ASTM_F_1316_-_90_2013.pdf

Designation:F131690(Reapproved 2013)Standard Test Method forMeasuring the Transmissivity of Transparent Parts1This standard is issued under the fixed designation F1316;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.INTRODUCTIONTest Method D1003 has received wide acceptance as a test method to measure luminoustransmissivity in transparent materials.However,because Test Method D1003 requires criticalalignment of equipment on both sides of the transparency,it is not suited to measuring thetransmissivity of large,curved parts or parts that are installed.In addition,Test Method D1003measures the luminous transmissivity of the material in a direction perpendicular to the surface of thematerial.For the majority of aircraft windscreens,the pilot is not viewing through the transparencyperpendicular to the surface.Since the transmissivity varies as a function of viewing angle the valuesof transmissivity measured perpendicular to the surface do not indicate what the pilot will see whenviewing through the windscreen.For the above reasons this test method has been developed to allow the measurement oftransmissivity of a transparent part at any angle.Since the relative alignment of the equipment itemson either side of the transparency is not critical,this test method can also be used on large,thick,orcurved parts and parts that are already installed.1.Scope1.1 This test method describes an apparatus and procedurethat is suitable for measuring the transmissivity of large,thick,or curved transparent parts including parts already installed.This test method is limited to transparencies that are relativelyneutral with respect to wavelength(not highly colored).1.2 Since the transmissivity(transmission coefficient)is aratio of two luminance values,it has no units.The units ofluminance recorded in the intermediate steps of this testmethod are not critical;any recognized units of luminance(forexample,foot-lamberts or candelas per square metre)may beused,as long as use is consistent.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1003 Test Method for Haze and Luminous Transmittanceof Transparent Plastics3.Terminology3.1 Definitions:3.1.1 black referencea light-absorbing,black material,such as black velvet flocking.3.1.2 photometera device that measures luminance asdefined by the spectral sensitivity of the photopic curve.3.1.3 Photopic curvethe photopic curve is the spectralsensitivity of the eye for daytime conditions as CommitteeInternationale dElairage(CIE)1931 standard observer.3.1.4 regulated light sourcea light source with electronicfeedback to ensure that its illuminance remains constant overtime.3.1.5 transmission coeffcientsame as transmissivity.1This test method is under the jurisdiction of ASTM Committee F07 onAerospace and Aircraft and is the direct responsibility of Subcommittee F07.08 onTransparent Enclosures and Materials.Current edition approved Dec.1,2013.Published December 2013.Originallyapproved in 1990.Last previous edition approved in 2008 as F1316-90(2008).DOI:10.1520/F1316-90R13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.6 transmissivitythe transmissivity of a transparent me-dium is the ratio of the luminance of an object measuredthrough the medium to the luminance of the object measureddirectly.4.Summary of Test Method4.1 Aregulated light source with a relatively large,diffuselyradiating surface area is placed on one side of a transparent partto be measured.A black,light-absorbing reference surface isplaced next to the light source.A photometer is used tomeasure the luminance of the light source and black referencedirectly and through the transparency.The light source readingmeasured through the transparency minus the black referencereading through the transparency is divided by the light sourcemeasured directly minus the black reference measured directly(see Eq 1).This ratio is the transmission coefficient of thetransparency.The black reference surface is used to correct themeasurement from the effects of light scatter due to haze andfrom reflections.35.Significance and Use5.1 SignificanceThis test method provides a means tomeasure the transmissivity of parts in the field(alreadyinstalled on ai