents about MPE's, audience scanning, etc. As far as I know now, MPE's are not calculated for projectors themselves, but for projectors in combination with the show they'll be running.

Yep. So you need to do the calculations for all the frames you'll have in your toolbox. Or, alternately, you can create a "worst case" frame with lots of points spaced close together and use that for your test case.

How would you calculate MPE's for a show done with LivePro? With all possible effects, live scanrate-settings, manual speed/rotation settings, position settings, scale settings? I don't think that's possible..

The rotation, position, transformation effects don't matter. All that matters is the frame, the scan speed, and the size of the scanned image. Scan speed should be a constant, and you pick the smallest size and use that.

As for all the different frames, you might want to give Bill Benner a call at Pangolin and ask him how he did it. I think he actually used a software package to calculate most of the MPE's for him. (If I understand the process correctly, you load up a "worst-case" frame and take a bunch of power measurements and then plug those into the software. Then the software looks at the rest of your frames and comes up with a table of numbers...)

The other methods you mentioned (no static beams, fast scan rate, large image size, etc) are common sense things you can do to minimize the risk, but there's more to it than that.

I'll do some research after this, can you maybe help me with a link to dealers selling those kind of lenses?

Just about any divergent lens will do the trick. I've even seen a pair of eyeglasses taped in front of the aperture on a projector! That is not an acceptable solution for a commercial show, of course! It was a ghetto solution at best, but it was for a private gathering involving just a few people and it was done as an extra precaution to be certain the show was safe. (The projector involved was only rated for 500 mw, btw.)

Again, give Bill Benner a call and ask him about the lens he specified in his variance. He actually showed me the lens the last time I was at the Pangolin office, but I didn't write down any of the particulars...

Being in a concert-hall with 101dB of music (yes, that's quite common.. more and more dance events have more than 115dB..) for more than 4 minutes will harm your hearing permanantly..

4 minutes exposure, as opposed to less than a second. Not quite the same thing. If the sound level is over 100 dB it will HURT your ears and you'll move back away from the speakers. (Unless you're really drunk!) But you don't have that option when the laser projector shoots out into the crowd. The damage to the retina can be done before you have a chance to blink.

As for a dance event having sound pressure levels of 115 dB - that's insane. I've experienced 104 dB at work for a few minutes, and it's *very* painful. Even with ear plugs in (rated for 28 dB reduction) it's still uncomfortable. 115 dB is unimaginable. What kinds of events are you attending where the sound pressure levels are that high? (And how come you're not already deaf?)

I'll try to have a conversation with Hugo about all this, and find out how things are done safe here.

That would be a good idea too. The most important fact is that you've already started looking into the issue, which means you'll be more aware of the risks in the future. That's a start!

Adam

[JeroenVDV]

As for all the different frames, you might want to give Bill Benner a call at Pangolin and ask him how he did it. I think he actually used a software package to calculate most of the MPE's for him. (If I understand the process correctly, you load up a "worst-case" frame and take a bunch of power measurements and then plug those into the software. Then the software looks at the rest of your frames and comes up with a table of numbers...)

I'll send an email to Bill (I'm not that good in English, a phone call wouldn't be a good idea I think).

4 minutes exposure, as opposed to less than a second. Not quite the same thing. If the sound level is over 100 dB it will HURT your ears and you'll move back away from the speakers. (Unless you're really drunk!) But you don't have that option when the laser projector shoots out into the crowd. The damage to the retina can be done before you have a chance to blink.

That 100dB or more is measured at the FOH of the show (so, like in the center of the hall). Not in front of the speakers. That wouldn't make any sense, because hornloaded speakers produce much more dB's some metres away than in front of the speakers.

As for a dance event having sound pressure levels of 115 dB - that's insane. I've experienced 104 dB at work for a few minutes, and it's *very* painful. Even with ear plugs in (rated for 28 dB reduction) it's still uncomfortable. 115 dB is unimaginable. What kinds of events are you attending where the sound pressure levels are that high? (And how come you're not already deaf?)

dBa? dBc? What type of measurement? Those are dance-events here in the Netherlands (picture in this tent).

