Safety tips (based on experience) and precautions

[Barabba]

Hi! Before posting here I read some topics about safety, a lot of staff but in my opinion not that "practical" and ready to use.

I would first kindly ask you, which are the issues that may eventually/usually occur basing on your experience,
when you refer about safety issue, are you meaning:

1) Maybe thin beams that may "hangs" to a certain point (and it can be in the area where are people) after a software/driver problem?
2) Are all effects always dangerous? or widing the angle (for example designing a "tunnel" or a cone) and driving the laser around fast to reduce the time where it stays in a zone.
3) There is a way to calculate the risk levels? Like a special calculator that consider distance, mWatt, angle, time of exposure.
4) You wrote about Pargolin lens, what they do exactly? How they make the laser safe? Reducing the intensity? or unfocusing the laser?

5) I also would ask about the emergency button and its usage. When is it useful? (I suppose in the case "1)" when if the beam fixed occur). Should it be place where anyone can press it? (including guests, that may annoying deactivating it on purpuse)

6) About avoiding the laser could enter in touch with human eyes directly, does it have sense to create an obstacle after certain limit? For example put a diagonal mirror that reflects lights up if the laser goes under a certain limit, like this:
---> --->
---> /
it may be also a kind of flat mirror.. like this: ---> ___

thank you a lot

[White-Light]

Only way to be safe unless you know how to calculate and measure MPE (Maximum Permissible Exposure) properly is to project overhead (to ILDA guidelines) and avoid reflective surfaces in doing so.

Any form of audience scanning is unsafe with a class 3 or 4 laser unless you have both the measuring equipment and knowledge to do it safely.

To specifically answer your questions:

1. A thinner beam increases the irradiance so the potential to damage eyes. Don't confuse beam diameter with projected effect as the beam diameter from the projector is a constant. Point 2 will explain it a little for you. A static beam is potentially the most dangerous as the exposure on any one person is the longest. That said you cannot make it safe by simply moving the beam as damage times with class 3 or 4 lasers are in the hundreds of a second. So an unsafe beam is an unsafe beam. Hot Beams are the most dangerous effect as they use software tricks to increase the intensity and thus irradiance of the beam.

2. Yes potentially. A wider effect such as a sheet is a simply a thin beam scanning across very quickly and repeatedly with the persistence of the eye making you believe it's a single wide beam. As such the irradiance is almost the same as for a single static beam of that width. As I said in point 1, damage time is in the hundreds of a second so moving a beam around cannot render an unsafe beam, safe. There is some value in movement, but only if the beam exposure is safe anyway.

3. Yes but it's complex even by the simple method and you need both a suitable calibrated power meter to take the measurements and an oscilloscope to measure the pulse width (repetition time not pulse as we're talking CW lasers here. Pulsed lasers are NEVER safe for audience exposure).

4. It increases the diameter of the beam thus reducing the irradiance. However, there is no lens you can simply drop in front without the need to calculate MPE, as without calculation the irradiance is an unknown and can still be unsafe even after expansion. Professionals will often use several methods to bring the exposure within safe (measured) levels.

5. An Emergency stop is essential as it covers you for any occasion where you suffer a static beam through eg scanner failure

6. If I understand you correctly, no. You have to measure MPE if you are to safely expose an audience. You can't try to cut exposure with moveable mirrors as damage time is in the hundreds of a second.

Be aware, there are no pain sensors in the back of the eye, so you cannot feel the retina being burnt.

[Bradfo69]

