There's a bright green (and definitely strong enough to give you eye damage) laser-light sensor on one of the fan-balancer machines at my job. I think I remember my boss pointing it out to me & told me not to look at it when I started; but you're not really ever supposed to be able to see it anyways, cause it faces directly up towards the ceiling & normally you have a part directly overtop of it anyways.

So anyways I looked at the laser-light the other day when I was trying to clean the machine. :cri: