What would be an approximate "safeish" mw level.

[snek]

I know the 5mw thing, however I doubt that 5mw is totally safe but 6mw suddenly causes severe retinal damage. For a greenish wavelength region laser what mw would most likely not cause permanent damage assuming that: 1. The beam did not hit anyones eyes directly but assuming a highly reflective surface (chrome or a bathroom mirror or something), and 2. that it was only for a short instant (the amount of time it would take to blink). I was unable to find a scale of reference for laser injuries.

edit: when I say "not cause permanent damage" I mean nothing that would do worse than creating a blurry patch or ghost image for 10 or 20 minutes.

 

[paul1598419]

You already answered your question in your post. Power is power, regardless of the wavelength or color of the laser. At 5 mW your blink reflex is fast enough to keep damage from happening to your retinas. That doesn't mean you can stair into a laser for a protracted amount of time. While the maximum isn't an edge which can't be broached, you won't find 6 mW lasers in a normal search for them. To see the the beam of a green laser it is better to have ~80 mW of power. That is considerably more than 5 mW. You only get two eyes and if you are going to use lasers, you need to protect them. As you get more familiar with them, you will know when it is necessary to use safety goggles and when you can dispense with them. But, an accident is always a possibility, so stay safe.

 

[lasersbee]

^^^^ What Paul said ^^^^

It's the power that your retina receives before
you can close your eye. Look into the noon sun
for a long time and you will damage your retina.


Jerry

 

[Benm]

Well yeah, the 5 mW seems like a very nice round figure, perhaps it should actually be 4 or 6, but it already at the point of exposure you definitely will want to avoid.

Shining a 5 mW laser into your eyes just to see if you blink fast enough not to sustain practical damage is NOT a good idea - perhaps you blink a bit slower that the average person.

The 5 mW should be considered an absolute upper limit that should never be exceeded, NOT as a target number up until which it is perfectly acceptable to shine lasers into peoples eyes.

If you are doing things like crowd scanning you definitely would not want to go anywhere close to prolonged exposure to 5 mW: it only means that you should install extra safety features to ensure that this limit is never exceeded, even if something like a galvo fails and sends the beam in a single plane instead of a 3d projection. Practically this means you need to use systems that detect 'scanfails' - if the feedback signal from the galvo does no longer confirm it's moving the laser is shut off right away as a precaution.