Multilayer dielectric gratings(MLDGs)are crucial for pulse compression in picosecond-petawatt laser systems.Bulged nodular defects,embedded in coating stacks during multilayer deposition,influence the lithographic pro...Multilayer dielectric gratings(MLDGs)are crucial for pulse compression in picosecond-petawatt laser systems.Bulged nodular defects,embedded in coating stacks during multilayer deposition,influence the lithographic process and performance of the final MLDG products.In this study,the integration of nanosecond laser conditioning(NLC)into different manufacturing stages of MLDGs was proposed for the first time on multilayer dielectric films(MLDFs)and final grating products to improve laser-induced damage performance.The results suggest that the remaining nodular ejection pits introduced by the two protocols exhibit a high nanosecond laser damage resistance,which remains stable when the irradiated laser fluence is more than twice the nanosecond-laser-induced damage threshold(nanosecond-LIDT)of the unconditioned MLDGs.Furthermore,the picosecond-LIDT of the nodular ej ection pit conditioned on the MLDFs was approximately 40%higher than that of the nodular defects,and the loss of the grating structure surrounding the nodular defects was avoided.Therefore,NLC is an effective strategy for improving the laser damage resistance of MLDGs.展开更多
The conditioning of grinding tools is one of the most important factors for achieving an optimal grinding process. It influences the grinding forces and temperatures and, therefore, the achievable material removal rat...The conditioning of grinding tools is one of the most important factors for achieving an optimal grinding process. It influences the grinding forces and temperatures and, therefore, the achievable material removal rate, dimensional accuracy and the surface integrity of the workpiece. Furthermore, the roundness, profile accuracy and the wear of the grinding tools are strongly influenced by the conditioning process. The conditioning process should be matched to the abrasive type and the bonding of the grinding tool. Laser conditioning is a promising unconventional and non-contact method, which is able to condition all kinds of abrasives and bonding types. The main advantages of this novel method are no tool wear, good repeatability and controllability, high precision and a relatively short process time. Additionally, using this method, grinding tools can be micro-structured. This paper reviews the literature on the laser conditioning of grinding tools, covering the associated setups, wheel conditioning and structuring mechanisms, and experimental results. It also discusses the technical barriers that have to be overcome before laser conditioning can be fully integrated into manufacturing.展开更多
目的评价不同表面处理方法对激光预备牙本质形态学变化和黏结强度的影响。方法2013年5月至7月在中国医科大学附属口腔医院收集20～40岁新鲜拔除的活髓第三磨牙20颗及根尖发育完全的前磨牙8颗，铒、铬：钇钪镓石榴石（Er，Cr：YSGG）激...目的评价不同表面处理方法对激光预备牙本质形态学变化和黏结强度的影响。方法2013年5月至7月在中国医科大学附属口腔医院收集20～40岁新鲜拔除的活髓第三磨牙20颗及根尖发育完全的前磨牙8颗，铒、铬：钇钪镓石榴石（Er，Cr：YSGG）激光处理暴露的牙争面牙本质，然后按照不处理、37％磷酸酸蚀、自酸蚀及0．5mol／LEDTA调节各自分为4组，使用扫描电子显微镜（SEM）观察前磨牙牙本质处理面形态；第三磨牙使用Adper easy bond或Single bond 2黏结，Z350树脂逐层堆积树脂冠后，制作哑铃型试件进行微拉伸黏结强度测试，采用单因素方差分析进行组间差异比较。结果SEM观察发现：前磨牙激光预备后不处理组（对照组）牙面不规则，无玷污层，牙本质小管开放；磷酸酸蚀组牙本质表面最规则，自酸蚀组和EDTA处理组处理后表面变化不如磷酸酸蚀组明显。微拉仲黏结强度测试结果显示，第三磨牙分组后的3种处理方式牙本质黏结强度均显著高于对照组（P〈0．05），磷酸酸蚀组黏结强度最强（P〈0．05），而自酸蚀组及EDTA处理组差异无统计学意义（P〉0．05）。结论37％磷酸酸蚀、自酸蚀及0．5mol／LEDTA调节3种处理均可提高激光预备的牙本质黏结强度，37％磷酸酸蚀组获得最佳短期黏结效果。展开更多
基金supported by the National Key R&D Program of China(Grant No.2018YFE0115900)the Key Foreign Cooperation Projects of Bureau of the International Cooperation of Chinese Academy of Sciences(Grant No.181231KYSB20210001)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA25020314).
