#RemainingEye
April 30, 2017 8:19 PM Subscribe
Are these laser "pointers" safe? Particularly the blue one that I can feel on my skin?
I bought a trio of 3 so-called laser pointers from Newegg Flash. Here is the product sale page. They shipped directly from China. The stickers on the side of them all say "class III" and "max output power [less than]5mw". Here's a gallery with pictures of the labeling. They came shipped in bubble wrap, in a paper envelope. They were not boxed and no documentation or paperwork was included in the package.
Once I got them I noticed they seem a lot "hotter" than the laser pointers I've owned in the past. By that I mean the red one is significantly brighter red than any other true laser pointer I've ever seen. I've only ever owned red ones before, so I'm most familiar with this. The green one is super bright, with a dimly visible beam inside a room lit by a 40 watt light bulb, but I know that green lasers are usually really bright compared to red ones so this seems ok.
The blue one is the one I'm most uh... concerned about. The blue one, when pointed at skin, produces a noticable warming, heat-tingly effect. It's not just me! I tested it out on my friends too, of course. It does not pop ballons, set paper on fire, light cigarettes, or anything like that, but if you point it at your wrist or other heat-sensitive parts of the body and hold it in place you can definitely feel it within 2 to 3 seconds. Is this um, normal?
FWIW, if it matters, the red and green ones are easily the best focused lasers (if that is the correct term) I've ever owned, with virtually no noticeable beam divergence at great distances. The blue one seems less so, with the beam noticably widening out a bit when pointed at objects far away.
I bought a trio of 3 so-called laser pointers from Newegg Flash. Here is the product sale page. They shipped directly from China. The stickers on the side of them all say "class III" and "max output power [less than]5mw". Here's a gallery with pictures of the labeling. They came shipped in bubble wrap, in a paper envelope. They were not boxed and no documentation or paperwork was included in the package.
Once I got them I noticed they seem a lot "hotter" than the laser pointers I've owned in the past. By that I mean the red one is significantly brighter red than any other true laser pointer I've ever seen. I've only ever owned red ones before, so I'm most familiar with this. The green one is super bright, with a dimly visible beam inside a room lit by a 40 watt light bulb, but I know that green lasers are usually really bright compared to red ones so this seems ok.
The blue one is the one I'm most uh... concerned about. The blue one, when pointed at skin, produces a noticable warming, heat-tingly effect. It's not just me! I tested it out on my friends too, of course. It does not pop ballons, set paper on fire, light cigarettes, or anything like that, but if you point it at your wrist or other heat-sensitive parts of the body and hold it in place you can definitely feel it within 2 to 3 seconds. Is this um, normal?
FWIW, if it matters, the red and green ones are easily the best focused lasers (if that is the correct term) I've ever owned, with virtually no noticeable beam divergence at great distances. The blue one seems less so, with the beam noticably widening out a bit when pointed at objects far away.
They have a sticker that says "DANGER" right on them, and you're asking if they're safe?
Don't point them at eyes. You're not going to burn a hole in your skin though.
posted by aubilenon at 8:51 PM on April 30, 2017 [3 favorites]
Don't point them at eyes. You're not going to burn a hole in your skin though.
posted by aubilenon at 8:51 PM on April 30, 2017 [3 favorites]
Best answer: Based on the pics you provide, these are designated Class III lasers, with a power output less than 5mW, so these seem to be Class IIIA as opposed to IIIB. From wikipedia:
Class IIIa
Lasers in this class are mostly dangerous in combination with optical instruments which change the beam diameter or power density, though even without optical instrument enhancement direct contact with the eye for over two minutes may cause serious damage to the retina. Output power does not exceed 5 mW. Beam power density may not exceed 2.5 mW/cm2 if the device is not labeled with a "caution" warning label, otherwise a "danger" warning label is required. Many laser sights for firearms and laser pointers commonly used for presentations are in this category.
Based on the presence of a "Danger" warning label, it seems that these may be on the somewhat more powerful end of the IIIa spectrum, but it still seems like they're unlikely to do damage to your skin at this level of exposure. Definitely avoid contact with your eyes.
It seems like you have to get closer to the 500mW (Class IIIb) or above (Class IV) before you start getting into serious skin damage territory.
Of course, I still wouldn't spend a lot of time shining the blue laser at my skin. The wavelength is pretty close to upper end (in terms of wavelength) for the UV region (around 400 nm). The blue laser says its wavelength is 405nm +/- 10 so there is that. But as they say, the dose makes the poison. Or something. And to be fair, if you shine any bright light a few inches from your skin, that might start to burn after a bit. It's also not a great idea to stare at any bright light for prolonged periods of time.
Also IANAD/IANYD/IANALaserSpecialist, etc.
posted by litera scripta manet at 9:07 PM on April 30, 2017
Class IIIa
Lasers in this class are mostly dangerous in combination with optical instruments which change the beam diameter or power density, though even without optical instrument enhancement direct contact with the eye for over two minutes may cause serious damage to the retina. Output power does not exceed 5 mW. Beam power density may not exceed 2.5 mW/cm2 if the device is not labeled with a "caution" warning label, otherwise a "danger" warning label is required. Many laser sights for firearms and laser pointers commonly used for presentations are in this category.
