Designation:C1652/C1652M−14StandardTestMethodforMeasuringOpticalDistortioninFlatGlassProductsUsingDigitalPhotographyofGrids1ThisstandardisissuedunderthefixeddesignationC1652/C1652M;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.INTRODUCTIONTransmittedandreflecteddistortioninannealed,heatstrengthened,andtemperedglasscanbemeasuredbyseveralmethods.(1,2,3,4)2Qualitativemethodsarebasedontheobservationofwavinessintheglassasviewedinofreflectedortransmittedimagesinasetofequidistantlines,calledZebraLines.Quantitativemeasuringtechniquesarebasedonseveralmethods,someofwhichare:(1)Measuringlocalcurvatureusingmechanicalradiusgages((1,5,6,andTestMethodC1651)(2)MoiréFringeanalysis(7,8)(3)Doubleexposureoftransmittedgridimages(PracticeF733)(4)Projectionofanarrayofrounddots(9)(5)Duallaserbeams(10)Theusershouldbefamiliarwithtechniquesthatareavailablesoastoselectthemostsuitableafterconsideringtheprecision,speed,andtestspecificationrequirements.Thetestmethoddescribedinthisdocumentusesadigitalcameratocaptureatransmittedorreflectedimageofasetofequidistantlines.Changesinthespacingoflinesareusedtoquantifyingthedistortion.1.Scope1.1Thistestmethodcoversthedeterminationofopticaldistortionofheat-strengthenedandfullytemperedarchitecturalglasssubstrateswhichhavebeenprocessedinaheatcontrolledcontinuousoroscillatingconveyanceoven.SeeSpecificationsC1036andC1048fordiscussionofthecharacteristicsofglasssoprocessed.Inthistestmethodthereflectedimageofprocessedglassisphotographedandthephotographicimageanalyzedtoquantifythedistortionduetosurfacewaviness.Thetestmethodisalsousefultoquantifyopticaldistortionobservedintransmittedlightinlaminatedglassassemblies.1.2ThevaluesstatedineitherSIunitsorinch-poundunitsareregardedseparatelyasstandard.Thevaluesstatedineachsystemmaynotbeexactequivalents;therefor...
