- May 8, 2014
While I would absolutely treat a 20mW beam as being dangerous, it is worth noting that the ANSI MPE values are based on a factor of safety of around 10. So in their studies, it actually must have taken something in the ballpark of 50mW to cause visible, measurable retinal burns from a brief exposure.
Regardless, 20mW is close enough to that number that it should be treated with a great deal of respect. It's just interesting to see how these power limits were initially established.
I have read the same info, im sure I have seen a study done by a US university that showed up to 40-50mw is still "blink reflex safe"
The 5mw # used is not taking into account the factor for safety the FDA and ANSI and all other standards associations use.
That said this is your eyesite we are talking about, DONT TAKE CHANCES. I use safety goggles anytime I am using anything class 3B or higher where its possible to catch a specular reflection off anything.