There are four main classiffications of
laser and these have been created to show their effect or damage on biological
material and hence their strength.
- Class I - These lasers are not known to be
hazardous to biological material.
- Class I.A. - Supermarket laser scanners as
well as others fall into this category and are "not intended for
viewing". The maximum power limit is 4 mW.
- Class II - A low-power visible laser that
can emit above Class I levels but with a maximum radiant power of 1
mW. The "human aversion reaction to bright light" should protect
somebody from this amount of light radiation, at least that is the theory.
- Class IIIA - An intermediate-power laser between
1-5 mW, which may be hazardous when viewing. Laser pointers fall into
- Class IIIB - Lasers of moderate power.
- Class IV - High-power lasers (cw: 500
mW, pulsed: 10 J/cm2 or the diffuse reflection limit), whether direct
or diffused these are hazardous, these can cause combustion and are
a biological hazard so need to come under significant control and regulations.