Development of removal process of carbon contaminated broadband optical components****

这个大学-工业项目的目标是开发一种去除宽带光学元件碳污染的工艺。这包括由franois lacimgar<e:1>教授组成的INRS-ÉMT小组与量子谷投资公司（QVI）的技术人员之间的合作。碳污染光学是同步加速器光束线设施的一个常见问题，在高真空下传播的高能VUV光子束解离含有碳原子的残余分子（例如：CO2， CH4）。经过多次操作循环后，光束线的光学元件将在其表面积累碳层并降低其性能。随着超短脉冲激光技术的发展，激光光束线具有更大的强度和平均功率，在光学反射镜表面也观察到碳污染，并成为激光系统工作占空比的严重限制因素。****在这种情况下，碳污染与入射激光脉冲的强度有关。要开发的去除工艺必须与高损伤阈值的宽带介质镜兼容，这些介质镜由30多个交替介质层组成，如SiO2， HfO2和TiO2。由于这些镜子的复杂性，它们本质上比同步加速器光束光学更脆弱。利用位于INRS-ÉMT的ALLS设备，我们将污染位于真空室中的宽带光学介电镜并分析碳层的结构。将完成基于臭氧光解作用的已知除碳工艺的研究，并将其应用于宽带光学反射镜。将建立一个原型清洁站，使用已确定的碳去除过程来清洁大型光学元件。在整个项目中，QVI将获得在真空条件下暴露在高强度超短脉冲下的光学元件修复的知识和能力。这将使QVI能够优化位于其工厂的激光系统的停机时间和运行成本

The goal of the university-industry project is to develop a removal process for carbon contaminated of broadband optical components. This consist of a collaboration between the INRS-ÉMT team of Prof. François Légaré and technical staff of Quantum Valley Investments (QVI). Carbon contaminated optics is a common problem on synchrotron beam-lines facilities, in which a beam of energetic VUV photons propagating under high vacuum dissociates residual molecules containing carbon atoms (ex: CO2, CH4). After many operating cycles, the optical components of the beamline will accumulate layers of carbon on its surface and degrade the performance. Through recent development in ultrashort pulse laser technologies, where laser beamlines have greater intensity and average power, observation of carbon contamination has also been witnessed on surfaces of optical mirrors and becoming a severe limitation factor for the operational duty cycle of laser systems.****In this case, the carbon contamination is related to the intensity of the incident laser pulse. The removal process to be developed has to be compatible with high damage threshold broadband dielectric mirrors which are composed of over 30 alternating dielectric layers such as SiO2, HfO2 and TiO2. Due to the complexity of these mirrors they are intrinsically more fragile compared to synchrotron beamlines optics. Using the ALLS facility located at INRS-ÉMT, we will contaminate broadband optical dielectric mirrors located in vacuum chambers and analyze the structure of the carbon layers. Study of known carbon removal process based on ozone photodissociation will be accomplished and adapted to broadband optical mirror. A prototype cleaning station using the identified carbon removal process will be built to clean large optics. Throughout this project, QVI will gain knowledge and capacity on reconditioning of optical elements that were exposed to high intensity ultrashort pulses under vacuum conditions. This will permit QVI to optimize the downtime and operating cost of the laser system located at their facility.**