Dangerous Laser Pointer Advice
Many people use green laser pointers at star parties to help point out objects in the sky. I have a small 5mw one that I use and it’s plenty bright enough to see the green line streak up into the sky toward the object I’m trying to help people find.
While I’ve never seen this happen personally, I’ve heard many stories about people burning their retinas during a star party while someone was being careless with the laser pointer they brought with them.
Then I read this article:
How powerful should the laser pointer be?
Green laser pointers can range in power levels from 1mW all the way to 200mW so deciding which power level to use can be tricky. The points to consider when choosing the power level for an astronomy laser are.
The number of people star gazing with you. If it is just one person, a low power such as 5mW will be suitable. If you are stargazing with a large group of people who will not be standing next to you, the laser needs to be more visible so a high power level such as 100mW would be suitable.
100mw? Yikes! This article was written by a guy who works for Dragon Lasers, who admittedly sell some pretty damn cool lasers, but I don’t think it’s a good idea to be advising people to bring a 100mw laser to a star party.
This same company was kind enough to help illustrate my point. Below is a video demonstration of someone playing around with a 125mw laser:
Can you imagine someone playing with this thing during a star party?
Here’s the YouTube link if this thing doesn’t show up for you.
It is amazing to me how powerful these tiny lasers have become.
The biggest problem I have with the idea is that they are so small and it’s dark outside. Accidents are all too common at star parties where there’s lots of people stumbling around in the dark, many of them neophytes who aren’t very practiced at doing complex tasks with no photons.
It’s waaayyyy too easy to hold that laser in the opposite orientation than you think it’s in and shine that thing in your face.
Many stargazing nights have been ruined when people have been paying more attention to the new and exotic high power laser used to point out objects than the actual objects themselves.
Caution.
Yeah, no s&*t.
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POSTED IN: observing the night sky
5 opinions for Dangerous Laser Pointer Advice
Astrogeek
Mar 11, 2008 at 9:27 pm
I have a 5mw and a 125mw. I have, on occasion, let my 12 year old daughter (under constant supervision) use the 5mw to point out stars, planets, and constellations at Fremont Peak. There is no way she’s ever getting near the 125mw. That’s reserved for me to use in bright conditions (moonlight, or under streetlights, etc).
As I say in my blog post on the topic, This is Not a Toy.
RapidEye
Mar 12, 2008 at 5:46 am
Anyone that recommends a 100mW laser for astronomy usage is an irresponsible idiot! Legally, they aren’t supposed to have anything over 5mW anyway: I’m certain he is leaving himself wide open for litigation now…
If local light pollution is so bad you can’t see a 5mW unit, there isn’t anything worth trying to see anyway!
I’ve got a 5mW unit and love it when I’m observing in my pasture at home, but if I pulled it out at a star party, I’d be shown the gate pretty quickly.
Tony
Mar 12, 2008 at 7:36 am
AstroGeek: Nice article and I’ve often thought about getting one of those lasers, but not as a pointer. I would like to have one because I’m a physics geek.
RapidEye: Excellent point. If it’s so bright outside that you need one of those then you’re not going to see much anyway. You also are correct about the 5mw limit regulating laser pointers. I wonder how they can sell these things?
Seeing how that thing heats up paper, lights matches, etc. this things would be disasterous at a star party. I never bring sensitve equipment, like a laptop or camera, to large star parties for fear of someone stumbling on them by accident, I think star parties, unless its one of those like Stellafane, should just be for looking up, talking about the night sky and casual telescope observing through an eyepiece.
Keep it simple and no one gets hurt.
Thanks guys, great comments!
Andrew Cooper
Mar 13, 2008 at 1:10 am
I too faced the choice of how power I needed to go when recently buying a new pointer to replace a dying one. 5mW was not sufficient, I work with large crowds every week or two, Moon or no moon I work with what the sky offers. The green laser is just too useful in communicating with your audience, I needed to figure out what was safe.
You can inflict injury with a 5mW unit. Some doctors at Mayo proved it, but it took ridiculously long exposures to do it, around 60 sec.
A 100mW unit can inflict damage in milliseconds! These should never be used as public pointers where accidental exposure is always a risk.
I compromised at 25-30mW where the beam visibility is good with a large crowd and it can be used with some moonlight. But damage would be difficult to inflict since the time needed is longer than the blink reflex.
I wrote an article over at my own website that gives some of the better references I used to come up with the power level. Real data, real damage inflicted, make the decision on more than a guess.
http://www.darkerview.com/darkview/index.php?/archives/144-Public-Astronomy-Laser-Power-and-Safety.html
Health- links 3/23
Mar 23, 2008 at 9:30 am
[…] I was intrigued about as a child has been long forgotten. Tony the Astronomy Buff warns us of the Danger Of Laser Pointers commonly used to point out objects in the […]
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