Lasers, producing an intense, highly-directional beam of monochromatic light found in various wavelengths on the electromagnetic spectrum, exist as remarkable phenomena while having the industrial ubiquity of a wrench. This is due to the fact that lasers—an acronym standing for Light Amplification by Stimulated Emission of Radiation—are relied upon in medicine, communication, and numerous other industries, in which they conduct bloodless surgery, send information over large distances with minimal loss through optical fiber communications, and cut a variety of materials, including metals, glass, and quartz.
Of course, these beams enhance the outcomes of these processes, but, when following the path of the beam, humans can be exposed to severe hazards. At the basis of comprehending these hazards for the purpose of applying adequate mitigation techniques is the classification of the laser’s intensity.
The international standard IEC 60825-1 Ed. 3.0 b:2014 – Safety of laser products – Part 1: Equipment classification and requirements addresses a great deal of information in relation to laser products, including the classification of their hazards. These laser classes have been incorporated into ANSI Z136.1-2022: American National Standard for Safe Use of Lasers, and they have been reiterated in other laser safety standards written and published by the Laser Institute of America (LIA), the ANSI-accredited standards organization that represents and safeguards the US laser industry.
The laser classes for safety are as follows:
Laser systems considered Class 1 are understood to be incapable of producing damaging radiation levels. Therefore, they are safe and are exempt from beam-hazard control measures.
These laser products are designed explicitly for contact application to the skin or non-ocular tissue. During operation, any ocular hazards need to be prevented by engineering means (i.e. the laser should not be able to damage anyone’s eyes by design), and, during operation, exposure levels may exceed the skin MPE (maximum permissible exposure, the “level of laser radiation to which, under normal circumstances, persons may be exposed without suffering adverse effects”), if necessary for their intended treatment procedure.
Furthermore, these laser products need to comply with applicable vertical standards, or stand-alone standard documents that address the necessary information specific to an application or product. Please note that Class 1C for lasers does not appear in ANSI Z136.1-2022, as the class was new to the recent edition of IEC 60825-1. Class 1C is included in more-recent LIA standards, however.
Laser products considered Class 1M are, much like Class 1 lasers, safe and incapable of producing hazardous exposure. However, when viewed with collecting optics, such as a telescope, Class 1M lasers can potentially be hazardous. Otherwise, they are exempt from control measures.
These lasers are visible, falling on the electromagnetic spectrum from 400 nm to 700 nm. These are usually safe for accidental exposure, but they are often handled with the aid of eye protection.
Much like Class 2 products, these lasers are visible, between 400 nm and 700 nm, and are normally afforded eye protection for viewing. While they are generally safe for accidental exposure, Class 2M lasers are potentially hazardous if viewed with collecting optics.
These laser products are potentially hazardous under certain viewing conditions and when the eye is properly focused and stable, but the probability of an actual injury is small, so they have reduced controls. Class 3R lasers will not pose either a fire hazard or diffuse reflection hazard, meaning that a change in the spatial distribution of a beam by scattering in various directions does not pose any sizeable threat.
These laser products are considered more hazardous and relatively unsafe under direct and specular reflection viewing conditions. A Class 3B laser product, however, is normally not a fire hazard, diffuse reflection hazard, or a laser generated air contaminant (LGAC) production hazard.
This type of laser is the most hazardous. Class 4 lasers care unsafe when a direct beam is exposed to the eye or skin. Furthermore, this laser can pose a fire hazard or diffuse reflection hazard, and it can also produce LGAC and even hazardous plasma radiation.
Please note that the laser classes apply to almost all laser products and/or systems, whether they are in the form of laser pointers or industrial cutting machines, assuming that they operate at wavelengths between 180 nm and 1000 μm.
IEC 60825-1 Ed. 3.0 b:2014 – Safety of laser products – Part 1: Equipment classification and requirements and LIA standards are available on the ANSI Webstore.