ASTM E903-96
(Test Method)Standard Test Method for Solar Absorptance, Reflectance, and Transmittance of Materials Using Integrating Spheres (Withdrawn 2005)
Standard Test Method for Solar Absorptance, Reflectance, and Transmittance of Materials Using Integrating Spheres (Withdrawn 2005)
SCOPE
1.1 This test method covers the measurement of spectral absorptance, reflectance, and transmittance of materials using spectrophotometers equipped with integrating spheres.
1.2 Methods of computing solar weighted properties from the measured spectral values are specified.
1.3 This test method is applicable to materials having both specular and diffuse optical properties. Except for transmitting sheet materials that are inhomogeneous, patterned, or corrugated, this test method is preferred over Test Method E1084.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
WITHDRAWN RATIONALE
This test method covers the measurement of spectral absorptance, reflectance, and transmittance of materials using spectrophotometers equipped with integrating spheres.
Formerly under the jurisdiction of Committee E44 on Solar, Geothermal, and Other Alternative Energy Sources, this test method was discontinued in August 2005 in accordance with section 10.5.3.1 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
Designation: E 903 – 96
Standard Test Method for
Solar Absorptance, Reflectance, and Transmittance of
Materials Using Integrating Spheres
This standard is issued under the fixed designation E903; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope Federal Test Method Standard No. 141, Method6101
1.1 This test method covers the measurement of spectral
3. Terminology
absorptance, reflectance, and transmittance of materials using
3.1 Definitions—The following definitions are consistent
spectrophotometers equipped with integrating spheres.
with Terminology E772. Additional terms appropriate to this
1.2 Methods of computing solar weighted properties from
test method are included in Terminology E772.
the measured spectral values are specified.
3.1.1 absorptance, a, n—the ratio of the absorbed radiant
1.3 This test method is applicable to materials having both
flux to the incident radiant flux.
specular and diffuse optical properties. Except for transmitting
3.1.2 diffuse, adj—indicates that flux propagates in many
sheet materials that are inhomogeneous, patterned, or corru-
directions, as opposed to direct beam, which refers to colli-
gated, this test method is preferred over Test Method E1084.
mated flux. When referring to reflectance, it is the directional-
1.4 This standard does not purport to address all of the
hemispherical reflectance less the specular reflectance.
safety concerns, if any, associated with its use. It is the
3.1.3 integrating sphere, n—anopticaldeviceusedtoeither
responsibility of the user of this standard to establish appro-
collect flux reflected or transmitted from a sample into a
priate safety and health practices and determine the applica-
hemisphereortoprovideisotropicirradiationofasamplefrom
bility of regulatory limitations prior to use.
a complete hemisphere. It consists of a cavity that is approxi-
2. Referenced Documents mately spherical in shape with apertures for admitting and
detecting flux and usually having additional apertures over
2.1 ASTM Standards:
which sample and reference specimens are placed.
E275 Practice for Describing and Measuring Performance
3.1.4 irradiance, E, n—a radiometric term for the radiant
of Ultraviolet, Visible, and Near Infrared Spectrophotom-
−2
flux that is incident upon a surface (W·m ).
eters
3.1.5 near normal-hemispherical, adj—indicates irradiance
E424 Test Methods for Solar Energy Transmittance and
to be directional near normal to the specimen surface and the
Reflectance (Terrestrial) of Sheet Materials
flux leaving the surface or medium is collected over an entire
E490 Solar Constant and Air Mass Zero Solar Spectral
hemisphere for detection.
Irradiance Tables
3 3.1.6 radiant flux, F, n—aradiometrictermforthetimerate
E772 Terminology Relating to Solar Energy Conversion
of flow of energy in the form of electromagnetic energy
E891 Tables for Terrestrial Direct Normal Solar Spectral
3 (watts).
Irradiance for Air Mass 1.5
3.1.7 reflectance, r, n—theratioofthereflectedradiantflux
E1084 TestMethodforSolarTransmittance(Terrestrial)of
3 to the incident radiant flux.
Sheet Materials Using Sunlight
3.1.8 solar, adj—(1) referring to radiometric quantities,
E1175 Test Method for Determining Solar or Photopic
indicatesthattheradiantfluxinvolvedhasthesunasitssource,
Reflectance, Transmittance, and Absorptance of Materials
or has the relative spectral distribution of solar flux, and (2)
Using a Large Diameter Integrating Sphere
referringtoanopticalproperty,indicatesaweightedaverageof
2.2 Other Document:
the spectral property, with a standard solar spectral irradiance
distribution as the weighting function.
