Modeling Max-of-N Fluence Distribution for Optics Lifetime

Local temporal shot-to-shot variation of a high-energy laser system is measured in order to model the maximum fluence that any location on the optic will be exposed to after N shots (Max-of-N). We constructed a model to derive an equivalent-Max-of-N fluence distribution from a series of shots of differing energy and contrast in order to calculate damage initiation and optics lifetime. This model allows prediction for Max-of-N effects when direct measurements of the fluence distribution are not available. Comparison to different laser systems will be presented in order to gain insight as to the physical origins of the Max-of-N effect.