Specular Gloss

1 Page 1 NATLINSTOFSTAND&TECH NI8T PUBUCATIONS NISTSpecialPublicationSP250-70 SpecularGloss MariaE.Nadal EdwardA.Early E.AmblerThompson Detector Condenser lens CoUimating lens Depolarizer Sampletable ICfO Open at page → 2 Page 2 NisrNationalInstituteofStandardsandTechnology •TechnologyAdministration •U.S.DeportmentofComm ii Open at page → 3 Page 3 NISTSpecialPublicationSP250-70 SpecularGloss MariaE.Nadal EdwardA.Early* OpticalTechnologyDivision PhysicsLahoratoiy NationalInstituteofStandardsandTechnology Gaithersburg,MD20899-0001 E.AmblerThompson WeightsandMeasures... Open at page → 4 Page 4 *AFRL/HEDO,2650LoiuseBauerDrive,BrooksCity-Base,TX78235 Certaincoinmercialentities,equipment,ormaterialsmaybeidentifiedinthis documentinordertodescribeanexperimentalprocedureorconceptadequately.Such identification isnoti... Open at page → 5 Page 5 Thecalibrationandrelatedmeasurement servicesoftheNational InstituteofStandardsand Technology(NIST)areintended toassistthemakersandusersofprecisionmeasuring instrumentinachievingthehighestpossiblelevelsofaccuracy,quality,... Open at page → 6 Page 6 ABSTRACT Thisdocumentdescribestheinstrumentation, standards,andmeasurementtechniques usedattheNationalInstituteofStandardsandTechnology(NIST)tomeasurespeculargloss. Theorganizationofthisdocument isasfollow. Section 1desc... Open at page → 7 Page 7 TABLEOFCONTENTS Abstract v 1 .Introduction 1 2.Theory 2 2.1.Definitions 2 2.2MeasurementEquations 3 3.ReferenceGoniophotometer 7 3.1Description 7 3.1.1 Illuminator 8 3.1.2Goniometer 9 3.1.3Receiver 9 3.2Characterization... Open at page → 8 Page 8 LISTOFTABLES Table2.1 Geometriesforspecularglossmeasurementsandapplications 2 Table2.2 Specularreflectancepoi6,Ad)ofthetheoreticalglossstandardforeach illuminationangleofthestandardgeometriesatwavelengthAn=589.3nm 5 Tabl... Open at page → 9 Page 9 LISTOFFIGURES Figure3.1 SchematicoftheNISTreferencegoniophotometer 8 Figure3.2 SpectralfluxdistributionoftheCIEstandardilluminantCandtheCIE spectralluminousefficiencyfunction 11 Figure3.3 Relativeresponsivity(ratioofthem... Open at page → 11 Page 11 1.Introduction ThisdocumentdescribestheNISTreferencegoniophotometer andprimarystandards,as theyexistedatthetimeofpubHcation,forthecahbrationofspecularglossatthe20%60and 85°standardgeometries. Updatedinformation aboutcali... Open at page → 13 Page 13 2.Theory Thissectiondetailsthebasicdefinitionsandtherelevantmeasurement equations to determinespeculargloss.Theapproachusedinthispaperisbasedupontheconceptspresented inRefs.[6-9]. 2.1Definitions Glossistheperceptionbyano... Open at page → 14 Page 14 2.2MeasurementEquations TheNISTreferencegoniophotometermeasuresluminousfluxOy[Im],definedby 0^.=K^-\m)-VA^)-dA , (2.1) whereKm =683Im/Wisthemaximumspectralluminousefficacyforphotopicvision,A[nm]is thewavelength,0(/l)[W/n... Open at page → 15 Page 15 whereA[V/A]istheampHfiergain.SolvingEq.(2.5)fortheluminousfluxandsubstitutinginto Eq.(2.2)yields A N-.A^ (2.7) wherethesubscripts iandrrefertomeasurementsmadeoftheincidentandreflectedluminous fluxes,respectively. Thespec... Open at page → 16 Page 16 cos9--^77"(/I)-sin'<9 cos6+ -sin^9 (2.12) where«istheindexofrefraction.Thespecularreflectanceforunpolarizedincidentradiantflux iscalculatedfrom (2.13) Fromthedocumentary standards, theindexofrefractionofthetheoretical st... Open at page → 17 Page 17 UsingtheluminousreflectanceoftheprimarystandardandEq.