Investigation of Grinding and Lapping Surface Damage Evolution of Fused Silica by Inductively Coupled Plasma Etching

Abstract

Surface damage has great influence on optical properties, especially the laser-induced damage threshold of optics, and it has become a difficult and basic issue to find suitable methods to efficiently remove the surface damage for improving the surface quality. In this paper, the characteristic evolution of brittle scratch and ground/lapped surface damage during inductively coupled plasma etching (ICPE) process are experimentally investigated on fused silica. Results of damage removal tests show ICPE can efficiently remove brittle scratch and eliminate the lateral and medial cracks. The PV (peak to valley) and RMS (root mean square) values of surface roughness increase with the exposure of lateral and medial cracks, and then gradually decreases with further etching. Finally, the ground and lapped fused silica surfaces with a size of 300 × 300 × 20 mm3 are efficiently processed by ICPE. The power spectral density analysis further demonstrates that the damage can be efficiently removed by ICPE. This study reveals the damage evolution during ICPE process and also provides technical guidance for optimizing the efficient damage removal process to rapidly improve surface quality, precision and fabrication efficiency of fused silica optics.