Based on the presence of a "Danger" warning label, it seems that these may be on the somewhat more powerful end of the IIIa spectrum, but it still seems like they're unlikely to do damage to your skin at this level of exposure. Definitely avoid contact with your eyes.
It seems like you have to get closer to the 500mW (Class IIIb) or above (Class IV) before you start getting into serious skin damage territory.
Of course, I still wouldn't spend a lot of time shining the blue laser at my skin. The wavelength is pretty close to upper end (in terms of wavelength) for the UV region (around 400 nm). The blue laser says its wavelength is 405nm +/- 10 so there is that. But as they say, the dose makes the poison. Or something. And to be fair, if you shine any bright light a few inches from your skin, that might start to burn after a bit. It's also not a great idea to stare at any bright light for prolonged periods of time.
Also IANAD/IANYD/IANALaserSpecialist, etc.
posted by litera scripta manet at 9:07 PM on April 30, 2017
Forgot to include a link to the relevant wikipedia article.
posted by litera scripta manet at 9:08 PM on April 30, 2017
posted by litera scripta manet at 9:08 PM on April 30, 2017
Best answer: That blue laser is worrisome. I know you're not shining it into anyone's eyes, but it's spreading intense blue light around the room and we're starting to learn that blue light can harm your retinas and promote macular degeneration.
I wouldn't use it in close quarters, or around people unaware of the hazards.
posted by JoeZydeco at 10:08 PM on April 30, 2017 [1 favorite]
I wouldn't use it in close quarters, or around people unaware of the hazards.
posted by JoeZydeco at 10:08 PM on April 30, 2017 [1 favorite]
Best answer: I wouldn't presume that the lasers were properly labelled.
posted by the Real Dan at 11:42 PM on April 30, 2017 [18 favorites]
posted by the Real Dan at 11:42 PM on April 30, 2017 [18 favorites]
Best answer: Having had laser safety training several times:
Lasers become particularly dangerous at the point where they can deposit enough energy on a spot on your retina to burn it before the blink reflex kicks in. This power (5 mW for visible lasers) is the difference between classes IIIa and IIIb (technically IIIa is "low risk," meaning you can damage your retina but it would have to be intentional). Other dangers, like skin burns, are only relevant for much more powerful lasers.
"Class III" is not a laser class, so I'd be suspicious that these are labeled incorrectly.
However, if the lasers are visible, continuous, less than 5 mW and you don't play around with lenses or specular reflectors there isn't any real danger. You can still permanently damage your sight, but you have to really want to. Your blink reflex will almost certainly save you.
For class IIIb, you should be wearing full-coverage goggles rated for the specific wavelength and power of your laser.
A UV sideband shouldn't be an issue--lasers are monochromatic, remember.
posted by lozierj at 11:53 PM on April 30, 2017 [5 favorites]
Lasers become particularly dangerous at the point where they can deposit enough energy on a spot on your retina to burn it before the blink reflex kicks in. This power (5 mW for visible lasers) is the difference between classes IIIa and IIIb (technically IIIa is "low risk," meaning you can damage your retina but it would have to be intentional). Other dangers, like skin burns, are only relevant for much more powerful lasers.
"Class III" is not a laser class, so I'd be suspicious that these are labeled incorrectly.
However, if the lasers are visible, continuous, less than 5 mW and you don't play around with lenses or specular reflectors there isn't any real danger. You can still permanently damage your sight, but you have to really want to. Your blink reflex will almost certainly save you.
For class IIIb, you should be wearing full-coverage goggles rated for the specific wavelength and power of your laser.
A UV sideband shouldn't be an issue--lasers are monochromatic, remember.
posted by lozierj at 11:53 PM on April 30, 2017 [5 favorites]
Also: class IIIa lasers typically don't heat your skin. I'd assume the blue laser is class IIIb until proven otherwise. This means proper safety gear.
posted by lozierj at 11:57 PM on April 30, 2017 [2 favorites]
posted by lozierj at 11:57 PM on April 30, 2017 [2 favorites]
Best answer: I am a laser expert, and I would not trust the labelling. For cheap lasers, especially the blue one, they possibly have not gone through the sort of quality control that would make me believe in the safety labels. The lasers may all be exceeding the limit of 5mW of coherent visible light, making them dangerous. For the blue and green lasers, it is also possible that invisible pump light is leaking out the front, at levels significantly higher than 5mW. I wouldn't use them without eye protection unless I'd measured the output myself.
posted by indecision at 4:43 AM on May 1, 2017 [13 favorites]
posted by indecision at 4:43 AM on May 1, 2017 [13 favorites]
Add me to the chorus that suspects these are putting out a lot more power than 5 mW. I know people who have bought cheap lasers online and checked them with a power meter. They sometimes emit far in excess of the rated power - sometimes as much as 10x over.
posted by pombe at 8:56 AM on May 1, 2017 [2 favorites]
posted by pombe at 8:56 AM on May 1, 2017 [2 favorites]
This thread is closed to new comments.
Blue light is generally higher energy than red (and green) and more likely to contain ultraviolet energy, since blue andviolet are adjacent to the UV spectrum. I think you are wise to be concerned.
Operationally, the eye has less ability to focus on blue light, so a blue laser point is kind of ... pointless :)
Great thread title.
posted by intermod at 8:47 PM on April 30, 2017 [2 favorites]