(2.10),Eq.(2.9)becomes G,(0,)=m- ^-^^"^ •^.Al , (2.16) where Pq{6q, /Id)iscalculatedandgiveninTable2.2,A.sC'^) ismeasuredandgivenbyEq. (2.15),andthesignals A^r.tandA^r... Open at page → 18 Page 18 " }dA-cD,,a)-p,(^o,^)-F,(A) jd/l-cDc,(i)-A(6'o,^,^)-i^.a) " ^^'^^^ Thecorrectionfactorfordeviationsfromtheangularrangesoftheilluminationbeamisgivenby jd^.,\dAOe,,{e,X)-A{6,A)V,(A)\dd\dA ,{6,A)a{9,A)V,(A) jd^„\dAcDe,,(0,A... Open at page → 19 Page 19 Figure3.1.SchematicoftheNISTReferenceGoniophotometer 3.1.1 IlluininatorTheilluminatorsuppliestheinfluxontothesample. Itconsistsofalight source,asetofcondenserlenses,asourceaperture,acollimating lens,adepolarizer, acolor... Open at page → 20 Page 20 Table3.1.ASTMspecificationsandtheNISTmeasuredvaluesforfullanglesof theilluminatorandreceiverapertureswithtolerancesanduncertainties /\periures Paralleltotheplaneof incidence Perpendicular totheplaneof incidence ASTMspec.... Open at page → 21 Page 21 3.2.1IlluminatorThelampisburnedinat100Wfor24hoursandihcnatihcoperational currentof6.3Aforanadditional48hpriortoperformingmeasurements. Thestabilityofthe sourcewasinvestigatedbymeasuringthefluxincidentonaSiphotodiode atth... Open at page → 22 Page 22 300 400 500 600 700 800 Wavelength[nm] Figure3.2.SpectraldistributionsofCIEstandardilluminantC(dashedline)and theCIEspectralluminousefficiencyfunction(solidline) 3.2.2Goniometer TheangularscalesofthesampleTableandreceive... Open at page → 23 Page 23 gainratioandrelativestandarddeviationoftheseoverlappingsettingsforsuccessivegainsare listedinTable3.2.Thegainratiosarenotexactlyequalto10,anditisbesttomeasuresignals betweentherangesof0.5Vto12V. Table3.2.Averagegainratio... Open at page → 24 Page 24 o CI. GO (U .>; 4— > C« <^ 1.020 1.015 1.010 1.005 1.000 0.995 ^0.990 0.985 0.980 5 7 A8•9 1 0.00001 0.001 0.1 10 1000 100000 Current[nA] Figure3.3.Relativeresponsivity(ratioofthemeasuredsignaltotheactualflux) ofthephoto... Open at page → 25 Page 25 3.3Operation Thelampcurrentisadjustedto6.3Aandallowedtowarmupforatleastanhour.An imageofthelampfilament isformedatthereceiveraperturebyadjustingthepositionsofihc lampandcollimatinglens.ThezeropositionofthesampleTableisse... Open at page → 26 Page 26 TypeAevaluationofuncertainty,whichisbasedonstatisticalanalysis,oraTypeBevaluation ofuncertainty,whichisbasedonothermeans.Therelativestandarduncertainty isgivenby u{xi)lxi.TherelativecombinedstandarduncertaintyWc(y)/visgi... Open at page → 27 Page 27 Thecomponentsofuncertaintyarisingfromthereceiverareuncertaintiesfromthedigital voltmeter(DVM),signalnoise,amplifiergainratio,andphotodiode linearity.Theuncertainty fromtheDVMiscausedbyasystematiceffectwithaTypeBevaluatio... Open at page → 28 Page 28 listedinTables3.4aand3.4b.TheISO2813standardspecifiesthatglossshouldbereportedto thenearestfullglossunit.Therefore,thecalibrationofthereferenceinstrumentandprimary standardshouldhaveanuncertaintyoflessthanoneglossunit.Th... Open at page → 29 Page 29 Table3.5.Relativeexpandeduncertaintiesofspecularglossmeasuredbythe NISTreferencegoniophotometer {k= 2)forthe20^60^and85^ standardgeometries. Standardgeometry Relativeexpandeduncertainty[%] 20° 0.35 60° 0.31 85° 0.29 4.Pr... Open at page → 30 Page 30 incidentonthereceiver,butthisoptionisnotfeasibleforsmall,porTableinstrumentscommonly usedinindustry. Thedisadvantagesofthepreviousprimarystandardsforspecularglossdescribedabove