Some safety eyewear fails to protect against ultrafast lasers

When used with ultrafast pulsed lasers, safety eyewear may fail to protect against eye damage, reported Hood College chemistry professor Christopher J. Stromberg at the meeting. Laser safety eyewear is typically tested and rated using low-power, continuous-wave conditions, assuming narrow-bandwidth lasers. Ultrafast laser pulses, however, have higher peak powers and wider bandwidths. Stromberg, undergraduate students Max Riedel-Topper and Sarah Wirick, and colleagues at NIST tested 22 eyewear filter samples from five manufacturers using an 800-nm Ti:sapphire laser system with 26-to-40-nm bandwidths and 40-to-80-femtosecond pulses (J. Laser Appl. 2017, DOI: 10.2351/1.5004090). Only 10 of the eyewear samples, all of them glass, performed as expected. All the plastic eyewear samples failed. These filters failed because of dye saturation, dye damage or bleaching, plastic substrate burning or melting, or a combination of these mechanisms. Stromberg and colleagues suspect that laser pulses’ higher bandwidths, along with their higher power punch, contributed to the filter damage. “Test eyewear filters under your own working conditions,” Stromberg advised others working with pulsed lasers. “It’s not a hard experiment to set up.”