1、Designation: E903 12Standard Test Method forSolar Absorptance, Reflectance, and Transmittance ofMaterials Using Integrating Spheres1This standard is issued under the fixed designation E903; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, 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 spectralabsorptance, reflectance, and transmittance of m
3、aterials usingspectrophotometers equipped with integrating spheres.1.2 Methods of computing solar weighted properties fromthe measured spectral values are specified.1.3 This test method is applicable to materials having bothspecular and diffuse optical properties.1.4 This test method is applicable t
4、o material with appliedoptical coatings with special consideration for the impact onthe textures of the material under test.1.5 Transmitting sheet materials that are inhomogeneous,textured, patterned, or corrugated require special consider-ations with respect to the applicability of this test method
5、. TestMethod E1084 may be more appropriate to determine the bulkoptical properties of textured or inhomogeneous materials.1.6 For homogeneous materials this test method is preferredover Test Method E1084.1.7 This test method refers to applications using standardreference solar spectral distributions
6、 but may be applied usingalternative selected spectra as long as the source and details ofthe solar spectral distribution and weighting are reported.1.8 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 s
7、tandard 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:2E275 Practice for Describing and Measuring Performance ofUltraviolet and Visible SpectrophotometersE424 Test Methods for So
8、lar Energy Transmittance andReflectance (Terrestrial) of Sheet MaterialsE490 Standard Solar Constant and Zero Air Mass SolarSpectral Irradiance TablesE772 Terminology of Solar Energy ConversionE971 Practice for Calculation of Photometric Transmittanceand Reflectance of Materials to Solar RadiationE1
9、084 Test Method for Solar Transmittance (Terrestrial) ofSheet Materials Using SunlightE1175 Test Method for Determining Solar or PhotopicReflectance, Transmittance, and Absorptance of MaterialsUsing a Large Diameter Integrating SphereE2554 Practice for Estimating and Monitoring the Uncer-tainty of T
10、est Results of a Test Method in a SingleLaboratory Using a Control Sample ProgramG173 Tables for Reference Solar Spectral Irradiances: DirectNormal and Hemispherical on 37 Tilted SurfaceG197 Table for Reference Solar Spectral Distributions: Di-rect and Diffuse on 20 Tilted and Vertical Surfaces2.2 O
11、ther Documents:Federal Test Method Standard No. 141, Method 61013ASHRAE Standard 74-19884CIE 38 Radiometric and Photometric Characteristics of Ma-terials and their Measurement5CIE 44 Absolute Methods for Reflection Measurement5NIST SP 250-48 Spectral Reflectance6NIST SP 250-69 Regular Spectral Trans
12、mittance73. Terminology3.1 The following definitions are consistent with Terminol-ogy E772. Additional terms appropriate to this test method areincluded in Terminology E772.1This test method is under the jurisdiction of ASTM Committee E44 on Solar,Geothermal and Other Alternative Energy Sources and
13、is the direct responsibility ofSubcommittee E44.20 on Glass for Solar Applications.Current edition approved Dec. 1, 2012. Published December 2012. Originallyapproved in 1982. Last previous edition approved in 1996 as E90396 which waswithdrawn August 2005 and reinstated in December 2012. DOI: 10.1520
14、/E0903-12.2For 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 Standardization Documents, Order De
15、sk, Building 4, Section D,700 Robbins Ave., Philadelphia, PA 19111-5049, Attn: NPODS.4Available from American Society of Heating, Refrigeration, and Air-Conditioning Engineers, Inc., 191 Tullie Circle, NE. Atlanta GA 30329.5Available from U.S. National Committee of the CIE (International Commissiono
16、n Illumination), C/o Thomas M. Lemons, TLA-Lighting Consultants, Inc., 7 PondSt., Salem, MA 01970, http:/www.cie-usnc.org.6Available on line at http:/www.nist.gov/pml/div685/pub/upload/sp250-48.pdf7Available on line at http:/www.nist.gov/calibrations/upload/SP250-69.pdfCopyright ASTM International,
17、100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2 Definitions:3.2.1 absorptance, ,nthe ratio of the absorbed radiantflux to the incident radiant flux.3.2.2 diffuse, adjindicates that flux propagates in manydirections, as opposed to direct beam, which refers to c
18、olli-mated flux. When referring to reflectance, it is the directional-hemispherical reflectance less the specular reflectance.3.2.3 integrating sphere, nan optical device used to eithercollect flux reflected or transmitted from a sample into ahemisphere or to provide isotropic irradiation of a sampl