motivatedasearchforanewprimarystandardatNIS... Open at page → 31 Page 31 4.2.1IndexofRefractionTheindexofrefractionofBaK50wasmeasuredonaprism-shaped samplepreparedfromthesamemeltasthewedgesamples.Theminimumdeviationtechnique [22]wasusedtodeterminetheindexofrefraction atfivedifferentwavelength... Open at page → 32 Page 32 Table4.2.CalculatedspecularreflectancePs{6,Ad)andspecularglossvalueGs{0) ofthenewprimarystandardBaK50atAd=589.3nmforeach standardgeometry Standardgeometry Ps(0,Ad) Gsi0) 20° 0.049172 100.19 60° 0.100167 100.11 85° 0.6192... Open at page → 33 Page 33 signaltothenetillumination signal.Fromthemeasuredluminousreflectanceoftlicprimary standard,thespecularglossvaluewascalculatedasdescribed inthepreviousparagraph. 1he 85°geometrywasnotmeasuredduetolimitations intheinstrume... Open at page → 34 Page 34 1.60 g 1.55 g1.50 31-45 1.40 ooooooo oooooooooooooc ooooooooooooooooooooo 300 400 500 600 Wavelength[nm] 700 800 XAverageBlackGlassNISTOldStandardoBaK50 Quartz Figure4.3.Fittedrefractive index, foraverageblackglassworkin... Open at page → 35 Page 35 References I] NISTCalibrationServicesUsersGuide,NISTSpecialPublication250. 2] R.S.HunterandR.W.Harold,TheMeasurementofAppearance, 2"'' Ed.,JohnWiley andSons,Inc.,NewYork(1987). 3] InternationalStandardISO2813,PaintandVar... Open at page → 36 Page 36 AppendixA REPORTOFCALIBRATION 38090SSpecularGloss for SpecularGlossPlates Submittedby: AnyCompany,Inc. Attn.:Ms.JaneDoe 123CalibrationStreet MeasurementCity,MD20800-1234 (SeeyourPurchaseOrderNo.12345,datedmonthDay,Year)... Open at page → 37 Page 37 REPORTOFCALIBRATION 38090SSpecularGloss SpecularGlossPlates AnyCompany,Inc. SerialNos.:SG-01,SG-02,SG-03,SG-04, SG-05,SG-06,SG-07,SG-OH, SG-09,SG-10,SG-11,SG-12 withpressedpolytetrafluoroethylene (PTFE).ASiphotodiodewith... Open at page → 38 Page 38 REPORTOFCALIBRATION 38090SSpecularGloss AnyCompany,Inc. SpecularGlossPlates SerialNos.:SG-01,SG-02,SG-03,SG-04, SG-05,SG-06,SG-07,SG-08, SG-09,SG-10,SG-11,SG-12 Thefinalspecularglossisobtainedbyaveragingthevaluesfrommult... Open at page → 39 Page 39 REPORTOFCALIBRATION 38090SSpecularGloss AnyCompany,Inc. SpecularGlossPlates SerialNos.:SG-01,SG-02,SG-03,SG-04, SG-05,SG-06,SG-07,SG-08, SG-09,SG-10,SG-ll,S(;-I2 References: [1]"StandardTestMethodforSpecularGloss,ASTMD52... Open at page → 40 Page 40 REPORTOFCALIBRATION 38090SSpecularGloss SpecularGlossPlates AnyCompany,Inc. SerialNos.:SG-01,SG-02,SG-03,SG-04, SG-05,SG-06,SG-07,SG-08, SG-09,SG-10,SG-11,SG-12 Table 1.20°speculargloss,uncertaintycontributions,andexpand... Open at page → 41 Page 41 AppendixB NISTReferenceGoniophotometer forSpecularGlossMeasurements MariaE.NadalandE.AmblerThompson OpticalTechnologyDivision NationalInstituteofStandardandTechnology Gaithersburg,MD20899-8442 ABSTRACT Anewreferencegonio... Open at page → 42 Page 42 I.Introduction Thecurrentglobaleconomyhasincreasedinternationalcompetitionandtheneedto improvethequalityofmanymanufactured products.Appearancemeasurements areusedto detenninethequalityandacceptabilityofavarietyofproducts... Open at page → 43 Page 43 Thesegeometrieswereselectedbasedontheirabilitytoproduceoptimumdiscrimmaiion betweensamplesandtocorrelatewithvisualrankings. Themeasurementofspecularglosscomparesthespecularluminousreflectancefroma testspecimentothatfroma... Open at page → 44 Page 44 