The OP said it was a green laser. Some are low powered and as you say pose no real eye threat. Other commonly available green lasers are plenty high-powered enough to blind instantly.
Given that the laser is already known to be operated by at best a thoughtless jerk, perhaps a harassing bully, and at worst a violent psychopath, how much are you wiling to bet your, the OP’s, or the target’s eyesight on your *assumption * that this person bought a mere laser pointer and not something more … entertaining for him?
The shorter the wavelength, the more energy required to generate the beam and the more technically exacting (and expensive) the components tend to be. Red light, having the longest wavelength of the visible spectrum, was the easiest to generate. Blue, having one of the shorter wavelengths, came relatively recently (i.e. the mid-1990s) and was quite the breakthrough, enabling technology like Blu-Ray optical storage.
I stand by my post. No one is going ‘blind instantly’ due to laser pointer harassment at a distance & through a window. That it’s green in color makes it even less risky since the blink reflex is near maximum sensitivity.
Download and read the owner’s manual and safety precuations. I’ll excerpt the relevant part:
The manual goes on to note that the green color is near the eye’s maximum sensitivity and the damage potential per milliwatt of output power is about 16x that of red lasers.
Yes, you’re right that there absolutely are laser toys out there that are essentially harmless. But there are also things like the above.
The key challenge here is there is no way to know which kind is aimed at you by some anonymous jerk.
It says that a 500 mW green laser (class IIIb) has a 50% chance of causing eye damage at a distance of 164 feet. If as the OP says, the source of the laser is another building “across the way”, it’s probably closer than this. This is assuming “an unwanted exposure where a person moves and/or blinks within 1/4 second to avoid the light”.
I had something similar, twenty years ago. Someone occasionally aimed a torch in her room, scaring her to bits. It turned out the kid with the torch was just signalling morse code to another kid across the block, and didn’t even know he had scared the neighbour.
When she told him, almost crying, how he had scared her, he was mortified.
Nobody’s going to go blind from a laser pointer, but we don’t know that this is just a laser pointer. There are also much more powerful lasers available, and we don’t know if this is one of them or not.
Folks, we know this isn’t a powerful laser because, if it was, the beam would light up the night sky like a neon tube. One legitimate use for these very bright visible laser pointers is for astronomy demonstration. Someone spots something cool off in the heavens and points to it with the laser. Others nearby can track the beam from the source on up. Since OP didn’t mention light sabers zinging about, we’re in conventional laser pointer territory.
Lasers should certainly be respected.
However, one shouldn’t whimper in the corner in fear that they’ll be permanently disabled by a flash from a visible laser pointer of any realistic output, up to a couple watts.
The risk is not at all comparable to truly dangerous things like, say, exposure to weaponized anthrax spores or dimethylmercury.
OP asked how to locate the source of a laser beam.
Setting up a chair near the window is the best, easiest way.
If someone points a laser anywhere in the vicinity of that window, the location of the source will be (heh) blindingly obvious.
Charts and tables don’t matter, no one will go blind or have a treatable injury.
Two words: Bull. Shit. And green lasers are particularly dangerous. The green is generated by taking an infra-red laser and doubling its frequency. Originally, the IR would be filtered out, but with the cheap Chinese knock-offs, the filtering is less effective or even left off all together. This leads to a laser with the IR component more powerful than the visible and, yes, IR will blind you even if it is not visible.
Because of the incident linked to, all hand-held lasers are banned from Burning Man and the (usually more powerful) ones mounted on art or mutant vehicles are inspected to be sure they cannot be lowered to the horizon.
I suggest you ask Halston how well her blink reflex worked for her.
I’d do the camera thing. Take a picture when it first appears (without powder in a way where you can see the windows behind it) then do the baby powder thing, take another photo from the EXACT same location, (just keep the camera setup on a tripod, trigger remotely if you can) you should see the direction the laser is going in. Now overlay the 2nd photo with the direction of the laser onto the first picture where you can clearly see the windows. Draw a line that follows the initial direction created by the powder. It should lead to the window.
If that makes sense? I’m terrible at explaining these things in writing.
If you do the baby powder thing alone with a photo of it you might obscure the window behind PLUS once the laser gets outside it’ll be invisible again. So take 2 pics and you’ll be able to see the specific window and then one with the direction and you should be able to find this annoying person. (Don’t be scared by the way, it’s probably a young guy who thinks you find it as funny as he does. He probably finds her attractive or something) You’ll need a tripod and a graphics program like GIMP or, better, Krita. Unless you already have Photoshop or whatever.
It’s sort of like blood splatter on Dexter. Follow the trajectory. I grew up in a terrible area so went to some pretty extreme lengths to catch pranksters on occasion.
Presuming that the laser is being operated by an idiot/13-year-old from an opposite apartment, the perp should already be blind. After all, what are the odds a jerk like this has not already accidentally reflected the beam to his own eye from the window glass while goofing off?
Again, it’s probably (!!) harmless. Some jerk might have gotten a higher-powered laser, but in general the average laser pointer is not that highly focused and not that powerful. From about 100 yards the laser pointer typically spreads to several inches or more. (It might be instructive to ask the neighbor how big the “green spot” appears to be - half a centimeter, or several inches?) The smaller the green dot, the fancier (and possibly more powerful more dangerous) the laser.
Just in case the idiot has actually go his hand on a powerful toy, it’s prudent not to try to look directly - however, the previous suggestions are correct - set up long-time video recording in the same window, and tantalize the idiot, and odds are the camera will be illuminated by the beam at some point (we’re presuming it’s hand-held, so it will wobble a lot). When a beam is aimed pretty much directly at you, it’s not hard to figure out where it’s coming from. Worth a try, anyway.
As others have said, don’t assume it’s a low powered laser pointer. Powerful handheld lasers are available to any idiot with internet access - just do a search for ‘burning laser’ - they’re commonly available, and cheap - so I stand by my earlier advice - the moment you notice or suspect that someone is shining a laser at you, drop your gave and shield your eyes - do not look in the direction of the beam. It simply isn’t safe enough to assume that it’s a ‘laser pointer’ that is being pointed at you.
