Classification of Lasers

Below are the main characteristics and requirements for the laser classification system as specified by the IEC 60825-1 standard:

Class 1 Laser
A class 1 laser is safe under all conditions of normal use. This means the maximum permissible exposure (MPE) cannot be exceeded. This class includes high-power lasers within an enclosure that prevents exposure to the radiation and that cannot be opened without shutting down the laser.

Class 1M Laser
A Class 1M laser is safe for all conditions of use except when passed through magnifying optics. Class 1M lasers produce large diameter beams, or beams that are divergent. The MPE for a Class 1M laser cannot normally be exceeded unless focusing optics are used to narrow the beam. If the beam is re-focused, the hazard of Class 1M lasers may be increased and the product class may be changed.

Class 2 Laser
A Class 2 laser is safe because the blink reflex will limit the exposure to no more than 0.25 seconds. It only applies to visible light lasers (400–700 nm). Class 2 lasers are limited to 1 mW continuous wave, or more if the emission time is less than 0.25 seconds or if the light is not spatially coherent. Intentional suppression of the blink reflex could lead to eye injury. Many laser pointers are class 2 lasers.

Class 2M Laser
A Class 2M laser is safe because of the blink reflex if not viewed through optical instruments. As with class 1M lasers, this applies to laser beams with a large diameter or large divergence, for which the amount of light passing through the pupil cannot exceed the limits for class 2 lasers.

Class 3R Laser
A Class 3R laser is considered safe if handled carefully, with restricted beam viewing. With a class 3R laser, the MPE can be exceeded, but with a low risk of injury. Visible continuous lasers in Class 3R are limited to 5 mW. For other wavelengths and for pulsed lasers, other limits apply.

Class 3B Laser
A Class 3B laser is hazardous if the eye is exposed directly, but diffuse reflections such as from paper or other matte surfaces are not harmful. Continuous lasers in the wavelength range from 315 nm to far infrared are limited to 500mW. For pulsed lasers between 400 and 700 nm, the limit is 30 mJ. Protective laser goggles is typically required where direct viewing of a class 3B laser beam may occur. Class 3B lasers must be equipped with a key switch and a safety interlock.

Class 4 Laser
Class 4 lasers include all lasers with beam power greater than class 3B. By definition, a class 4 laser can burn the skin, in addition to potentially devastating and permanent eye damage as a result of direct or diffuse beam viewing. These lasers may ignite combustible materials, and thus may represent a fire risk. Class 4 lasers must be equipped with a key switch and a safety interlock. Many industrial, scientific, military, and medical lasers are in this category.

Learn more about laser classifications.