High Power Laser Calibrations

1 Page 1 NATLINSTOFSTAND&TECH NISTMeasurementServices: HighPowerLaserCalibrations nist atNIST l^tr^\- Publication 250-77 XiaoyuLi JoshuaHadler CliristopherCromer JohnLehman MariaDowell •^57 NationalInstituteofStandardsandTechnolo... Open at page → 3 Page 3 NISTSpecialPublication250-77 NISTMEASUREMENTSERVICES: HighPowerLaserCalibrations atNIST XiaoyuLi JoshuaHadler ChristopherCromer JohnLehman MariaDoweii Optoelectronics Division ElectronicsandElectricalEngineeringLaborator... Open at page → 4 Page 4 Certaincommercialentities,equipment,ormaterialsmaybeidentifiedinthisdocumentinordertodescribe anexperimentalprocedureorconceptadequately.Suchidentification isnotintendedtoimply recommendation orendorsementbytheNationalIn... Open at page → 5 Page 5 1 Introduction 1 2 CalibrationServiceSummary 1 3 TheoryofMeasurement 2 3.1 SystemBasicsandMeasurementPrinciple 2 3.1.1 NISTPrimaryStandardforHighPowerLaserMeasurements 3 3.1.2 MeasurementSystem 4 3.2 MeasurementEquations... Open at page → 6 Page 6 6.2 MeasurementSystemUncertainties 15 6.2.1 OpticalShutter(TypeA) 15 6.2.2 Laser/System Instability(TypeB) 16 6.2.3 ApertureEffects 16 6.2.4 ChopperWheelRatio(TypeA) 16 6.2.5 TestMeterMeasurement(TypeA) 16 7 QualityContr... Open at page → 7 Page 7 HighPowerLaserCalibrationsatNIST XiaoyuLi,JoshuaHadler,ChristopherCromer,JohnLehman,andMariaDowell NationalInstituteofStandardsandTechnology OptoelectronicsDivision 325Broadway Boulder,Colorado80305 Thisdocumentdescribes... Open at page → 8 Page 8 systemconsistingofadetectoranddisplaycombination iscalibratedasaunit.Thatis, componentsofthesystemarenotcalibratedindependently. Normally,theabsolute responsivity ischaracterizedbutnophysicaladjustments aremadetothecusto... Open at page → 9 Page 9 detectorandtransmittingaportionofthebeamontoeithertheDUTorNISTstandard. ThesignalfromthemonitordetectorisusedtonormalizetheresponsesofboththeDUT andNISTstandard.Sincearotatingchopperwheelisinvolved, thissystemisonly suit... Open at page → 10 Page 10 3.1.2MeasurementSystem AschematicdiagramofthehighpowermeasurementsystemisshowninFigure3.1.A diamond-turned reflectivechopperwheelservesasabeamsplitter,directingonebeamto aNISTstandardandtheotherbeamtoamonitordetector.Int... Open at page → 11 Page 11 R CD 3.3 MS where0sand0m-sarethelaserpower(orenergy)asrecordedbysimultaneous measurementsofthestandardandthemonitordetector,respectively.Theabsolutevalue ofthechopperwheelratioisnotcritical;thecriticalissueisthatthevalue... Open at page → 12 Page 12 showngraphicallyasthedurationbetweentheshutteropenconditionandthestarting pointofthemeasurementperiod. Afterthesettlingperiod,NreadingsoftheDUToutputareacquiredandthenaveraged. Theshutterisclosedforanotherperiodequaltoth... Open at page → 13 Page 13 3.3.3Calorimeter LasercalorimetersareaspecialtypeofenergymeterdescribedbyE.DWestandK.L. Chumey inTheoryofIsoperibol Calorimetry forLaserPowerandEnergy Measurements.