Hierarchy of controls
This is typically presented as a triangle of working through risk:
- Elimination – Can you not use the laser
- Substitution – Can you substitute it with something which has less risk
- Engineering Controls – Isolate people from the hazard
- Administrative controls – Change the way people work
- PPE
Engineering Controls are really relevant when considering laser design and operation
Enclosure – stops beam energy escaping in the event something goes wrong inside the unit (thick metal, able to absorb laser energy)
Beam stops / attenuators
Galvanometer scanners – directs and shapes the beam
Safety interlocks
Key kills emission (not power necessarily)
Remote interlock, e.g. EStop
Safety switches (e.g. lid removed)
Beam shaping
Diverging lenses
Diffraction gratings
Mirrors
Performers and beams nearby them
Is the risk managed?
There’s not hard and fast rules, the key things to consider is no reliance on software, use physical shuttering and then manage the rest of the risks through eyes on (visual monitoring of) the risk area. You don’t need to create 2.5m clearance for instance, you can place a 20W laser beam just above a performer’s head, but only if you’ve managed the risk:
Communicate – Performer told, put it in writing (for big-name performers you often won’t get to speak to the performer, put it in writing and get a confirmation it has been received to ensure you are covered).
Eyes – Laser only enabled if you have eyes on the risk area. It is considered OK to disable it at the console, you don’t have to estop it out, you are allowed to be practical and not stop the entire laser show. Do you think it needs 2 sets of eyes on it (e.g. operator by stage + 1 person)?
Performer height
Particularly tall or short?
Will the performer be wearing headwear, so become higher? Do we need to keep beams off their headwear? (is it reflective or combustible?)
General safety practices
Setting up
When setting up the lasers. You don’t have to shutdown the whole stage if you can limit the risk to one area, keep people out of that section, eyes on if you need them, do the setup then move onto the next section and repeat.
Step back and review the setup.
Positive safety culture is essential
Fire Fighting Equipment
FFE – carry appropriate Fire Fighting Equipment. Not water extinguishers (electricity), have CO2 (powder is also fine but it causes lots of damage when used, gets everywhere).
Spotters
Spotters do not need to be a LSO (laser safety officer), they are an extension of you as a LSO, another set of eyes. Anyone can be a spotter, you just need to give them clear instructions on what they are to do.
Checklist
Zones all correctly set?
Where are beams terminating? Any flamabillity risk?
Spike mark the position of all floor mount lasers so you can easily perform a visual check they’ve not been moved (e.g. use tape to indicate correct tilt, spike marks for placement). Also spike floor mount stands so you’d know if they’ve been crashed into and moved say.
Estops where they need to be and tested
Where is suitable FFE (fire fighting equipment)?
No possibility of your computer being used with lasers enabled (if you need to leave it enabled front of house for remote control to work from stage when setting up, remove the keyboard and mouse so there can be no accidental control by someone).
Injuries
Eye injury – someone comes to you and says they have an eye injury. Send them to first aid. Ultimately they should go to hospital. An eye specialist would need to look into it.
From a liability point of view find out where they were when the injury took place.