文摘Multilayer dielectric gratings(MLDGs)are crucial for pulse compression in picosecond-petawatt laser systems.Bulged nodular defects,embedded in coating stacks during multilayer deposition,influence the lithographic process and performance of the final MLDG products.In this study,the integration of nanosecond laser conditioning(NLC)into different manufacturing stages of MLDGs was proposed for the first time on multilayer dielectric films(MLDFs)and final grating products to improve laser-induced damage performance.The results suggest that the remaining nodular ejection pits introduced by the two protocols exhibit a high nanosecond laser damage resistance,which remains stable when the irradiated laser fluence is more than twice the nanosecond-laser-induced damage threshold(nanosecond-LIDT)of the unconditioned MLDGs.Furthermore,the picosecond-LIDT of the nodular ej ection pit conditioned on the MLDFs was approximately 40%higher than that of the nodular defects,and the loss of the grating structure surrounding the nodular defects was avoided.Therefore,NLC is an effective strategy for improving the laser damage resistance of MLDGs.
文摘The conditioning of grinding tools is one of the most important factors for achieving an optimal grinding process. It influences the grinding forces and temperatures and, therefore, the achievable material removal rate, dimensional accuracy and the surface integrity of the workpiece. Furthermore, the roundness, profile accuracy and the wear of the grinding tools are strongly influenced by the conditioning process. The conditioning process should be matched to the abrasive type and the bonding of the grinding tool. Laser conditioning is a promising unconventional and non-contact method, which is able to condition all kinds of abrasives and bonding types. The main advantages of this novel method are no tool wear, good repeatability and controllability, high precision and a relatively short process time. Additionally, using this method, grinding tools can be micro-structured. This paper reviews the literature on the laser conditioning of grinding tools, covering the associated setups, wheel conditioning and structuring mechanisms, and experimental results. It also discusses the technical barriers that have to be overcome before laser conditioning can be fully integrated into manufacturing.
文摘目的评价不同表面处理方法对激光预备牙本质形态学变化和黏结强度的影响。方法2013年5月至7月在中国医科大学附属口腔医院收集20～40岁新鲜拔除的活髓第三磨牙20颗及根尖发育完全的前磨牙8颗，铒、铬：钇钪镓石榴石（Er，Cr：YSGG）激光处理暴露的牙争面牙本质，然后按照不处理、37％磷酸酸蚀、自酸蚀及0．5mol／LEDTA调节各自分为4组，使用扫描电子显微镜（SEM）观察前磨牙牙本质处理面形态；第三磨牙使用Adper easy bond或Single bond 2黏结，Z350树脂逐层堆积树脂冠后，制作哑铃型试件进行微拉伸黏结强度测试，采用单因素方差分析进行组间差异比较。结果SEM观察发现：前磨牙激光预备后不处理组（对照组）牙面不规则，无玷污层，牙本质小管开放；磷酸酸蚀组牙本质表面最规则，自酸蚀组和EDTA处理组处理后表面变化不如磷酸酸蚀组明显。微拉仲黏结强度测试结果显示，第三磨牙分组后的3种处理方式牙本质黏结强度均显著高于对照组（P〈0．05），磷酸酸蚀组黏结强度最强（P〈0．05），而自酸蚀组及EDTA处理组差异无统计学意义（P〉0．05）。结论37％磷酸酸蚀、自酸蚀及0．5mol／LEDTA调节3种处理均可提高激光预备的牙本质黏结强度，37％磷酸酸蚀组获得最佳短期黏结效果。
