LVR Optical - Laser & Optical Radiation Safety

SAGE / PLASA Lasers in Entertainment Meeting

On the 22nd of September 2011, a meeting was held at Earls Court in London, hosted jointly by the Safety Advisors Group in Entertainment (SAGE) and the Professional Light and Sound Association (PLASA) to discuss a range of topics relating to the safe use of lasers in entertainment.

There were approximately 30 people in attendance representing a range of staff from the larger entertainment venues, broadcast companies, and safety personnel. Four laser providers were present, as were representatives from the Health and Safety Executive (HSE), the Health Protection Agency (HPA), and an entertainment insurance provider.

The two and a half hour meeting began with separate presentations from the HPA, a laser show provider, and a safety practitioner, before moving into a round table discussion between all those present. A lot of ground was covered during the session, and the plan is that further meetings will help to build a better understanding between laser show providers and venue operators, so that the use of lasers in venues can be less troublesome in the future. That said, there were some important points to come out of the first meeting, which are definitely worth a mention at this point.

Perhaps the hot topic of the day, and a key area that had acted as a catalyst for the meeting, was the discussion on the use of laser effects that are used to illuminate an audience. i.e. “audience scanning”. Much of the meeting debated whether is was acceptable or not to point laser light into the faces of audience members, and to a large extent, the arguments both for and against audience scanning were set out by tone of the laser providers and the HPA respectively during their respective presentations; the laser provider explaining that they consider it to be an important type of effect to provide to clients, citing that they were meeting client and audience expectations in delivering such effects. While the HPE took the opportunity to explain to those present the risks involved in direct laser exposure, the difficulties of taking field measurements of laser radiation, and highlighting some of the problems that can occur even when laser light is below the MPE.

Several of the venue operators present stated that they require all laser beams to remain above the audience during performances. This in itself is not an entirely new policy, with many venues having outlawed audience scanning since the early nineties, often under the influence of licensing conditions. It was noted that some venues had more recently introduced the policy, primarily as a result of reviewing laser practice as part of the new Control of Artificial Optical Radiation at Work Regulations 2010. The regulations themselves do not specifically ban audience scanning, but they do require venue operators to undertake a risk assessment of the use of harmful sources of light. A few venues have been less than impressed with basic health and safety practices of some laser providers. So part of the premise for not allowing audience scanning, is that if providers can’t demonstrate getting the basics right, is it wise to allow higher risk activities to place? Leading on from this, one of the topics discussed was the preparation of standard format for laser safety documentation that would be easier for all parties to work with, and interpret. - Although it was noted that it was important for such a document not to become too generic and used (or abused) as such.

Interestingly, one person present noted that a relative had been to one of this year’s summer festivals where laser light had been permitted to scan the audience, and noted that bright flashes were distracting and uncomfortable. (this seeming to support the HPA’s previous assertion that audience scanning effects are often uncomfortable for those whom the beams actually strike)

There was some discussion as to whether putting a ‘hazard distance’ label on a laser projector could be a useful addition. The author’s own view is that whilst the intention may be good, the fact that most laser show lasers have hazard distances of several hundred metres, it may not have the benefits initially envisaged. (Note: until the lasers are set into their final position, typically the whole arena becomes a laser protection zone.)

One point the author did raise during the round table session was the fact that experience has shown that performer and crew exposure still continues to be a concern. Often it is noted that personnel on the stage of a production during setup or performance are not aware of the laser beam risk present. And with it commonplace to see 10W or 20W beams in use, often from multiple sources, this is an area that needs improvement, as it is probably the situation most likely to result in an injury.

All in all, it was probably a worthwhile afternoon for those that attended, and although some passionate views were aired, it all remained quite civil. It will be interesting to see that with the main points have been discussed and HSE and the HPA having made their views known, if there is appetite have similar meetings in the future, and where things could lead. But both the SAGE and PLASA have stated they are happy to facilitate further work to help benefit all those involved. We’ll keep you posted on further developments. In the meantime a summary of the some of the important key points established during the meeting are noted as follows:

  • The HPA do not approve the use of any particular audience scanning laser effect.
  • The HPA define ‘audience scanning’ as being any laser effect intended to direct beams into the faces of members of the audience. Specifically this includes light from scanners (galvanometers), mirror balls, and diffraction gratings.
  • Laser light significantly below the MPE can cause temporary visual disturbances that may have to be considered in a venue.
  • The MPE for deliberate audience exposure should be 10W/m^2 (or 1mW/cm^2 if you like to work in ANSI notation). This equates to a power reading of 0.4mW or 400μW through a 7mm aperture.
  • Unless specifically designed as safety critical software, software masking should not be relied upon for protecting audience members when a laser projector is set up in a venue. Current software masking is only deemed suitable for protecting accidental exposure to equipment such as video projectors etc.
  • HSE said that any installation that employs audience scanning must always fail safe under a single component failure mode.
  • HSE said that they would support venues that have a no audience scanning allowed policy.
  • HSE added that they were not impressed at what they saw at a 2010 festival where laser beams were seen scanning an audience.

© 2011 LVR Optical