Having purchased various laser pointers. Some seem quite a bit brighter than others. Can the rating which is less than 1mW be trusted? Im talking about the ones you can buy from non optics specialist retailers online. It made me concerned potential dangerous pointers could be being used.
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I think with any laser light source one would have to be more careful. Although, the thought is that 1mW is safe . Exposure of radiation over time can affect. Other than, just being an annoyance.
No, in general the power label can’t be trusted, especially cheap devices from generic online retailers - it’s a big problem. I don’t have the data to hand, but I have seen some studies where the power of many laser pointers has been measured. IIRC, the vast majority of devices claiming to be 1 mW are in fact higher. In some cases the power is much higher, 100s of mW, well into Class 3B and very dangerous. The statistics on the number of people per annum (especially children) being blinded by mis-sold laser pointers are frightening.
You can buy laser pointers with automatic power control circuitry from reputable suppliers (e.g. Roithner) but these are more expensive. As a minimum, I would advise always checking the power of a laser pointer on a calibrated optical power meter before use.
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I can only second the reply by Paul Ryder. Following a (serious and permanent) retinal injury of both eyes of a 11 year old kid, we measured 60 mW for a laser pointer labeled and advertised as Class II with < 1 mW. Our test house also did a study for the European forum PROSAFE with widely varying results of the emitted power and labeling.
From UK authorities I was informed that a reply of a distributer of mislabeled laser pointers (i.e. labeled Class 2, but had higher power) was that they have to label as Class 2 as otherwise they are not permitted to sell them!
With respect to reputable suppliers: about 10 years ago, I specifically ordered 1 mW but we received 5 mW (at least that is not really hazardous - really bad would be > 5 mW).
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Definitely do not trust it. Some may be significantly higher, and in some cases, you may not be even able to see the wavelength, for example with cheap green laser pointers without a proper IR cut filter may have significantly higher output from 1064nm light, and cause eye damage or worse, you can see this link for more details. https://skyandtelescope.org/astronomy-news/observing-news/green-lasers-a-hidden-danger/