LASER SAFETY


BULLETIN INFORMATION


LASER HAZARD CLASSIFICATION


Research studies, along with an understanding of the hazards of sunlight and conventional, manmade light sources have permitted scientists to establish safe exposure limits for nearly all types of laser radiation. These limits are generally referred to as Maximum Permissible Exposures (MPEs) by laser safety professionals. In many cases it is unnecessary to make use of MPEs directly. The experience gained in millions of hours of laser use in the laboratory and industry has permitted the development of a system of laser hazard categories or classifications. The manufacturer of lasers and laser products is required to certify that the laser is designated as one of four general classes, or risk categories, and label it accordingly. This allows the use of standardized safety measures to reduce or eliminate accidents depending on the class of the laser or laser system being used. The following is a brief description of the four primary categories of lasers:


CLASS 1 AND CLASS 1M A Class 1 laser system is considered to be incapable of producing damaging radiation levels during operation, and is exempt from any control measures or other forms of surveillance. Although some Class 1 lasers emit very weak, non-hazardous beams, most Class 1 laser systems incorporate “embedded” higher-power lasers, which can be accessed only if important safety features such as interlocks are defeated or deliberately bypassed as sometimes done during servicing. In this case, the system temporarily reverts back to the original laser classification (requiring special safety procedures).


A Class 1M laser system is considered to be incapable of producing hazardous exposure conditions during normal operation unless the beam is viewed with an optical instrument such as an eye-loupe (diverging beam) or a telescope (collimated beam), and is exempt from any control measures other than to prevent potentially hazardous


optically aided viewing; and is exempt from other forms of surveillance. NOTE: Products which have been previously classified as Class 2a should be treated the same as Class 1.


CLASS 2 AND CLASS 2M A Class 2 laser system emits in the visible portion of the spectrum (400-700 nm), and eye protection is normally afforded by the human aversion response, which is 0.25 second.


A Class 2M laser system emits in the visible portion of the spectrum (400-700 nm), and eye protection is normally afforded by the human aversion response for unaided viewing. However, Class 2M is potentially hazardous if viewed with certain optical aids.


CLASS 3 (MEDIUM-POWER) Class 3 laser systems may be hazardous under direct and specular reflection viewing conditions, but is normally not a diffuse reflection hazard or fire hazard. There are two subclasses, Class 3R and Class 3B. A Class 3R laser system is potentially hazardous under some direct and specular reflection viewing conditions if the eye is appropriately focused and stable, but the probability of an actual injury is small. This laser will not pose either a fire hazard or diffuse reflection hazard. A Class 3B laser system may be hazardous under direct and specular viewing conditions, but is normally not a diffuse reflection or fire hazard. NOTE: Products which have been previously classified as Class 3a should be treated the same as Class 3R.


CLASS 4 (HIGH-POWER) A Class 4 laser system is a hazard to the eye and skin from the direct beam, and may pose a diffuse reflection or fire hazard, and may also produce laser generated airborne contaminants and hazardous plasma radiation.


4 | LASER INSTITUTE OF AMERICA | www.lia.org


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