19、e froma complete hemisphere. It 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.3.2.4 irradiance, E, na radiometric term for the radiantflux that
20、is incident upon a surface (Wm2).3.2.5 near normal-hemispherical, adjindicates irradianceto be directional near normal to the specimen surface and theflux leaving the surface or medium is collected over an entirehemisphere for detection.3.2.6 photovoltaic solar, adjreferring to an optical prop-erty;
21、 indicates a weighted average of the spectral propertyusing the number of photons per second per unit area per unitwavelength derived from a standard solar irradiance distribu-tion as the weighting function.3.2.7 radiant flux, ,na radiometric term for the time rateof flow of energy in the form of el
22、ectromagnetic energy(watts).3.2.8 reflectance, ,nthe ratio of the reflected radiant fluxto the incident radiant flux.3.2.9 smooth, adjhaving an even and level surface, havingno roughness or projections. Free from inequalities or uneven-ness of surface.3.2.10 solar, adj(1) referring to radiometric qu
23、antities,indicates that the radiant flux involved has the sun as its source,or has the relative spectral distribution of solar flux, and (2)referring to an optical property, indicates a weighted average ofthe spectral property, with a standard solar spectral irradiancedistribution as the weighting f
24、unction.3.2.11 spectral, adj(1) for dimensionless opticalproperties, indicating that the property was evaluated at aspecific wavelength, , within a small wavelength interval, about , symbol wavelength in parentheses as L(350 nm), or asa function of wavelength, symbol L(), and (2) for a radiomet-ric
25、quantity, the concentration of the quantity per unit wave-length (or frequency), indicated by the subscript lambda, asL= dL/d; at a specific wavelength, the wavelength at whichthe spectral concentration was evaluated may be indicated bythe wavelength in parentheses following the symbol, L(350nm).3.2
26、.11.1 DiscussionThe parameters of frequency, ,wavenumber, , or photon energy may be substituted forwavelength, , in this definition.3.2.12 specular, adjindicates the flux leaves a surface ormedium at an angle that is numerically equal to the angle ofincidence, lies in the same plane as the incident
27、ray and theperpendicular, but is on the opposite side of the perpendicularto the surface.3.2.12.1 DiscussionDiffuse has been used in the past torefer to hemispherical collection (including the specular com-ponent). This use is deprecated in favor of the more preciseterm hemispherical.3.2.13 textured
28、, adjthe nature of a surface other thansmooth. Having some degree of unevenness, roughness orprojections.3.2.14 transmittance, ,nthe ratio of the transmittedradiant flux to the incident radiant flux.4. Summary of Test Method4.1 Measurements of spectral near normal-hemisphericaltransmittance (or refl
29、ectance) are made over the spectral rangefrom approximately 300 to 2500 nm with an integrating spherespectrophotometer.4.2 The solar transmittance, reflectance, or absorptance isobtained by calculating a weighted average with a standard orselected solar spectral irradiance as the weighting function
30、byeither direct calculation of suitable convolution integrals, or theweighted (see 8.3.3) or selected (see 8.3.4) ordinate method.5. Significance and Use5.1 Solar-energy absorptance, reflectance, and transmittanceare important in the performance of all solar energy systemsranging from passive buildi
31、ng systems to central receiverpower systems. This test method provides a means for deter-mining these values under fixed conditions that represent anaverage that would be encountered during use of a system inthe temperate zone.5.2 Solar-energy absorptance, reflectance, and transmittanceare important
32、 for thermal control of spacecraft and the solarpower of extraterrestrial systems. This test method also pro-vides a means for determining these values for extraterrestrialconditions.5.3 This test method is designed to provide reproducibledata appropriate for comparison of results among laboratories
33、or at different times by the same laboratory and for comparisonof data obtained on different materials.5.4 This test method has been found practical for smoothmaterials having both specular and diffuse optical properties.Materials that are textured, inhomogeneous, patterned, orcorrugated require spe
34、cial consideration.5.4.1 Surface roughness may be introduced by physical orchemical processes, such as pressing, rolling, etching, ordeposition of films or chemical layers on materials, resulting intextured surfaces.5.4.2 The magnitude of surface roughness with respect tothe components of the spectr
