Laser is an acronym for "light amplification by stimulated emission of radiation." Radiation in this case occurs in the portions of the electromagnetic field with insufficient energy to induce ionization or breaking up on the atom (i.e., it is non-ionizing). Non-ionizing radiation occurs in the radio frequency, microwave, infrared visible and ultraviolet ranges.
Lasers operate in two modes: pulsed (e.g. Q-switched lasers) and continuous wave (CW). Generally, pulsed lasers are more hazardous than CW lasers. Lasers using C02 and certain other materials emit beams that are not visible to the eye, hence they are particularly hazardous.
Biological damage caused by lasers includes thermal burns, photochemical burns and retinal injury. Electrical safety and fire are also important concerns.
In the use of a laser, safety procedures must be established and followed so that protection is provided for students, teachers, workers, visitors, bystanders and passersby.
Hazards may include:
- Vaporized target material from high-energy laser cutting, drilling and welding operations.
- Gases from lasers
- Gases from cyrogenic coolants
- Ultraviolet infrared radiation
- Electrical hazards--cables between the power supply and laser head must be properly selected and placed and the capacitor system safeguarded.
All electrical equipment must be well-maintained to prevent shocks and burns. Energy sources for lasers are essentially high-voltage equipment. Capacitors must be de-energized before cleaning or any repairing. All voltage on capacitors must be removed before leaving equipment. Interlocks must be provided to prevent access to components of high-voltage currents. Fire buttons must be remote from the charge and hold buttons to prevent accidental discharge of a laser. All ultraviolet and infrared radition must be shielded.
Hazard controls in the operation of lasers are:
- Do not look into the primary beam or at reflections of the beam.
- Avoid aiming the laser with the eye to prevent looking along the axis because of the hazard of reflection.
- If possible, work with lasers should be done in areas of high general illumination to keep pupils constricted.
- Proper safety glasses should be worn to filter out specific injurious frequencies of the unit.
- Terminate the laser beam with material that is non-reflective and fire resistant.
- Provide adequate clear space around the laser path.
- Provide protection from electrical shock from the potentially dangerous electrical sources of high and low voltage.
- High-voltage rectifiers may generate Xrays and require protection.
There are many special precautions that must be taken from the particular lasers as high-powered pulsing lasers and low-powered gas and semiconducted systems. Carbon dioxide and nitrogen lasers are fire hazards.
Any room where a laser is located must be adequately marked on the entering door and in the room so that everyone (students, faculty, staff, and/or visitors) is aware of its presence.
Security of the equipment against inadvertent intrusion must always be considered when operating a laser.
At least two people should be present at all times when lasers are in operation. Under no circumstances should a room containing an active laser be left unattended or unlocked.
Ventilation of the room must be considered to remove any accumulation of hazardous gases or fumes that are generated in the operation of the laser.
All personnel in the laser area should be informed about the potential eye hazard of accidental exposure to the beam. It is the responsibility of the project supervisor to give each person concerned a copy of these rules and ensure that all safety precautions are observed.
More detailed information is given in the American National Standard for the safe use of lasers (ANSI Z136.1-1973) and OSHA 29 CFR 1910.32 for eye protection; 21 CFR 1040 (U.S. Food and Drug Administration's control of commercial devices); and OSHA's 29 CFR 1926.54 construction uses. These standards cover facilities, program requirements and safety measures. It is strongly recommended these standards be reviewed as supplementary information to be followed.