Ohio State is in the process of revising websites and program materials to accurately reflect compliance with the law. While this work occurs, language referencing protected class status or other activities prohibited by Ohio Senate Bill 1 may still appear in some places. However, all programs and activities are being administered in compliance with federal and state law.

Safety Procedures

General Basic Precautions:


No attempt shall be made to place any shiny or glossy object into the laser beam other than that for which the equipment is specifically designed.

Eye protection devices which are designed for protection against radiation from a specific laser system shall be used to eliminate the possibility of potentially hazardous eye exposure (i.e., whenever levels of accessible emission exceed the appropriate MPE levels). This generally applies only to Class IIIB and Class IV lasers. All laser protective eyewear shall be clearly labeled with optical density values and wavelengths for which protection is afforded.

Skin protection can best be achieved through engineering controls. If the potential exists for damaging skin exposure, particularly for ultraviolet lasers (200-400 nm), then skin covers and or "sun screen" creams are recommended.

HANDS - Most gloves will provide some protection against laser radiation. Tightly woven fabrics and opaque gloves provide the best protection.

ARMS - A laboratory jacket or coat can provide protection for the arms. For Class IV lasers, consideration should be given to flame resistant materials.

Class I, Class II and Class IIIA Lasers


Accident data on laser usage has shown that Class I, Class II Class IIA and Class IIIA lasers are normally not considered hazardous from a radiation standpoint unless illogically used.

Direct exposure on the eye by a beam of laser light should always be avoided with any laser, no matter how low the power.

Class IIIB Lasers


Laser beams shall be contained whenever possible. When uncontained beams are used, the following precautions shall be taken:
  • A Class IIIB warning sign shall be placed at all entrances to the area when the laser beam is operating and access must require authorization of persons responsible for the area.
  • The laser beam shall be terminated at the limit of its useful distance. A dull black (highly absorbing/low reflectance) surface is recommended for visible frequency lasers and beam traps or terminators with total absorbers appropriate to the wavelength for UV and IR lasers.
  • Specularly reflecting surfaces in or near the beam path shall be minimized.
  • The area shall be well lighted to constrict pupils. A standard operating procedure is suggested for all Class IIIB lasers including emergency procedures.
  • The laser shall be positioned and the beam contained such that the beam does not exit the immediate area of use.

Class IV Lasers


The same requirements as for Class IIIB lasers shall be followed. In addition, the following safeguards are required:
  • A total hazards review shall be conducted before a high power laser is used. This shall include evaluation of Nominal Hazard Zones (NHZ), measurements (if deemed necessary and other such analytical techniques.
  • Devices shall be located in an area designated specifically for laser operations (laser-controlled area). Access during operation must require authorization of the person responsible for the area. In conditions where the beam path is not completely enclosed, access shall be limited.
  • An entryway control shall be used. This may include:
    • A non defeatable entryway interlock at the doorway, or
    • A defeatable entryway interlock at the doorway; or
    • Procedural entryway controls including a warning light immediately outside the room. One form of such a warning light could indicate conditions of enabled laser (high voltage on), laser on (beam on) and area clear (no high voltage or beam on).

Such measures shall permit rapid egress by the laser personnel at all times and admittance to the area under emergency conditions.
  • A control-disconnect switch or equivalent device shall be available near the exit for deactivating the laser.
  • A notice outside the area shall indicate the meaning of the blinking light.
  • Care must be taken to insure that the hands, arms, or other parts of the body do not intersect the beam.
  • The system must have provision(s) for quickly disengaging the laser power source from the electrical main during emergency.
  • The beam shall be terminated by a highly absorbent beam trap of fire resistant material.
  • For infrared lasers, since the radiation is invisible, areas that are exposed to reflections of the beam shall be protected by fully enclosing the beam and target area.
  • Ultraviolet laser beam radiation shall require a beam shield, which attenuates the radiation to acceptable levels.
  • A countdown procedure shall be used to signify the firing of single pulse laser types (i.e. Q-switch) to ensure all present are aware of the time of the operation.
  • The use of laser protective eyewear is mandatory with Class IV lasers. Protective eyewear shall be fabricated of plastic or glass absorption filters appropriate for the laser. All laser protective eyewear shall be clearly labeled with optical density values and wavelengths for which protection is afforded.

