ASTM_E_1175_-_87_2015.pdf

Designation:E117587(Reapproved 2015)Standard Test Method forDetermining Solar or Photopic Reflectance,Transmittance,and Absorptance of Materials Using a Large DiameterIntegrating Sphere1This standard is issued under the fixed designation E1175;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.1.Scope1.1 This test method covers the measurement of the absolutetotal solar or photopic reflectance,transmittance,or absorp-tance of materials and surfaces.Although there are severalapplicable test methods employed for determining the opticalproperties of materials,they are generally useful only for flat,homogeneous,isotropic specimens.Materials that arepatterned,textured,corrugated,or are of unusual size cannot bemeasured accurately using conventional spectrophotometrictechniques,or require numerous measurements to obtain arelevant optical value.The purpose of this test method is toprovide a means for making accurate optical property measure-ments of spatially nonuniform materials.1.2 This test method is applicable to large specimens ofmaterials having both specular and diffuse optical properties.Itis particularly suited to the measurement of the reflectance ofopaque materials and the reflectance and transmittance ofsemitransparent materials including corrugated fiber-reinforcedplastic,composite transparent and translucent samples,heavilytextured surfaces,and nonhomogeneous materials such aswoven wood,window blinds,draperies,etc.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.4 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.(For specific safetyhazards,see Note 1.)2.Referenced Documents2.1 ASTM Standards:2E772 Terminology of Solar Energy ConversionE892 Tables for Terrestrial Solar Spectral Irradiance at AirMass 1.5 for a 37 Tilted SurfaceE903 Test Method for Solar Absorptance,Reflectance,andTransmittance of Materials Using Integrating Spheres3.Terminology3.1 Definitions:3.1.1 absorptance,nsee Terminology E772.3.1.2 integrating sphereoptical device used to either col-lect flux reflected or transmitted from a sample into a hemi-sphere or to provide isotropic irradiation of a sample from acomplete hemisphere.3.1.2.1 DiscussionIt consists of a cavity that is approxi-mately spherical in shape with apertures for admitting anddetecting flux and usually having additional apertures overwhich sample and reference specimens are placed.3.1.3 photopicopticalproperties,nabsorptance,reflectance,and transmittance of a sample evaluated as theweighted average of the measured property,with the wave-length by wavelength of the product of the spectral irradiancefor the measurement and the Commission Internationale delEclairage(CIE)photopic spectral response,3as the weightingfunction.3.1.4 photopic response,nspectral response of the averagehuman eye when fully adapted to daylight conditions.3.1.5 reflectance,nsee Terminology E772.3.1.6 transmittance,nsee Terminology E772.1This test method is under the jurisdiction of ASTM Committee E44 on Solar,Geothermal and OtherAlternative Energy Sources and is the direct responsibility ofSubcommittee E44.05 on Solar Heating and Cooling Systems and Materials.Current edition approved March 1,2015.Published April 2015.Originallyapproved in 1987.Last previous edition approved in 2009 as E117587(2009).DOI:10.1520/E1175-87R15.2For 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.3Available from Commission Internationale de lEclairage(CIE),InternationalLight Vocabulary,3rd Ed.,Bureau Central de la CIE,Paris,1970.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.Summary of Test Method4.1 This test method describes a procedure and apparatusfor determining the area-averaged optical properties of com-plex or nonuniform materials and surfaces.This test methodemploys a large diameter integrating sphere and a sourcecapable of illuminating a representative area of the testspecimens surface.4.2 Transmittance is determined with the specimen mountedexternally at the sphere entrance port.4,5Reflectance is deter-mined by placing the specimen in the center of the integratingsphere,4in accordance with the diagram in Fig.A1.2 of TestMethod E903.For measurement of reflectance of partiallytransmitting samples,the sample should be backed by a black