> I'd just like to add to Mike's reply immediatly above, > Kenneth's assumption that an I.R. filter would "filter out the harmful > radiation" is wrong. Ever heard of an infrared heat lamp Kenneth ? > If the radiated form of light (whatever the frequency), stops without > reflection then the light energy is converted to heat energy. Making > assumptions otherwise is asking for the full laser output to be utilised > in COOKING your retina. > Graham Daniel. > > Except that at infra red, the eye's focus changes. You will not burn the > retina, you could however heat up the inside of the eyeball (vitrious > humor? Can't remember.) where most of the IR would be absorbed. I work > with IR lasers ( mostly around 1330nm) all the time and I can tell you > that the safe exposure levels are much higher for IR lasers than for > visible ones. > > Regards > > Mike Rigby-Jones > mrjones@nortel.co.uk >