Thermal damage behavior of contaminated mirror by continuous wave high-power laser

High-power continuous wave (CW) lasers are widely used in manufacturing, military, medical, and other fields. These applications often need optical elements, especially mirrors. However, environmental contamination is inevitable. Contaminated mirrors can be damaged by CW laser irradiation. We present the thermal damage behavior of contaminated optical mirrors under CW laser irradiation and establish a thermal damage simulation model for single and multiple contaminant particles. Carbon (C) particle has greater harm on optical mirrors compared with iron (Fe) and silicon dioxide (SiO2) particles. The safe and damage ranges of laser power, spot radius, and incident angle are obtained by simulation models to avoid damage. In fact, multiple contaminant particles have a high probability of damage, and particles near the center area of laser irradiation can cause a sudden temperature change on the surface of optical mirrors, resulting in thermal damage. Finally, the simulation model we proposed was validated through laser damage experiments on contaminated mirrors. We contributed to understanding the impact of contamination on optical elements and can be used to prevent thermal damage in high-power CW laser systems.