Ocean-Optics-光纤光谱仪PPT课件下载推荐.ppt

Ocean-Optics-光纤光谱仪PPT课件下载推荐.ppt

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OceanOpticsSpectrometersSimplesolutionsforIntricateproblems,Spectroscopyis,Spectroscopyisthescienceandmeasurementofemission&@#@absorptionspectraoflightandotherformsofelectromagneticradiationandhowmaterials（matter）interactswithradiantenergy,Spectrumisaviewofradiantenergydispersedintoitswavelengthconstituents,LightandMatter,Absorbance,Transmission,Reflection,Refraction,Lightenterstheopticalfiberandisefficientlytransmittedtothespectrometer.Onceinthespectrometer,thedivergentlightemergingfromtheopticalfiberiscollimatedbyasphericalmirror.Thecollimatedlightisdiffractedbyaplanegrating,andtheresultingdiffractedlightisfocusedbyasecondsphericalmirror.Animageofthespectrumisprojectedontoa1-dimensionallinearCCDarray,andthedataistransferredtoacomputerthroughanA/Dconverter.,OpticalBenchFeatures,Grating,Detector,CrossedCzerny-Turneropticalpath,DetectorCoating,CollectionLens,SlitBlockingfilterModeStripper,OrderSortingFilter,TheFundamentalBalanceofSpectrometerConfiguration,Resolution,Sensitivity,SpectralRange,Everythingbeginshere,Spectrometersareselected.,BydetectortypeByopticalbenchtypeByconfigurationtypeByapplication/function,DetectorTypes,SilinearCCDarrayBack-thinnedareaCCDSilinearphotodiodearrayInGaAslineararrayCMOS（OEMonly）,Sony2048-element,Toshiba3648-element,QE/MAYAback-thinnedDetector,WhatisaCCD?

@#@CCDstandsforcharge-coupleddevice.ACCDisadetectormadeonasiliconwafer.Duetothephysicalnatureofsilicon,photonsoflightthathititgenerateelectronsinthesilicon.ThejoboftheCCDistocollecttheseelectronsinitslightbuckets（calledpixels）duringthelengthoftheexposuretolight.Themorelightfallingonaparticularlightbucketorpixel,themoreelectronsthatpixelwillcontain.Thebucketsthentransfertheirelectrons（thinkwaterbucketbrigade）outtotheCCDcontroller（whichcontainstheelectronicstocontroltheCCD）andontothecomputer.Thecomputerregeneratestheimageandwenowseethespectra,CCDPIXELBUCKETS,LightEnergy,PHOTONS,CCDOperation,PhotonsstrikingPixelscauseChargetoleaktoGroundDarkcurrentChargeleaksalittleanywayExposurelastsfordurationofintegrationperiodQuantumefficiency,PixelWells,PHOTONCharge,Pixels,Ground,Atendofintegrationperiod,remainingchargeindicateshowmanyphotonsweredetectedA/DconvertschargetoCounts,Saturated!

@#@Nochargeleft,sonoresponsetofurtherphotons,Counts,Pixels,Saturated!

@#@,Quantumefficiency（QE）isameasureofhowwellaspecificsensorrespondstodifferentwavelengthsoflight.ThehighertheQE,themoresensitiveaCCDwillbeataparticularwavelength.Thequantumefficiency（QE）offront-illuminatedCCDisaround40%.Thismeans40outof100incidentphotonsweredetected.Back-illuminatedCCDshaveapeakquantumefficiencyupwardsof90%-90outof100photonsofacertainwavelengtharedetected!

@#@Ontheotherhand,photographicfilmandthehumaneyehaveapeakQEofabout10%.,Infront-illuminatedCCDs,lightmustpassthroughthepolysilicongatestructurelocatedabovethephotosensitivesiliconlayercalledthe“depletionlayer.”,Inback-thinneddevices,alsoknownasback-illuminatedCCDs,theincidentphotonfluxdoesnothavetopenetratethepolysilicongatesandisabsorbeddirectlyintothesiliconpixels.,FrontIlluminated,BackIlluminated,BackThinningTheetchingawayofsiliconfromthebacksideofaCCD.Thinningisdoneinalargebathofacid.Thedeviceismountedonasupportandisthenagitated.Waxisusedtomountthedevicetoitssupport,sincetheaciddoesnotattackwax.Whentheacidhaseatenawayacertainamountofsilicon,theCCDthatwasonce0.010thickbecomes0.0005thick!

@#@,Whatisthedifference?

@#@,OpticalBenchFeatures,Grating,Detector,CrossedCzerny-Turneropticalpath,DetectorCoating,CollectionLens,SlitBlockingfilterModeStripper,OrderSortingFilter,SpectrometerPerformanceCriteria,Signal-to-NoiseRatio（Detector）SensitivityResolution,SmallestdetectablesignalchangeisafunctionoftheS:

@#@NforthespectrometerWecanaccuratelydetectasignalthatis2xtheS:

@#@NTheS:

@#@NdependsonlyonthedetectorchoiceTheS:

@#@Ndoesnotdependonopticalbenchconfiguration,SpectrometerSensitivity,EntranceOpticsandResolution,FixedSlitsNomovingpartstoalignorcomelooseFixedopticalresolutionvalueCanuselargerfiberstocollectmorelightNoSlits（usingthefiber）SlitwidtheasilychangedAllthelightfromthefiberisusedFiberdiameterdeterminesopticalresolution,OpticalResolution,wavelength,real,FWHM,perfect,SpectrometerResolution,Measuredasfull-widthathalf-maximum（FWHM）forapeak,Wavelength,Intensity,nm,TheFundamentalBalanceofSpectrometerConfiguration,Resolution,Sensitivity,SpectralRange,Everythingbeginshere,SpectrometerResolution,Dependson:

@#@OpticalBenchdesignBigger=betterresolution（worsespectralrange）Sizeofd