A study of burn-through times for laser protective eyewear

The authors studied the performance of laser protective eyewear currently in use at the Lawrence Livermore National Laboratory: a goggle with a cellulose propionate filter from Glendale Protective Technologies and a goggle with a glass optical filter from Spectra Optics. A new polycarbonate optical filter material from Glendale was studied also, and its performance was compared with that of the cellulose propionate material. The authors used three lasers in the study: a single-pulse (variable pulse length) Nd:YAG laser with a wavelength of 1064 nm; a pulsed copper-vapor laser with a pulse-repetition frequency of 6.08 kHz and a wavelength of 510.6 nm; and a pulsed xenon-fluoride laser with a repetition rate variable up to 100 Hz and a wavelength of 351 nm. Where possible, the output power of each laser was increased systematically to the damage threshold of the material and beyond. The results showed that the new polycarbonate optical filter suffered less damage at equivalent laser beam challenges than the cellulose propionate optical filter. The glass goggle, which was designed specifically for use at the 510.5-nm wavelength, sustained no visible damage from the specified laser light at the highest power levels the authors could achieve.