Laser Safety - Signage

Laser Signs and Warning Labels

OSU Researchers who use lasers are responsible for ensuring that all lasers are appropriately labeled and warning signs are conspicuously posted.

The following requirements must be followed for proper labeling of lasers and posting of signs:

• The signal word Caution must be used with all signs and labels associated with class 2 and some 3a lasers or laser systems.
• A class 2 laser or laser system must be labeled with the warning "Avoid Long Term Viewing of Direct Laser Radiation." This label must be visible during operation and bear the designation "Class 2 Laser."
• The signal word Danger and “the white triangle with the red explanation mark” must be used with all signs and labels associated with class 3b and 4 lasers and laser systems.
• Appropriate space must be left on all signs and labels to allow inclusion of pertinent information. Such information may be included during the printing of the sign or label or may be handwritten in a legible manner to include the following:
  
  • Above the tail of the sunburst, the following special precautionary instructions or protective actions may be required for individuals entering the area:
    
    1. For class 2 - "CAUTION - Laser Radiation - Do Not Stare Into Beam"
    2. For class 3a - "DANGER - Laser Radiation - Do Not Stare Into Beam or View Directly With Optical Instruments"
    3. For class 3b - "DANGER - Laser Radiation - Avoid Direct Exposure to Beam"
    4. For class 4 - "DANGER - Laser Radiation - Avoid Eye or Skin Exposure to Direct or Scattered Radiation"
  • Above the tail of the sunburst, precautionary instructions or protective actions to be taken by the reader should be provided such as "invisible beam, knock before entering, do not enter when light is on, restricted area, etc."
  • Below the tail of the sunburst, the type of laser (e.g., Ruby, Helium-Neon, etc.) or emitted wavelength, the pulse duration if appropriate, and the maximum output must be provided.
  • At the lower right, the class of the laser or laser system must be provided.

Laser Classes

• Class 1
  Class 1 lasers or laser system that under normal operating conditions cannot produce a hazard. The laser beam is enclosed or embedded either by manufacture design or modification. Once the beam is enclosed a Class 3b or 4 laser can be designated as a Class 1. If the beam is not enclosed the laser can be classified as Class 1. Remaining exempt from all control measures or other forms of surveillance providing the maximum exposure duration is no more than 30,000 sec or 100 seconds for an infra red laser given that the MPE is not exceeded and the beam is not concentrated by optics.
• Class 2
  Class 2 lasers are in the visible range (400nm to 700nm). Both continuous wave (cw) and repetitive pulsed lasers in this classification cannot exceed 1 mW. The pulse duration of repetitive pulsed lasers can be no faster than the eye aversion reflex of .25 sec.
• Class 3a
  Class 3a lasers or laser systems include all lasers that have an accessible output between 1 and 5 mW. These lasers do not present a problem for momentary viewing due the aversion reflex however viewing with an optical instrument is a hazard. An example would be a laser pointer.
• Class 3b
  Class 3b lasers and laser systems include wavelengths from 180nm to 1mm ultra violet, visible and infrared. The average radiant power for Class 3b of CW lasers cannot exceed 500mW for more than 0 .25 seconds. Repetitive pulsed lasers in the UV and far IR range cannot produce a radiant energy greater than 125 mJ within an exposure time less than 0.25 seconds. Lasers in the visible or near IR range, also know as “The Optical Hazard Region” from (400nm to 1400nm) cannot emit an average radiant power in excess of 500mW equal to or greater than 0.25 seconds and cannot produce a radiant energy greater than 30 mJ per pulse. Lasers and laser systems in this Class 3b are capable of eye injury if viewed directly or from specular reflection.
• Class 4
  Class 4 lasers or laser systems pose the most threat of injury to the eye and skin. They are a hazard from intrabeam viewing, specular, diffuse reflection and are capable of starting fires. Lasers and laser systems in this Class 4 are those that emit radiation that exceed levels of a Class 3b.