Lasers - general information
Hazard Classification for Lasers
A system of laser classification is used to indicate the level of laser beam hazard, and maximum Accessible Emission Levels (AELs) have been determined for each class of laser.
Class 1: Lasers that are safe under reasonably foreseeable conditions of operation, either because of inherently low emission of the laser, or because human access to higher levels is not possible under normal operation. If access panels of a totally enclosed system are removed for servicing, etc, then the laser product is no longer Class 1 and the precautions applicable to the embedded laser must be applied until the panels are replaced.
Class 1M: Laser products emitting in the wavelength range 302.5 nm to 4000 nm, whose total output is in excess of that normally permitted for Class 1 laser products but because of their diverging beams or very low power density do not pose a hazard in normal use and comply with the measurement conditions for a Class 1M product.
Class 2: Lasers that only emit visible radiation in the wavelength range from 400 nm to 700 nm and whose output is less than the appropriate AEL. They are safe for accidental viewing as eye protection is afforded by aversion responses, including the blink reflex.
Class 2M: Laser products that only emit visible radiation in the wavelength range 400 nm to 700 nm, whose total output is in excess of that normally permitted for Class 2 laser products but because of their diverging beams or very low power density are safe for accidental viewing during normal use and comply with the conditions for a Class 2M product.
Class 3R: Lasers that emit in the wavelength range from 302.5 nm to 1 mm where direct intrabeam viewing is potentially hazardous but the risk is lower than for Class 3B lasers, and fewer manufacturing requirements and control measures for the user apply. The AEL is restricted to no more than five times the AEL of Class 2 for visible wavelengths and no more than five times the AEL of Class 1 for other wavelengths.
Class 3B: Lasers that are normally hazardous when direct intrabeam exposure occurs (i.e. within the Nominal Ocular Hazard Distance - the distance within which the beam irradiance or radiant exposure will exceed the maximum permissible exposure). Viewing diffuse reflections is normally safe. Output levels must be less than AELs for Class 3B devices.
Class 4: High power lasers that exceed the AELs for Class 3B products that are also capable of producing hazardous diffuse reflections. They may cause skin injuries, could also constitute a fire hazard and could cause hazardous fumes to be produced as well as being a hazard to the eyes. Their use requires extreme caution.
Laser Hazard/Risk Assessment
Excessive exposure to laser radiation will result in biological damage. The main areas at risk are the eyes and the skin. Visible and near infra-red lasers are a special hazard to the eye because the very properties necessary for the eye to be an effective transducer of light result in high radiant exposure being presented to highly pigmented tissues.
Before the appropriate controls can be selected and implemented, laser hazards must be identified and evaluated together with non-beam hazards that may be present. The laser's capability of injuring personnel and the environment and the way in which the laser or lasers are to be used needs consideration.
A risk assessment must be carried out to establish the significant risks and whether suitable and effective controls exist.
Lasers - specific information
Safety Department links