简介：ThisLetterproposesabrand-newfilamentdiametermeasurementmethodbasedonwhatiscalled'dualdiffraction,'inthatagratingisaddedbehindthefilamenttomakefulluseofitssubdivisionandamplificationcharacteristics.Highermeasurementaccuracyisachievedbythismethodcomparedwiththetraditionaldiffractionmethod.Toverifyitsaccuracy,threestandardfilamentswithnominalvaluesof100.2,120.1,and140.8μmaremeasuredbythedualdiffractionmethodandtraditionaldiffractionmethodunderthesameexperimentalconditions.Therelativemeasurementerrorsofthenewmethodarelessthan0.75%,anditsaveragerelativeerrorisreducedby56%comparedwiththetraditionaldiffractionmethod.

简介：Thenumericalmoirémethodwithsensitivityashighas0.03nmhasbeenpresented.Aquantitativedisplacementandstrainanalysisprogramhasbeenproposedbyusingthismethod.Itisappliedtoauedgedislocationandastackingfaultinaluminum.ThemeasuredstrainofedgedislocationiscomparedwiththeoreticalpredictiongivenbyPeierls-Nabarrodislocationmodel.Thedisplacementofstackingfaultisalsoobtained.

简介：Toconfirmtheexistenceandpropertiesofhumanmeridians,theopticaltransportpropertiesalongthepericardiummeridianandtissuesaroundthepericardiummeridianarestudiednoninvasivelyontwentyhealthyvolunteersinvivoandthencomparedwitheachother.Ourstudyshowsthatthelightpropagatingalongthemeridianandnon-meridiandirectionsbothconformtotheBeer’sexponentialattenuationlaw.However,statisticalanalysisoftheresultssuggeststhattheopticaltransportpropertiesofhumanmeridiandifferfromthoseofthesurroundingtissuesoveralowmodulatedfrequencyrange(P<0.01),andlightattenuationalongthepericardiummeridianissignificantlylessthanthatalongthenon-meridiandirection.Thesefindingsnotonlyindicatetheexistenceofacupuncturemeridianfromthepointofviewofbiomedicaloptics,butalsoshednewlightonanapproachtoinvestigationofhumanmeridians.更多还原

简介：ThespinHalleffectoflight(SHEL)canbeobservedbythedarkstripresultingfromweakmeasurement.WefindthattheSHELofapartiallycoherentbeam(PCB)hasasimilarphenomenonaswell.However,thedarkstripintheSHELofaPCBcannotbeexplainedbyconsideringthebeamasanassemblanceofcoherentspeckles.Also,thedarkstripinaPCBisnotpurelydark.Byanalyzingtheautocorrelation,weshowthattheSHELofaPCBistheresultofoverlappingcoherentspeckles'SHEL.Wefurtherproveourconclusionbyadjustingconvergenceandincidentangles.Finally,wedevelopaqualitativetheorytoclarifytheSHELofaPCB.

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简介：Weproposeanovelphotonictechniqueformicrowavefrequencymeasurementbasedontransversalmicrowavefilterswithhighresolution.Twoparallelmicrowavefilterswithsineandcosinefrequencyresponsesareobtainedbycrossgainmodulationinasinglesemiconductoropticalamplifier,whichintroducestwodifferentfrequencyresponsestoachieveanamplitudecomparisonfunction.Wealsodemonstrateaproof-of-conceptexperiment.Themeasurementerrorislessthan±0.04GHzforthefirstbandrangeof0–3.45GHzandlessthan±0.03GHzforthesecondbandrangeof3.45–5.8GHz.Ourschemeisfoundtobecapableofbeingextendedforlargerfrequencyrangemeasurementsusingashorterfiberlength.

简介：Apavementreflectancemeasurementsystemisestablishedbasedonagonio-photometerexistingbychangingabrackettocarrytheroadsampleandluminancemeter,addingacollimatedlightsourcetoprovideincidentlight.Thisautomatedsystemcouldfinishthereflectionmeasurementofaroadsamplein4h.AnuncertaintybudgetofthismeasurementsystemismadeandthecombinedstandarduncertaintyofQ0is5.26%.

简介：Weproposeanovelsmall-anglemeasuringopticalmethodbasedontheastigmaticeffectoftwoorthogonallyplacedcylindricallenses.Accordingtotheone-to-onecorrespondencebetweenthelaserspotshapeandtheangle,theangleisdetermined.Wetheoreticallyanalyzethemeasuringrangeanddemonstratethatalongerdistancebetweentherotatingaxisandtheopticalaxisleadstoasmallermeasuringrange,butbettersensitivity.Also,anassociatedexperimentalsystemisestablishedandameasuringrangeof0.94mrad(cubicfitr=0.9993)aswellasagoodlinearrangeof0.37mrad(linearfitr=0.9994)witharesolutionof8μradisachieved.