3.1.9 spectral, adj—( 1) for dimensionless optical proper-
These test methods are under the jurisdiction of ASTM Committee E44 on
ties, indicating that the property was evaluated at a specific
Solar, Geothermal, and Other Alternative Energy Sources and is the direct
responsibility of Subcommittee E44.05 on Solar Heating and Cooling Subsystems
wavelength, l,withinasmallwavelengthinterval, Dlabout l,
and Systems.
symbol wavelength in parentheses as L(350 nm), or as a
Current edition approved April 10, 1996. Published May 1996. Originally
e1
published as E903–82. Last previous edition E903–82(1992) .
Annual Book of ASTM Standards, Vol 03.06.
3 5
Annual Book of ASTM Standards, Vol 12.02. AvailablefromStandardizationDocuments,OrderDesk,Building4,SectionD,
Annual Book of ASTM Standards, Vol 14.02. 700 Robbins Ave., Philadelphia, PA 19111-5049, Attn: NPODS.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
E903–96
function of wavelength, symbol L(l), and (2) for a radiometric 6.1.1 Spectrophotometer—Aspectrophotometer with an in-
quantity, the concentration of the quantity per unit wavelength tegrating sphere attachment capable of measuring the spectral
(or frequency), indicated by the subscript lambda, as L = dL/ characteristics of the test specimen or material over the solar
l
dl; at a specific wavelength, the wavelength at which the spectralregionfromapproximately300to2500nmisrequired.
spectral concentration was evaluated may be indicated by the Double beam, ratio recording instruments are recommended
wavelengthinparenthesesfollowingthesymbol,Ll(350nm). because of their low sensitivity to drift in source brightness or
3.1.9.1 Discussion—The parameters of frequency, n, wave- amplifier gain. Recording spectrophotometers with integrating
number, k, or photon energy may be substituted for wave- spheres that have been found satisfactory for this purpose are
length, l , in this definition. commercially available.
3.1.10 specular, adj—indicates the flux leaves a surface or
NOTE 1—For determining extraterrestrial solar optical properties using
medium at an angle that is numerically equal to the angle of
Standard E490, the spectral region should extend down to 250 nm.
incidence, lies in the same plane as the incident ray and the
6.1.1.1 The integrating sphere shall be either a wall-
perpendicular, but is on the opposite side of the perpendicular
mounted type such that the specimen may be placed in direct
to the surface.
contact with the rim of an aperture in the sphere wall for
3.1.10.1 Discussion—Diffuse has been used in the past to
transmittance and reflectance measurements or an Edwards
refer to hemispherical collection (including the specular com-
type such that the specimen is mounted in the center for
ponent). This use is deprecated in favor of the more precise
reflectance and absorptance measurements.
term hemispherical.
3.1.10.2 Discussion—Reversing the order of terms in an NOTE 2—The interior of the integrating sphere shall be finished with a
stable highly reflecting and diffusing coating. Sphere coatings having the
adjective reverses the geometry of the incident and collected
required properties can be prepared using pressed tetrafluoroethylene
flux respectively.
6 7
polymer powder, airbrushed Eastman White Reflectance Paint.
3.1.11 transmittance, t, n—the ratio of the transmitted
NOTE 3—For high accuracy (better than 60.01 reflectance units)
radiant flux to the incident radiant flux.
measurements, the ratio of the port area to the sphere wall plus port area
should be less than 0.001 (1). In general, large spheres (> 200 mm) meet
4. Summary of Test Method
these requirements and are preferred while small spheres (< 100 mm) can
give rise to large errors.
4.1 Measurements of spectral near normal-hemispherical
transmittance (or reflectance) are made over the spectral range 6.1.1.2 For the evaluation of near normal-hemispherical or
fromapproximately300to2500nmwithanintegratingsphere
hemispherical-near-normal reflectance, the direction of the
spectrophotometer. incidentradiationorthedirectionofviewingrespectivelyshall
4.2 The solar transmittance, reflectance, or absorptance is
be between 6 and 12° from the normal to the plane of the
obtained by calculating a weighted average with a standard specimen so that the specular component of the reflected
solarspectralirradianceastheweightingfunctionbyeitherthe
energy is not lost through an aperture. Ambient light must be
weighted (see 8.3.3) or selected (see 8.3.4) ordinate method. prevented from entering the sphere by placing a ring of black
velvet around the external rim of the specimen ports or by
5. Significance and Use covering the entire sphere attachment with a light tight
housing. Several acceptable system configurations are illus-
5.1 Solar-energyabsorptance,reflectance,andtransmittance
trated in Annex A1.
are important in the performance of all solar energy systems
ranging from passive building systems to central receiver
NOTE 4—The hemispherical near-normal irradiation-viewing mode is
power systems. This test method provides a means for deter- also allowed under this test method since the Helmholtz reciprocity
relationshipwhichholdsintheabsenceofpolarizationandmagneticfields
mining these values under fixed conditions that represent an
guarantees equivalent results are obtainable.
average that would be encountered during use of a system in
the temperate zone.