All good points.
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Barabba, for you, and for what you are thinking about doing, you should probably just follow some fairly standard guidelines in that, your projector, once you get it, should be mounted so that the beam coming out is no less than 3 meters off the highest point at which a person could stand. If that's the floor, then the floor. If it's a riser, then 3 meters from the top of the riser. If there are stairs, then you need to keep it aimed away from the staircase. If you have dancers on poles, then you need to make sure they're not hitting them either. Then, most projectors these days have a metal aperture cover that moves up and down and, that can make an excellent beam block. So once you have your projector mounted and have it displaying a test pattern at the largest useable size, physically slowly slide the aperture cover up until it's just a millimeter or two below the beam and tighten it. That way you have prevented any chance of a beam going down into the audience.
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That's is what we mean in number 1 of your example. A number of things can cause a full power beam to unexpectedly shoot down into an audience. Whether it's a software issue, cable issue, a suddenly broken mirror or failed scanner. Even someone tripping over a power cord and pulling it out the wall. To be perfectly honest, the risk of it happening is not huge but, there is absolutely a risk and, most people that do shows can relay a story of something happening totally unexpectedly. Now.. that beam may not necessarily hit someone in the eye. And yes, that's a small risk but, it is a risk nonetheless. The other issue is if that static beam hits something easily flammable and stays on it long enough to burn. A dark surface can start causing smoke to appear in a split second. And if you're in a club, 2:30 am, fatigued, music blaring, people dancing, you may not notice a projector failure for a couple seconds and, in the interim, have hit someone in the eye or, you've made what looks like a cigarette burn on the wooden bar surface, or worse.
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As White-Light stated, yes, potentially they are all dangerous. It's all a single beam. It just may be moved at different rates of speed. You're not "spreading it out over a larger area". It's just it's moving so fast your mind "thinks" it's seeing a line or a cone or something.
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If you have an iPhone, (and maybe it's available for Android), there is a free app you can download called Laser NOHD from James Stewart which can help calculate the distance away from a laser you need to be for it to be considered eye safe. Take your Venus II you are considering as an example, and run a full power static beam out of it. To view it safely, you need to be 334 meters away. I don't think your club is that big! I'm guessing you have a vision of being able to scan people less than 5-10 meters away. It doesn't take into consideration angle, time of exposure and things like that. Most all of that you can learn about in a laser safety course. Plan to be good in math or, be very adept in using a scientific calculator.
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4) Again White Light answered it but, to elaborate, a Pangolin safety scan lens is really a set of 6 lenses of varying diopters because every situation is different and may require a different lens - once you take all the necessary measurements. And just the lens alone isn't enough if you're planning on audience scanning. It's a piece of the puzzle but, the projector should also have scan fail boards and something along the lines of Pangolin's PASS board installed. There are other companies that make things similar to PASS such as Eye Magic in Greece and HB-Laserscan in Germany but, there is a lot that goes into doing it safely besides just slapping a lens on the front. Even people I know who have taken laser safety courses and have done shows for years tend to shy away from audience scanning because of the risks involved and not being entirely certain they know 110% that they're doing it correctly. Proper laser software has certain safeguards built in as well. It's a lot of time, money and practice that many people just don't do.
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The E stop should be right alongside the laser operator so they can hit it if necessary in a split second. This is another reason why I have told you that running patterns off your SD card that were triggered via DMX in sort of a "just push play' fashion wasn't a great idea and that if you're going to do lasers, you should... do lasers. You need to stay focused on that task and not necessarily try to run lights, manage the club, chat with a friend that walks in, tend bar, stare at the hot babe in the corner, break up the fight. Stay focused on the laser and just the laser.
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6) What you're talking about is a shutter and, yes ideally the projector will have one of those too. And yes it can help prevent a static beam from going in the audience for certain situations but, a shutter for example has no idea if a mirror has broken off a galvo or, if a galvo has gone haywire. It's more for loss of signal disconnects and things like that.
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All of these things are things that help make the laser (and the operator) safer. And as I have said, with being a club owner and wanting to do this for your patrons, you have an obligation to them to keep them safe. Probably legally as well as morally and ethically.

Or... revisit the suggestion in one of your other threads about using a video projector to emulate a laser. MUCH easier and safer if you want the look of audience scanning for your patrons.

[White-Light]

One of the things Brad suggested above with a video projector is known as Emu-laser. It's only found in Beyond though unfortunately so does step up the spend considerably especially as you'd need a £3k projector as well (there's a particular projector that does this well - contrast is more important than brightness) as well as a small laser for maximum effect.

One of the things you could do then is use the projector to project the audience scanned effects and mount the laser above to project beams and hot beams.

I haven't had emulaser running but I believe you should probably be able to use Zoning to separate effects out by zoning different pages of the grid to different zones and thus types of projector. I'm sure someone could confirm.

