Laser damage and damage performance caused by near-field of final optics assembles for high power laser system

Laser-induced damage is still the key issue to restrict the development of high power laser system for inertial confinement fusion (ICF). Based on a high power laser prototype, laser-induced damage behaviors and performance of large aperture final optics were experimentally studied. And, the damage inducement and morphology were comprehensively analyzed. Probability density functions (PDF) for laser fluence of near field with different resolution were obtained to analyze the influence of optical field distribution on the optical damage. High fluence of the near field was revealed in PDF with higher resolution, and the missing strong modulation fractions in the measured near field was most probably damage the optical elements. The surface damage morphology was observed and the main damage mechanism was discussed. Several kinds of surface damage morphologies with individual characteristics were sorted. The ratio of width and depth and the main contributors of laser damage were discussed.