New EU directives making scanning over MPE 'illegal'. Discuss

[White-Light]

Thanks James for pointing out this legislation ... incredible the employees are protected yet theres no protection for the audiance ? or is that covered in separate legislation ?

One thing to remember Paul is that 10xMPE is an ILDA approved standard for audience scanning so provided scanning is carried out within the ILDA guidlines, there's no need or justification for legislation for the audience to be protected from more lasers exceeding the MPE in those circumstances.

It would probably be helpful to actually have legislation making it lawful to scan up to the maximum level of the current standards set by ILDA as this would then avoid this type of legislation problem and allow for future adjustments (either up or down) of the standard by ILDA.

Also, lets not forget why the 10xMPE standard was introduced - simply because the MPE safety level is too dim to be effective for audience scanning in many clubs and because all the available safety data indicates that 10xMPE is a safe level (indeed research indicates a lack of reported injuries at levels far in excess of 10xMPE, but I believe 10xMPE was chosed as a compromise because it was a very safe level whilst still appearing bright enough for club use).

The alternative to a 10xMPE standard is that many clubs have traditionally simply ignored MPE and scanned at dubious levels many hundreds or even thousands of times higher than MPE.

Its far better to set a safe level that still bright than leave clubs having to break the law to satisfy their audiences and put their health and safety at risk by doing so.

[JStewart]

An important point to remember is that ILDA has no legal jurisdiction over workplace exposure levels set throughout Europe (even if they haven’t told their members about the new law!)

The ILDA 10x MPE Standard is not a safety standard. It is just a proposal put together by a trade association. From the evidence I’ve seen elsewhere, the proposal is not very well understood either.

Legal aspects aside, insurance is the other big stumbling block. As far as I am aware, there are no insurance companies that offer cover for 10x MPE scanning. And it also has been suggested by some parties that when people do so, they are invalidating their insurance cover, and that of the venue.

If it came down to it, and a member of the audience rightly or wrongly accused the laser show of causing harm to their eyesight, if the exposure levels were shown to be 10x that of occupational exposure limits, I’m not sure if HSE could say that is acceptable. Furthermore it would give a personal injuries lawyer something to get their teeth into too.

The reality is that if the only audience scanning to take place were only 10x MPE, and it was being carried out with properly designed laser effects, then the likelihood of people reporting injuries would probably be low. However in the real world, we all know that scanning at much higher levels routinely takes place, and with what are increasing levels of output, increasing the likelihood that someone somewhere is going to end up spoiling it for everyone.

James

[dzodzo]

If it came down to it, and a member of the audience rightly or wrongly accused the laser show of causing harm to their eyesight, if the exposure levels were shown to be 10x that of occupational exposure limits, I’m not sure if HSE could say that is acceptable. Furthermore it would give a personal injuries lawyer something to get their teeth into too.

i wonder, how would they prove the damage is caused by use of overpowered beams? imagine someone cheating the measurements and writing in that it's not running 10xMPE but within MPE, is there a possibility to prove they were really 10x stronger?

[norty303]

I think it would be very difficult to prove it was over MPE personally. Even if the relevant authorities were on site at the time of the incident, what's to stop the operator from dialling another 20% or whatever into the BAM and saying its been running like that all night.
And investigating after the event is just about unprovable I'd guess.

[The_Doctor]

i wonder, how would they prove the damage is caused by use of overpowered beams? imagine someone cheating the measurements and writing in that it's not running 10xMPE but within MPE, is there a possibility to prove they were really 10x stronger?

Fast photodiode, logger with very fast sample rate, logged samples to be triggered by onset of bright illumination. You'd need to adjust calculation for wavelength, to correct the measured power, then take into account the length of the exposure. The photodiode size should be perhaps 8mm wide, enough to be larger than the most dilated pupil in the room. The operator would attempt to intercept the beam as often as possible to get measurements.

Firmware embedded in the meter could be written on a PIC chip, and made to beep a warning if a calculated threshold is exceeded. Cost of such a meter would likely exceed a LaserCheck by at least twice its value though, so they wouldn't be very common. On the other hand, Coherent might be persuaded to extend the LaserCheck design to do exactly this task.


It might be that the large area photodiodes can't be fast enough though, in which case a PIN diode and a collecting lens would be needed.

EDIT: Ownership of such a meter would be very useful to laser operators, as it will give real-time warnings while setting up shows, though it would also be possible to use show-making software to calculate proportion of laser's full power and speed of scan to maintain safe exposure per area per unit time. (I bet Pangolin and other well established software already does this, if not, people need to be asking for it). Being able to demonstrate safety with the same kind of meter an inspector uses would always help with pacifying nervous club owners though, same as noise meters for PA engineers.

[colouredmirrorball]

So, does this apply yet to the rest of Europe?
From what I understand, the ELV = MPE, so not 10xMPE? Isn't that just begging for a constant break of the law? There aren't much people who think 10 mW/cm² is very spectacular...

[The_Doctor]

So, does this apply yet to the rest of Europe?
From what I understand, the ELV = MPE, so not 10xMPE? Isn't that just begging for a constant break of the law? There aren't much people who think 10 mW/cm² is very spectacular...

You need to consider the time too. I haven't read this latest stuff but I bet 10 mW/cm² is a static constant measure. If the beam is ten times the power but persists on that area a tenth of the time it will still be within limits. And that would be a very slow scan, too, passing less than 10 mm in a tenth of a second. Though at speeds that low, beam width becomes important too. Fast scans will let you use more power within limits, narrower beams will let you use less. So a fast narrow beam (best) is the easiest to be safe with if you use a scanfail device to shut it off. (Easier to calculate safe limits for anyway).

EDIT: If you take that logic to extremes it stops being true though, because there are pulsed lasers that are dangerous even if the average power is low. I don't think scan systems with CW sources are likely to make that kind of high power combination with very short duration though. Those regs would probably be re-written yet again before that became common.

[colouredmirrorball]

From what I have understand from the MPE, is first of all that it is very complicated. It depends on a lot of parameters. One of them is the scan speed. Most laserists prefer to get around the big equation with the scan speed and use a limit of 10 mW/cm² for a static beam. This way they don't have to measure each frame and be sure it is safe.
Note that it is 10 mW per square centimeter. This doesn't mean that your beam is 10 mW. It can be bigger or smaller. But in this case it has to be 10 mW/cm² at the nearest point where the audience can look into the beams. If you are above this 10 mW/cm² you need to expand your beam or lower the power, two things a laser operator doesn't want to do.

This is what I understand, or have wrongly understood. Correct me if I'm wrong.

[The_Doctor]

Looks ok to me. Though I guess if you want a strong static beam, just make sure no-one can intercept it without finding a tool or structure to help them do it.

If you're scanning an audience, low power is plenty, as those who see the beam pass across their face will see plenty of light anyway. Even if it passes low over their heads out of reach this will still be true.

[smogthemog]

i wonder, how would they prove the damage is caused by use of overpowered beams? imagine someone cheating the measurements and writing in that it's not running 10xMPE but within MPE, is there a possibility to prove they were really 10x stronger?

I guess not, well not without the revevant bodies taking actual MPE measurments while the display is in progress. How this will be prooved is going to be a bit of a minefield for the people inforcing these laws.