Evaluation of alumina and silica coating materials for the NIF final turning mirrors
On demand starting 12 October 2021
One third of the final turning mirrors on the National Ignition Facility are laser damaged by 351 nm target backscattered light. The mirrors are spectrally complex hafnia and silica multilayer coatings with high 1 reflection for the forward propagating beam and high 3 transmission to suppress propagation of target backscatter. Alumina, a wider bandgap high index material, was selected to improve the 3 laser damage resistance despite a significantly lower refractive index resulting in increased layer count and reduced angular bandwidth. The impact on 3 laser damage fluence, coating stress, and spectral performance will be reported.
Lawrence Livermore National Lab. (United States)
Christopher Stolz has been in the laser program at Lawrence Livermore National Laboratory (LLNL) since 1989 researching high-power laser coatings. He is currently responsible for the Optics Production group for the National Ignition Facility (NIF). Chris has served as a cochair or program chair for numerous conferences including Laser-Induced Damage in Optical Materials and Optical Interference Coatings. He has coauthored over 100 journal and proceeding articles and 2 book chapters.