Class I lasers - Lasers that are not hazardous for continuous viewing or are designed in such a way that prevent human access to laser radiation. These consist of low power lasers or higher power embedded lasers. (i.e. laser printers)

Class II visible lasers (400 to 700 nm) (UK AND EUROPE LEGAL) - Lasers emitting visible light which because of normal human aversion responses, do not normally present a hazard, but would if viewed directly for extended periods of time. (like many conventional light sources).

Class Iia visible lasers (400 to 700 nm) - Lasers emitting visible light not intended for viewing, and under normal operating conditions would not produce a injury to the eye if viewed directly for less than 1000 seconds. (i.e. bar code scanners). Some laser pointers are of this class, but very rare.

Class IIIa lasers - (USA LEGAL)Lasers that normally would not cause injury to the eye if viewed momentarily but would present a hazard if viewed using collecting optics (fiber optics loupe or telescope).

Class IIIb lasers - Lasers that present an eye and skin hazard if viewed directly. This includes both intra-beam viewing and specular reflections. Class IIIb lasers do not produce a hazardous diffuse reflection except when viewed at close proximity. May singe or burn through certain materials.

Class IV lasers - Lasers that present an eye hazard from direct, specula and diffuse reflections. In addition such lasers may be fire hazards and produce skin burns