On 1 May 2016 15:02, "Bruce Griffiths" <bruce.griffi...@xtra.co.nz> wrote: > > The solution with high power is to use a beam expander so that the unaided eye cannot collect a power greater than the safe limit. Using near IR beams also helps. > Bruce
It is a long time since I worked with lasers, so my knowledge is both out of date and my memory not perfect. But I was a long while ago regularly using and sometimes aligning a picosecond pulsed laser at about 800 nm. The average output power was 1 W, so a very dangerous class IV laser. It certainly hurt if one had the beam on ones skin, but it was not sufficiently powerful to noticeably burn the skin if one did the obvious thing and moves ones hand away. But I believe people need to be particularly careful using IR lasers. The lens in the eye will not focus Iinfra red on the retina, so that is probably why you say IR is safer. However one of the protective methods the eye has is a "blink response". One blinks if one perceives a light source as bright. Blinking offers some protection to the eye. But since one does not see an IR laser source, one does not blink, so IR lasers disable one of the eyes protective mechanisms. Hence there are various complications that arrive when discussing laser safety issues. I don't have the knowledge to advise on what is or not safe, but will warn there are several effects which are important, and many people don't realise this. Laser safety is a nontrivial subject. Dave. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