Theexperimentallymeasuredquantityistheratiooftheluminousfluxesreflectedfrom thetestsampleandprimarystandard, 0v,t,rand^v,s,rrespectively, Pv,t(<9o) ^ ^v.s,i ^v.t.r ^ /l^v,s,iRs A^t -^s Pv,s(^0) ^v,t,i ^v,s,r^v,U A whereR... Open at page → 45 Page 45 C=^^. (12, Thecorrectionfactorfordeviationsfromtheidealspectralfluxdistribution isgivenby fdA • 5,-(i) • A{6,,A)-V^iA) fd/L •S{A) i0„A)V(A) C^- ^ (13) ^ JdA •S,(A)A(Oo U) jd/l •S{A) {0, ,A)V(A) Thecorrectionfactorfordevi... Open at page → 46 Page 46 withdimensionsupto110mmby200mmandthicknessupto35mm.Inaddition,asampler holderwithvacuumsuctionisusedfornon-rigidsamplessuchaspaper.Theopticalcomponents forthereceptorarmareenclosedinalight-tightbaffletubewithanirisdiaphr... Open at page → 47 Page 47 Acolorfilterwasdesignedsothatthespectralfluxdistribution ol"thesource-fiher combination willcloselyresemblethatofCIEStandardIlluminantC.TheCorrelatedColor Temperature(CCT)andthespectralfluxdistributionofthesourceforthesp... Open at page → 48 Page 48 werecommontosuccessivegainsettings.Theaveragevalueofthegainratioandrelative standarddeviationoftheseoverlappingsettingsforsuccessivegainsarelistedinTable4.The gainratiosarenotexactlyequalto10,andforbetterresults,itisbest... Open at page → 49 Page 49 polishedblackglassasthetestsampleandtoahighlypolishedwedgeofBaK50astheprimary standard. Thecomponentofuncertaintyarisingfromthespecularreflectanceoftheprimarygloss standard isuncertainty intherefractiveindexmeasurements.... Open at page → 50 Page 50 dependentand-independentcomponents, respectively. Therelativeexpandeduncertainties giveninTable7arecalculatedfromtheroot-sum-squareoftheuncertainties listedinTables6a and6b.TheISO2813standardspecifiesthatglossshouldberep... Open at page → 51 Page 51 [5] Hsia,J.J.,"TheNBS20-,60-,and85-DegreeSpecularGlossScales,"NISTTech.Note 594-10(1975). [6] Nicodemus,F.E.,Richmond, J.C,Hsia,J.J.,Ginsburg, 1.W.,andLimperis,T., "GeometricalConsiderationsandNomenclature forReflectance... Open at page → 52 Page 52 ListofFigures 1. Luminousreflectanceasafunctionoftheobservationanglesforasetofblackglasses withdifferentlevelsofglossanindicatedinthelegend. 2. AschematicdiagramoftheNISTreferencegoniophotometer. 3. Spectralfluxdistribut... Open at page → 53 Page 53 Figure1 0.40 ObservationAngle[°] 13 Open at page → 54 Page 54 Figure2 14 Open at page → 55 Page 55 Figure3 300 400 500 600 700 800 Wavelength[nm] 15 Open at page → 56 Page 56 Figure4 16 Open at page → 57 Page 57 Figure5 1.020 1.015 1.010 1.005 1.000 o g 0.995 I 0.990 ^ 0.985 0.980 5 7 A8•9 0.00001 0.001 0.1 10 1000 100000 Current[nA] 17 Open at page → 58 Page 58 ListofTables 1. Standardgeometriesforspecularglossmeasurementsandtheirapplications. 2. Specularreflectance yOtj(6',/Id)ofthetheoreticalglossstandardforeachincidentangleof thestandardgeometriesatwavelength X,d=589.3nm. 3.... Open at page → 59 Page 59 Table1 SpecularAngle Applications 20° Highglossofplasticfilm,applianceand automotivefinishes 30° Highglossofimage-reflecting surfaces 45° Porcelainenamelsandplastics 60° Allrangesofglossforpaintand nlastirs 75° Coatedwax... Open at page → 60 Page 60 Table5 Deviation Correctionfactors 20 60 oco 85 Source-polarizer,Cp 0.999890 1.000137 1.000222 Source-depolarizer, Cp 0.999999 1.000001 0.999995 Divergence,Cd 0.999999 0.999806 0.999999 Nominalangle,Ca 0.999996 0.999875... Open at page → 61 Page 61 