Mitigating damage precursors to improve the laser resistance of ion beam sputtered antireflective coatings

We manufactured and tested ion beam sputtered antireflection coatings for 355 nm using several defect mitigation strategies to improve the damage resistance of laser optics for LIDAR satellite missions. The first approach to avoid the damage precursors in the film is based on a secondary ion source. The goal is to remove the particles that settle on the surface of the growing film. A second strategy is to avoid the damage precursors in the ultraviolet wavelength range by laser conditioning of the thin films during the coating process. A laser beam at the application wavelength scans the deposited layer on the sample during deposition still in vacuum. Optical coatings produced with both technologies show a significantly increased damage threshold when tested in ramped raster scan tests.