Designation:E1392–96StandardPracticeforAngleResolvedOpticalScatterMeasurementsonSpecularorDiffuseSurfaces1ThisstandardisissuedunderthefixeddesignationE1392;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheDepartmentofDefense.1.Scope1.1Thispracticeexplainsaprocedureforthedeterminationoftheamountandangulardistributionofopticalscatterfromanopaquesurface.Inparticularitfocusesonmeasurementofthebidirectionalreflectancedistributionfunction(BRDF).BRDFisaconvenientandwellacceptedmeansofexpressingopticalscatterlevelsformanypurposes(1,2).2AdditionaldatapresentationformatsdescribedinAppendixX1haveadvan-tagesforcertainapplications.Surfaceparameterscanbecalculatedfromopticalscatterdatawhenassumptionsaremadeaboutmodelrelationships.SomeoftheseextrapolatedparametersaredescribedinAppendixX2.1.2Opticalscatterfromanopaquesurfaceresultsfromsurfacetopography,surfacecontamination,andsubsurfaceeffects.Itistheuser’sresponsibilitytobecertainthatmeasuredscatterlevelsareascribedtothecorrectmechanism.Scatterfromsmallamountsofcontaminationcaneasilydominatethescatterfromasmoothsurface.Likewise,subsurfaceeffectsmayplayamoreimportantscatterrolethantypicallyrealizedwhensurfacesaresuperpolished.1.3Thispracticedoesnotprovideamethodtoextrapolatedataforonewavelengthfromdataforanyotherwavelength.Datatakenatparticularincidentandscatterdirectionsarenotextrapolatedtootherdirections.Inotherwords,nowavelengthoranglescalingistobeinferredfromthispractice.Normallytheusermustmakemeasurementsatthewavelengthsandanglesofinterest.1.4ThispracticeappliesonlytoBRDFmeasurementsonopaquesamples.Itdoesnotapplytoscatterfromtranslucentortransparentmaterials.Therearesubtlecomplicationswhichaffectmeasurementoftranslucentortransparentmaterialsthatarebestaddressedinseparates...
