Question about the Beam

Say I've got about a 50mW laser, any color of the spectrum (from UV all the way to IR)..The reason we see light is because it reflects off of our retina. Therefore, if we see the beam, we are technically viewing the beam indirectly right? If you don't wear goggles and you're staring at the trajectory of the beam, from the side (assuming it doesn't bounce off of anything...let's say you're in an open area), would this cause any form of eye damage over long-term exposure?

Not an expert on the subject but the light you see in the beam is the photons bouncing off dust and crap in the air... This stuff is not particularly reflective so you would only be getting a small dose of diffused radiation... In theory it shouldn't harm you but if the power levels were high enough there is a possibility... I don't think anything handheld could do and damage by viewing the beam offset but I could be wrong.

That's what I thought, I had a lengthy discussion with a friend of mine about this. He said basically though that if you see the light, it's got to be bouncing off of something that lets you see it...so then that would mean that the radiation is still getting to you.

But hey, if it were true (I thought), then the dot shown at the end of the beam would cause eye damage too, even if it was pointed at a wall and you're not looking directly at the beam dot. So we really don't know. Thanks for your input!

we see the beam because of the rayleigh scattering. I doubt you can get your eye damaged from a beam of 50mW, any laser color. You could start thinking of that with a class IV green

but not wearing goggles just seem unsafe..

True about the whole goggles thing; it IS unsafe. I haven't bought one yet, but trust me, I'm not willing to try it out and test it on myself any day lol

Thanks for the info (+1)

np.
check your last link on your sig - it don't work.

No no no. How bright is the beam? It just looks like a green line, right? Well, that's essentially what it is. Point being, yes, the radiation IS getting to your eye, but the only dangerous part of a laser is the fact that the electromagnetic radiation (light) that is the laser produces is concentrated in such a powerful and small point. However, the majority of this light does NOT get lost in the beam, which is why the beam is much, much dimmer than the light.

If you want to try out an experiment, try shining a 500mW green laser perpendicular to the target of an LPM so that the beam passes by the face of the target. That'll tell you how much power is being "produced" when the light from the laser reflects off of the atmosphere (due to Rayleigh scattering). Trust me - it's hundreds of times less dangerous than looking at a 60W lightbulb (unless the laser is REALLY powerful, probably on the order of hundreds of watts).

Wearing goggles while attempting to view the beam is ridiculous - then you can't see it!

Here you go.. 1.1W 445 beam... with the LPM placed 8 cm from the beam.



TBH I think those couple of mW at the start was from having my fingers near it when I was moving it.

The scattering from the beam a 5W 532nm laser isn't even brighter than a 1 mW dot, so your lpm won't pick it up. The scattering is the strongest at small angles from beam, if you place is perpendicular it won't pick up much.

The scattering may be a danger at ridiculous powers, 5W is far below that. The dot that hits a matte surface will be dangerous with a class 4 laser, but even with less than 500mW it's far from comfortable to look at.

I actually found this topic to be very interesting, never really thought of some of the things being brought up here.