Eye Safety of side view of beam and infrared leakage

[1234username]

Hello,

I want to know if safety glasses are needed if you only point a 1 watt green laser into the sky? every website talks about direct and indirect exposure but it doesn't specify what type of indirect exposure to the laser light. If you are holding the laser and then point it into the sky away from you and you only look at the beam going through the air is there danger of eye damage?

Nobody talks about this. They only talk about "don't point it at aircraft" or "don't look directly into the beam" ...duh of course I wouldn't. Also they talk about don't even look at the spot on a wall the laser is hitting. Of course, yes I know that. That's not what I'm asking.

I know the light is only visible when reflecting off of dust particles or the humidity or the air itself. The question is on a 100% humidity and very dark night can the beam itself, viewed going past you from the side, be enough to cause eye damage. If so what are the mW strenghts for 532nm light that this starts to become a problem for the user.

The 2nd question I had is for cheap green lasers that emit infrared light does that infrared light stay within the visible green light beam, or does it diverge like a flashlight?

 

[diachi]

Hello,

I want to know if safety glasses are needed if you only point a 1 watt green laser into the sky? every website talks about direct and indirect exposure but it doesn't specify what type of indirect exposure to the laser light. If you are holding the laser and then point it into the sky away from you and you only look at the beam going through the air is there danger of eye damage?

Nobody talks about this. They only talk about "don't point it at aircraft" or "don't look directly into the beam" ...duh of course I wouldn't. Also they talk about don't even look at the spot on a wall the laser is hitting. Of course, yes I know that. That's not what I'm asking.

I know the light is only visible when reflecting off of dust particles or the humidity or the air itself. The question is on a 100% humidity and very dark night can the beam itself, viewed going past you from the side, be enough to cause eye damage. If so what are the mW strenghts for 532nm light that this starts to become a problem for the user.

The 2nd question I had is for cheap green lasers that emit infrared light does that infrared light stay within the visible green light beam, or does it diverge like a flashlight?

Indirect exposure usually refers to diffuse reflections from walls and other surfaces. Looking at the beam pointing into the sky is perfectly safe - you'd need an astounding amount of power for the light reflected off of particles in the air to be damaging.

As for IR - It will diverge more rapidly than the green beam but likely not as much as a flashlight.

 

[vortish]

In all seriousness you should wear eye protection any time that you turn on a laser. You have to think of what you have in your hands. Also you should never point a one watt any laser toward the sky especially green! Those lasers go a long way! If your near any plane routes you could get nailed for a federal charge if caught! Just some words of advice

 

[Benm]

Well, if the point is to actually SEE the beam, like for pointing out stars and such, you cannot use safety glasses as they will block out all the laser light.

From an eye safety perspective there is NO problem with pointing a 1 watt green skywards outdoors, even when it's really foggy. You may want to be a bit cautions when it's raining or snowing since droplets and snowflakes could reflect badly (never happened to me or anyone i know). Few people will do this though as lasers generally don't like to get wet, not operate well under freezing conditions (the latter for dpss).

You don't -always- have to wear safety goggles when using a laser, it's just a must when working on them (adjusting mirrors, mounts, lenses etc), and a good idea when using them indoors (reflections from windows and such). If you're standing out in a field pointing skywards nothing will reflect the beam back at you.

Obviously things like avoiding airplanes and such are important, but have nothing do to with eye safety unless they start fitting them with retroreflectors

 

[Isaac Clarke]

i seconded that.

 

[Razako]

Well, if the point is to actually SEE the beam, like for pointing out stars and such, you cannot use safety glasses as they will block out all the laser light.

From an eye safety perspective there is NO problem with pointing a 1 watt green skywards outdoors, even when it's really foggy. You may want to be a bit cautions when it's raining or snowing since droplets and snowflakes could reflect badly (never happened to me or anyone i know). Few people will do this though as lasers generally don't like to get wet, not operate well under freezing conditions (the latter for dpss).

You don't -always- have to wear safety goggles when using a laser, it's just a must when working on them (adjusting mirrors, mounts, lenses etc), and a good idea when using them indoors (reflections from windows and such). If you're standing out in a field pointing skywards nothing will reflect the beam back at you.

Obviously things like avoiding airplanes and such are important, but have nothing do to with eye safety unless they start fitting them with retroreflectors

/This.
It's best to find a middle ground between total paranoia and being reckless. Just check the sky for planes prior to using your laser and don't use it if you see any planes or helicopters anywhere nearby. For a 1W laser you don't want to use it indoors without goggles and even looking at the spot on nearby surfaces may be harmful. A good margin of safety would probably 100+ feet away from what you're shining the laser at. Even then beware of reflective objects.

 

[Benm]

For the spot to be harmful you'd have to get -really- close to it with your eye.

On a matte surface, you should simply imagine that the spot becomes a more or less omnidirectional radiator. Even if the surface is perfectly white, as long as it is matte it will spread the light around a more or less gaussian pattern.

With lasers we count light output as power whereas other light sources usually count electrical input, so there is a big difference there. The dot from a 1 watt laser emits roughly the same amount as the filament of a 20 watt bare halogen bulb.

These can be unconfortably bright, but as long as you keep about arms length away from them will do no damage to your eye, and neither will a diffused laser reflection from a matte surface.

That said, i mentioned 'matte' quite often, since not all surfaces are. A piece of standard white copier paper would be close, but things like doors often have a sort-of-glossy paintjob on them that can result in more danger compared to the simple 'matte surface' calculations.

So be sensible about it - don't stare into the sun, car headlights up close or lasers reflecting off shiny things. Also don't go hide in a dark corner from sunlight hitting the pavement - you will be fine.