毕业论文外文翻译-激光测距仪

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1、山东科技大学学士学位论文外文翻译LaserrangefinderAlongrangelaserrangefinderiscapableofmeasuringdistanceupto20km;mountedonatripodwithanangularmount.Theresultingsystemalsoprovidesazimuthandelevationmeasurements.Alaserrangefinderisadevicewhichusesalaserbeamtodeterminethedistancetoanob

2、ject.Themostcommonformoflaserrangefinderoperatesonthetimeofflightprinciplebysendingalaserpulseinanarrowbeamtowardstheobjectandmeasuringthetimetakenbythepulsetobereflectedoffthetargetandreturnedtothesender.Duetothehighspeedoflight,thistechniqueisnotappropriateforhig

3、hprecisionsub-millimetermeasurements,wheretriangulationandothertechniquesareoftenused.PulseThepulsemaybecodedtoreducethechancethattherangefindercanbejammed.ItispossibletouseDopplereffecttechniquestojudgewhethertheobjectismovingtowardsorawayfromtherangefinder,andifs

4、ohowfast.PrecisionTheprecisionoftheinstrumentisdeterminedbytheriseorfalltimeofthelaserpulseandthespeedofthereceiver.Onethatusesverysharplaserpulsesandhasaveryfastdetectorcanrangeanobjecttowithinafewmillimeters.RangeDespitethebeambeingnarrow,itwilleventuallyspreadov

5、erlongdistancesduetothedivergenceofthelaserbeam,aswellasduetoscintillationandbeamwandereffects,causedbythepresenceofairbubblesintheairactingaslensesranginginsizefrommicroscopictoroughlyhalftheheightofthelaserbeam'spathabovetheearth.Theseatmosphericdistortionscouple

6、dwiththedivergenceofthelaseritselfandwithtransversewindsthatservetopushtheatmosphericheatbubbleslaterallymaycombinetomakeitdifficult17山东科技大学学士学位论文外文翻译togetanaccuratereadingofthedistanceofanobject,say,beneathsometreesorbehindbushes,orevenoverlongdistancesofmorethan1

7、kminopenandunobscureddesertterrain.Someofthelaserlightmightreflectoffleavesorbrancheswhicharecloserthantheobject,givinganearlyreturnandareadingwhichistoolow.Alternatively,overdistanceslongerthan1200ft(365m),thetarget,ifinproximitytotheearth,maysimplyvanishintoamira

8、ge,causedbytemperaturegradientsintheairinproximitytotheheatedsurfacebendingthelaserlight.Alltheseeffectshavetobetakenintoaccount.CalculationThedi