Scan rate and epilepsy

[Bradfo69]

My morning drive to work musing was the following...
.
I had a client recently wonder if they should get lasers for their event because of a worry about any guests with epilepsy and I told them the problem is usually more strobing type lights and that they should generally be fine with lasers however, what about those instances where an operator purposely slows down the scan rate as an effect? Does that sort of flicker cause a potential issue?

[dkumpula]

Hmmm. Just a thought, but even if the scan rate did result in equaling the magic flash rate that can induce seizures with lighting like strobes, a pattern being scanned at x times per second doesn't mean its flashing at x times per second. Its likely just more and less light during that range of time from one person's view as opposed to totally light and dark.

That said, you could flash one or more projectors on and off at almost any rate you'd like (assuming your DAC and software can achieve the intended rate). Assuming its a bright enough strobing to the sensitive person, I don't see why you couldn't trigger a seizure just like you can with standard strobes.

-David

[White-Light]

I found some information about strobing and seizures some time ago. From memory, the optimal flash rate for inducing seizures was 15-20 flashes per second.

One thing to remember with lasers is that irrespective of what you've discussed above, many laser programs specifically have a strobe function.

Might be worth banning the use of that function. In Pangolin Software at least (QS & Beyond), it's a QuickFX Effect and as such can be deleted from the workspace.

[mixedgas]

You might wish to contact the ILDA Safety Chair and get any factual information available prior to assuming.

ON a personal note, I belive this to be very rare or nonextant with show lasers.

Steve

[Photonbeam]

I can recall at least three corporate shows in the '80's where we were required to post a disclaimer at the door regarding possible epileptic seizures from the lasers. I have never heard of it happening though.

[Bradfo69]

I generally figured that lasers are probably fine because similar to a tube television or movie, frames are flipping by too fast to cause an issue but earlier this week when I was trying to get a logo to display smoothly, the flicker also made me think about how sometimes for example, buffo likes to use slowing down the scan rate as an effect. I also didn't think about White-Lights observation of the strobe Quick Effect. Good point I've never heard of anyone reporting an issue either though but, figured I'd ask.

[masterpj]

With a corporate or public event I can understand the concern of using a laser strobe effect...
But banning it... no if it's at a big indoor event or a rave who would not assume there are strobes and other kind of flashing lights???

[White-Light]

With a corporate or public event I can understand the concern of using a laser strobe effect...
But banning it... no if it's at a big indoor event or a rave who would not assume there are strobes and other kind of flashing lights???

When I said banning it I meant it in the context of the op's own situational requirements, not generally. I would never advocate or support a ban on strobe lighting. Its one of my most loved effects. I should have been clearer in that regard . Also I believe the strobe rate in Pangolin software is designed to be as safe as strobe lighting can be. I had a conversation with them some time ago about strobe rates. From memory, (not used it for a while), the flash rate in their software is quite slow.

[DrEvil]

I had wondered about that myself. I don't know much about normal strobe effects since I've never done detailed research on it.