I have professional earplugs when doing shows like this (and yes, even then I'm exposed to more than the 80dB's "allowed").

[buffo]

The sound pressure meter we have here at the plant measures dBa. Yeah, I know that's not really accurate for low frequency sound, but we're not all that concerned with low frequencies. Most machinery produces high frequency noise. (It was a large compressor that produced the 104 dB reading.)

I agree that dBc is probably more appropriate for a concert hall though.

Adam

[Lampy]

Laser Visuals makes a piece of software called Scanguard that helps you caluclate MPE. The top level package also has a piece of hardware that monitors the ILDA signal to give you a real-time MPE level. James is a member here, perhaps he'll drop by and tell us some more. He also runs a good course here in the UK.

[mliptack]

That 100dB or more is measured at the FOH of the show (so, like in the center of the hall). Not in front of the speakers. That wouldn't make any sense, because hornloaded speakers produce much more dB's some metres away than in front of the speakers.

Unless these hornloaded speakers are made to have a focal point I HIGHLY doubt that. And even then, a speaker with a focal point.... no reason for it. V-dosc is the closest thing to a speaker that one can focus, its one of the most advanced Line Arrays money can buy. And even then the sound output is squished vertically and spreads horizontally which allows you to shim over the top and bottom of balconies and such (allows you to avoid slapback and other issues).

Even V-Dosc obeys the physical properties of sound. Inverse Square Law! If you get twice as far away from a sound source the music will be 1/2 as loud. Just keep in mind if you test that with a dB meter keep in mind that the dB curve is just that CURVED, its not linear.

Also 120dB is fairly standard at FOH for a rock concert. But I am pretty sure the dBc rating would show a bit less, since it ignores the massive amounts of low end that are also prominent.

-Max

[Dr Laser]

Now where do you get "everyone waving their arms" from that question?

After it was clear that the calculations were not performed, yes, a few others (myself included) joined in and asked more questions. But that's hardly "everyone".

It sounds to me like you feel threatened by this topic, Doc... What do you have at stake?
Adam

No I'm just trying to be fair to the JeroenVDV. All started because of 2 photos. If you have big enough ISO on the camera you can get pictures like that even with moving patterns. I would not judge based on the photo or a video.

The best test to see if it's safe enough for people is actually go where lasershow is projected and test for yourself.

[buffo]

The best test to see if it's safe enough for people is actually go where lasershow is projected and test for yourself.

If you mean, go there and test it with a power meter before the show starts, I agree with you.

If you mean, go there and watch the show with the rest of the crowd and if you get flashed a couple times and it seems like it's OK, then the show is OK, then I completely disagree, and so would just about any jury...

Adam

[Dr Laser]

I'm thinking you're being hard on a new guy. And don't take me wrong sometimes I like to play a devil's advocate. Just to spice up the topic
Most of us started with a very weak lasers and progressed up to watts. Because of that we understand the danger of hight power lasers. 1.3 Watt is a very powerful laser. And with power comes a great responsibility. People who start with a powerful lasers don't really get how powerful it is and what it can do. Once again don't be hard on a new guy. People learn better when they are approached with true guru behaver, suggestive manner not bossy manner. I understand that most of our gurus here are over 40. New comers are normally just over 20s. Do you remember when you were in your 20s?.
And beside that there are different regulations in different countries. And like I said 1200 ISO and very short shutter speed makes a very big different when you're taking a picture.

[dsli_jon]

Hey Cats - Ok, first off, kudos to Jero for his projector work (which I think was the original purpose of this thread, LOL - nice job!

