Morphology evolution mechanisms and localized structural modification of repaired sites on fused silica optics processed by CO2 laser rapid ablation mitigation

•Morphology formation mechanism and surface quality control methods during CO2 laser rapid ablation mitigation are studied.•Bottom morphology processed by laser arc scanning presents uneven concave-convex features, and the cone angle decreases as the trajectory indentation increases.•Thickness of the heat-affected zone characterized by the fictive temperature is consistent with the experiments.•Negative factors caused by the thermal effect in laser repair process can be suppressed by reducing laser pulse width.