An eye exposure to pulsed 1064 nm laser radiation was reported on the evening of August 28, 2020. In-depth medical imaging of the person's eye confirmed the beam penetrated all the way through the retina to the choroid, resulting in permanent retinal damage. The estimated exposure was ~6100 times the maximum permissible exposure limit (MPE). The exposed person now has a blind spot in their central field of vision about the size of a baseball held at arm's length.

 

 

  • The exposure occurred during beam alignment activities. 
  • The incident investigation revealed the following causes/contributing factors: 
    • Written alignment procedures had not been developed prior to the alignment activities 
    • The person was fatigued and rushing to make progress on the setup 
    • A damaged beam card was being used that rendered the alignment spot less visible 
    • The individual is color blind, making the spot less visible on the beam card at any given beam energy 
    • The laser eyewear had been fogging up, so a different pair was worn that wasn't fogging as badly. Unfortunately, the fogging was reduced because the lenses were smaller allowing a significant unprotected gap to exist between the bottom of the lens and the face. 
    • The optic being aligned was held in place on the optical table by the person's hand directly below the person's face 
    • The setup was complex, and the user was trying to do too many things at once in an awkward physical position: 
      • The user had to reach around other optics with their right arm, avoiding getting it in the active beam path, to a location in the middle of the optical table in order to hold a flashlight used to charge the beam card, simultaneously propping up a beam card against an optic on the table (and having to do so repeatedly as the beam card kept falling over) with the same hand. 
      • The left hand was holding the optic being aligned. 
    • During this maneuvering, the optic in the left hand tilted backwards, at which point the person instinctively looked down through the lens/face gap, being easier to only slightly move the head and swivel the eyes down rather than moving the entire head down to look through the eyewear (this was due to the proximity of the optic to the edge of the table the person was leaning against while reaching across the table as described above). It was at this point the exposure occurred.

Action Items for All Laser Supervisors and Laser Users 

  • Use only laser eyewear that fits well, especially during laser alignment
  • Remember, alignment activities typically pose the highest risk of laser exposure! Always develop a written SOP for both alignment and normal operating activities. The writing of these procedures provides the opportunity to assess the potential exposure hazards at each step. Appropriate safety measures can then be determined and added to the procedure to mitigate those hazards and reduce the possibility of laser exposure. As part of this, sketch out the beam path, optics, and beam blocks/dumps prior to beginning alignment.   
  • Laser Users shall not conduct alignment activities unless they have been specifically trained in how to do so safely by the Laser Supervisor
  • DO NOT rush through beam alignment activities in particular; give yourself plenty of time
  • DO NOT support optics being aligned with your hands
  • DO ask a trained colleague to assist with alignment activities
  • Especially when aligning invisible beams, consider whether a low-power visible laser can be used to do the initial optics alignment
  • Use only undamaged beam alignment cards
  • Use a holder for beam alignment cards when possible instead of propping them against optics in order to prevent them from falling over
  • Consider using an infrared or UV beam viewer camera instead of beam cards for visualizing these invisible beams
Newsletter Issue
Fall 2020