Each laser product is classified as Class I, IIa, II, IIIa, IIIb, or IV in accordance with definitions established by FDA in paragraphs (b)(5) through (11) of 21 CFR §1040. The product classification is based on the highest accessible emission level(s) of laser radiation to which human access is possible during operation. Lasers are classified into four broad areas, depending on the potential for causing biological damage. Laser emission ranges for each class are provided in 21 CFR §1040(d)(2).
The standard establishes the following limits for the Classes:
• Class I limits (1040.10(b)(5) and 1040.10(d)(Table I)) apply to devices that have emissions in the ultraviolet, visible, and infrared spectra, and are limits below which biological hazards have not been established. In the visible and near infra-red spectra there are separate Class I limits for radiant energy (power) and integrated radiance (radiance); both limits must be exceeded for the device to move from Class I. These lasers cannot emit laser radiation at known hazard levels. Class IA—This is a special designation that applies only to lasers that are “not intended for viewing”, such as a supermarket laser scanner. The upper power limit of Class IA is 4.0 mW.
• Class Ila limits (1040.10(b)(6) and 1040.10(d)(Table II-A)) apply to products whose visible emission does not exceed Class I limits for emission durations of 1000 seconds or less, and are not intended for viewing. Class IIa limits therefore may not exceed the Class II limits. An example of a Class IIa laser product might be a supermarket scanner.
• Class II limits (1040.10(b)(7) and 1040.10(d)(Table II)) apply to products that have emissions in the visible spectrum (400-710 nm) for emission durations in excess of 0.25 seconds, providing that emissions for other durations and/or wavelengths do not exceed the Class I limits. Class II products are considered a hazard for direct long-term ocular exposure. These are low-power visible lasers that emit above Class I levels, but at a radiant power not above 1 mW.
• Class Ilia limits (1040.10(b) (8) and 1040.10(d)(Table III-A)) apply to products that have emissions in the visible spectrum and that have beams where the total collectable radiant power does not exceed 5 mw. Class IIIa products include most heliumneon lasers and laser pointers. These are intermediate – power lasers (cw: 1-5 mW), which are hazardous only when viewed directly in the beam.
• Class Illb limits (1040.10(b)(9) and 1040.10(d)(Table III-B)) apply to devices that emit in the ultraviolet, visible, and infrared spectra. Class IIIb products include laser systems ranging from 5 to 500 mw 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. These are moderate-power lasers.
• Class IVlevels (1040.10(b)(ll)) exceed the limits of Class IIIb and are a hazard for scattered (diffuse) reflection as well as for direct exposure. These are high-power lasers (> 500 mW) which are hazardous to view under any condition (directly or diffusely scattered). Significant controls are required of Class IV laser facilities.