激光测距 外文翻译.docx
- 文档编号:10741252
- 上传时间:2023-02-22
- 格式:DOCX
- 页数:11
- 大小:27.48KB
激光测距 外文翻译.docx
《激光测距 外文翻译.docx》由会员分享,可在线阅读,更多相关《激光测距 外文翻译.docx(11页珍藏版)》请在冰豆网上搜索。
激光测距外文翻译
Laserrangefinder
Alongrangelaserrangefinderiscapableofmeasuringdistanceupto20km;mountedonatripodwithanangularmount.Theresultingsystemalsoprovidesazimuthandelevationmeasurements.
Alaserrangefinderisadevicewhichusesalaserbeamtodeterminethedistancetoanobject.Themostcommonformoflaserrangefinderoperatesonthetimeofflightprinciplebysendingalaserpulseinanarrowbeamtowardstheobjectandmeasuringthetimetakenbythepulsetobereflectedoffthetargetandreturnedtothesender.Duetothehighspeedoflight,thistechniqueisnotappropriateforhighprecisionsub-millimetermeasurements,wheretriangulationandothertechniquesareoftenused.
Pulse
Thepulsemaybecodedtoreducethechancethattherangefindercanbejammed.ItispossibletouseDopplereffecttechniquestojudgewhethertheobjectismovingtowardsorawayfromtherangefinder,andifsohowfast.
Precision
Theprecisionoftheinstrumentisdeterminedbytheriseorfalltimeofthelaserpulseandthespeedofthereceiver.Onethatusesverysharplaserpulsesandhasaveryfastdetectorcanrangeanobjecttowithinafewmillimeters.
Range
Despitethebeambeingnarrow,itwilleventuallyspreadoverlongdistancesduetothedivergenceofthelaserbeam,aswellasduetoscintillationandbeamwandereffects,causedbythepresenceofairbubblesintheairactingaslensesranginginsizefrommicroscopictoroughlyhalftheheightofthelaserbeam'spathabovetheearth.
Theseatmosphericdistortionscoupledwiththedivergenceofthelaseritselfandwithtransversewindsthatservetopushtheatmosphericheatbubbleslaterallymaycombinetomakeitdifficulttogetanaccuratereadingofthedistanceofanobject,say,beneathsometreesorbehindbushes,orevenoverlongdistancesofmorethan1kminopenandunobscureddesertterrain.
Someofthelaserlightmightreflectoffleavesorbrancheswhicharecloserthantheobject,givinganearlyreturnandareadingwhichistoolow.Alternatively,overdistanceslongerthan1200ft(365m),thetarget,ifinproximitytotheearth,maysimplyvanishintoamirage,causedbytemperaturegradientsintheairinproximitytotheheatedsurfacebendingthelaserlight.Alltheseeffectshavetobetakenintoaccount.
Calculation
ThedistancebetweenpointAandBisgivenby
D=ct/2
wherecisthespeedoflightintheatmosphereandtistheamountoftimefortheround-tripbetweenAandB.
where
isthedelaywhichmadebythelighttravelingand
istheangularfrequencyofopticalmodulation.
ThensubstitutethevaluesintheequationD=ct/2,D=1/2ct=1/2c·φ/ω=c/(4πf)(Nπ+Δφ)=c/4f(N+ΔN)=U(N+)
inthisequation,Ustandsfortheunitlength.
Δφstandsforthedelaypartwhichdoesnotfulfillπ.
ΔNstandsthedecimalvalue.
Discrimination
Someinstrumentsareabletodeterminemultiplereturns,asabove.Theseinstrumentsusewaveform-resolvingdetectors,whichmeanstheydetecttheamountoflightreturnedoveracertaintime,usuallyveryshort.Thewaveformfromalaserpulsethathitsatreeandthenthegroundwouldhavetwopeaks.Thefirstpeakwouldbethedistancetothetree,andthesecondwouldbethedistancetotheground.
Usingwavefrontsensing,itispossibletodetermineboththeclosestandthefarthestobjectatagivenpoint.Thismakesitpossibleforaircraft-mountedinstrumentstosee"through"densecanopies[clarificationneededPleaseexplainhowlasersseethroughcanopies]andothersemi-reflectivesurfacesuchastheocean,leadingtomanyapplicationsforairborneinstrumentssuchas:
1.Creating"bareearth"topographicmaps-removingalltrees
2.Creatingvegetationthicknessmaps
3.Bathymetry(measuringtopographyundertheocean)
4.Forestfirehazard
Technologies
Timeofflight-thismeasuresthetimetakenforalightpulsetotraveltothetargetandback.Withthespeedoflightknown,andanaccuratemeasurementofthetimetaken,thedistancecanbecalculated.Manypulsesarefiredsequentiallyandtheaverageresponseismostcommonlyused.Thistechniquerequiresveryaccuratesub-nanosecondtimingcircuitry.
Multiplefrequencyphase-shift-thismeasuresthephaseshiftofmultiplefrequenciesonreflectionthensolvessomesimultaneousequationstogiveafinalmeasure.
Interferometry-themostaccurateandmostusefultechniqueformeasuringchangesindistanceratherthanabsolutedistances.
Applications
Military
AnAmericansoldierwithaGVS-5laserrangefinder.
ADutchISAFsniperteamdisplayingtheirAccuracyInternationalAWSM.338LapuaMagnumrifleandLeica/VectronixVECTORIVlaserrangefinderbinoculars.