{\2]CalorimetertheoryisamaturefieldandthediscussioninWes... Open at page → 14 Page 14 4MeasurementSystem 4.1MeasurementStandards Energyandpowermeasurementscanbeacquiredbyavarietyoftypesofdetectors.Such detectorsmightinclude,butarenotHmited to,thermopiles (surfaceandvolume absorbers),andcalorimeters.Moreth... Open at page → 15 Page 15 4.3.4ChopperWheels Aselectionofchopperwheels isusedtoaccommodate differentpowerlevels.The chopperwheelratioismeasuredforeachcalibration setupbeforeandaftertheDUT measurement.Thematerialsselectedforuseaschopperwheelsarech... Open at page → 16 Page 16 asecondsetofchopperwheelmeasurements istakentoassurethattherehasbeenno significantdriftinthechopperwheelratio.Ifbothmeasurements areconsistent,thefinal valueforthechopperwheelratio istheaverageoftheallchopperwheelratio m... Open at page → 17 Page 17 SincethebeamareaissmallerthantheactiveareaoftheDUTandNISTstandards,the alignmentitselfisnotcriticalaslongasthelaserbeamiscenteredon,andperpendicular to,theDUT,thestandards,andthemonitordetector.Spatialnon-uniformities in... Open at page → 18 Page 18 •Monitordetector/Standard used:bothdetectors(transmittedandreflected)are identifiedandselectedinthesoftwareinterface. •Typeofdetector:Power,Energy,orCalorimeter. •Electronicssettingsthatareenabledforremotecontrol:Gainran... Open at page → 19 Page 19 settingsscalesthemeasurement totheinstrument's gain,andyieldsthetrue powermeasured. •Powerand/orenergylevelsofbothtransmittedandreflectedbeamsduringthe DUTmeasurementsarecalculated. •Fromthesepower/energy levels,thecalib... Open at page → 20 Page 20 6.1MeasurementStandardUncertainties TheuncertaintiesspecifictoanygivenreferencestandardaredocumentedintheK-series QMIIIspecifictothe421IOCand4211ICcaHbrationservices.[6]However, itisproper todiscussthenatureofthesetypeso... Open at page → 21 Page 21 designatedas"Electronics" inTable6.1.Theheatercurrent ischosensuchthatthe averagepowerdissipatedbytheelectricalheaterisapproximately equivalent tothe averageopticalpowerincidentonthecalorimeterduringoperation.Thesourceso... Open at page → 22 Page 22 6.2.2Laser/System Instability(TypeB) Thevariationoflaserpowerduringagivenmeasurementcanimpacttheaccuracyofthe measurement.Mostlaserswilltendtoexhibitsomeformofpowerinstabilityoverthe relatively shorterdurations(100to300s... Open at page → 23 Page 23 IntheOptoelectronics Division,allcalibration,MAP,andremotemeasurementservices maintaincheckstandardsandcontrolchartsforperiodictestofthemeasurementservice. Theprocedureforselecting,storing,maintaining,andmeasuringcheckst... Open at page → 24 Page 24 9 References [I]BarryN.Taylor,TheInternationalSystemofUnits(SI),NISTSpecialPublication 330,2001Edition. [2]BarryN.Taylor,GuidefortheUseoftheInternationalSystemofUnits(SI),NIST SpecialPublication811,1995Edition. [3]D.E.We... Open at page → 25 Page 25 [16]EricG.Johnson Jr.,Evaluating theinequivalence andacomputational simplification fortheNBSlaserenergystandards.AppliedOptics,Vol16,page 2315,August1977. [17]DavidLivigni,HighAccuracyLaserPowerandEnergyMeterCalibrationS... Open at page → 27 Page 27 TechnicalPublications Periodical JournalofResearchoftheNationalInstituteofStandardsandTechnology-ReportsNISTresearchand developmentinmetrologyandrelatedfieldsofphysicalscience,engineering,appliedmathematics, statistics,... Open at page → 28 Page 28 U.S.DepartmentofCommerce NationalInstituteofStandardsandTechnology 325Broadway Boulder,CO80305-3337 OfficialBusiness PenaltyforPrivateUse$300 Open at page →