Characterization and simulation of laser-induced contamination effects on laser beam propagation in the UV sub-picosecond regime

This study investigates the effects of laser-induced contamination (LIC) on ultraviolet (UV) laser beam propagation in the sub-picosecond regime. Using a sub-picosecond UV laser source operating at 343 nm with 30 W of mean power at 800 kHz, we examine the influence of prolonged UV exposure on the degradation of beam quality. The experiments are carried out on calcium fluoride (<i>C</i><i>a</i><i>F</i>₂) substrates, where contamination deposits are induced by high-power UV radiation under ambient air. We characterize the chemical composition, physical structure, and optical properties of the deposit. A numerical model is developed to simulate the influence of a phase defect corresponding to the LIC deposit and to estimate its impact on beam quality by calculating <i>M</i>² and beam intensity distribution. This study highlights the challenges posed by contamination when using high-power ultraviolet laser sources, particularly in industrial, and space applications.