简介：Targetdynamicsareassumedtobeknowninmeasuringdigitalspeckledisplacement.Useismadeofasimplemeasurementequation,wheremeasurementnoiserepresentstheeffectofdisturbancesintroducedinmeasurementprocess.Fromtheseassumptions,Kalmanfiltercanbedesignedtoreducevarianceofmeasurementnoise.Anopticalandanalysissystemwassetup,bywhichobjectmotionwithconstantdisplacementandconstantvelocityisexperimentedwithtoverifyvalidityofKalmanfilteringtechniquesforreductionofmeasurementnoisevariance.

简介：ThisLetterpresentsamethodofanopticalsensorformeasuringwavelengthshifts.Thesystemconsistsofadiffractiongratingandatotalinternalreflectionheterodyneinterferometer.Asaheterodynelightbeamstrikesagrating,thefirst-orderdiffractionbeamisgenerated.Thelightpenetratesintoatotalinternalreflectionprismatananglelargerthanthecriticalangle.Awavelengthvariationwillaffectthediffractiveangleofthefirst-orderbeam,thusinducingaphasedifferencevariationofthelightbeamemergingfromthetotalinternalreflectionsinsidethetrapezoidprism.Boththeexperimentalandtheoreticalresultsrevealthat,forthefirst-orderdiffractivebeam,thesensitivityandresolutionlevelsaresuperiorto5°/nmand0.006nm,respectively,intherangeofwavelengthfrom632to634nm,andaresuperiorto3.1°/nmand0.0095nmintherangefrom632to637nm.Forthetheoreticalsimulationofthefourth-orderdiffractivebeam,theyaresuperiorto6.4deg∕nmand0.0047nmintherangefrom632to637nm.

简介：AprototypeRamanlidarwasdesignedformonitoringtroposphericCO_2profileandotherscientificin-vestigations.ThethirdharmonicofNd:YAGlaser(354.7-nmwavelength)wasusedasstimulatedlightsourcetoprovidenighttimemeasurements.FilterwithhighrejectionratioperformancewasusedtoextractCO_2RamansignalsfromRayleigh-Miescatteringsignalseffectively.Toimprovetherealtimemonitoringfunction,atwo-channelsignalcollectionsystemwasdesignedtocollectCO_2andN_2Ramanscatteringsig-nalssimultaneously.TheN_2Ramanscatteringsignalswereusedtoretrieveaerosolextinctioncoefficient.TypicalfeaturesofCO_2concentrationprofileandaerosolextinctioncoefficientinHefeiwerepresented.ThemixingratioofatmosphericCO_2inHefeicanreachabout360-400ppmv.

简介：WeestablishasystemtomeasurethefunctionalabsorptioncrosssectionofphotosystemII(PSII)(σPSII)andmaximumquantumyieldofphotochemistryinPSII(Fv/Fm).Thesystemutilizesasequenceofhighfrequencyexcitationflashesatmicrosecondintervalstoinduceamicrosecond-levelfluorescenceyieldcurve.ParametersσPSIIandFv/Fmarecalculatedbyfittingthecurveusingnonlinearregression.Experimentalresultsshowthattherelativestandarddeviation(RSD)ofthesystemislessthan3%,andthecorrelationcoefficientofFv/Fmvaluesmeasuredbythissystemandthosemeasuredbypulseamplitudemodulationmethodis0.950.

简介：Wemeasurethehalf-wavevoltageofLiNbO3phasemodulatorsina26-GHzwidebandfrequencyrange,andthenanalyzeitbythephasemodulationphotonicpeakgainlinkedtotheinterferometricdemodulation.Theopticalinterferometerisconstructedwithtwo50:50couplersandtwofiberarmswitha1-mdifferenceinfiberlength.Thephotoniclinkgainpeaksarefrequencydependent,asindicatedbythedifferentialtimedelayintheinterferometer.Theproceduredescribedisanewandpracticalhalf-wavevoltagemeasurementmethodthatcanaccuratelypredictthenonlinearfrequencycharacteristicsofthephasemodulator.Moreover,themethodcanbeappliedtovarioustypesofLiNbO3phasemodulators.

简介：Wepresentamethodthataccuratelymeasureslargeopticalsurfacesbeforepolishingusingalasertracker.Usingthescanningmodeofthelasertrackerconsiderablyimprovesmeasurementefficiencyandminimizesthedominanterrorscausedbyenvironmentalchange.WeusethismethodtomeasureaΦ1.3-masphericmirrorandobtainameasurementuncertaintyof0.72μm(rootmeansquare,RMS).

