Lightandlaser光與激光1/4單選題(1分)Whichoneisnotthefunctionofresonator?下列哪項(xiàng)不屬于光學(xué)諧振腔的功能？Feedbackforstimulatedemission反饋受激輻射Spatialmodeselection選擇空間模式MediumActivation激發(fā)介質(zhì)Frequencyselection選擇頻率答案：C2/4單選題(1分)Whichonecanhelpwithpopulationinversion?以下哪一項(xiàng)有助于粒子數(shù)狀態(tài)翻轉(zhuǎn)？enhancedpumping更強(qiáng)的激勵(lì)抽運(yùn)coolingsystem冷卻系統(tǒng)photonresonating光子諧振AandB答案：D3/4單選題(1分)Whichoneisnotthebasicpartofalasersystem?下列哪一項(xiàng)不是激光器的基本組成部分？pump激勵(lì)源resonator諧振腔activemedium工作介質(zhì)Fresnellens菲涅爾棱鏡答案：D4/4單選題(1分)Whichlaserhasdifferentenergystatefromothers?下列哪種激光具有與其它激光不同的能級？HeNe氦氖激光器Diode二極管激光器Nd:YAGCO2二氧化碳激光器答案：D1/3單選題(1分)Whichoneisnotthedifferencebetweenthermalradiationandlaserradiation?propagationdirectionspectrumintensityradiationsourcewavelength答案：D2/3單選題(1分)Whichoneisthespectraldensityofstates?(8πv^3)/(c^3)(8πv^2)/(c^3)(8πv^3)/(3c^3)(8πv^2)/(3c^3)答案：B3/3判斷題(1分)AccordingtoPlanck’slawofblack-bodyradiation,thewavelengthofmaximumemissiongoeslowerwithrespecttotheincreasingtemperature.答案：√Resonators諧振腔1/4判斷題(1分)Therearefourelementswhicharenecessaryforthelaser,includingPump,Resonator,ActivemediumandLens(Beamshapingelements).答案：√2/4單選題(1分)Theresonatorbasicallydoesthreethings,notincluding()FeedbackforstimulatedemissionDirectionselectiontransversalmodeselectionFrequencyselection,linewidth答案：C3/4判斷題(1分)Inthecaseasthefigureshows,theresonatorcangetfourlongitudinalmodes.Ifwewanttogetasinglemodelaser,oneapproachistoincreasingthefrequencyspacingbydecreasingthecavitylengthL.答案：√4/4單選題(1分)Inthestabilitydiagram,thepointAstandsforthe().PlaneresonatorConfocalresonatorConcentricresonator答案：AActivemedium活性介質(zhì)1/3判斷題(1分)Therateconstantforspontaneousemission(B)isthesameastherateconstantforstimulatedemission(A).答案：×2/3單選題(1分)Forthecompetitionofspontaneousemissionandstimulatedemission,whichofthefollowingstatementsiscorrect:Witheffective“cooling”,wewillhavelowinversion△N=N2-N1Withlowpumprate,wewillhavehighinversion△N=N2-N1Withhighphotondensity,stimulatedemissiondominatesevenforlowpopulationinversion答案：C3/3判斷題(1分)Atthelaserthreshold,verysmallchangesofthepumppowerwillresultinsignificantchangesintheproductionofstimulatedphotons.答案：√Characterizationofthelaserbeam激光光束的表征1/4判斷題(1分)Lasercannotbefocusedtoarbitrarysmallspots答案：√2/4單選題(1分)Whatistheintensityatthebeamwaist(comparedtothehighestintensityI)?0I/eI/（e^2）I/(2π)答案：C3/4單選題(1分)What’sthefactorofSVE?exp(-ikz)exp(-kz)exp(ikz)exp(kz)答案：A4/4判斷題(1分)Thesolutionofthescalarwaveequationcandescribethebehaviorbothinthefocusandinthefarfield.答案：×1/5判斷題(1分)Hermite-Gaussianmodeshavebothradiusquantizationandangularquantization.答案：×2/5判斷題(1分)TheBBPofareallaserbeamisalwayslargerthantheBBPofaGaussianbeamwiththesamewavelength.答案：√3/5判斷題(1分)Foraspecificlaser,theGaussianbeamcangetsmallerwaistifwechooselenswithhigherdivergenceangle.答案：√4/5判斷題(1分)Fordifferentlasers,ifonehaslargerwaistofGaussianbeam,itshouldhavesmallerdivergenceangle.