Laser Classifications

Virtually all U.S. domestic and international standards divide lasers into four major categories called the laser hazard classifications. A scheme of graded risk creates the basis for the classes.

Laser hazard classification serves as a user warning about the accessible level of laser radiation. The use of labels and instructions demonstrate hazard identification. It also serves as a basis for defining control measures and medical surveillance.

Laser hazard classification is based primarily on the ability of the beam to cause damage to the eye and skin. A laser's capacity to cause harm is based on the following parameters:

Laser output energy or power
Radiation wavelengths
Exposure duration
Cross-sectional area of the laser beam at the point of interest

Federal law (21 CFR Part 1000) requires manufacturers to classify and appropriately label all off their lasers and laser systems. Classification is a required specification provided by the laser manufacturer, and the label that specifies the class is found in only one location on the laser product, the lower left-hand corner of the warning logotype label. The classification may change whenever the laser or laser system is modified to accomplish a given task.

The laser classifications are as follows:

Class 1: Class 1 is considered to be incapable of producing damaging laser exposure during operation and is exempt from any control measures. Class 1 lasers have no required labeling indicating the Class 1 status.
Class 1M: Class 1M is considered to be incapable of producing hazardous exposure conditions during normal operation unless the beam is viewed with an optical instrument. It is exempt from any control measures, other than to prevent potentially hazardous, optically aided viewing.
Class 2: Class 2 is considered incapable of emitting laser radiation at levels that are known to cause skin or eye injury within the time period of the human eye aversion response.
Class 2M: Class 2M lasers emit in the visible portion of the light spectrum. The aversion response typically affords enough eye protection, but this class is potentially hazardous if viewed with optical aids.
Class 3: Class 3 is divided into two subclasses, 3R and 3B. Class 3 lasers may be hazardous to the eye under direct and specular reflection viewing conditions, but the diffuse reflection is generally not a hazard. They are not usually a fire hazard or a significant hazard to the skin.
- Class 3R: Class 3R is potentially hazardous under some direct and specular viewing conditions if the eye is appropriately focused and stable, but the probability of injury is small.
- Class 3B: Class 3B may also be hazardous under direct and specular viewing conditions but is normally not a diffuse reflection or fire hazard.
Class 4: Class 4 is a high-power system. This class is a hazard to the eye or skin from the direct beam and from a diffuse reflection. It can also be a fire hazard.

The hazard classification system deals only with laser radiation to which human access is possible during operation of the laser.

Note that this system of classification is relatively new, and some products may still be labeled using old FDA equivalents: