Laser Show Safety in Practice
By Roberta McHatton, LSO, Laser Safety Services LLC
The laser show provider assigns a Laser Safety Officer (LSO) who establishes a laser safety program designed to address all the possible risks of using lasers in open beam path settings. In most cases, the laser operator is the on-site LSO. Ideally, this person will have had extensive safety training and experience, both in the classroom and on the job.
Setup is the most critical time for safe laser show operation, as the potential for injury to personnel such as stagehands and riggers is present. Setup is when everyone is busy racing against the clock, each dedicated to their assigned tasks. It is easy to know where the general public is during the performance; it is not so easy to know where staff and crew are during setup.
In accordance with the NIOSH hierarchy of controls, engineering controls are always the preferred method of risk mitigation—the laser show operator’s first line of defense. Engineering controls include securely mounting lasers on stable stands tall enough to ensure lasers are at least 3 meters above the audience’s feet. If laser projectors are clamped onto trusses, are the clamps secure from slipping? Are lasers on a lift—will lift vibration cause clamped lasers to slip? Is the audience on a flat field or is the audience elevated, e.g., in a balcony or stadium seating?
Projectors are made of anodized aluminum enclosing the lasers. The only laser emission will be from the aperture. Projectors are required to have emission indicators that light up when the laser is active, and interlock switches prevent the laser from firing if the projector housing is opened. Projectors should incorporate beam blocks/attenuators which physically block beams from lasing into unwanted areas such as artists’ positions on stage or into the audience. Each projector must have proper labeling, such as a warning label at the aperture to warn against looking into the aperture. Once lasers are mounted properly, beam blocks are in place, and bounce mirrors (if used) are determined to be secure, the next step involves turning the lasers on to set the zones into the areas where laser beams will be propagated.
Imagine, if you will, that your lasers are set up in an older theater projecting over a seating area that is on the ground floor and in a balcony. Can you project lasers under the balcony safely—do you have 3 meters above the ground floor audience? If you project above the balcony, is there a glassed-in production booth that you must avoid? Is there a huge sparkly chandelier hanging in the middle of the ceiling area over the audience? How is the laser operator supposed to avoid all these reflective surfaces? Speaking of avoiding "objects," where are the staff and crew, especially the balcony ushers?
All the solutions to these issues involve procedural control measures, which mean a human being/operator/LSO must take action to control the laser hazard. Once the zoning program is locked in, the zoning software becomes an engineering control measure, meaning it does not require a human to do anything except watch the beams in case a mylar balloon floats into the beam path or the audience starts crowd surfing up into the beams. The operator is responsible for stopping laser emission whenever a hazard is present!
You now have some idea of the challenges an operator/laser safety officer faces and that the most critical time is not after the audience has entered the venue but during setup. We have discussed that engineering control measures are the first method of risk mitigation because they do not depend on human behavior. However, in the laser show industry, we depend a great deal on the laser operator/LSO to implement procedural control measures such as turning on the laser at the lowest power possible for alignment and zoning, verbally discussing safety with staff, training security personnel to warn people entering laser areas, assigning extra people/stagehands to observe the intended beam path, and posting entryway warning signs to ensure safety during setup. With training and experience, laser show personnel can be depended on to provide a safe, dynamic, and exciting experience for your audience while guaranteeing that artists and crew are informed of laser hazards and know to avoid direct viewing of laser beams.