Accurate measurement and reduction of losses in ion beam sputtering coatings

Ion Beam Sputtering systems are well established as state-of-the-art deposition tools for the coating of high quality optical thin films with high density and low losses. These coatings are used for many laser applications, with an ever-increasing demand for higher sustained fluence. Ion Beam Sputtering (IBS) is a known technique to provide such high optical quality thin films [1]. Indeed, it allows to achieve high density layers with low absorption and scattering. In this work, various coatings were developed using Bühler IBS technology. Then, total losses were measured using Cavity Ring Down, absorption using Laser Induced Deflection or Laser thermography, and Total Integrated Scatter using dedicated scatterometers. A correlation between the effect of the chosen deposition method and parameters and the measurement performances were made with the aim of a better understanding of the level and the origin of losses in the coatings. Finally, highly reflecting mirror coatings for 1064 nm wavelength were fabricated with different designs and deposition parameters. The results of the different measurements of absorption, scattering and total losses using different equipment are presented and discussed.