Latest developments in the CO2 laser remediation process of LMJ optics supported by COMSOL numerical modelling

Laser-induced surface damage of fused silica components a crucial point for high-energy laser systems like the French Laser MégaJoule (LMJ), will be addressed. Surface damage, originating from high-energy photon interacting with optics, is initially small but can rapidly expand under successive laser irradiation. CO₂ laser processing is effective for mitigation but sensitive to material properties and laser intensity fluctuations, leading to negative effects like surface deformation and debris formation. Collaborative efforts between CEA-CESTA and Institut Fresnel have developed a CO₂ laser mitigation technique involving microablation of damaged sites. This work focuses on reducing post-processing negative effects and increasing performance, such as the LIDT of cones. We will discuss the use of numerical simulations and measures for insight and guidance in improving processing parameters.