Laser safety evaluation for high-energy laser interaction with solids

Laser safety regulating the deployment of kW-class high-energy laser (HEL) technologies in outdoor applications can rapidly cause significant planning and operations issues due to the ranges involved. Safety templates based on a simplistic approach of assuming a continuous wave laser beam incident on a highly reflective totally flat solid surface of infinite size can easily result in ranges of tens of kilometers for kW-class lasers. Due to the complexity of HEL-matter interactions, the assumptions underlying the aforementioned approach are, however, deemed inappropriate. We identify a more suitable approach, which assumes a time-variant reflection pattern as well as a change in the variance of beam divergence as it reflects from the target's surface. Based on experimental results, we instead propose to assess the nominal ocular hazard distance by applying the American National Standard Institute rules for time-variant multipulse laser exposure and using measured divergence angles from the target's surface. The resulting safety templates, thus, exhibit a higher fidelity with respect to the behavior of the reflection patterns while reducing the hazard zones. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)