Hand Held Lasers used by Laser Performers - Safety?

[cadcoke5]

I am evaluating adding a laser performer to a show, and its safety issues. I am aware of all the issues with laser scanners, and safety regulations. I am also aware of the systems designed to permit safe audience scanning. My question is about the laser performers, who pretend to grab a light beam and manipulate it. They use lasers that they hold in their hands. (the picture below is using a hand-held set of lasers)
Laser Performer.jpg
Sorry for the large image... It shows much smaller in the editing window. But a preview shows it much bigger. I can't find a way to control the size of the image in a messge.

Looking at the many videos of the laser performers, I've seen varying intensity of the beams, and varying beam widths, which obviously is closely related to the wattage of the laser. What concerns me, is that the aim of those laser beams is purely controlled by the performer. Consequently, I see a lot of performers doing audience scanning with this hand-held laser. I doubt there is a system, comparable to the ones used on scanning system, that will work with these hand-held lasers. Please correct me if I am wrong.

I have seen videos of laser performers at Disney. So I presume it is possible to do this sort of thing safely. The one I just reviewed of a Disney performer, when he used the hand-held lasers, there was no scanning of the audience. So, apparently the performer own skill was the safety system. Also the show design was a factor, since the hand-held beam segment was actually fairly short. So, the performer could devote more attention to safety.

I know divergence of the beam has been discussed in other threads, as being an important feature to make the beam safe for audience scanning. I didn't realize it before, but now that I am looking for it, I do notice more divergence. The way the beam is handled tends to reduce the perception of the divergence.

Is anyone here familiar with this type of performance?

-Joe

[buffo]

You have a good understanding of the issue. Your post summarizes the problem (potential audience scanning that is above the permissible exposure limit, and thus not allowed) from these "Laserman" style shows that Theo Dari pioneered, along with the likely solution options (train the performer well to prevent beams from going into the audience, and/or use a diverging lens to reduce the irradiance of the laser) that performers would use to keep people safe. Clearly, you've spent some time looking into this. Nicely done.

One thing to consider is that these performances are often done in completely dark environments (in part to add to the mystique, but also to make the beams more visible, and to hide some of the tricks used to make the effect look real). This dark environment allows you to use lower-powered lasers in the hands of the performer. If you start with a lower power beam, and you increase the divergence a bit, and you ensure the audience is far enough away, you might be able to get the effect you want with a beam that is eye-safe by the time it reaches the audience. That way, even if the performer misses his cue and accidentally dips the beam into the audience, it's still OK because the irradiance is below the MPE level. If I were designing a show like this, I would strongly advocate for this method.

If you are the producer for this show, and you are located in the USA, keep in mind that you'll need to have a laser light show variance from the CDRH for this show, which must address the concerns you've already stated. If you're looking for assistance with the design and certification of a show like this, you may want to hire a laser safety professional. Casey Stack (lasercompliance.com) and Roberta McHatton (lasersafetyservices.com) are two ILDA members I'm aware of who are acknowledged experts in this field.

Adam

[TheHermit]

My question is about the laser performers, who pretend to grab a light beam and manipulate it. They use lasers that they hold in their hands.
What concerns me, is that the aim of those laser beams is purely controlled by the performer. Consequently, I see a lot of performers doing audience scanning with this hand-held laser. I doubt there is a system, comparable to the ones used on scanning system, that will work with these hand-held lasers. Please correct me if I am wrong.
Also the show design was a factor, since the hand-held beam segment was actually fairly short. So, the performer could devote more attention to safety.

Is anyone here familiar with this type of performance?

-Joe

Hi Joe,
As it happens, during the mid '80s, I did the lasers for an off Broadway theatrical performance of 'Carrie', during the prom destruction sequence.
I had a 10 W krypton, underneath the stage, with a 45 degree popup mirror in the floor to shoot white laser 'planks' from behind Carrie onto the front of the balcony.
Your concerns about performers' irresponsible behavior is well justified. One of the dancers thought it was cool to run up to the laser, only a few feet from the projector, and spread his arms in front of my planks (obstructing the effect, intended to be above the audience), as if he was caught within the force field of a death ray, sucking the energy from his body.
So I installed photoelectric IR detection beams to shut down the laser if interrupted by dancers. Immediately after summoning them on stage to instruct them about NYC safety regs, the producer shut the show down. Don't know whether it was due to that dancer or not, TBH. But, local safety officials have that authority.
Regarding your endeavor, my 1st thought is to add a small MCU controlled accelerometer to the handheld lasers, which would cut their power, if directed downwards @ a given angle from the stage and/or towards the audience. 'Safe' zones could be defined, similar to scanning software, but based upon the accelerometer's positional data. ESP32 dev boards are low power and have wifi for remote control/override from a phone's web page. Perhaps they could be sewn into the back of a glove.
Sounds like a great project.
BR
Roj