Classifications

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.

Before reviewing the classifications of lasers, it is important to understand that the use of optical aids (magnifiers, binoculars, and telescopes) increases the hazard level and risk of injury for each type of laser.

The 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 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 emits in the visible portion of the 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. Other non-beam hazards must be dealt with separately and will be addressed later in this section.

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

• I (Class 1, 1M)
• IIa, II (Class 2, 2M)
• IIIa (Class 3R)
• IIIb (Class 3B)
• IV (Class 4)

To learn more about LSO visit our Medical Laser Safety Officer Online Training web page.