Environmental Health & Safety
Laboratory Safety Unit
Laser Safety for Research and Teaching Laboratories
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- GENERAL CONTROLS FOR CLASS 3 AND CLASS 4 LASERS
- PIs/supervisors are required to have the operating manuals available in the laboratory for Class 3 and Class 4 lasers. All users are to observe proper procedures for alignment, operation and maintenance of the laser.
- Labels: A laser classification label shall be conspicuously affixed to the laser housing.
- Warning Signs
- For all Class 3R lasers and laser systems, each entrance shall be posted with a sign that conforms to ANSI Z136.1 - 2014 (Figure 1a) or ANSI Z136.1 - 2007 (Figure 1a).
- For Class 3B laser and laser systems, each entrance shall be posted with a sign that conforms to ANSI Z136.1 - 2014 (Figure 1b) or ANSI Z136.1 - 2007 (Figure 1b).
- For Class 4 laser and laser systems, each entrance shall be posted with a sign that conforms to ANSI Z136.1 - 2014 (Figure 1b, 1c) or ANSI Z136.1 - 2007 (Figure 1b, 1c).
- Controlled access in laser labs:
- Laser controlled areas shall be established that have doors that lock (but non-lockable from the inside in case of an emergency), window coverings, and surfaces consisting of diffuse reflected material. The facility shall be a fully enclosed room or laboratory with floor-to-ceiling walls.
- Access to the area during laser operation requires the permission of the authorized laser operator.
- Key Control
- A Class 3B laser should be provided with a master switch. This master switch shall be operated by a key or by a coded access.
- A Class 4 laser shall be provided with a master switch. This master switch shall be operated by a key or by a coded access.
- Safety Interlocks
- All protective enclosures/housings that surround commercial laser devices and high-voltage electrical sources shall also be protected with interlocks. Interlocks shall be designed so that after they are actuated, the capacitor banks, shutters, or power supplies cannot be re-energized except by manually resetting the system.
- If interlocks are not feasible, the PI/Lab Supervisor may consider the use of alarms or voice warnings. The EH&S Laboratory Safety Unit shall be consulted for these options.
- Securely fasten all mirrors, prisms, beam stops, etc., in the beam path. Ensure that the laser is also securely fastened.
- Circuit breakers shall be identified and labeled for each laser and accessible for emergency shutdown.
- Beam Enclosure: The entire beam path of Class 3B and Class 4 lasers, including the target area, should be surrounded by an enclosure, if practical. When total enclosures of the laser beam path is not practical, both the non-enclosed laser beam and any strong reflections shall be terminated at the end of the useful path. Such devices include backstops, shields, or beam traps.
- Reflection Control: Materials that diffusely reflect laser radiation shall be used in place of specular reflective surfaces whenever possible. To minimize personnel exposure, specular reflecting surfaces that are needed for beam-path control shall be enclosed or shielded.
- Invisible Beams: Ultraviolet (UV) and infrared (IR) lasers that emit invisible beams require additional controls. Shields shall be installed that will attenuate UV radiation to levels below the MPE for the wavelength being used. Hazardous concentrations of by-products formed by the reaction of intense UV radiation with materials in the area shall be controlled. IR beam enclosures and backstops shall be fabricated of IR-absorbent material. For Class 4 lasers, the absorbent material shall also be fire-resistant.
- Direct Viewing: Personnel shall never look directly into any laser beam unless such action is specifically approved by the LSO or the EH&S Laboratory Safety Unit. The primary beam and specular reflections of Class 3B and Class 4 lasers are particularly hazardous. In those cases where it is necessary to directly view a beam from a Class 3B or Class 4 laser, special provisions, such as filters, are mandatory.
- Alignment: High-power laser optical systems shall never be aligned by direct beam viewing if the radiant exposure or irradiance exceeds the MPE. Appropriate alignment goggles, diffuse reflectors, image-retaining screens, exposed Polaroid film, and other devices that will minimize eye exposure are to be used to properly align a low-power laser.
- Optical Viewing Aids: Using optical systems such as cameras, microscopes, etc., to view laser beams may increase the eye hazard. All collecting optics shall incorporate suitable means (such as interlocks, filters, or attenuators) to prevent eye exposures above the MPE.
- Unattended Equipment: When lasers are to be left unattended, de-energize the power supplies or capacitor banks or lock the door to prevent unauthorized entry or activation of the equipment. The operation of unattended lasers is only allowed when a specific SOP has been written and approved by the PI/Lab Supervisor.
- Temporary Installations: Occasionally, it may be necessary to remove protective enclosures or override equipment interlocks or other safety devices for service adjustments, maintenance, special training exercises, etc. In these instances, a temporary controlled laser area shall be set up. Because the area will not have all the standard safety features, the SOP shall describe provisions for protecting personnel who could potentially be exposed. See Section IX.
Continue to the next section - Converting to a Class 1 Enclosure
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This page last updated 7/11/2019. Disclaimer.
