Green lasers: how much power is too much?

[acey]

So far as I understand, energy pollution differs from particle pollution in that it is not cumulative. So while shining the laser at the sky will increase the total light output of my city into the sky, the second that I disable the laser the sky will return to it's previous state.

Perfectly true. And as long as light is shining into the sky it's reducing everyone's view, which is why we try and encourage people to reduce light pollution.

A fairground in my town last week featured a searchlight beam shining into the sky, projecting a bright spot that moved across the clouds. As an astronomer I have no right to object, if I'm going to do the same thing on a smaller scale with a laser.

I add to light pollution with my own car headlights every time I drive miles to reach a dark site, not to mention carbon emissions from my exhaust. I don't advocate that everyone gives up driving so we can cut global warming and get a better view of the sky. But if we object to streetlights and security lights that our neighbours find essential then we really shouldn't go letting ourselves off with little lights whose only purpose is to shine into space.

[themos]

As an astronomer I have no right to object, if I'm going to do the same thing on a smaller scale with a laser.

That surely is false as you demonstrate with your very next words "I add to light pollution with my own car headlights". So even if you turn off your laser, you would still have no right to object.

Could it be that you are ideologically opposed to the lasers?

:-)

[Milamber]

Could it be that you are ideologically opposed to the lasers?

:-)

I thought I was until this thread - goes to show eh? Still hate the blumming things but... time and place, eh?

Arthur

[themos]

Well, I wouldn't like to annoy anybody by using one, that's for sure. So I will monitor people's actual experiences with them. Astronomical twilight should be an OK period for their use, I'm guessing.

[George]

Living under the Manchester airport approach path would make owning one of these an open invitation for a visit from the sky police for sure

[Beyond_Vision]

Folks can we leave any mention of politics out of the discussion as it is not relevant to the thread and not allowed on SGL

Regards

Kevin

[PeterW]

Used correctly lasers with many Watts of power are perfectly safe... think laser light displays. "Total safety" ends at 1mW, beyond that and eye damage is possible, especially with additional optical instruments. Personally much beyond 5mW and it's not worth the risk. I've used mine on many occasions as a finder on my own and with others and I live quite close to Heathrow.... use common sense. Bans do not help anyone.

Thanks

PEter

PS Another point to remember is that the cold will really affect the output, so keeping these things warm is vital.

[Jarndyce]

GLPs vary in quality, and in my experience, you really don't need more than 5mW.

I recently got one of these:

Finders - Celestron Green Laser Finderscope

and although pricey, it works beautifully as a finder.

Wouldn't use it a starparty, shine it at anyone etc. but for finding stuff, it's excellent.

I figured if FLO sells them, they can't be all bad...

[kev 102 42]

wheres the fun owning a lazer,if you cant bring a jumbo jet down....kev

[Mikea]

PS Another point to remember is that the cold will really affect the output, so keeping these things warm is vital.

Actually, lower temperatures improve the efficiency of the pump laser, so possibly the pump laser power will increase at low temperatures. However, it's wavelength will shift as well, and this will also have an effect on the final output power- could be up or down depending on the initial wavelength, actual temp shift.