The University of Iowa

SAFETYmatters - Laser Safety Glasses, Not just for Looks

Article published 11/1/17

Users of Class 3B and 4 lasers are required to wear appropriate eye protection whenever there is potential for eye exposure.  Laser exposures can occur for a variety of reasons including misalignment, equipment malfunction, and human error. Exposures from the direct beam, and even scattered laser radiation can cause instant, and in some cases, permanent eye damage.  That is why the use of proper eye protection is of the utmost importance.  Use the following guidelines when selecting and using laser eye protection:

  • Ensure that the eyewear provides protection for the wavelength(s) that are being used.
    • The wavelengths or range of wavelengths for which the glasses provide protection are typically printed on the frame, along with the O.D. value for each.
  • The eyewear should provide a minimum of O.D. value of 3 for class 3B lasers and O.D. 4 for Class 4 lasers.  O.D. stands for Optical Density and describes the degree of laser energy attenuation using a logarithmic scale.  
    • For example, an O.D. of 3 provides a factor of 1000 beam attenuation, whereas an O.D. of 4 provides an attenuation value of 10,000.
  • Always check your eyewear for damage.  Cracked or scratched lenses may provide greatly reduced protection from the laser beam.
  • Buy glasses from a reputable source, and look for some type of certification (i.e. ANSI).  Some glasses may not provide an adequate degree of protection.
  • If you are concerned about your glasses, contact Gordon Axt at 335-8503.