Goggles: Always when lasing or...

[Neroy]

For instance a 400mW Spartan 447. Would it be dangerous for others if they are standing around me without goggles at night watching the light beam going up into the sky?
Or would they only be dangered by looking at the dot at a closer range?
Or is any exposure to the laser light at 400mW generally damaging? I don't want to 'cause friends any harm when showing them magnificent beam obviously as I don't have multiple goggles.

Since already on this safety topic, when does viewing the dot without goggles become dangerous? At what power level for green/blue?

 

[Arayan]

generally the reflections of the spot in a closed place are very dangerous but also in open space some accidents could happen. Is better to use always the safety glasses

Since already on this safety topic, when does viewing the dot without goggles become dangerous? At what power level for green/blue?

Over 5 mW (class IIIa)

 

[Spartan X]

If your just pointing the Laser into the sky and at distant objects, you should be fine.

Just don't hand them the laser when they ask...because you KNOW they are going to ask.

I've found its neat to produce a great WTF expression from people, but I don't usually show my lasers off much more then that. It's mostly a selfish/solitary hobby since you can't really enjoy the laser as it was meant to be if you are not controlling it and have goggles ;-)

 

[Benm]

The dot on a matte surface isnt dangerous, unless you look at it from really close range. Looking at the beam for starpointing and such is also fine, and wouldnt be possible with goggles obviously.

The dangers are in direct exposure, and in accidental reflections (such as from a window pane). With these 1-watt class lasers this becomes a real concern, since the reflection from a normal window would be 40 mW when you hit it more or less straight on. At a shallow angle the reflection is much stronger.