Why would you want both? Because the way video projectors work means they are brightest with the fans, cones, boxes etc and dim with single beams (the opposite to laser).

So although you could use both for both effects, just keeping the laser above, to my mind it would be most effective visually to separate them out so only 1 of them was ever in action at the same time. That way the lasers brightness doesn't detract from the projector's effects.

There's a video here that Brad made at SELEM a year or two ago with a laser on top and video projector on the bottom. You can see the projector is quite effective in a smallish space, although the fact they ran them both at the same time, obviously because they were making a comparison, does detract slightly from the video projector.

However, I reckon that if you only ever sent audience scanned effects to the projector in the form of large effects ie cones, boxes, fans, fences etc and only ever sent hot beams and effects with small numbers or single beams to the laser with them set to project overhead, then with only 1 on at a time, you'd probably get a convincing and totally safe effect.

[Barabba]

thank you! Really exaustive and important, you're absolutely right.. being scary isn't just enough.

There is one more question, also concerning a "practical way". Buing a powerful laser often means good quality, a better realiability, better functions, and of course more cost.. reducing its power its a pity, but it can make it "safer"..
A beam of 200-300mW (or even lower) running fast at about 3-4 meters could it be considered high dangerous? I suppose you reply yes, because even a 3W running far from the eyes in a open space is safe.. but a smaller beam that may be reflected by something in a close place can create the problem.
The question is not silly as it appears.. but it's orienting me if buy a quality laser and reduce its power and (after a careful installation/effects) consider me in the "ok" zone, or avoid spending such money and buy a much smaller one (Bradfo69 the one you kindly suggested me is cheap and not powerful, it may be enough (look on video behind)), or yes definely evaluate the video projector.
https://www.youtube.com/watch?v=FpOxW0wwVuY

[White-Light]

Making a lot of assumptions here....

beam dia 3.5mm, divergence 2mrad, distance to audience 3m (your suggestion), power 200mw (your suggestion) = 28 times MPE (the safe limit)!

[Barabba]

thanks White-Light, the video is very interesting, it's a pity the laser and video projector aren't displaying always the same effect, sometime they do anyway and we can appreciate it. There are three particular disadvantages of the video projector, the biggest is cost.. at least double price then laser (do you have a model to suggest? that may be comparable to 500mW-1W laser, thanks), the second is the single beams are close to absence.. if they are considered an important effect this solution can't be used, the third is the lack of remote controlling the .ild files playing.. by DMX or remote light console. Triggering cues by Music beam, live, isn't an option.. it should be asked if possible to create this feature..

[Barabba]

Making a lot of assumptions here....

beam dia 3.5mm, divergence 2mrad, distance to audience 3m (your suggestion), power 200mw (your suggestion) = 28 times MPE (the safe limit)!

Thanks for calculations, exposure for how much time?


I expressed me wrongly, audience will be kept outside the direct beam (by metal shutters), just a reflection may cause the problem, and I suppose this is difficult to calculate

[Bradfo69]

White-light, one of the things we discovered in another thread (I wasn't the first to suggest video) is that there are other programs out there that can work similar to emu laser without the high cost of getting Beyond. I haven't had a chance to look at it yet but, it may prove to be a good alternative for people on tight budgets.
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Baraba - I think you may also be underestimating your audience. I'm willing to bet that if you get the Venus, run the beam shows overhead, and run it full power, they are going to be suitably impressed in your club. It sounds like your desire is for this to be a sales tool to get people talking and frequent your establishment. What is more important than whether you have 1.6 watts, 2.7 watts or even 800mW, is what you DO with it. Honestly, in a club of your size,,there will be very little perceivable difference between say 1.6 versus 2.7 watts. I think you'd notice a difference between 800mW and 2.7 so, don't necessarily go with a less powerful projector. Go with the Venus and simply don't scan the audience. It's the way most people ever see lasers anyway. Focus more on learning how to create a good show and impressive effects. Timing to music. Maximizing the impact. Focus more on your craft than on the laser itself.

[Bradfo69]

Thanks for calculations, exposure for how much time?

Usually it's based on a quarter of a second.