What are the classes of lasers?

Although there are hundreds of different types of lasers, only about a dozen laser systems are found in everyday clinical use. Nearly all treatment laser products used in surgery are Class 4 as they are designed to deliver laser radiation for the purpose of altering biological tissue. A breakdown of classifications include:

• Class 1—A Class 1 laser system is considered to be incapable of producing damaging radiation levels during normal 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 is sometimes done during servicing. In this case, the system temporarily reverts back to the original laser classification (requiring special safety procedures). NOTE: Products which have been previously classified as Class 2a should be treated the same as Class 1.
• Class 1M—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.
• Class 2—A Class 2 laser system emits in the visible portion of the spectrum (400-700 nm), and eye protection is normally afforded by the aversion response. The aversion response is the closure of the eyelid, eye movement, pupillary constriction, or movement of the head to avoid an exposure to a bright light stimulant. The aversion response to a bright visible laser source is assumed to limit the exposure of the retina to 0.25 seconds or less.
• Class 2M—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 3R—A Class 3R laser system is potentially hazardous under some direct and specular reflection (shiny or mirror-like) 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. NOTE: Products which have been previously classified as Class 3a should be treated the same as Class 3R.
• Class 3B—A Class 3B laser system may be hazardous under direct and specular viewing conditions, but is normally not a diffuse reflection or fire hazard.
• Class 4—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.