Laser Safety Manual

9 Laser Safety Manual The following section describes the classification for continuous- wave lasers. The same hazard levels also apply to pulsed lasers with pulse duration of less than 0.25 seconds(s), but classification is more complex for these devices. The ANSI Z136.1 Standard is available by contacting either EH&S or ESH for details of both continuous-and pulsed laser classification. Class 1 and 1M Lasers Class 1 lasers are considered to be incapable of producing damaging radiation levels during operation and are exempt from any control measures or other forms of surveillance. A completely enclosed laser that does not emit hazardous radiation under normal operating conditions would be considered a Class 1 laser. Equipment such as laser printers and laser disc players are examples of this class. Class 2 and 2M Lasers Class 2 lasers emit accessible, visible (0.4 to 0.7µm) laser light with power levels less than 1 milliwatt (mW) radiant power and are capable of causing eye damage through chronic exposure. The human eye blink reflex, which occurs within 0.25 s, provides adequate protection. It is possible to overcome the blink response and stare into the Class 2 laser long enough to damage the eye. Class 2 equipment housing lasers/laser systems shall bear a label warning against staring into the beam. Some visible continuous- wave Helium-Neon lasers and some laser pointers are examples of Class 2 lasers. Class 2M lasers emit laser light in the visible portion of the spectrum and eye protection is normally afforded by the aversion response for unaided viewing. Class 2M is potentially hazardous if viewed with certain optical aids such as a microscope. Class 3R Lasers Class 3R laser systems are 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. Some visible continuous-wave Helium- Neon lasers and some solid-state hand held lasers are examples of Class 3R laser systems. Class 3R lasers have power levels of 1 to 5 mW and normally do not produce a hazard if viewed only momentarily by the unprotected eye. However, they pose severe eye hazards when viewed through optical instruments (microscopes, binoculars, or other collecting optics). Therefore, Class 3R lasers shall bear a label warning against direct eye exposure or viewing directly with optical instruments.