Experimental study on removal of antireflection sol-gel SiO_2 coating of fused silica assisted by ion beam etching

摘要

The nondestructive and economical removal of sol-gel SiO_2 coating is significant for the recovery and reuse of fused silica optical elements. Compared with conventional wet cleaning process, ion beam etching as a dry cleaning process has atomic-scale removal capacity which is highly stable, non-contact and environment-friendly. In this research, a series of ion beam etching experiments is conducted to investigate the removal efficiency of antireflection sol-gel SiO_2 coating and substrate material. The etched surface roughness and optical performance are also studied. The best removal parameters during ion beam etching are determined based on the maximum removal efficiency ratio between antireflection sol-gel SiO_2 coating and substrate material. Moreover, the surface roughness and shape of fused silica are both improved during ion beam etching process. The optical transmission of etched surface is reduced to the substrate level and the surface chemical structure remains the same. The results can be a reference for using ion beam etching process technology to clean antireflection sol-gel SiO_2 coating of fused silica optics in inertial confinement fusion facility.