Laser Controlled Areas


The following control measures apply to Laser Controlled Areas containing Class IIIB and Class IV lasers and laser systems (Laser laboratories containing Class IIIB and Class IV lasers or laser systems are considered laser controlled areas.):
  • Laser devices shall be isolated in an area designed solely for laser operations. Access to such an area shall require appropriate authorization.
  • Special emphasis shall be placed on control of the path of the laser beam.
  • All persons using such lasers or laser systems shall be duly informed about the potential hazards of laser operations.
  • Only authorized personnel shall operate laser systems.
  • Visitors shall not be permitted into the laser-controlled area unless appropriate supervisory approval has been obtained and protective measures taken.
  • Alignment of laser optical systems (mirrors, lenses, beam deflectors, etc.) shall be performed in such a manner that the primary beam or specular reflections cannot expose the eye to a level above the appropriate intra-beam MPE.
  • Whenever possible, the entire beam path, including the interaction area, that is, the area in which irradiation of materials by the primary or secondary beam occurs, should be enclosed. Enclosures should be equipped with interlocks so that the laser system will not operate unless such enclosures are properly installed.
  • For pulsed systems, interlocks shall be designed so as to prevent firing of the laser by dumping the stored energy into a dummy load. For CW lasers, the interlocks shall turn off the power supply or interrupt the beam by means of shutters. Interlocks shall not allow automatic reenergizing of the power supply but shall be designed so that after tripping the interlock, the power supply or shutter must be reset manually.
  • Eye protection devices, which are designed for protection against radiation from a specific laser system, shall be used when engineering and procedural controls are inadequate to eliminate potentially hazardous exposures.
  • An alarm system (e.g., an audible sound or a warning light, which is visible through protective eyewear) or a verbal "countdown" command should be used prior to activation.
  • The audible system may consist of a bell or chime which commences when a pulsed laser power supply is charged for operation, for example, during the charging of capacitor banks. Systems should be used in which a warning will sound intermittently during the charging procedure (pulsed systems) and continuously when fully charged.
  • In order to safely operate a Class IV laser or laser system, a laser warning system shall be installed.
    • A laser activation warning light assembly shall be installed outside the entrance to each laser room facility containing a Class IV laser or laser system.
    • In lieu of a blinking entryway warning, the entryway light assembly may alternatively be interfaced to the laser in such a manner that a light will indicate when the laser is not operational (high voltage off) and by an additional light when the laser is powered up (high voltage applied) but not operating and by an additional (flashing) light when the laser is operating.
    • A laser warning sign shall be posted both inside and outside the laser controlled area.
  • Under conditions where the entire beam path is not enclosed, safety latches or interlocks shall be used to prevent unexpected entry into laser-controlled areas. Such measures shall be designed to allow both rapid egress by the laser personnel at all times, and admittance to the laser controlled area in an emergency condition. For such emergency conditions, a "panic button" (control-disconnect switch or equivalent device) shall be available for deactivating the laser.
  • Under conditions where the entire beam path is not completely enclosed, access to the laser controlled area shall be limited only to persons wearing proper laser protective eyewear when the laser is capable of emission. In this case all other optical paths (for example, windows) from the facility shall be covered or restricted in such a way as to reduce the transmitted intensity of the laser radiation to levels at or below the MPE for direct irradiation of the eye. Specularly reflecting surfaces, which are not required when using the laser shall be removed from the beam path.

Temporary Laser Controlled Area


Should overriding interlocks become necessary for special training, or during service, or maintenance, and access to Class IIIB or Class IV lasers is possible, a temporary laser controlled area shall be devised, following specific procedures approved by the LSO. These procedures shall outline all safety requirements necessary during such operation.

Such temporary laser controlled areas, which by nature will not have the built in protective features, as defined above for a laser controlled area, shall nevertheless provide all of the safety requirements for all personnel, both within and without the temporary laser controlled area during periods of operation with the interlocks defeated.