AppendixC NewPrimaryStandardforSpecularGlossMeasurements ManaE.NadalandE.AmblerThompson OpticalTechnologyDivision NationalInstituteofStandardandTechnology Gaithersburg,MD20899 ABSTRACT Themeasurementofspecularglossconsis... Open at page → 62 Page 62 I.Introduction Specularglossistheperceptionbyanobserverofthemirror-likeappearanceofasurface. Thisappearancecannotbemeasured;onlythespecificreflectancecharacteristicsofthesurface aremeasured. Glossisacommerciallyimportant... Open at page → 63 Page 63 ^'=arcsin(sin(6')//7(/L)). (2) Ingeneral,theluminousfluxOvisgivenby 0^,^K^-lSiA)-V,{A)dA, (3) whereKm=683Im/Wisthemaximumspectralluminousefficacyforphotopicvision,SiA)isthe spectralfluxdistribution,andV/XA)isthespectrall... Open at page → 64 Page 64 G,ia)=m.^.^^^^ . ,10) Thisequationexpressestheglossvalueofthetestsampleasafunctionofthemeasuredreflected luminousfluxesforthetestsampleandprimarystandardandthespecularreflectancesofthe primaryandtheoreticalstandards. Fro... Open at page → 65 Page 65 cleanable,durable,uniform,andhomogeneous withknownopticalproperties.Theselection criteriaforthenewprimarystandardwerethreefold. First,thestandardwouldbea commercially available,high-purityopticalglasswithhighchemicalandm... Open at page → 66 Page 66 oftheincidentbeam,thedetectorisrotatedintothebeampath,andthenetincidentsignalis measured.Thesampleisthenplacedintothebeampath,thesampletableanddetectorarmare rotatedtothedesiredgeometry,andthenetreflectedsignalismeasured... Open at page → 67 Page 67 VI.Conclusions ThenewNISTprimarystandardforspecularglosshasthreeimportantadvantagesover othermaterialsusedasprimarystandards. First,BaK50isacommerciallyavailablehigh-purity glasswithgoodhomogeneity. Second,sincenoofBaKSO... Open at page → 68 Page 68 References [I] InternationalStandardISO2813,"PaintandVarnishes-Measurements ofSpecularGloss ofNonmetallic PaintFilmsat20°,60°,and85°" (International Organization for Standardization 1978). [2] "StandardTestMethodforSpecu... Open at page → 69 Page 69 ListofTables Table 1 Specularreflectance Pq{0,Ad)ofthetheoreticalglossstandardforeachstandard geometry Table2 IndexofrefractionnofBaK50glassasafunctionofwavelength Table3 CalculatedspecularreflectancepJ^O,Xr>)andspecular... Open at page → 70 Page 70 Table1 StandardGeometiy p^){0,Ad) 20° 0.049078 60° 0.100056 85° 0.619148 Table2 Wavelength[nm] n 435.8 1.5800 480.0 1.5753 546.1 . 1.5702 589.3 • 1.5677 643.9 1.5654 Table3 StandardGeometry p^{9, X^,) Gs{0) 20° 0.049172... Open at page → 71 Page 71 ListofFigures Figure 1 GraphicalrepresentationofthespectralpowerdistributionoftheCIEllluminant Candtheluminousefficiencyfunction. Figure4.1 SchematicdiagramofthenewNISTprimarystandardshowingtheincomingand reflectedbeamat... Open at page → 72 Page 72 Figure1 U 4— » C o5 a. is C3 o.2 n.3 C/2 -5 140 120 100 80 60 H40 20 300 400 500 600 Wavelength[nm] 700 800 Figure2 Source BaK50Wedge Detector 12 Open at page → 73 Page 73 Figure3 1.600 1.590 X <D 1.580 i1.570 ^ 1.560 •••• 1.550 J I IL J I IU 300 400 500 600 700 800 Wavelength[nm] Figure4 1.60 1.58 1.56 g1.54 -a B1.52 1.50 I 1.48 Pi 1.46 1.44 1.42 1.40 300 ooooooi °°oooo6 oooooooooooooo --... Open at page → 74 Page 74 ure5 X o -o c l-H o a o 1.015 1.010 1.005 1.000 0.995 0.990 300 A **''^^^^JI J \L 400 500 600 700 800 Wavelength[nm] oBaK50 )KAverageofblkglass Quartz 14 Open at page → 76 Page 76 I ( Open at page →