LSO Workshop: Hazards from uncharacterized secondary reflected emissions: findings from a Canadian Armed Forces Laser Safety investigation

ABSTRACT: Hazards from uncharacterized secondary reflected emissions: findings from a Canadian Armed Forces Laser Safety investigation

Findings from a laser safety incident in a Canadian Forces workshop involving a laser ablator. In late 2024 three workers were using a laser ablator using a p100 laser to remove paint from metal surfaces. The workers experienced eye discomfort and were diagnosed with photokeratitis by an ophthalmologist. There was no recent history of any of the affected workers being exposed to wielding flash or other mechanism other than to conclude that the mechanism of injury must have come from exposure to the laser system. All workers were wearing the laser eye protection (LEP) provided from the manufacture. Wavelength shift off the ablated material, working SOPs, LEP design, optical density, and a recharacterization of the laser system involved were investigated to determine the root cause of the photokeratitis. Findings showed no UV wavelength shift from the ablated material. However, deficits in the design of the LEP and SOPs were discovered and characterized. The laser system operated within the design specifications of the manufacture. However, a IR spectral analysis used to confirm the wavelength and any secondary emissions from the reflected beam found a previously unknown secondary emissions at the corneal-retinal IR hazard transitionary zone. Other findings showed the LEP was not properly designed for this hazard, and the SOPs enhanced exposure to the secondary emissions. The recommendations from this incident support beam reflective categorization in addition to laser performance testing, and to assess LEP or other personal protective equipment for human factors to include fit and adaptivity to task completion. SOPs should be continually evaluated for compliance, and suitability for the tasks at hand.