Effect of static/dynamic etching on surface quality andlaser-induced damage of fused silica

In order to investigate evolution rules of surface quality and laser damage resistance performance during static/dynamic etching process, and optimize chemical etching technologies, fused silica were treated by static/dynamic etching for different time respectively using the buffered hydrofluoric(HF) acid.Experiment results show that the dynamic etching rate of fused silica is higher than the static etching rate due to megasonic agitation. The surface root-mean-square(RMS) roughness and reflection profile peak valley (PV) value of dynamically etching surface are < 1 nm and 0.46λ, respectively, and 355 nm transmission of dynamically etched surface first increases in a small range (0.1%) and subsequently remains steady. Moreover, the surface RMS roughness and reflection profile PV of statically etched surface increase to ~5 nm and 0.82λ, respectively, and the 355 nm transmission of statically etched fused silica first remains basically steady and subsequently decreases by 0.4% aproximately. Damage thresholds of fused silica treated by static/dynamic etching present obviously different changement laws:the damage thresholds of fused silica increase by about 30% and then decrease gradually during static etching, while that increase by about 100% and then keep relatively steady during dynamic etching. The results above show that the properties of fused silica optics treated by dynamic etching are significantly better than that of static etching.