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We just bought a green laser pointer on Ebay and had a discussion about the safety. The laser is low end chinese one (5 USD, free shipping :-) ) and the seller says this:

Green Laser Pointer Point Pen 532nm Output power: 5mW (Class IIIb)

the most confusion comes from the "Class IIIB" which, according to Wikipedia should be not safe for common use because it can damage eye even with accidential look or reflection.

However, directly on the pointer is this:

Max power output less than 5mW Wavelegnth 532nm Class III laser product This product complies with 21 CFR 1040

so this looks that it should not be Class IIIB, also because the power is less than 5mW while according to Wikipedia the "B" class should be for 5-200 mW.

I also have a couple of small red keychain lasers which all are the same power output and class.

I do not intend to shine anybody in the eyes but my sister was afraid that there could be potential risk to damage someones eyes with accidential quick exposure (reflection from window in a class or directly from the chalkboard to the class). The green pointer seems to have very intensive light compared to the red ones but it could be a subjective impression caused by the different color.

I think there is rather an incorrect information on the selling page and that the pointer should be safe but I am rather asking to be sure.

thanks

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First and foremost, you should know that the legal restrictions on laser pointers are not enforced. Therefore you should not assume the class labelling is correct. One study found that 90% of green lasers in the US had an illegally high power level.

You also should not assume the power rating is correct. It says 5mW probably because that's the most desired power level that consumers want: As bright as possible without being obviously illegal. But really it could be 2mW, or 10mW, or who knows.

Every laser pointer is dangerous, is not a toy, and should not be pointed anywhere close to other people ...but it takes extreme and unusual bad luck to cause permanent eye damage if its labeling is correct and it is really under 5mW (Note: I am talking specifically about visible-light, continuous-wave green lasers here). Here is a literature review, and you'll see that some injuries were indeed caused by laser pointers with less than 5mW of power, but most were injured by much more powerful lasers, like 30mW and higher.

Best is to find, buy, or borrow a light power meter. They're not expensive, and they're fun to have anyway.

Finally, stepping back, the review cited above found 111 patients with eye injuries from green laser pointers. Given how many green laser pointers are around, I wouldn't consider owning a legally-compliant green laser pointer to be a notably risky activity, compared to other day-to-day risks.

Owning a super-bright one (e.g. 30mW or higher) is something I would consider awfully risky. Treat a super-bright green laser pointer just like you would treat a circular saw: You store it well out of reach of children (and out of reach of irresponsible adults!), you leave it unplugged / remove the batteries when it's not in use, you don't use it if you're drunk, you don't have fun with it, etc. etc. etc.

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    $\begingroup$ If it was easy and probable to cause extensive permanent damage then, yes. But with low-powered lasers, the damage can accumulate slowly. If you burn one tiny pinprick in your retina, you'll never know it. Your brain fills in the missing part of the picture---just like your natural blind spot. en.wikipedia.org/wiki/Blind_spot_(vision) It's only after you've made hundreds of tiny scars that you begin to notice you can't quite see details the way you used to do. By the time you notice it, you might not even realize that the laser was the cause. $\endgroup$ – Solomon Slow Feb 19 '17 at 19:56
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The classification is dependent on wavelength, and the potential for damage. I would heed the classification, it is right on the edge of safe.

If you want a safe green laser buy a lower rated one.

Realistically it is unlikely to cause damage unless the beam is incident directly into the eye, but damaging the eyes with lasers is pretty much irreversible and will result in vision loss (usually just partial loss). Lasers in the visible range damage the retina, which is what makes them so dangerous.

Personally (and I work with lasers often) I would use the one that you purchased for Astronomical pointing (i.e., star gazing) only. If I wanted to do something else I would get a lower power laser, it isn't worth the risk of eye damage...

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  • $\begingroup$ Concur. And the thing about green ones is that the human eye is most sensitive to that color so you can afford lower power and still have a highly visible spot. $\endgroup$ – dmckee --- ex-moderator kitten♦ Jan 3 '13 at 18:31
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Classs IIIb lasers may be harmful to your eyes because their range is from 5mW-500mW. In addition, this laser can represent a fire hazard and may burn your skin lightly.

Cited from: https://en.wikipedia.org/wiki/Laser_safety#Class_IIIb

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