Amethodtoevaluatedamageinopticalelementswiththenearfieldofanamplifiedspontaneousemission(ASE)beamhasbeendeveloped.Localpeakintensitiesaregenerallydistributedrandomlyinthenearfieldofalaserbeam.ThepartialcoherenceoftheASEsourceresultsinaverysmoothbeamprofile.ThecoherencetimeofASEismuchlessthanthepulsewidth.Small-scaleintensitymodulationscanbesmoothedoutrapidlywithinthetimeofapulsewidth.Intheexperiments,ASEisgeneratedfromamultifunctionalhigh-performanceNd:glasssystem,withapulsedurationof3ns,aspectralwidth(fullwidthathalfmaximum,FWHM)of1nmandanadjustableenergyrangefrom1to10J.ThedamagethresholdsofsamplesinducedbyASEaretwotothreetimeshigherthanthoseinducedbyalaserwiththesamesizeoftestspot.Furthermore,theASEbeamhasgreatpotentialforthedetectionofdefectsoveralargeareaandtheconditioningofopticalelements.
