![]() ![]() Be alert to the possibility of producing hazardous by-products, such as ozone, and the formation of skin sensitizing agents.Use appropriate shielding materials to attenuate the radiation level below MPE for the specific UV wavelength.Many surfaces which visually appear "dull" can act as a reflector of infrared radiation. Terminate the beam from class 4 IR lasers with a fire-resistant material.Terminate the beam from class 3B IR lasers with a highly absorbent backstop.Use a visible coaxial aiming beam, if possible, or a phosphorus card for alignment.Since infrared and ultraviolet radiation is invisible, follow the special precautions described below for these laser systems, in addition to the laser control measures required by hazard classification. Practice special control measures for invisible laser radiation if infrared or ultraviolet radiation is involved. An audible warning system notifies personnel that the laser is either about to be activated or deactivated. Built-in activation warning systems for class 4 lasers and laser systems may include audible sound (bells or chimes), warning lights, or verbal countdown.The beam stop or attenuator must be capable of preventing laser radiation in excess of the appropriate MPE level. A beam stop or attenuator is required for class 4 lasers and is strongly recommended for class 3 lasers.A completely exposed or partially exposed beam path from a class 3B or 4 laser or laser system requires the EH&S Laser Safety Officer to conduct a hazard analysis to establish the Nominal Hazard Zone (NHZ) if not furnished by the manufacturer.Collecting optics (lenses, telescopes, microscopes, etc.) intended for viewing use with a laser or laser system must incorporate suitable means (such as interlocks, filters, or attenuators) to maintain the transmitted laser radiation at levels at or below the appropriate MPE.Viewing portals and diffuse display screens, which are part of a laser or laser system, must incorporate a suitable means (such as interlocks, filters, or attenuators) to maintain the laser radiation at the viewing position at or below the applicable MPE.Disable the master switch when the laser is not in use. Restrict the key or code that enables operation of a class 4 laser or laser system to an appropriate supervisor or authorized laser operator. Key control is required for class 4 lasers.When the terminals of the connector are open circuited, the accessible radiation must not exceed the appropriate MPE levels. ![]() Interlocks facilitate electrical connections to an emergency master switch. Remote interlock connectors are required for class 4 lasers and strongly recommended for class 3B lasers. ![]() The interlock is designed to prevent access to the beam above the applicable maximum permissible exposure (MPE) limit. Interlocked protective housing is activated upon removal of the protective housing during operation and maintenance. Interlocks on protective housing are required for class 3B and 4 lasers.Other controls, not designated as required, are strongly recommended. Use the required engineering control measures described below for class 3B and 4 lasers and laser systems. Evaluate non-beam hazards and incorporate mitigation procedures into your Laser Safety Plan.Contact the Laser Safety Officer, (858) 822- 2850, if you have questions about MPE.Use an alignment laser whenever possible, or use the lowest power setting during alignment.Perform alignment of laser optical systems so that the primary beam, specular, or diffuse reflection does not expose the eye above the applicable maximum permissible exposure (MPE) limit.In these cases, contact the Laser Safety Officer, (858) 822-2850, to arrange alternative control methods. ![]()
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