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Section XII

Additional Control Measures for Class 3b and Class 4 Lasers and Laser Systems

All of the control measures outlined in Section X must be met. The following are additional requirements for Class 3b and Class 4 lasers and laser systems.

  1. Nominal Hazard Zone (NHZ)
    A NHZ shall be established for Class 3b and Class 4 laser applications which require an open beam. The NHZ is the area in which the level of direct, reflected or scattered laser radiation exceeds the MPE. The LSO can assist in defining the NHZ.
  2. Laser-Controlled Area
    A laser-controlled area shall be established for Class 3b and Class 4 lasers. The laser-controlled area will contain the NHZ, if needed. The walls, ceiling and floor of the room often define the laser-controlled area.
    • Class 3b Laser Controlled Area
      1. Only personnel trained in the operation of the laser and laser safety shall be permitted to operate the laser or laser system.
      2. An individual knowledgeable in laser safety shall directly supervise the laser-controlled area.
      3. The area shall be posted with the appropriate warning signs. (See Section XIX.)
      4. Restrict access to the laser controlled area.
      5. Control the beam to prevent any misdirected beams or reflections. (See Section X.C.)
      6. Provide eye protection for all personnel working in the laser-controlled area. (See Section XVII.)
      7. Cover all windows and other openings to prevent laser radiation from extending beyond the laser-controlled area
    • Class 4 Laser-Controlled Area
      All of the requirements for a Class 3b laser-controlled area must be met. In addition, one of the following entryway controls must be incorporated into a Class 4 laser controlled area.
      1. Non-Defeatable Entryway Safety Controls: Non-defeatable safety latches or interlocks that deactivate the laser or reduce the output to levels below the MPE in the event of unexpected entry are the preferred method of entryway control.
      2. Defeatable Entryway Safety Controls: If non-defeatable controls limit the intended use of the laser, defeatable entryway safety controls may be used. Defeatable entryway controls allow authorized personnel to override the controls. Defeatable entryway controls may be used only if there is no laser radiation hazard at the point of entry. Personnel must be properly trained and provided with adequate personal protective equipment.
      3. Procedural Entryway Controls: If safety latches or interlocks are not feasible, procedural entryway controls may be used. When procedural entryway controls are used, the following conditions must be met:
        1. All authorized personnel shall be adequately trained.
        2. Personal protective equipment shall be provided.
        3. A door, barrier, screen or curtains shall be used to block or attenuate the laser radiation below the MPE at the entryway.
        4. The entryway shall be equipped with a lighted laser warning sign that indicates the laser is operating
  3. Permanently Attached Beam Stop or Attenuator
    Some lasers or laser systems have long warm-up times, and it may not be practical to turn the power off to the laser when the laser is not in use. In these cases, Class 3b lasers should be equipped with a permanently attached beam stop or attenuator and Class 4 lasers shall be equipped with a permanently attached beam stop or attenuator. The beam stop or attenuator must limit accessible laser radiation to below the MPE and be employed when the laser is not in use. For lasers that do not require warm-up time, turn the power off to the laser when not in use.
  4. Standard Operating Procedures
    Written Standard Operating Procedures (SOPs) are required for operating, alignment, maintenance and service activities. The SOPs shall be written by the Principal Investigator and available to the LSO for review. SOPs shall be reviewed with all laser personnel and be posted in the area of the laser or laser system.
    The manufacturer’s operating manual is not a substitute for an SOP.
    SOPs must include: (See Appendix 3 for a sample SOP)
    • Laser data
    • Contact information
    • Laser application
    • Control measures
    • Personal protective equipment
    • Start up and shut down procedures
    • Experimental procedures
    • Emergency procedures
    • Storage
    • Non-beam hazards
  5. Output Emission Limitations
    Operate the laser or laser system at the lowest level of power or radiant energy required for the application.

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