Laser-induced damage and contamination testing for the next generation of LIDAR space optics

Abstract

We have recently reported a method to improve the laser-induced damage threshold of UV laser optics by mitigating damage precursors (nano-sized absorbers) during the manufacturing of ion-beam sputtered, anti-reflective optical coatings. To further optimize parameters of the coating and particle mitigation schemes, we had to assess the damage resistance of laser optics with a low density of damage precursors. This was achieved using large area raster scans in which a highintensity laser beam was scanned over the optical surface. Via image processing of microscopic data, we then derived the density and size distribution of laser-induced damages for each raster scan. This advanced test method is described in this work and prepared the path to the manufacturing of improved laser optics that can be used to increase the performance and reliability of lasers in future space missions. Furthermore, we report on the comparison of standard and improved laser optics in tests of laser-induced contamination at 355 and 266 nm.