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Safety Instruction Number:70
Last Update:Tue, 09/04/2007
Principal Investigator is responsible for ensuring that lasers under his/her control are used safely. The following control measures are recommended as a guide to safe laser use. Some of the measures may be required, particularly in the case of high powered lasers or lasers that emit invisible non-ionizing radiation; see engineering controls and administrative controls. The following laser controls and work area controls are to be used as guidelines while preparing laser work areas and safety protocols.
Recommended Work Area Controls
- Access by non-laser users to the laser work area should be limited. Doors should be closed and secured.
- An active laser should never be left unattended unless it is a part of a controlled environment.
- The illumination in the area should be as bright as practical so that the pupils of the user's eye will be constricted.
- The laser should be set up so that the beam path is not at normal eye level (i.e., path should be below 4.5 feet or above 6.5 feet).
- Where practical, the laser system or beam should be enclosed with polyvinyl chlorine (PVC) tube or a similar material to prevent accidental exposure to the beam.
- The potential for inadvertent reflections should be minimized by shields and by removal of unnecessary shiny surfaces. Flat black spray paint is inexpensive and handy.
- Practice good housekeeping to ensure that no device, tool, or other reflective material is left in the beam path.
- Windows in the laser work area should be provided with adequate shades or covers (class 3b and 4).
- The main beams and reflected beams should be terminated or stopped by a protective device such as a beam block. This is required for any accessible laser that may exceed the maximum permissible exposure. Contact EH&S if you have any questions or are unsure if this situation exists.
- Lasers with beams operating at wavelengths outside the visible spectrum should be equipped with audible or visual warning devices informing users of the presence of invisible beams.
General Laser Use Controls
- Class 1 Controls:
- No user safety rules are necessary. However, general laser safety training should be provided to all users.
- Class 2 Controls:
- Never permit a person to continuously stare into the laser source.
- Never point the laser at an individual's eye unless a useful, approved purpose exists.
- Class 3 Controls:
- Never aim the laser at an individual's eye.
- Permit only authorized personnel to operate the laser.
- Enclose as much of the beam as possible. Even a transparent enclosure will prevent individuals from placing their head or reflecting objects within the beam path. Terminations (beam stops) should be used at the end of the useful paths of the primary and any secondary beams.
- Shutters, polarizers, and optical fibers should be placed at the laser exit port to reduce the beam power to the minimal required level.
- A warning light or buzzer should indicate laser operation. All invisible beams (i.e., infrared lasers) must have a warning device.
- Do not permit laser tracking of non-target vehicles or aircraft.
- Operate the laser only in a restricted area (e.g. closed laboratory without windows and an appropriate warning sign on the door).
- The laser beam path must be well below or above the eye level of any sitting or standing observers (locate path below 4.5 feet or above 6.5 feet). The laser should be mounted firmly to ensure that the beam travels only along its intended path.
- Proper laser eye protection for the direct beam or an inadvertent reflection must be provided and worn if a potential eye hazard exists.
- A key switch should be installed to prevent activation by unauthorized personnel.
- The beam or any inadvertent reflections should never be directly viewed with optical instruments such as telescopes or binoculars.
- Remove all mirror-like surfaces from within the vicinity of the laser beam path to avoid inadvertent reflections.
- For 3b lasers, eye exams are mandatory prior to participation in laser work. Contact EH&S.
- Class 4 Controls:
- Strictly control access to laser area or localized enclosure to necessary personnel.
- Indoor laser operations should be in a light-tight room with interlocked entrances to ensure that the laser cannot operate while the door is open.
- Eye protection is needed for all individuals working in the controlled area. If laser beam irradiance is sufficient to be a serious skin or fire hazard, suitable shielding or protective clothing must be present between the laser beam and any personnel or combustible material.
- Operating the laser or laser system with remote controls and video monitoring or other remote (safe) viewing techniques should be done whenever feasible.
- Beam shutters, beam polarizers, and beam filters should always be used to limit exposure. The flash lamps in optical pump systems should be shielded to eliminate any direct viewing.
- Backstops should be diffusely reflecting and fire-resistant target materials. Safety enclosures should be used around micro welding and micro drilling work pieces to contain hazardous reflections from the work area. Microscopic viewing systems used to study the work piece should prevent hazardous levels of reflected laser irradiation back through the optics.
- Eye exams are mandatory prior to participation in laser work. Contact EH&S for details.