Optical-sensor

获取信息的技术和材料获取信息主要使用探测器和传感器。目前光电子学技术是或取信息的主要手段传感器材料半导体传感器材料和光纤传感器材料，在外场（光、热、电、磁等）作用下半导体的电性能发生变化，由此获得外场信息，对压力敏感的半导体，有由于压力影响产生电阻变化的压阻半导体材料，如Si、Ge、InSb、GaP等；有靠压电效应的II－VI和III－V族半导体化合物以及压电陶瓷（以BaTiO3为代表）等。对热敏感的半导体材料可分正温度系数（NTC）和负温度系数（PTC）材料。光电探测器皆为光敏半导体材料；磁电阻效应和霍耳效应将磁场强度转换成电信号的为磁敏半导体材料。光在光纤中传输时，受外场的作用能引起振幅、位相、频率和偏振状态的变化。I’mMr.Sensitivity...Abriefoverviewofsensors(andwhyyoushouldlovethem)WhySensorsAreImportant:TheworldisNOTstatic.Itcanalsobeincrediblycomplex.Ohno.Ithoughtyousaidthe40’thcanalonsector15..Sometimes,theenvironmentwherearobotwillbedeployedissimplyunknowable...WhatIsaSensor?Anythingthatdetectsthestateoftheenvironment.Yep.You’vealreadyusedsensorsbeforeintheBraitenburglab.Arethefollowingsensors?positioningdevicesEncodersVisionMinedetectors(detectorvs.sensor)SometypesofSensors:Ladar(laserdistanceandranging)TimeofflightPhaseshiftSonarRadarInfra-redLightsensingHeatsensingTouchsensingTopicsPhotonicsTechnologyDistributedSensingApplicationsMultipointSensingApplicationsofFBGSensorsWondersofFibre-OpticSensorsAgeneralopticalsystemOpticalcommunications:UselasersorLEDsastransmitters,opticalfibreastransmissionmediumandphotodiodesasdetectors.Fibreopticssensors:Canbeconsideredasasmallscaletransmissionsystembutthetransmitterinthiscaseisreplacedwithphotonicsensorsilluminatedbyalightsource.Fibre-OpticsTechnologyBasiccomponentsofafibreopticssystemOpticalFibrePhotodetector[SensorSignalProcessing]MessageDestinationMessageSourceLightSourceTransmitter[Sensors]BasicComponentsofPhotonicsSystemsLightSources–LED–LaserdiodeOpticalFibres–Glassfibre–PlasticfibrePhotodetectors–PIN–APDFibre-OpticsTechnologyCharacteristicsofGlassFibreVirtuallyinfinitebandwidth(1,000,000,000,000bits/s)Extremelylow-loss(50%lossforevery15km)Smallsize(0.250mmindiameter)Lightweight(2mmcable:4kg/km,coaxialcable1000kg/km)ImmunitytoelectromagneticinterferenceHighsecurityNosparksCorrosionandtemperatureresistantFibreLosses:SinglemodefibreLossesofGlasses&PolymerFibresMediumAttenuationdB/km10%lengthmWindowglass50,0000.2Opticalglass3,0003.3Glassfibre0.250,000PMMA15067PerfluorinatedPOF15667Polycarbonate1,00010FibreOpticSensorsOpticalsensorsarereplacingconventionalsensorsinmanyareasofscience,engineering,andmedicine.Createsnewkindsofsensorswithuniquepropertiesthatcouldnotbeachievedbefore.NoisefreeLongtransmissionHighdurabilitySmallsize-integratedintosmartmaterialsEasyinstallationFibreOpticSensorsFibreOpticsSensorTechnologiesOTDR–RayleightRaman-OTDRBrillouin-OTDRFibreGratingSensors*OTDR–OpticalTime-DomainReflectometerMonitoring:Astructure’sfeelingsPainDiagnosisCureExamsMonitoringInspectionRepairDiagnosisApplicationDomainsOil&GasRailwayBridgesTunnelsGeostructuresDamsNuclearIndustryHeritageHarborsPipeLinesOtherApplicationsDistributedSensingFFeT1Position[m]Temp.[°C]Position[m]Strain[me]ReadingUnitDistributedSensor0m1m100m1000m20kmT1eT2T2BrillouinScatteringTheinteractionbetweenacousticandopticalwavesdependsonthestrainandtemperaturestateofthefiber.TheMeasuringMethodofthedistributedfibreopticaltemperaturesensingtechniqueOpticalfibreWavelengthIntensityIsIaTIncoupledlightBackscatteredlightTransmittedlightbackscatteringspectrumAdvantages...simultaneoustemperaturemeasurementandlocalizingoftemperaturedataalongtheentirelengthofthefibreeasyinstallationofthesensingcabletotalimmunitytoelectromagneticinductionnoactiveelectroniccircuitswithinthemeasuringobject(explosionprotection)useincorrosiveenvironmentspossibleAccuracyoftheMeasurementsMeasuringconditions:*25repetitionsofmeasurementatconstanttemperature*Measurementtime:1min*AveragedtemperaturedistributionReproducibilityoftheMeasurementsMeasuringconditions:*100repetitionsofmeasurementatconstanttemperature*Measurementtime:1min*Standarddeviation(1)ofasinglemeasurement:0,9°C•SpatialResolution:0.8mover1km5mat10km15mat25km•Strainresolution:20me•TResolution:±1°C•Measurementtime:typ.5min.orfewsecondsforthresholddetection.B-OTDR:PerformancesFeatures&benefitsofDistributedSensingTemperaturemonitoringofnumerouspointsTraditionalmethod:multiplepointsensorsMultiplexedSensorsNsensors,Nwires,NcalibrationOneopticalfibersensorrepacesthousandsofpin-pointsensorsRemotemonitoringFeatures&benefitsofDistributedSensingApplications用途AnopticalfiberasasensingelementOpticalfibercharacteristicsandfeaturesLowloss,lowcost,smallsize,…VariouscabledesignavailablewithdifferentperformancesOpticalfiberasasensingelementMeasurementofthemodificationofthepropagationpath(delay,attenuation,polarization,…)MeasurementoftheinteractionoflightwiththepropagationmediumThePhysicsbehindtheinstrumentScatteringprocessesLaser,loLaser,loScatteringmediumScatteringprocessesThePhysicsbehindtheinstrumentTemperatureandstraineffectsonBrillouinscatteringBrillouinscatteringischaracterizedbytheBrillouinshiftTheBrillouinshiftdependsontheacousticvelocityofthemedium,whichtemperatureandstraindependentBrillouinFrequencyShift:nB=2nVA/lnB(T,e)dependsontemperatureandstrainThePhysicsbehindtheinstrumentT=ToTemperatureeffectsontheBrillouin