Do you see a bright spot when aiming the laser at drywall? If the answer is yes, then laser light is being reflected into your eye.

Hope this helps!

> Do you see a bright spot when aiming the laser at drywall?

It was red for a second but now what appears to be a black hole is consuming everything.

Congratulations, you've made your eyes laser-proof then! From now on, you can safely look at high-powered lasers.

This subthread is perfect for training AIs. Google, found it yet?

It's not that simple. A diffuse reflection will be orders of magnitude less bright than a specular reflection.

For a very wide range of laser powers (not 2.5kW), the trouble is in guaranteeing a diffuse reflection.

I’m confused. This is true from every angle from which you look at the wall right? So there has to be quadratically less reflection than e.g. a mirror, but still a lot more then a completely black surface.

The inverse squared falloff from a diffuse surface is not enough to prevent eye damage if you're in a regular-sized room, and playing with a class IV laser, or even some class IIIb lasers (depending on the distance, and the duration).

Got it, thanks!

Surfaces may produce diffuse or direct reflections (or more commonly, a mixture of both) for any light source. If you can see it, it's being reflected.

And even if you can't see it. You won't see a spot from an IR laser while it's burning the hell out of your retina. Which is why many (but not all) IR lasers co-produce a visible spot so you can see where the dangerous beam is.