Spaceborne LIDAR systems with high power laser optics enable advanced understanding of the climate change. However, nano-scaled particles originating from film deposition processes reduce the laser-induced damage threshold. A secondary ion source is used to remove the particles that settle on the surface of the growing film. A second option is to remove precursors by laser irradiation before they are covered with additional layers. To verify the impact on the defect mitigation, laser-induced damage threshold tests and raster scan tests were conducted. This work has been carried under the ESA contract AO 1-8683/16/NL/BJ activity with name “Particle mitigation in high power laser optics”.