Omron ZG User Manual page 196

Class
Class IIIa/3a Limits to products that have emissions in the
visible spectrum and that have beams where
the total collectable radiant power does not
exceed 5 milliwatts.
Class IIIb/3b Limits applicable to devices that emit in the
ultraviolet, visible, and infrared spectra.
Class IIIb products include laser systems
ranging from 5 to 500 milliwatts in the visible
spectrum. Class IIIb emission levels are
ocular hazards for direct exposure
throughout the range of the Class, and skin
hazards at the higher levels of the Class.
Class IV/4 Exceeding the limits of Class IIIb and are a
hazard for scattered reflection as well as for
direct exposure.
194
Requirements from Regulations and Standards
FDA definition ANSI description
Class 3 lasers are divided into two
subclasses, 3a and 3b. A Class 3 laser may
be hazardous under direct and specular
reflection viewing conditions, but the diffuse
reflection is usually not a hazard.
A Class 4 laser is a hazard to the eye or skin
from the direct beam and sometimes from a
diffuse reflection and also can be a fire
hazard. Class 4 lasers may also produce
laser-generated air contaminants and
hazardous plasma radiation.
ZG User's Manual