Q: How much power is bad for my eyes?
5mW is the "limit" for taking a direct hit to the eye. This is because a laser above 5mW can cause damage before the blink reflex kicks in, shutting out the beam. This is also why the FDA doesn't let lasers above 5mW get into the US. So kids don't blind themselves. The usual maximum for looking a the dot of the laser is 30mW, although I definitely wouldn't stare at a dot of that power for long. There is no limit for looking at the beam, so you can point any laser at the sky and stare at any beam as long as you want.
This is a little rant I'm adding in (more recent), you can skip it if you want. First of all, some of you guys are taking this FDA limit thing WAY to seriously. The FDA states that laser damage CAN occur from a >5mW beam, this is the lowest power that they could come up with. They have done scientific tests to find the absolute lowest power that could damage your eyes, with every worse possible condition (basically point blank range, low divergence, the most sensitive part of your eye, etc.).
UNDER NORMAL CONDITIONS a 6mW laser is extremely unlikely to cause damage. Especially considering that almost every hit will come from a distance, or a reflection which will distort the beam, double the distance, and lower the power of the laser. With most accidents, the beam will have diverged/diffracted to a point where it isn't even a danger. Most people picture getting hit with a laser beam as the beam being exactly as it comes out of the device, and if you could recreate the incident, the beam would most likely not be the same.
Now I'm NOT saying that a close ranging hit from a 20mW+ laser wouldn't harm you, it would, I'm just saying that you don't have to go yelling that a 6mW laser is completely unsafe and you can't do any reflections with it, just because the FDA says not to. Those people are wrong.
Bottomline, they are just exaggerating to the point of telling you the worse conditions, and under normal conditions, you could probably get hit with a random reflection from a 15mW laser with no problems. Thanks for listening, and please don't go test this. lol
