How-to-select-a-laser

Wehavecarefullyselectedthelasersfoundtobemostpopularandusefuloverthedecadesforourcatalogline.WehaveincludedHeNeandsemiconductordiodelasers,bothofwhichhavetraditionallyfoundbroadOEMuse,aswellasdiode-pumpedsolidstate(DPSS)lasers,arapidlygrowingtoolinOEMapplications.Ourlonghistoryinthemanufactureoflasersresultsinconsistentanddependableoperation,aswellassmoothtransitionsforcustomproductsintomanufacturing.Bywayofexample,theopticalresonatormirrorqualityiscriticaltotheperformanceofalaser.Wemanufacturethesein-housetohighstandards,anduseonlythemostdurableopticalcoatings.Thehighlaserdamagethresholdofourcavitymirrorshelpstomaintainconsistentpoweroutputovertime.Additionally,allofoursystemscomplywiththeapplicableCDRHstandardsandIECdirectivesforstand-alonelaserequipment.Thisselectionguideisintendedtoserveasanintroductiontosomeoftheconsiderationswhenselectingalaser,withspecificcommentsonouroff-the-shelfproducts.OEMversionsoftheselasers,designedspecificallyforinclusioninothersystems,areavailableuponrequest.PleasecallaMellesGriotapplicationsengineertodiscuss.Selectingalaserisabalancebetweenfindingtherightwavelength,optical,andoperationalparameters,includingpower,modepurity,divergence,stability,andlifetime.Arequirementforaparticularwavelengthmaydrivethechoicetoaparticulartypeoflaser,butthereversecanbeequallytrue.TypesoflasersofferedTheHeNelaserisperhapsthemostubiquitouslaser,duetoacombinationofperformanceandpracticalfactors.Smallandcompactcomparedtoothergaslasersandtraditionalsolidstatelasers,theyalsohavethebestinherentbeamquality,producingavirtuallypuresingletransversemodebeam.TheyareattractivetoOEMsbecausetheyareextremelyreliable,easilyconvectioncooled,andarerelativelylowcostandefficient.MellesGriotistheworldwideleaderinHeNelasermanufacturing,deliveringovertwomillionunitstodatewithahighdegreeofunit-to-unitrepeatability,excellentpointingstability,longcoherencelength,andlowoutputnoise.HeNelasersworkbyusingalowcurrentdcdischargetoexciteamixtureofheliumandneongas.Neonistheactivelasingmedium,whileheliumactsasabuffergastopopulatetheupperneonlevelsforlasingthroughcollisions.Thelasercavityiscreatedbyendmirrorsmounteddirectlytoaplasmatubecontainingthegases,mountedwithinametalsleeveforprotectionandheatdissipation.Thisdesignisveryreliable,anditisnotunusualforsomeHeNelaserstooperatefor50,000hoursormore.ThemostpopularHeNelaserwavelengthis632.8nm.LowpowerHeNelasers(0.95mW,orIECClassII)finduseinFTIRspectroscopy,alignment,pointing,barcodescanning,andteachingapplications.Moderatepowerlasers(upto35mW)areusedinRamanspectroscopy,holography,andtestandmeasurement.Stabilizedsingle-frequencylasers,withcoherencelengthsmeasuredinkilometers,areidealforwavelengthcalibration,precisionmeasurements,interferometry,andrangingapplications.Thoughmuchlesscommonandlowerinopticalgain,the543.5nmgreenlineand594.1nmyellowlineintheneonspectrumhavetheirownuniqueuses.GreenHeNelasersHowtoSelectaLaser2|IDEXOptics&PhotonicsMarketplace(photons),togetherwithanopticalcavitywherestimulatedemissionandlightamplificationtakeplace.Thehighefficiencyofthisprocess(nearly50%),lowpowerconsumption,compactsize,andthevarietyofemissionwavelengthsavailablemakesthemaveryattractivelightsource.AvailableinUVthroughNIRwavelengths,theyhaveincreasinglyreplacedotherlasertypesinmanyresearchandindustrialapplications.Theoutputpowerofadiodelaserisheavilydependentonthecurrentsuppliedtothediodejunctionanditstemperature.Singlemodeoperationoccursonlyaboveathresholdcurrent,butoutputpoweristhendirectlyproportionaltothatcurrent.Thisallowsadiodelaser’soutputtobequicklyandeasilycontrolledbyananalogordigitalsignal.Italsoenablesmodulationoftheoutput,reducingsystemcostbyeliminatingacousto-opticmodulators,andallowssynchronousdetectionschemes.Temperaturevariations,however,affectbothoutputpowerandwavelengthstability.Botheffectsunderscoretheimportanceofeithermaintainingaconstantjunctiontemperaturethroughthermoelectriccoolingormaintainingoutputpowerusingautomaticpowercontrol(APC).Coolingcanalsoextendadiodelaser’slifetime,asoperatinglifedoublesforevery10°Creductioninoperatingtemperature.Atroomtemperature,somediodelaserscanbeexpectedtohavealifetimeof50,000hoursormore.Diodelasersarefabricatedusingphotolithographicpatterninginastripeformatonasinglecrystalwafer,whichisthencleavednormaltothestripedirectiontocreateapairofplanar,alignedcrystalsurfacesthatactasendmirrors(sometimesdielectricallycoatedforenhancedreflectivityorpowe