搜索
289Vol.28,No.920089ACTAOPTICASINICASeptember,2008:025322239(2008)0921649206M2(,710048)M2,,M2,,,;1M2M2;;;TN958.98Adoi:10.3788/AOS20082809.1649EffectofM2FactorofLaserBeamforaNon2CoaxialLidarSystemGaoFeiHuaDengxinWuMinMaoJiandongZhouYi(SchoolofMechanical&InstrumentEngineering,Xi’anUniversityofTechnology,Xi’an,Shaanxi710048,China)AbstractThepropagationpropertiesofGaussianbeamaredirectlyinfluencedbybeamqualityfactorM2andthefieldofviewofthereceiveroflidarislimitedmainlybythefibercore.Thegeometricalformfactorwhichinfluencesthemeasurementperformanceofthelidarsystemisrelatedstrictlywiththetransmissionpropertiesoflaserbeamandtheconfigurationofthereceivingsystemcombinedwiththecouplingfiberandthereceivingtelescope.ThispaperdiscussesmainlythepropertiesofthegeometricalformfactorduetothebeamqualityfactorM2andthecouplingfibercore,inordertooptimizethedesignofthetransmitterandreceiverofthelidarandtoimprovethedetectioncapabilityofthelidar.Thenumericalcalculationshowsthatthecouplingefficiencyofthefiberislargelyrelatedwithlocationpositionoffiberfromthefocusofthetelescopeanditscore;andtherangeinwhichthegeometricalformfactorislessthanoneislargelyinfluencedbyM2factorandisincreasedwiththeenhanceofthevalueoftheM2.Thepreliminaryexperimentisusedtosupporttheanalysisoftheinfluencefactorsontheperformanceforanon2coaxiallidarsystem.Keywordsatmosphericoptics;geometricalformfactor;beamqualityfactor;fibercoupling:2007208207;:2008203201:(40675015)(207117):(1981-),,,E2mail:gaofei_339@163.com:(1964-),,,,E2mail:xauthdx@163.com1,[13],()(SO2,NOx),,[47],(),,,,,[8]28,,J.Jenness[9],,,,,,[10],,[11],,M2,1Fig.1Schematicofthenon2coaxiallidarsystem21NdYAG355nm,10ns,20Hz,100mJ9mm,0.5mrad5250mm,,2.1,,,,2,,,,,,,1,f1=-32.6mm,,f2=162.4mm,,,,,,,1(s/f)+(ZR/f)2/(s/f-1)+1(s/f)=1,(1)ZR,ZR=20/;s,s,f(s/f)(s/f)max=1+1/(2ZR/f)at(s/f)=1+(ZR/f),(2a)(s/f)min=1-1/(2ZR/f)at(s/f)=1-(ZR/f),(2b),,,,2.2,D0=250mm,f=1200mm,,,0.1mm,0.2mm,0.8mm05619:M2F:F=f/D0,(3)f,D0J.Jenness[9],NAF:F=0.5[(1/NA)2-1]1/2,(4)NA,f,,,,,2(a)2(b),s=f,2Fig.2SchematicofreturnsignalsreceivedbythefiberTEM00,,2,I(x,y)=I0220exp-(x-s)2+y2220,(5)I(s)=I020y20dyx3x1exp-(x-s)2+y2220dx,(6)x1,x3ABBC,y2Bx2+y2=a2,(x-s)2+y2=20NAF,,100m,0.1mm,0.2mm,0.8mm,s,33Fig.3Couplingefficiencyofthefiber(Beampointstability),,50rad,3,,,(),,,4,,,;,,,,4Fig.4Spatialirradianceinthefocalplane2.3M2,156128[10,11],,,W(z)=W0+zbeam2=Mw0+zM2,(7)W0w0TEM00;beamTEM00z,Dtel(z)=D0+zFOV,(8)FOV,df,FOV=df/f,,,:Y(z)=Prec(z)Ptran(z)=kD1(z)h(x,y,z)dxdykD(z)h(x,y,z)dxdy,(9)D1(z)z,D(z)z,h(x,y,z)5,5,1/5beamFOV,FOVbeam/5,,,Y(z)=1;FOVbeam/5,,,Y(z)11200mm,240mm,9mm,0.5mrad,M22350.1mm,0.2mm,0.8mm,M21,2,2.5,3,,M2,5M2Y(z)Fig.5HeightdistributionofthegeometricalformfactorwithdifferentM2factors25619:M25(a)0.1mm,,1,M2,Y(z),M22,2.5,3,Y(z),,5(c)0.8mm,M2,,,Y(z)1,,;,,,5(b)0.2mm,,M22.78,M22.78,Y(z)1,,Y(z)1,M2=1,,4kmM2=2,10km,M22.5,2.78,,M2,,,,3,,M22.562007119230024000.1mm,0.2mm,0.8mm50mJ,10006,,M22.5,0.1mm,,0.55,1;6Fig.6Lidarrange2correctedreturnsignals0.2mm,1,(5km)1,0.9;0.8mm,0.6km1,,,,,,4,,,,,,,0.1mm,1,Y(z),0.8mm,M2,600m1,,,0.2mmM2,M21,,,,,,356128,1LiuJun,HuaDengxin,LiYan.RotationalRamanlidarfordaytime2temperatureprofilingoftheatmosphericboundarylayer[J].ActaOpticaSinica,2007,27(5):755759,,.[J].,2007,27(5):7557592WuYonghua,HuHuanling,ZhouJunetal..MeasurementsofstratosphereaerosolwithL625Lidar[J].ActaOpticaSinica,2001,21(8):10121015,,.L625[J].,2001,21(8):101210153DengxinHua,JunLiu,KiyotakaUchidaetal..DaytimetemperatureprofilingofplanetaryboundarylayerwithultravioletrotationalRamanlidar[J].JapaneseJ.Appl.Phys.,2007,46(9A):584958524R.M.Measures.LaserRemoteSensingFundamentalsandApplications[M].Malabar,Florida:KriegerPublishingCompany,19925YanJixiang,GongShunsheng,LiuZhishen.LidarforEnvironmentMonitoring[M].Beijing:SciencePress,2001.135172,,.[M].:,2001.1351726JamesD.Klett.Stableanalyticalinversionsolutionforprocessinglidarreturns[J].Appl.Opt.,1981,20(2):2112207JohnA.Reagan,M.PatrickMcCormick,JamesD.Spinhirne.Lidarsensingofaerosolsandcloudsinthetroposphereandstratosphere[C].Proc.IEEE,1989,77(3):4334488HeYinghong,ZhengYucheng,ChengJuanetal..Thecorrectionofshort2rangelaserlidarreturnwithfittingtolidarrangeadjustedpower[J].ActaOpticaSinica,2005,25(3):289292,,.[J].,2005,25(3):2892929JamesR.Jenness,DanielB.Lysak,RussellPhilbricketal..Designofalidarreceiverwithfiber2opticoutput[J].Appl.Opt.,1997,36(18):4278428410HuKewei,LiSong,ZhouHuietal..Calculatingofthelidaroverlapfunction[J].InfraredandLaserEngineering,2005,34(2):164167,,.[J].,2005,25(3):28929211ZhangGaixia,ZhangYinchao,TaoZangmingetal..Lidargeometricalformfactoranditseffectonaerosoldetection[J].Chin.J.Quant.Electron.,2005,22(2):299304,,.[J].,2005,22(2):2993044561