Classification Criteria

The government recommended safety practices for a given laser system will depend on its classification. The following list highlights the criteria used to classify lasers, as well as listing the key safety considerations when operating a system within the indicated classification. See “See ANSI Z136.1 or IEC 60825-1” for a comprehensive discussion of these safety topics.

Wavelength:
If the laser is designed to emit multiple wavelengths the classification is based on the most hazardous wavelength.

Output Characteristics:
For continuous-wave (CW) or repetitively pulsed lasers the average output power (watts) and limiting exposure time inherent in the design are considered.
For pulsed lasers the total energy per pulse (joule), pulse duration, pulse repetition frequency and emergent beam radiant exposure are considered.

Laser Classification

Class 1 and 1M Lasers and Laser Systems:
These systems are also classified as “Exempt” lasers. They are normally not hazardous with respect to continuous viewing, or are designed in a way that prevents human access to laser radiation (e.g., laser printers).

Class 2 and 2M Lasers and Laser Systems (Low Risk):
These lasers emit visible light, which, due to normal human reflex responses, do not present a hazard. However, a safety risk would be posed if the output source were brought to within close proximity of the eye and then viewed for an extended period of time.

Class 3R and 3B Lasers and Laser Systems (Moderate Risk):
Class 3 lasers can cause eye injury if viewed momentarily, but are not capable of causing serious skin injury or hazardous diffuse reflections without the use of collecting/conditioning optics (e.g., fiber optics, telescopes, etc.).

Class 4 Lasers and Laser Systems (High Risk) :
These lasers present an eye hazard from direct and diffuse reflections. In addition, class 4 lasers can cause combustion of flammable materials and produce serious skin burns and injury from direct exposure. Most laser systems manufactured by Coherent fall into this classification.