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

该大学-产业项目的目标是开发一种宽带光学元件碳污染的去除工艺。这包括由弗朗索瓦·L教授领导的INRS-ERMT团队与量子谷投资公司的技术人员之间的合作。碳污染光学是同步加速器束线装置中常见的问题，在高真空下传输的高能真空紫外光子束会分解含有碳原子(例如：CO2、CH4)的残余分子。在多次运行周期后，光束线的光学组件会在其表面积聚碳层，从而降低性能。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。待开发的去除工艺必须与高损伤阈值宽带介质镜兼容，该介质镜由30多个交替的介质层组成，如SiO_2、HfO_2和TiO_2。由于这些反射镜的复杂性，与同步加速器光束线光学系统相比，它们本质上更加脆弱。使用位于INRS-ERMT的ALLS设施，我们将污染真空室中的宽带光学介质镜，并分析碳层的结构。已知的基于臭氧光解的除碳过程的研究将被完成，并适用于宽带光学反射镜。将建造一个使用已确定的碳去除工艺的原型清洗站来清洗大型光学元件。在整个项目中，QVI将获得在真空条件下暴露于高强度超短脉冲下的光学元件修复方面的知识和能力。这将允许QVI优化位于其设施中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.**