Green Laser

[zhamid]

Hi,

I am interested in buying a green laser to point at constellations and stuff (and only that). I am not interested in popping balloons or seeing the dot in day light :-).

My question is... what is adequate power for pointing stars etc. out to other people? I dont want to get something too weak but at the same time, I dont want to get a pointer that's more powerful than my use requires. I live in Canada and there is no regulation here.

I searched but did not find an answer. since this forum has been so helpful in the past, I figured some of you may own this and may be able to help :). Thanks.

Zeeshan.

[Ronald Brak]

I don't think that will work. Conditions in which there is good viewing tend to be conditions in which a laser can't be seen.

[RickJ]

I've used a "standard" .5 MW one with groups of up to 50 without a problem. You do need them to be well dark adapted but that's needed to point out much anyway. I've never found need for anything more powerful and the risk of hurting someone unintentionally, kids can be fast and try and jump up to look into the pointer for instance, to great. I also once had the on switch stick so when I pulled it down it was still on and could have hit someone in the eye. I'll stick with the .5 mw, it does the job.

Rick

[Tobin Dax]

I've used a "standard" .5 MW one with groups of up to 50 without a problem. You do need them to be well dark adapted but that's needed to point out much anyway. I've never found need for anything more powerful and the risk of hurting someone unintentionally, kids can be fast and try and jump up to look into the pointer for instance, to great. I also once had the on switch stick so when I pulled it down it was still on and could have hit someone in the eye. I'll stick with the .5 mw, it does the job.

Rick
I agree with RickJ. A regular 0.5 mW laser is fine.
Ronald, it does work better in worse seeing, but it's worth using for general public or educational settings.

[hhEb09'1]

A regular 0.5 mW laser is fine.Looking around telescope.com and skyandtelescope.com, it looks like the 5 mW are standard, and about $50. How expensive are the 0.5 mW green lasers?

[redshifter]

Don't plan on using a laser at a star party, most star parties ban or restrict their use because they wreak havoc on those observing through telescopes or astrophotography. FYI.

[Tobin Dax]

Looking around telescope.com and skyandtelescope.com, it looks like the 5 mW are standard, and about $50. How expensive are the 0.5 mW green lasers?
I was going from RickJ's number, since I can't remember what my laser pointer says. It's currently sitting in my desk at work, and I was more interested in the wavelength than the power output last time I looked at that information. I probably have a 5 mW laser. My predecessor bought it, and I have no idea how much it cost him.

[RickJ]

My bad. I meant 5 mw. My wife was calling for lunch and I didn't review it. Sorry for the confusion.

Rick

[Nekota]

The green (532 nm) laser pointers with 5 milliwatt use a (1064 nm) laser and a frequency doubling 'cavity' to create the green light. While 5mw green is not damaging to eyesight, the 1064 power is much higher than 5 mW and should be filtered out with an IR filter. If the filter is missing then looking at the green plus IR would not be a good thing to do for your vision.

[zhamid]

Got it, thanks :). I'll stay away from fancy shmancy stuff then. 5mw it is :)

[Nick Theodorakis]

I have a 5 mW green laser, and use it much as you describe in the OP, and it works pretty well for that.

Nick

[Swift]

At the couple of star parties I've been involved with, we are very careful that the green laser is only used by an adult (usually a staff person for the park system) and we only use it when there are no aircraft in the part of the sky we are pointing at.

Here is a whitepaper (http://knightware.biz/community/whitepapers/GreenLasers.pdf) discussing the issue with aircraft.

[Tobin Dax]

At the couple of star parties I've been involved with, we are very careful that the green laser is only used by an adult (usually a staff person for the park system) and we only use it when there are no aircraft in the part of the sky we are pointing at.

Here is a whitepaper (http://knightware.biz/community/whitepapers/GreenLasers.pdf) discussing the issue with aircraft.
When I've used mine in the past two years, I've been just off an army base. :) So, yeah, I'm watching for aircraft. I tend to get a little paranoid when the choppers get close.

[hhEb09'1]

That's a good white paper, worth reading. I just ordered a 10mW (Class IIIB) green laser pointer that I found on Amazon for $14, it arrived today, seems to work as advertised.

[Gandalf223]

A 0.005 watt GLP is plenty.

[matthewota]

I find that the green laser pointer's use in amateur astronomy is best at astronomy outreaches, and not at star parties. They are great for showing constellations to the general public, and also to point out the objects that they are looking at through the telescope.

[Glom]

The big question is what strength of green laser to play Secret Agent Laser Obstacle Worms. It's a derivative of Secret Agent Laser Obstacle Chess played by the guys on The Big Bang Theory.

They probably used focused beams, which would be much safer.

[matthewota]

Here is a graphic diagram showing the safe distances of 5 mw green lasers

[tdvance]

and remember--that's for a legal pointer! A member of my local astro club, whose name I won't mention, had a 30mw shipped to him from some Asian country, then showed it off to everyone's annoyance at a star party.

[matthewota]

5mW is the "legal" limit. The one I own is "juiced" to 14mW, so I am very careful with it.

[Papa Surf]

I bought one from China off ebay for 99 cents (+$17.00 shipping!) it worked well for about 2 months then it began to falter. I have since purchased one from Orion (5mw) with a telescope mounting bracket for $99.00 and has worked beautifully for months.

[Timothy Reed]

There is no "legal limit" on the maximum output power from laser pointers. Federal regulations stipulate that the manufacturer of laser products comply with labelling and safety feature standards based on output power. If the laser complies with these regulations, there is no issue with owning one. There are federal statutes barring certain activities (most prominently illuminating aircraft), and local jurisdictions may pass legislation barring use of laser pointers in certain manners.

[stu]

5 mW works alright, but I've found that if someone is more than ~10' off-axis, they can't see it. 15 mW works well for a public open house or night lab for me.

[matthewota]

Recently, major league baseball games have been interrupted by green lasers. The more this gets into the media, the more likely that the government will get involved in banning them outright.

Irresponsible people are abusing this technology.

[hhEb09'1]

Recently, major league baseball games have been interrupted by green lasers. The more this gets into the media, the more likely that the government will get involved in banning them outright.
Just green lasers?

Green lasers make it easier to identify the perp, so I'm kinda surprised at that. Of course, not in a well lit situation, so that doesn't really apply to that example.

[tdvance]

Well, you can get the high-intensity lasers in any color, but green seems to be cheapest for a given apparent brightness.

[kookbreaker]

At the beginning of this year the FCC cracked down hard on Class IIIb (>5mw) laser pointers. You can still sell them, but there's a lot of grey area that the seller is now responsible for: use as a toy, for light shows, similar activities. All of these are not considered proper use. A few companies cut down on their advertising, some dropped IIIb's altogether.