Rangefindersprovideanexactdistancetotargetslocatedbeyondthedistanceofpoint-blankshootingtosnipersandartillery.Theycanalsobeusedformilitaryreconciliationandengineering.
Handheldmilitaryrangefindersoperateatrangesof2kmupto25kmandarecombinedwithbinocularsormonoculars.Whentherangefinderisequippedwithadigitalmagneticcompass(DMC)andinclinometeritiscapableofprovidingmagneticazimuth,inclination,andheight(length)oftargets.Somerangefinderscanalsomeasureatarget'sspeedinrelationtotheobserver.Somerangefindershavecableorwirelessinterfacestoenablethemtotransfertheirmeasurement(s)datatootherequipmentlikefirecontrolcomputers.Somemodelsalsoofferthepossibilitytouseadd-onnightvisionmodules.Mosthandheldrangefindersusestandardorrechargeablebatteries.
Themorepowerfulmodelsofrangefindersmeasuredistanceupto25kmandarenormallyinstalledeitheronatripodordirectlyonavehicleorgunplatform.Inthelattercasetherangefindermoduleisintegratedwithon-boardthermal,nightvisionanddaytimeobservationequipment.Themostadvancedmilitaryrangefinderscanbeintegratedwithcomputers.
Tomakelaserrangefindersandlaser-guidedweaponslessusefulagainstmilitarytargets,variousmilitaryarmsmayhavedevelopedlaser-absorbingpaintfortheirvehicles.Regardless,someobjectsdon'treflectlaserlightverywellandusingalaserrangefinderonthemisdifficult.
3-DModelling
ThisLIDARscannermaybeusedtoscanbuildings,rockformations,etc.,toproducea3Dmodel.TheLIDARcanaimitslaserbeaminawiderange:
itsheadrotateshorizontally,amirrorflipsvertically.Thelaserbeamisusedtomeasurethedistancetothefirstobjectonitspath.
Laserrangefindersareusedextensivelyin3-Dobjectrecognition,3-Dobjectmodelling,andawidevarietyofcomputervision-relatedfields.Thistechnologyconstitutestheheartoftheso-calledtime-of-flight3Dscanners.Incontrasttothemilitaryinstrumentsdescribedabove,laserrangefindersofferhigh-precisionscanningabilities,witheithersingle-faceor360-degreescanningmodes.
Anumberofalgorithmshavebeendevelopedtomergetherangedataretrievedfrommultipleanglesofasingleobjecttoproducecomplete3-Dmodelswithaslittleerroraspossible.Oneoftheadvantagesthatlaserrangefindersofferoverothermethodsofcomputervisionisthatthecomputerdoesnotneedtocorrelatefeaturesfromtwoimagestodeterminedepthinformationasinstereoscopicmethods.
Laserrangefindersusedincomputervisionapplicationsoftenhavedepthresolutionsoftenthsofmillimetersorless.ThiscanbeachievedbyusingtriangulationorrefractionmeasurementtechniquesasopposedtothetimeofflighttechniquesusedinLIDAR.
Forestry
LaserrangefinderTruPulseusedforforestinventories(incombinationwithField-Maptechnology)
Speciallaserrangefindersareusedinforestry.Thesedeviceshaveanti-leaffiltersandworkwithreflectors.Laserbeamreflectsonlyfromthisreflectorandsoexactdistancemeasurementisguaranteed.Laserrangefinderswithanti-leaffilterareusedforexampleforforestinventories.
Sports
Laserrangefindersmaybeeffectivelyusedinvarioussportsthatrequireprecisiondistancemeasurement,suchasgolf,hunting,andarchery.Someofthemorepopularmanufacturersare:
Opti-logicCorporation,Bushnell,LaserTechnology,Trimble,Leica,NewconOptik,Nikon,andSwarovskiOptik.
Industryproductionprocesses
AnimportantapplicationistheuseoflaserRangefindertechnologyduringtheautomationofstockmanagementsystemsandproductionprocessesinsteelindustry.
Safety
Laserrangefindersforconsumersarelaserclass1devicesandthereforeareconsideredeyesafe.Somelaserrangefindersformilitaryuseexceedthelaserclass1energylevels.
History
Developmentofthemethodsusedinmodernprintedcircuitboardsstartedearlyinthe20thcentury.In1903,aGermaninventor,AlbertHanson,describedflatfoilconductorslaminatedtoaninsulatingboard,inmultiplelayers.ThomasEdisonexperimentedwithchemicalmethodsofplatingconductorsontolinenpaperin1904.ArthurBerryin1913patentedaprint-and-etchmethodinBritain,andintheUnitedStatesMaxSchoopobtainedapatent[1]toflame-spraymetalontoaboardthroughapatternedmask.CharlesDurcasein1927patentedamethodofelectroplatingcircuitpatterns.
TheAustrianJewishengineerPaulEislerinventedtheprintedcircuitwhileworkinginEnglandaround1936aspartofaradioset.Around1943theUSAbegantousethetechnologyonalargescaletomakeproximityfusesforuseinWorldWarII.Afterthewar,in1948,theUSAreleasedtheinventionforcommercialuse.Printedcircuitsdidnotbecomecommonplaceinconsumerelectronicsuntilthemid-1950s,aftertheAuto-SemblyprocesswasdevelopedbytheUnitedStatesArmy.
Beforeprintedcircuits(andforawhileaftertheirinvention),point-to-pointconstructionwasused.
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 激光测距 外文翻译 激光 测距 外文 翻译