AMERICANSOCIETYFORTESTINGANDMATERIALS#/bDesignation:D881-901916RICISI.,Philadelphia.Fa.1S1WReprintedfromlhaAnnualBookdACTMStandardsCapyf~IWACTMIInotlisledinlhecurmnlcombinedindu,rmiwirinihafwl&ilion.StandardTestMethodforDeviationofLineofSightThroughTransparentPlastics'ThisstandardisissuedunderthefixeddesignationD881;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope6.Apparatus1.1Thistestmethoddescribesaprocedureformeasuring,bymeansofatelescopeandatarget,thedeviationofthelineofsightthroughflatorcurvedsectionsmadeoftransparentplastics.1.2Thevaluesstatedinminutes(?r/10800rad)unitsaretoberegardedasthestandard,1.3Thisstandarddoesnotpurporttoaddressthesafetyproblemsassociatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.2.ReferencedDocument2.1ASTMStandard:D618MethodsofConditioningPlasticsandElectricalD883DefinitionsofTermsRelatingtoPlastics*InsulatingMaterialsforTesting3.Terminology6.1Telescope,rigidlymounted,equippedwithcrosshairs(Notei).Thetelescopeshallbesufficientlyfreeofparallaxsothatwhentheeyeoftheobserverisshifted,thecorre-spondingmovementoftheimageofthetargetrelativetothecrosshairsshallnotexceedonetenthofthesmallestscaledivisionofthetarget.Themagnifyingpowerofthetelescopeshallbeadequatetopermitaccuratereadingofthepositionofthecrosshairsonthetarget.Themountingofthetelescopeshallbesuchthatitcannotbedisplacedreadilyafterbeingclampedinposition.Toobtainclearimagesthroughsomespecimens,itmaybenecessarytostopdowntheobjectiveofthetelescope(Note2).NOTE1-Anengineer'stransitisaverysuitableinstrumentformeasuringdeviationsoflineofsight.NOTE2-Theintendeduseofthearticleormaterialundertestmaydeterminethesizeofstoptobeused.Thus,iftheuserwilllookthroughthe...
