Influence of Ambient Humidity on the Performance of Complex Spectral Dielectric Films on SiO₂/K9 Substrates

Ambient humidity is an important factor to consider when maintaining dielectric films' component performance. Herein, humidity-influenced experiments were conducted on complex spectral dielectric films based on SiO2 and K9 substrates. Firstly, complex spectral dielectric films' spectral and surface stresses in different humidity environments were measured. Subsequently, laser-induced damage threshold measurements were carried out on these components. The experimental results indicate that the environmental humidity will induce the evolution of the internal structure of the dielectric films on the mirror, resulting in the deformation of the coating surface and a slight shift of the reflection spectrum. At the same time, the environmental humidity also greatly influences the anti-laser damage performance of the dielectric film mirror. Dielectric films based on SiO2 have excellent damage resistance in high-humidity environments. Conversely, K9-based dielectric films have better damage resistance in low-humidity environments.