Laser Safety :: Lasers Info :: Ultralasers, Inc


Laser Classification

 The government recommended safety practices for a given laser system will depend on its classification. The following highlights the criteria are used to classify lasers, as well as the key safety considerations when operating a system with the indicated classification. The reader is directed to the 'Code of Federal Regulations' for a comprehensive discussion of these safety topics.

Classification Criteria

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 power output (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.

Class I Lasers

Low-power lasers and laser systems that cannot emit radiation levels greater than the Maximum Permissible Exposure (MPE). Class 1 lasers and laser systems are incapable of causing eye damage. These systems are also classified as, or termed, '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 II Lasers (Low Risk)

Visible, low power lasers or laser systems that are incapable of causing eye damage unless they are viewed directly for an extended period (greater than 1000 seconds). They are less than 1 mW in power.

Class III Lasers (Moderate Risk)

Medium-power lasers and laser systems capable of causing eye damage with shortduration (<0.25 s) exposures to the direct or specularly reflected beam. Includes Class 3a and 3b lasers. Class 3a : Lasers or lasers systems that normally would not produce a hazard if viewed for only momentary periods with the unaided eye. They may present a hazard if viewed using collecting optics. They have power levels between 1 and 5mW. Class 3b : Lasers or lasers systems that can produce a hazard if viewed directly. This includes intrabeam viewing of specular reflections. They have power levels between 5 and 500 mW.

Class IV Lasers (High Risk)

High power lasers and laser systems (> 500 mW) capable of causing severe eye damage with short-duration (<0.25 s) exposures to the direct, specularly reflected, or diffusely reflected beam. Class 4 lasers and laser systems are also capable of causing severe skin damage and igniting flammable and combustible materials.