3-ω damage threshold evaluation of final optics components using Beamlet Mule and off-line testing

A statistics-based model is being develop to predict the laser- damage-limited lifetime of UV optical components on the NIF laser. In order to provide data for the mode, laser damageexperiments were performed on the Beamlet laser system at LLNL. An early protoype NIF focus lens was exposed to twenty 351 nm pulses at an average fluence of 5 J/cm 2 , 3ns. Using a high resolution optic inspection inspection system a total of 353 damagesites was detected within the 1160 cm 2 beam aperture. Through inspections of the lens before, after and, in some cases, during the campaign, pulse to pulse damage growth rateswere measured for damageinitiating both on the surface and at bulk inclusions. Growth ratesas high as 79 micrometers/pulse were observed for damageinitiating at pre-existing scratches in the surface. For most damagesites on the optic, both on the surface and at bulk inclusions. Growth ratesas high as 79 micrometers/pulse were observed for damageinitiating at per- existing scratches in the surface. For most damagesites on the optic, both surface and bulk, the damage growth ratewas approximately 10(Mu) m/pulse.