green lasers

Not sure where you heard that Janek. I agree that they are very dangerous, but the US army has officially equipped many of their troops (2000 of them) in Iraq with high power green laser pointers (class 3b up to 20mw) to disorient foes, despite anything in the Geneva Convention.

It is strange for astronomy though. Surely 5mw is enough...

Trev

I read it in Geneve convention... it prohibits laser guns which can potencialy demage eyes. US army and their respect for international convetions is different thing.

Are the 5mw very dangerious for eyes. That is would a accidental flash in the eye cause permanent damage?

I think so. As far as I know even the 5mw ones are extremely dangerous if someone happens to get the beam in their eye. In fact even shining a 5mw one on a wall produces a painfully bright glow.

Trev

You certainly dont one one of these in the eye, they are very bright, even in daytime. as for geneva convention/US army, who cares.

You certainly dont one one of these in the eye, they are very bright, even in daytime

This is generally the type of answer people give. I obviously don't want a 5mw laser in the eye, however friends often produce them in the field and it is very easy for beam to accidently hit polished tripod leg and god knows where it is going to reflect.

If an accidental flash in the eye will blind then surely we are all mad using them at all ?

Folks - I did a bit of work on laser safey a few years back.

First, there is a discrepency between US and EU classification. If a laser is classed as a IIIa by the FDA, I have seen them reclassified in the EU as IIIb.

Second - class I and II are unlikely to cause eye damage. For IIIa and IIIb lasers, direct viewing of the beam, especially if it is viewed through optics, can cause eye injury (but a specular reflection usually will not). Direct viewing of a class IV will damage your eyes as will viewing any specular reflection of a class IV laser. I have also seen a class IV laser burn a hole in ceiling tiles :shock:

If I were to choose a laser I would choose the lowest class product that would do the job for me (I or II). And if I were using a high powered laser (IIIa or IIIb) outside, I would be extremely careful and would avoid anything hand-held. I would only use a class IV laser for world domination

Cheers

Dave