简介：AnovelfiberBragggrating(FBG)withtwotransmissiondipsin1310-and1550-nmregionsisproposedandinscribedbyaninfraredfemtosecondlaser.Formedbymulti-photonionization,thistypeofgratingcanwithstandtemperatureashighas800℃whichmakesitsuitableforharshenvironmentsensing.Inaddition,thetemperatureandstrainaffectthesetwodipsindifferentways,whichenablessimultaneousstrainandtemperaturesensing.Thefabrication,spectrumcharacterization,andtemperatureperformanceofthisgratingareintroduced.

简介：Influenceoftemperatureonmeasurementofsurfaceplasmonresonance(SPR)sensorwasinvestigated.SampleswithvariousconcentrationsofNaClweretestedatdifferenttemperatures.Itwasshownthatiftheaffectionoftemperaturecouldbeneglected,measurementprecisionofsaltsolutionwas0.028wt.-%.Butmeasurementerrorofsalinityca,usedbytemperaturewas0.53wt.-%inaveragewhenthetemperaturedriftwas1℃.Toreducetheerror,adouble-cellSPRsensorwithsaltsolutionanddistilledwaterflowingrespectivelyandatthesametemperaturewasimplemented.更多还原

简介：Anewscreen-spotimagingmethodbasedonopticalmeasurementisproposed,whichisapplicabletotheclose-rangemeasurementofaircraft'sthree-dimensional(3D)attitudeparameters.Lasertrackerisusedtofinishtheglobalcalibrationsofthehigh-speedcamerasandthefixedscreensontestsite,aswellastoestablishmedia-coordinate-framesamongvariouscoordinatesystems.Thelasercooperationobjectmountedontheaircraftsurfaceprojectslaserbeamsonthescreensandthehigh-speedcamerassyn-chronouslyrecordthelight-spots'positionchangingwithaircraftattitude.Therecordedimagesequencesareusedtocomputetheaircraftattitudeparameters.Basedonthematrixanalysis,theerrorsourcesofthemeasurementaccuracyareanalyzed,andthemaximumrelativeerrorofthismathematicalmodelisestimated.Theexperimentalresultshowsthatthismethodeffectivelymakesthechangeofaircraftpositiondistinguishable,andtheerrorofthismethodisnomorethan3′whiletherotationanglesofthreeaxesarewithinacertainrange.

简介：Anovelno-guidelightpentype3D-coordinatemeasurementsystemwiththreesetsofpositionsensitivedevices(PSDs)torealizeintersectionconvergeinagingisintroduced.Itiscalledasthelightpentypemeasurementsystem,becausethemeasuringheadisshapedasapenwithseverallightsourcesonit.Thestructuredesign,measurementprincipleandexperimentalresultsarepresented.Thetheoreticalanalysisandexperimentalresultsprovethatthissystemhasadvancedfeaturesofsimplestructure,highautomation,andhighaccuracy,andcanbeusedinthemeasurementfieldsofmechanicalmanufacture,robot,auto,aviationandmedicineeffectively.

简介：Anovelmethodofmeasuringnon-uniformstrainalongafiberBragggrating(FBG)usingopticalfrequencydomainreflectometry(OFDR)isproposedandexperimentallydemonstrated.Thismethodcanovercometheproblemsoftraditionalnon-uniformstrainmeasurementmethodsforFBGs,i.e.,thelikelihoodofchirpingandmultiplepeakinginthespectrumwhenFBGissubjectedtoinhomogeneousstrainfields.WavelengthinterrogationisrealizedbyOFDRwithanarrow-line-widthtunablelaserastheopticalsource.Whennon-uniformstraindistributionsalongareasadjacenttostructuraldamagearemeasuredbythismethod,goodagreementisobtainedbetweenmeasurementsandtheoreticalsimulationresults.

简介：Anovelphotonic-assistedapproachtomicrowavefrequencymeasurementisproposedandexperimentallydemonstrated.Theproposedschemeisbasedonthefrequency-to-powermappingwithdifferenttransmissionresponses.Apolarizerisusedinoneoutputbranchofaphasemodulatortosimultaneouslyimplementphasemodulationandintensitymodulation.OwingtothecomplementarynatureofthetransmissionresponsesandtheMach-Zehnderinterferometers(MZIs),thisschemetheoreticallyprovideshighresolutionandtunablemeasurementrange.Themeasurementerrorsintheexperimentalresultscanbekeptwithin0.2GHzoverafrequencyrangefrom0.1to5.3GHz.