
– iv –
LASER CLASSIFICATIONS
All manufacturers of lasers used in the United States must conform to regulations admin-
istered by the Center for Devices and Radiological Health (CDRH), a branch of the U.S.
Department of Health and Human Services. CDRH categorizes lasers as follows:
Class Description
IA laser or laser system, which does not present a hazard to skin
or eyes for any wavelength or exposure time. Exposure varies
with wavelength. For ultraviolet, 2 to 4 µm exposures is less than
from 8 nW to 8 µW. Visible light exposure varies from 4 µW to 200
µW, and for near-IR, the exposure is < 200 µW. Consult CDRH
regulations for specic information.
II Any visible laser with an output less than 1 mW of power. Warning
label requirements – yellow caution label stating maximum output
of 1 mW. Generally used as classroom lab lasers, supermarket
scanners and laser pointers
IIIa Any visible laser with an output over 1 mW of power with a
maximum output of 5 mW of power. Warning label requirements
– red danger label stating maximum output of 5 mW. Also used
as classroom lab lasers, in holography, laser pointers, leveling
instruments, measuring devices and alignment equipment.
IIIb Any laser with an output over 5 mW of power with a maximum
output of 500 mW of power and all invisible lasers with an output
up to 400 mW. Warning label requirements – red danger label
stating maximum output. These lasers also require a key switch
for operation and a 3.5-second delay when the laser is turned on.
Used in many of the same applications as the Class IIIa when
more power is required.
IV Any laser with an output over 500 mW of power. Warning label
requirements – red danger label stating maximum output. These
lasers are primarily used in industrial applications such as tooling,
machining, cutting and welding. Most medical laser applications
also require these high-powered lasers.