6.2 Standards:
5.2 Solar-energyabsorptance,reflectance,andtransmittance
6.2.1 In general, both reference and working (comparison)
are important for thermal control of spacecraft and the solar
standards are required. Reference standards are the primary
power of extraterrestrial systems. This test method also pro-
standard for the calibration of instruments and working stan-
vides a means for determining these values for extraterrestrial
dards. Reference standards that have high specular reflectance,
conditions.
high diffuse reflectance, and low diffuse reflectance are avail-
5.3 This test method is designed to provide reproducible
able from the National Institute of Standards and Technology
data appropriate for comparison of results among laboratories
as Standard Reference Materials (SRM).
oratdifferenttimesbythesamelaboratoryandforcomparison
of data obtained on different materials.
5.4 This test method has been found practical for materials Halon, available from the Allied Chemical Co., P.O. Box 697, Pottsville, PA
17901, has been found satisfactory for this purpose.
having both specular and diffuse optical properties except for
Available from Kodak Laboratory and Specialty Chemicals, Eastman Kodak
those materials that are inhomogeneous, patterned, or corru-
Co., 343 State St., Rochester, NY 14650.
gated.
The boldface numbers in parentheses refer to the list of references appended to
this test method.
National Institute of Standards and Technology, Office of Standard Reference
6. Apparatus
Materials,RoomB311,ChemistryBldg.,Washington,DC20234.Additionaldetails
6.1 Instrumentation: covering the appropriate SRMs(2019–2022) are available on request.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
E903–96
6.2.1.1 Working standards are used in the daily operation of 7. Test Specimens
the instrument to provide comparison curves for data reduc-
7.1 Specimens for Wall-Mounting Spheres:
tion. In general, ceramic and vitrified enamel surfaces are
7.1.1 The size of test specimens required depends on the
highly durable and desirable. A working standard shall be
dimensions of the integrating sphere. For wall-mounted
calibrated by measuring its optical properties relative to the
spheres the specimen must be large enough to cover the
properties of the appropriate reference standard using proce-
aperture of the sphere. There may be no limit on maximum
dures given in 8.2.
dimension. For patterned samples, either the specimen shall be
largeenoughtomakeanumberofmeasurementsoverdifferent
NOTE 5—Even the best standards tend to degrade with continued
handling. They should be handled with care and stored in a clean, safe areas, or several specimens representing the different areas of
manner. Working standards should be recalibrated periodically and
the material shall be used.
cleaned,renewed,orreplacedifdegradationisnoticeable.Avoidtouching
7.1.2 Opaque specimens shall have at least one surface that
the optical surfaces. Only clean soft cloth gloves should be worn for
is essentially plane over an area large enough to cover the
handling the standards. Only lens tissue or sterile cotton is recommended
aperture of the sphere.
for cleaning. This is especially important for reference standards carrying
7.1.3 Transparent and slightly translucent specimens shall
NBS calibration.
have two surfaces that are essentially plane and parallel. In
6.2.2 Fortransmittingspecimens,incidentradiationshallbe
order to reduce light scattered out the edges of translucent
used as the standard relative to which the transmitted light is
specimen,theminimumdistancebetweentheedgeofthebeam
evaluated.Forsomeapplicationscalibratedtransmittancestan-
and the edge of the aperture shall be ten times the thickness of
dards are available.
the specimen.
6.2.3 For diffuse high-reflectance specimens, a working
7.1.4 The transmittance of highly scattering translucent
standard that has high reflectance and is highly diffusing over
samples is not easily measured with an integrating sphere
the range of the solar spectrum is required.
instrument, because a significant portion of the incident flux
NOTE 6—Identified suitable working standards are tablets of pressed
will be scattered outside the aperture. For such materials the
tetrafluoroethylene polymer, BaSO , BaSO -based paints, and white
4 4
standard test method using the sun as a source (Test Methods
ceramic tile. The Halon (2) has superior reflectance at the longer
E1084 or E1175) is preferred.
wavelengths of interest but is less durable and more difficult to reproduce
accurately. Magnesium oxide either pressed or smoked is no longer
NOTE 10—If such a sample must be measured, the edge losses can be
recommended for use as a standard.
greatly reduced by using a circular sample of diameter slightly less than
that of the aperture, and coating the edge with silver, using the wet mirror
6.2.4 For specularly reflecting specimens, a working stan-
process. Alternatively small stops can be cemented to the edges of the
dard that is highly specular is required. Identified suitable
sample, so that it can be suspended in the aperture with about half of its
...
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