Say I took my 5mW green laser and aimed it at the ISS, 200 miles away - if my aim was perfect, at night, could the light be seen by someone looking directly at the beam? Some online calculations show the beam would have spread to 200-400 meters across after 200 miles.
OK, I found this.
Looks like a 1mW green laser should be visible at 50km, so 5mW would be visible at 250km, which is about 70% of the distance to the ISS. Although, the author goes on to say that in practice, a red laser was quite a bit brighter than theory would predict, so it might be possible.
Cool.
I don’t know if you can just multiply the power to multiply the distance in such a linear fashion. You may need perhaps 25 times the power to get 5 times the distance, perhaps not.
What about my 1W blue laser?
What on Earth (or off of it) do you have a 1 W laser for? That’s just begging for accidental eye damage.
And the power should fall off as the inverse square, so increasing the source power by a factor of 5 will only increase the effective range by a factor of sqrt(5), all else being equal.
I was using a 1W infrared laser in undergrad to pulse heat water. In retrospect, I’m a bit surprised everyone left with 2 working eyes.
Someone linked to one here on the Dope and I just had to get it. I also bought a 500mW violet laser, but I haven’t even had a chance to play with it. The 1W Blue laser is freaking insane. It is capable of popping balloons, melting trash bags, and igniting matches. I was hoping I could light a cigar with it, but no luck. How cool would that be!?
I had been meaning to ask about that on here. The thing came with a million warnings about eye damage and some laser proof eye protection. I was wondering, though, is it on par with the way everything says “Use hearing protection” even when it isn’t going to harm your hearing in moderation. Like going to a rock concert or a loud night club. An occassional loud night out isn’t going to make you deaf. Is this laser going to actually cause damage just by playing with it for 10 minutes? Provided you don’t shine it directly in your eyes, of course. The warnings say to not even look at the spot it makes on the wall.
So how dangerous is this thing. What if it reflects into my eye for just a fraction of a second?
Its mostly NOT like the occasional loud sound or cigarette or all night everclear bender, where its just cummulative damage or just some damage here or there.
A “bad luck” very short moment with a high powered laser beam can fuck up all or part of your eye. And it probably won’t heal.
Be fricking careful. And, IMO if you don’t understand enough to understand how dangerous a high powered laser is you shouldn’t be playing with one.
You’ll put your eye out Timmy!
I say we wheel out the ol’ Nd:YAG, hook up the doubling crystal, and do some science. It’s a bit hard to aim though, so I might need some help figuring out how to get this thing shoulder-mounted.
Bear, it can be dangerous but it is difficult to say how much.
It depends on things like the optics in use and the specific wavelength and exposure time. However, for you, the good news is that the power is fairly low and the laser is solidly within the visible spectrum. Your 1 watt blue visible laser can do some damage (just ask the balloons) but the blink reflex should limit your exposure. I wouldn’t want to find out the extent to which the damage is limited, though.
The really hazardous lasers are either very high power or invisible or both. A visible laser in the kilowatt range will obviously burn garbage bags and pop balloons or light cigars or sizzle retinas in short order and likely before the blink reflex kicks in. This could be hazardous even with a fairly brief flash or reflection. An invisible laser make have time to damage the eye because you can’t see it and won’t blink and turn away.
As the owner of a 3.5W multiline argon laser, I can tell you that old record albums make cool burn targets.
Essential equipment in setting up a resonance cascade.
Oh, yeah, they’re obviously useful in laboratory settings. That’s not what I meant, though.
And Bear, the real danger is that you might accidentally shine it into your eyes. No, it’s not guaranteed, but it can happen, and if it does, the consequences would be bad.
…but *nothing *compared to accidentally dropping a crystal into the cascade. That’s why I’m always sure to keep a crowbar on hand just in case.
But can Bear_Nenno’s high powered laser be seen from the ISS?
The danger of the laser isn’t so much from cumulative exposure (unless you’re dealing with UV light); rather, it’s about acute exposure to flashes of light that cause near-instantaneous damage. Don’t think of a rock concert: a better analogy is someone firing a shotgun with the muzzle three feet from your unprotected ear. There will be damage if this laser hits your eye even briefly.
As lasers go, 1 watt of output is pretty damn powerful. Lasers receive a class designation depending on their potential for damage. At these levels, yes, eye damage even just from reflections is possible. A laser like this in a lab setting would require rigorous safety protocols: signage, interlocked lab doors (kills the laser if the door is opened), everyone in the room wearing laser safety goggles, and a beam dump.
A laser eye injury report crossed my desk some time back. The entire report is here (warning: long boring government .pdf); a much shorter Powerpoint presentation (including a diagram of the eye and laser positions at the moment damage occurred) is here (warning: Powerpoint slides embedded in a webpage; press the arrows at the top to page through the slides).
My understanding from skimming the report is that a senior researcher and a (new) student assistant were staying late working on a project. The senior person had become complacent about safety protocols (notably failing to insist on protective eyewear and to police the work area for possible route of reflection). For various reasons, one of the lasers used was lasing but neither person realized it.
Student leaned down to make an observation and a beam went right into the eye.
And the outcome:
Please do treat powerful lasers cautiously.
Oh, fiddlesticks.
Someday there is going to be a war between nerds and jocks: “you brought a rifle to a *laser *fight”.
This might answer your question. go to http://www.wickedlasers.com/arctic then click on the words underlined that say visible from outerspace.