答案：×5/5單選題(1分)Thereare4differentlaserswithdifferentwavelengthsλ.Whichonehasthebestquality?λ=1μmλ=800nmλ=600nmλ=1.2μm答案：CPulsedLaserRadiation脈沖激光1/5判斷題(1分)Theshorterwemakethepulsewidth,thesmallerthermalpenetrationdepthwewillget.答案：√2/5填空題(2分)Foratypicallaserparameters:repetitionrateν=1KHz,pulseenergyE=1mJ,pulseddurationτ=10ns,sotheaveragepowerpm=____,peakpowerp=____;答案：:["1W"]2正確答案：:["100kw"]3/5單選題(1分)Intherateequationsforphotondensity:thesignFΩstandsfor:pumprateEinsteincoefficientforstimulatedemissioninversiondensityresonatorselectivity答案：D4/5判斷題(1分)Withhigherreflectionandverysmalltransitionresonator,thequalityfactorQoftheresonatorwillbelow.答案：×5/5多選題(2分)PleaseselectQ-switches:saturableabsorbepuncheddiskacousto-opticalmodulator(AOM)electro-opticalmodulator(EOM)答案：ABCDRadiationatinterfaces激光與界面1/3單選題(1分)Whichapplicationoflaserthefiguremeans?CuttingWeldingHardeningofadrillhole答案：C2/3多選題(2分)Whathappenedwhenthelaserhitsurfaceofmaterials.（）Reflectionabsorptiontransmission答案：ABC3/3判斷題(1分)Therearetwodifferentcomponents(normalcomponentsandparallelcomponents)fortheplanewavesatinterface.答案：√Absorption激光的吸收1/3判斷題(1分)Ifω＞ωp,R(w)=1答案：×2/3單選題(1分)ThewavelengthofNd:YAGlaseris__10.6μm1.06μm0.25μm答案：B3/3單選題(1分)Whichlaserhasthebestabsorptivity()?CO2laserNd:YAGlaserFiberlaserKrFlaser答案：D1/5判斷題(1分)Usually,fordistanceslargerthanDebyescreeninglength,thetestchargewouldalmosthavenoinfluenceofthesurroundingcharges.答案：√2/5判斷題(1分)TheDebyescreeninglengthisafunctionofcarrierdensity,andthehighercarrierdensitygetthelargerDebyelength.答案：×3/5單選題(1分)InlaserinducedplasmaoverasteelworkpieceprocessedwithpulsedCO2laserradiation,whenthelaserintensityI=5x10^7W/cm^2,whichthingmaybenotcorrespondingtoreality.()Completeabsorptionofthelaserradiationinsidetheplasmaispossible.Lowabsorptionofthelaserradiationinsidetheplasma.Theplasmadetachesfromtheworkpiecesometimes.答案：B4/5單選題(1分)ForLaser-Supported-Combustion(LSC)regime,whichoneiscorrespondingtoreality()AbsorptioninsidetheplasmaAp≈0AbsorptioninsidetheworkpieceAT≈0LaserintensityIsatisfiesIB<I<ID(whereIBisthebreakthrough-thresholdintensity,IDisthethresholdintensityfordetonationwaves)答案：C5/5判斷題(1分)Inthecaseshowedinthefigure,itworksinLSCregimeorbelow.答案：√HeatConductionandMeltpool熱傳導(dǎo)與熔池1/3判斷題(1分)Fortheenergyfluxesatsurface,radiativeandconvectivelossescanbenegligibleifAl＜10^3Wcm^(-2)答案：×2

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判斷題

(1分)Thetwofiguresshowstheresultsofshortplusesandultrashortpluses,respectively.

答案：√3/3判斷題(1分)Theequationisonlysuitableforidealgas.答案：√1/3判斷題(1分)Usually,thesurfacetensionoftheedgeofthemeltpoolislargerthanthatofthecenter.答案：√2/3判斷題(1分)Atthefundamentalsofthemeltflow,thetotalmomentum答案：×3/3判斷題(1分)Usually,formeltpooldynamics,thebalanceequationsformassandmomentuminmostcasescanbesolvedanalytically.答案：×Laserbeamsources激光源1/1多選題(2分)Whatlasersourcesaremainlyusedinmaterialsprocessing?gassolidstatesemiconductorpolymer答案：ABC