【英语翻译DesignofDiffractiveOpticalElementsUsedforBeamShapingintheFresnelDomainFENGDi,YANYing—bai,LUSi,TANQiao-feng(StateKeyLab．ofPrecis．Measur．Techno1．andInstrum．,Dept•ofPrecis•Instrum•TsinghuaUn】

　　英语翻译

　　DesignofDiffractiveOpticalElementsUsedfor

　　BeamShapingintheFresnelDomain

　　FENGDi,YANYing—bai,LUSi,TANQiao-feng

　　(StateKeyLab．ofPrecis．Measur．Techno1．andInstrum．,Dept•ofPrecis•Instrum•TsinghuaUniversity,Bejing100084,CHN)

　　Abstract

　　IntheFresneltransformdomain,aneffectiveimprovementtotheconventionaliterativeaIgorithmfordesigningthediffractiveopticalelements(DOEs)usedforspatialbeamshapinghasbeenproposed．ThealgorithmcansuccessfullyachievetodesignDOEsforbeamshaping．Comparedwithconventionalalgorithm,thisalgorithmcanprovidefasterconvergence,morepowerfulabilitytoovercomelocalminimumproblemandbettershapingquality．Bycomputersimulation,theresulthasshownthattheDOEsdesignedbythisaIgorithmhassnchadvantagesashighuniformityatthemainlobe,lowprofileerrorandsteepedge．

　　Keywords：Fresneldomain；Diffractiveopticalelements；Beamshaping

　　CLCnumber：0437．4；0438Documentcode：A

　　1Introductio

　　Spatialbeamshapingisessentialincouplingthelaserenergytosomeapplications'suchassemiconductorelementprocessandlaserfusionwhichneedtoconvertthelaseroutputbeam(aGaussianprofile)intoabeamwithuniformprofile[1,2]．Forthesepurposes,thediffractiveopticalelements(DOEs)withthelowprofileerroranduniformoutputprofilesarerequired．MostopticalsystemsforbeamshapingarebasedontheFouriertransformortheFraunhofertransform,whichlimitstheobservationplanetothefocalp1anesoitisusefulfordesigningDOEsintheFresneldomain．InthedesignoftheDOEsforbeamshaping,theGerchbex．g-Saxton(GS)algorithm[3]isaconventionaloneandusuallyemployed．Butitdidnotpayattentiontothehighuniformityatthemainlobeandthelowprofileerrorofthephaseplate•Recentlv,Sanghasproposedaneffectivemodification[4]forGSalgorithmandgotagoodresultfordesigningDOEsintheFourierdomain．MotivatedbytheworkofSang,etal.’andatthesametimeinordertoincreasethespeedofalgorithmicconvergenceandmeetthestrictrequirementforbeamshaping,suchashighuniformity(),andobtainlowprofileerror()andnon-obviou