Effect of residual stress on laser-induced damage characterization of mitigated damage sites in fused silica

Effect of annealing on the laser induced damage of polished and CO2 laser-processed fused silica surfaces

“…The result of these experiments was that the stresses are not be completely released after annealing at 700 C, but no residual birefringence was observed after 900 C. Similar observations conducted by Jiang et al with similar annealing temperatures at 10 h (Ref. 45) have also shown that the residual stresses of mitigated sites could be completely eliminated.…”

Improved laser induced damage thresholds of Ar ion implanted fused silica at different ion fluences

“…Hence, it has been one of the major focuses in research on how to improve damage resistance and lifetime of fused silica optics in the past decades. The methods such as wet chemical etching, plasma and ion beam etching, UV and CO2 laser treatments [5][6][7][8] have been reported to effectively improve the laser-induced damage threshold (LIDT) of the fused silica optics. However, the LIDT value of the fused silica surface is still much lower than the dielectric breakdown threshold of the bulk material mainly due to the surface and subsurface defects.…”

Influence of secondary treatment with CO 2 laser irradiation for mitigation site on fused silica surface

“…For the same-size irradiated laser beam and intensity of illumination light source of PTC-702, the more obvious the residual stress, the greater the retardance and residual stress are. [9] However, the stress magnitude lies on the sizes of stress depth and irradiation laser beam in mitigation sites, it is difficult to distinguish the specific difference between the mitigation site and secondary treatment site, which will be quantitatively analyzed by numerical simulation.…”

“…[8] It is shown that residual stress will lead to the crack propagation once the re-initiation damage of the mitigation site takes place. [9] The ablation debris will reduce the damage resistance of optics, [10] and the raised rim will modulate the transmitted light, even leading to the damage of downstream optics. [11] To avoid those negative effects, one of the methods, i.e., buffered HF treatment, is chosen to clean the ablation debris.…”