Designation:F2469−15StandardTestMethodforMeasuringOpticalAngularDeviationofTransparentPartsUsingtheDouble-ExposureMethod1ThisstandardisissuedunderthefixeddesignationF2469;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversthemeasurementoftheopticalangulardeviationofalightrayimposedbyflattransparentpartssuchasacommercialormilitaryaircraftwindshield,canopy,orcabinwindow.1.2ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.2.1Exceptions—Thevaluesgiveninparenthesesareforinformationonly.Also,printsizeisprovidedininch-poundmeasurements.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2F801TestMethodforMeasuringOpticalAngularDeviationofTransparentPartsF1181TestMethodforMeasuringBinocularDisparityinTransparentPartsF733PracticeforOpticalDistortionandDeviationofTrans-parentPartsUsingtheDouble-ExposureMethod3.Terminology3.1Definitions:3.1.1angulardeviation—theangulardisplacementofalightrayfromitsoriginalpathcausedbynon-parallelismofoppositesurfacesasitpassesthroughatransparentmaterial,whichisexpressedinunitsofangle(degree,minutesofarc,milliradi-ans)andisafunctionoftheangleofincidenceateachsurfaceofthematerialandtheindexofrefractionofthematerial.3.1.2gridboard—anopticalevaluationtoolusedtodetectthepresenceofdistortionintransparentparts.Itisusually,butnotalways,averticalrectangularbackboardwithhorizontalandverticalintersectinglineswithmaximumcontrastbetweenthewhitelinesandtheblackbackground.4.SummaryofTestMethod4.1Theflattransparentpartismountedataspecifieddista...
