Safe laser's distance

[White Light]

Hi!

I have few questions because I got my first brand new laser. It's red ~227mW power laser.
How far should I stay from white wall (which I point with laser) if I want look at the laser dot without safety glasses?
And dark wall?

P.S Why my laser dot sometimes shine in green color threw my safety glasses?

 

[Guyfromhe]

I don't recommend using a handheld laser without glasses unless you are completely sure that there is nothing shiny around and even then accidents can happen...

If you are 5-8 feet away you PROBABLY won't damage your eyes from a diffuse reflection off a dark or light wall but it will probably be unpleasant to look at.

EDIT: I highly recommend wearing and using good safety glasses at all times when using a handheld laser indoors.
Accidents happen quickly and damage is instant!

 

[White Light]

I have eagle pair one. Sometimes I want to play without glasses when I know that reflection is impossible (I have tripod).

So I can't light matches without glasses? :/

 

[Guyfromhe]

I have eagle pair one. Sometimes I want to play without glasses when I know that reflection is impossible (I have tripod).

So I can't light matches without glasses? :/

If you know that you won't get a reflection or an accidental drop or anything else that could get it into your eye play away, just be careful.

I am not a glasses or die person but you need to have a proper respect for it and don't come blaming us if something does go wrong.

I sometimes (infrequently) use my green pointer on my ceiling without glasses so I can see the beam (but it's hard on the eyes), and I use it outside without glasses as well.

I would not recommend burning anything without glasses on. It's not safe to be that close to it and something could easily go wrong. I never will and never do.

 

[Wolfman29]

There are a lot of misconceptions about diffuse reflections here. A while back, Infinite and I did some calculations as well as some empirical testing, and we found that, even at a foot from a diffuse reflection, the transmitted power to a source the size of the eye was negligible from a 1W blue laser. The thing is, a diffuse reflection spreads out all that power in every direction, so you are only receiving a small fraction of that power to your eye.

That said, it doesn't mean that it is pleasant to observe - it's still REALLY bright. But having figured this out, I have stopped using glasses entirely when just pointing except when dealing with things that may possibly be reflective or if I am burning really up close. Even then, burning at 2ft away is fine for my eyes (must have adjusted to the brightness of the laser or something).

All that having been said, I am *not* advocating not wearing glasses. Just putting some more information out there.

 

[InfinitusEquitas]

I generally still always wear goggles whenever I do burning or lpming.

I just find the dots to be far too bright to look at.

Also Wolfman29 even though at past a foot I wasn't able to get any kind of reading off of an LPM... at closer range like say 3 inches IIRC I was getting 2-3mW from a 1.1W laser dot.

While 2-3mW is not a problem over a second... it's not healthy to look at either.

Anyway, bottom line is, the true real danger comes from pure accidents, like say a stationary laser moving, or from reflections off of truly shiny/reflective surfaces.

IMO goggles are a must when experimenting with ANYTHING at all.

Just the other day, I was LPMing a 100mW greenie, to test that it's still up to spec/the same since I want to sell it. The laser rolled and the beat hit a the shiny handle of nail clippers.... if it wasn't for goggles I would have experienced a hit.

Had quite a few close calls where I was VERY thankful I was wearing goggles, but so far only two where goggles actually saved me. That was the second time.

 

[Wolfman29]

Yeah - generally, my "safe" limit is a foot or more. Anything closer is ridiculously bright anyway.

But yeah - shiny things are a problem. But some shiny things actually reflect nearly diffusely, i.e. in a circular arc. So it would be interesting to test that sort of effect as well.

 

[InfinitusEquitas]

Well, the object in question has to be no only shiny, but also even... not really sure how to test that.

Maybe once I get my hands on an ophir... it would make for an interesting bit of experimentation.

 

[Wolfman29]

Indeed it would.

 

[magmabeam]

Depends on how small the dot is, i can look at dot of 500mw because it's quite big and im fine, but my 100mw has a tiny dot which is uncomfortable to look at

you can burn without goggles but it's a bit dumb, you can hold the match in front of it with your eyes closed, but u cant focus it

if you can't afford safety glasses, then you shouldn't have bought such a strong laser

 

[White Light]

From which color of surface reflection is the most dangerous? I suppose white...

 

[InfinitusEquitas]

^^^From the color of a front surface mirror actually

You're correct though, a white/lighter surface will reflect more than a black or dark one.

That's why most people use black surfaces for beam dumps... to have less reflection and to be able to enjoy the beam itself more.

 

[ShortyInCanada]

To be safe, if you are trying to burn something you should always err on the side of safety and wear eye protection.
To be trying to monitor the brightest and most powerful energy state of the laser on an object without eye protection is asking for trouble, no matter what color the laser is.
Think about it...you are trying to use a source of light that is so powerful it will trigger a combustion process on a normally "safe" object. Matches are considered to be safe enough to be carried in your pocket without risk of accidental ignition. And you are going to shine an intensely bright light on it to get it hot enough to burst into flame.
I sure wouldn't even consider looking at that without protection of some sort, even if the reflected light was a fraction of the input. I don't want to risk slightly warming my retinas.
I don't know if Wolfman & Infinite considered the eye focusing that energy into a smaller area or the length of time of exposure and the cumulative effects.
But it wouldn't matter to me as I just wouldn't take that chance.
I only have one set of eyes and I've done enough damage already. I need to keep what's left working as good and long as I can.

Lower powered lasers are fine for fun and much safer.