BUT in reading thru this spirited thread (and others relating to that amazing-but-controversial vid from Qlimax '04) and the volleys between Adam (Buffo) and Aijii (Adrian ?) and Dave from LVP and Dream Beamz (George ? - I am still new, here...)- I just gotta throw my 2 cents in here, for whatever its' worth...but I wanna throw them at the TOPIC instead of at only one member...First off, in the spirit of being helpful, while I was reading, I was like, holding my breath waiting to 'raise my hand in class' and shout this: if you just HAVE to do audience scanning, make SURE you have at least one SafeGuard-type (http://www.medialas.de/showlaser/scanning_drivers_e.htm) scan-fail detector in each system that will do A.S.; and as to designing for MPEs - - - JUST GET SCANGUARD!!! http://www.laservisuals.com/sgstandard.php#4 (thanks, Lampy! it is excellent, simple and VERY helpful, especially for doing outdoor calcs for FAA approvals...and the Pro version http://www.laservisuals.com/sgpro.php promises to make things even easier, with IN-LINE, realtime analysis for you...it was $450. - small price for piece of mind... Granted, this STILL does not remove the OPERATORS reponsibility to DO a safe show, no matter WHAT the promoter or DJ wants - or even what the LAW says - f#@k the laws, it's PEOPLE we care about protecting, here, and I think it is comments like "I don't need to get anything approved. This show was in the Netherlands, a country where we're allowed to do audience scanning." and " It may be a far call from carefully measuring every single frame for MPE compliance...: that ignite the 'firecrackers' over here - what seems to be a callous ATTITUDE toward an actually serious subject - I mean, if MPEs are really all subjective and the actual measurements don't matter (or too much trouble, due to the 'risk of losing 'hundreds or even thousands of dollars') - Try this: get drunk, but only to the point where you still 'feel in control' (like say 4-5 shots of good tequila, but how much depends on YOU cause everybody is different, right?); now, go get in your car and drive and seek the nearest cop and slam on your brakes in front of him - whatever - point is, get him to stop you, and when he asks you if you've had anything to drink, tell him: 'yes, officer, but I FEEL FINE, and I tested myself by standing up and counting backwards, etc and I AM under the limits!!!' and when he asks you to blow the breath-test and you jack the thing at 0.8 - I'll send you a laser-postcard in jail, OK?? I know it is wacky hyperbole, but you get the point: THE NUMBERS DO MATTER, and that is WHY Bill Benner and others have gone thru SO much trouble to establish HOW and THAT we CAN do it - but SAFELY. The point is, don't hurt the people, and as I posted in another thread, I gotta hand it to Hugo - the man is a God - the guys werk is just plain SICK... http://www.3d69.be/pixelscreen/PICS/ (but I am NOT too keen on his pics in the section of "10W Green" - if in fact, those are 10W units, (cause, yeah, f-Stop can make 3W look like 30W...) and they are in fact full-on face-scanning people with 10W, as it seems to show, I don't care HOW spread-out or fast-moving those fans are, that's just plain WRONG and irresponsable, laws or no...ESPECIALLY since most (as far as I currently know) DPSS greens above 7-8W are Q-Switched (help me, here if someone knows of a pure-CW 10W that I am un-aware of) which means potentially MUCH higher peaks, even if for nanoseconds...if that doesn't seem to matter, another 'hyperbole': Prostitution - legal in Amsterdam, but would you whore-out your mom or sis or G/F - even if the money was reeal good - cause they CAN use a condom??? NO!!! There's still HIGH risk to GOOD PEOPLE, and that should be the ultimate 'scan-guard' - self-and projector-control and responsability. And as for those that say "well, we've been doin it for yeers, and NO ONE has ever been injured"... Oh, yeah?? Just how the funk do you know that so surely??? Read this: http://en.wikipedia.org/wiki/Audience_scanning under the heading "Possible reasons for the lack of reported injuries"... Food for thought, ay, mates?? I, for one, as a show designer, don't really LIKE to see A.S. as much as it is done sometimes - yeah, staring a cone down can be a real trip, but CONSTANT flashing me every bloody second - no thanks, whether it hurts or not - me, I'd rather tease an audience with massive, wall-wall, just-above-legal-height sines and incredible, enveloping beam-matrixes - a good mix of everything, and ONCE in awhile, take their breath away with a quick sweep or cone - but SAFELY - NOT with friggin' 10W of 532!!! Like Bill Benny said: "Safe audience scanning shows are more enjoyable than unsafe ones" - well spoke, Bill...Bottom line, 'lase the planet' but love the people. Ok, I'll shut up now...

[JimBo]

@dsli_jon

It is very hard to read your replies when they are just one solid block of text.

Jim