35、ophotometer and attachments(light beam sizes, sphere apertures, sample holder configura-tion) can significantly affect the accuracy of measurementsusing this test method.5.4.3 Even if the repeatability, or precision of the measure-ment of textured materials is good, including repeated mea-surements
36、at various locations within or orientations of theE903 122sample, the different characteristics of different spectropho-tometers in different laboratories may result in significantdifferences in measurement results.5.4.4 In the context of 5.4.3, the term significant meansdifferences exceeding the ca
37、libration or measurementuncertainty, or both, established for the spectrophotometersinvolved, through measurement of or calibration with standardreference materials.5.4.5 The caveats of 5.4.3 and 5.4.4 apply as well tomeasurement of smooth inhomogeneous or diffusing materials,where incident light ma
38、y propogate to the edge of the testmaterial and be lost with respect to the measurement.5.5 This test method describes measurements accomplishedover wider spectral ranges than the Photopic response of thehuman eye. Measurements are typically made indoors usinglight sources other than natural sunligh
39、t, though it is possible toconfigure systems using natural sunlight as the illuminationsource, as in Practice E424. Practice E971 describes outdoormethods using natural sunlight over the spectral response rangeof the human eye.5.6 Light diffracted by gratings is typically significantlypolarized. For
40、 polarizing samples, measurement data will be afunction of the orientation of the sample. Polarization effectsmay be detected by measuring the sample with rotation atvarious angles about the normal to the samples.6. Apparatus6.1 Instrumentation:6.1.1 SpectrophotometerA spectrophotometer with an in-t
41、egrating sphere attachment capable of measuring the spectralcharacteristics of the test specimen or material over the solarspectral region from approximately 300 to 2500 nm is required.Double beam, ratio recording instruments are recommendedbecause of their low sensitivity to drift in source brightn
42、ess oramplifier gain. Recording spectrophotometers with integratingspheres that have been found satisfactory for this purpose arecommercially available.NOTE 1For determining extraterrestrial solar optical properties usingStandard E490, the spectral region should extend down to 250 nm.NOTE 2This test
43、 method is used primarily for solar thermal and somephotovoltaic applications that require the full spectral range be covered.There are other applications for which a narrower range is sufficient andthat could otherwise use the procedures of this test method. For example,some applications involving
44、photovoltaic cells utilize a narrower spectralresponsive range and some others pertain only to visible light propertiesthat have an even narrower spectral range. In such cases, the user of thetest method is permitted to use a narrower range. Similarly, a user with anapplication requiring a broader s
45、pectral range is permitted to use a broaderrange. Any deviations from the spectral range of this test method shouldbe noted in the report.6.1.1.1 The integrating sphere shall be either a wall-mounted type such that the specimen may be placed in directcontact with the rim of an aperture in the sphere
46、 wall fortransmittance and reflectance measurements or an Edwardstype such that the specimen is mounted in the center forreflectance and absorptance measurements.NOTE 3The interior of the integrating sphere shall be finished with astable highly reflecting and diffusing coating. Sphere coatings havin
47、g therequired properties can be prepared using pressed tetrafluoroethylenepolymer powder, or other highly reflective, stable material.NOTE 4For high accuracy (better than 60.01 reflectance units)measurements with absolute sphere configuration, the ratio of the port areato the sphere wall plus port a
48、rea should be less than 0.001 (1).8In general,large spheres ( 200 mm) meet these requirements and are preferred whilesmall spheres ( 100 mm) can give rise to large errors.6.1.1.2 For the evaluation of near normal-hemispherical orhemispherical-near-normal reflectance, the direction of theincident rad
49、iation or the direction of viewing respectively shallbe between 6 and 12 from the normal to the plane of thespecimen so that the specular component of the reflectedenergy is not lost through an aperture. Ambient light must beprevented from entering the sphere by placing a ring of blackor white material around the external rim of the specimen portsor by covering the entire sphere attachment with a light tighthousing. Black backing or border material may result insignificant light absorption or loss, while white backing mate-rial should b
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