ASTM_E_1651_-_94_1999.pdf

Designation:E 1651 94(Reapproved 1999)Standard Test Method forTotal Luminous Reflectance Factor by Use of 30/tIntegrating-Sphere Geometry1This standard is issued under the fixed designation E 1651;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(e)indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis test method has a long but undocumented history.The electric lighting industry for many yearsused a visual reflectometer with 30 unidirectional illumination and a sphere to collect all the reflectedlight so as to obtain a measure of total luminous reflectance factor,specular plus diffuse,for 30/tgeometry.The original visual design was later equipped with a photovoltaic cell and microammeter.The lighting industry has preferred to maintain this geometry rather than to use a standard CIEgeometry,such as 6/t.In 1975,the original 30/t geometry was incorporated in an instrument of moderndesign.This test method documents the calibration and measurement procedures for such aninstrument.1.Scope1.1 This test method covers measurement of total luminousreflectance factor of opaque,nonfluorescent specimens by useof an integrating-sphere reflectometer with illumination at anangle of 30 from the surface normal and diffuse viewing withspecular component included.1.2 This test method is intended to be used for evaluation oftotal luminous reflectance factor of reflector lighting sheetmaterial.It may be used for evaluation of other material whenits specific geometry has been found to be applicable.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:E 177 Practice for Use of the Terms Precision and Bias inASTM Standards2E 179 Guide for Selection of Geometric Conditions forMeasurement of Reflection and Transmission Properties ofMaterials3E 259 Practice for Preparation of Pressed Powder WhiteReflectance Factor Transfer Standards for Hemisphericaland Bi-Directional Geometries3E 284 Terminology of Appearance3E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2E 1345 Practice for Reducing the Effect of Variability ofColor Measurement by Use of Multiple Measurements3E 1347 Test Method for Color and Color-Difference Mea-surements by Tristimulus(Filter)Colorimetry33.Terminology3.1 Definitions in Guide E 179 and Terminology E 284 areapplicable to this test method.4.Summary of Test Method4.1 This test method requires the use of a reflectometerequipped with an integrating sphere with an angle of illumi-nation of 30 to the surface normal and diffuse viewing withthe specular component included.In other respects,the detailsof the instrument geometry are as specified in Guide E 179.The use of the 30 angle of illumination allows completecollection of flux reflected at angles near the specular angle.4.2 This test method utilizes only the Y tristimulus function,leading to the measurement of luminous reflectance.In otherrespects,the spectral characteristics and methodology used aresimilar to those described in Test Method E 1347.It should benoted that,when and if suitable equipment is available,1This test method is under the jurisdiction of ASTM Committee E-12 on ColorandAppearance and is the direct responsibility of Subcommittee E12.02 onSpectrophotometry and Colorimetry.Current edition approved Nov.15,1994.Published January 1995.2Annual Book of ASTM Standards,Vol 14.02.3Annual Book of ASTM Standards,Vol 06.01.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.spectrophotometric measurement is equally as acceptable asthe(filter)colorimetric method described in this test method.5.Significance and Use5.1 Procedures of this test method provide a quantitativemeasure of total luminous reflectance,which is related toreflection efficiency of lighting reflectors.This test method isextensively used to assess total reflectance factor of reflectorsheet used in the manufacture of lighting fixtures.5.2 The measurement of this test method includes bothspecularly and diffusely reflected light,weighted by the CIEspectral luminous efficiency function V(l)of the eye toprovide a reasonable approximation of visual assessment.6.Apparatus6.1 Reflectometer,4with a hemispherical optical measuringsystem as described in 6.1.1,capable of measuring CIE 1931tristimulus value Y for CIE standard illuminant C(totalluminous reflectance).A diagram of a suitable reflectometer isgiven in Fig.1 and is described as follows:6.1.1 The light from quartz-tungsten-halogen lamp,(1),passes through infrared absorbing filte