6 August 2014 Subsurface damage on ground fused silica surfaces
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Proceedings Volume 9281, 7th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Advanced Optical Manufacturing Technologies; 92810M (2014) https://doi.org/10.1117/12.2069746
Event: 7th International Symposium on Advanced Optical Manufacturing and Testing Technologies (AOMATT 2014), 2014, Harbin, China
Abstract
The low surface laser damage threshold of fused silica components in high power laser systems such as NIF restricts the improvement of the output fluence of those systems. Once damage is initiated and grows under subsequent laser shots, the components will go unusable. Subsurface damage (SSD) introduced during manufacturing has been identified as a main damage initiator. A good knowledge of SSD and how manufacturing influences it is essential to optimize manufacturing processes for damage free optics. Using the magneto-rheological finishing (MRF) wedge technique of better accuracy attributed to a tip, we have characterized the subsurface damage on fused silica optical surfaces ground with loose Al2O3 abrasives of different sizes. Larger abrasives generates longer cracks and the number density of cracks decreases sharply with the depth for each size. Rogue particles account for the occurrence of trailing indent scratches. Addition of rogue abrasives into relatively small base abrasive extends SSD more deeply than that induced by rogue abrasives alone. The linear model, with the proportional coefficient 3.511, fits the relationship between SSD depth and surface roughness (SR) better than the quadratic polynomial one. We believe SSD depth relates to SR more statistically than following some specified physical law. The linear relationship between SSD depth and the abrasive size was also established. The abrasive size turned out not to be as a good indictor of SSD depth as SR.
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Jiafeng Xu, Xueke Xu, Wenlan Gao, Chaoyang Wei, Minghong Yang, Jianda Shao, "Subsurface damage on ground fused silica surfaces", Proc. SPIE 9281, 7th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Advanced Optical Manufacturing Technologies, 92810M (6 August 2014); doi: 10.1117/12.2069746; https://doi.org/10.1117/12.2069746
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