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

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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.**