Ma Ping

Subsurface damage distribution and processing method of ground fused silica

Subsurface damage (SSD) has been identified as a main initiator of laser-induced damage in fused silica, and the most of SSD is produced during grinding process. The distribution and morphology of SSD in fused silica samples ground with loose abrasive are investigated by magneto-rheological finishing (MRF) dimpling and buffered oxide etch (BOE) etching method. The results demonstrate that the SSD depth is most responsive to the loose abrasive size and the BOE etching is good for removing the SSD. Based on these results, an efficient grinding technique combined with BOE etching is proposed to reduce the SSD of fused silica, and the damage threshold is obviously improved by this routine as a result.

Study on fine annealing process of the large-aperture K9 glasses

Study on fine annealing process of the large-aperture K9 glasses was carried out in the report. The process parameters of glass placed way, fan speed and design of the cavity for keeping temperature uniformity were attained. By the fine annealing experiment, the stress distribution was improved evidently. The stress changed from Irregular distribution to consistency symmetric distribution and the stress max was reduced. The surface profile accuracy of the large-aperture K9 glasses was controlled steadily during CNC polishing.