ASTM E1651-94(1999)

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Designation: E 1651 – 94 (Reapproved 1999)
Standard Test Method for
Total Luminous Reflectance Factor by Use of 30/t
Integrating-Sphere Geometry
This standard is issued under the fixed designation E 1651; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
This test method has a long but undocumented history. The electric lighting industry for many years
used a visual reflectometer with 30° unidirectional illumination and a sphere to collect all the reflected
light so as to obtain a measure of total luminous reflectance factor, specular plus diffuse, for 30/t
geometry. 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 CIE
geometry, such as 6/t. In 1975, the original 30/t geometry was incorporated in an instrument of modern
design. This test method documents the calibration and measurement procedures for such an
instrument.
1. Scope E 259 Practice for Preparation of Pressed Powder White
Reflectance Factor Transfer Standards for Hemispherical
1.1 This test method covers measurement of total luminous
and Bi-Directional Geometries
reflectance factor of opaque, nonfluorescent specimens by use
E 284 Terminology of Appearance
of an integrating-sphere reflectometer with illumination at an
E 691 Practice for Conducting an Interlaboratory Study to
angle of 30° from the surface normal and diffuse viewing with
Determine the Precision of a Test Method
specular component included.
E 1345 Practice for Reducing the Effect of Variability of
1.2 This test method is intended to be used for evaluation of
Color Measurement by Use of Multiple Measurements
total luminous reflectance factor of reflector lighting sheet
E 1347 Test Method for Color and Color-Difference Mea-
material. It may be used for evaluation of other material when
surements by Tristimulus (Filter) Colorimetry
its specific geometry has been found to be applicable.
1.3 This standard does not purport to address all of the
3. Terminology
safety concerns, if any, associated with its use. It is the
3.1 Definitions in Guide E 179 and Terminology E 284 are
responsibility of the user of this standard to establish appro-
applicable to this test method.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4. Summary of Test Method
4.1 This test method requires the use of a reflectometer
2. Referenced Documents
equipped with an integrating sphere with an angle of illumi-
2.1 ASTM Standards:
nation of 30° to the surface normal and diffuse viewing with
E 177 Practice for Use of the Terms Precision and Bias in
2 the specular component included. In other respects, the details
ASTM Standards
of the instrument geometry are as specified in Guide E 179.
E 179 Guide for Selection of Geometric Conditions for
The use of the 30° angle of illumination allows complete
Measurement of Reflection and Transmission Properties of
3 collection of flux reflected at angles near the specular angle.
Materials
4.2 This test method utilizes only the Y tristimulus function,
leading to the measurement of luminous reflectance. In other
This test method is under the jurisdiction of ASTM Committee E-12 on Color respects, the spectral characteristics and methodology used are
andAppearance and is the direct responsibility of Subcommittee E12.02 on
similar to those described in Test Method E 1347. It should be
Spectrophotometry and Colorimetry.
noted that, when and if suitable equipment is available,
Current edition approved Nov. 15, 1994. Published January 1995.
Annual Book of ASTM Standards, Vol 14.02.
Annual Book of ASTM Standards, Vol 06.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 1651 – 94 (1999)
spectrophotometric measurement is equally as acceptable as illuminates the specimen, (9), through specimen opening, (8).
the (filter) colorimetric method described in this test method. Total reflectance (consisting of specular and diffuse compo-
nents) is integrated by the sphere and read by the filter/
5. Significance and Use
photocell. The digital display, (11), shows the ratio of this
reflectance to that stored in memory, displayed in percent.
5.1 Procedures of this test method provide a quantitative
measure of total luminous reflectance, which is related to 6.1.2 The optical characteristics of the integrating sphere
and its coating shall be as recommended in Guide E 179 except
reflection efficiency of lighting reflectors. This test method is
extensively used to assess total reflectance factor of reflector that the angle of illumination shall be 30 6 1° with a maximum
aperture angle of 10°. Viewing shall be diffuse, with the
sheet used in the manufacture of lighting fixtures.
specular component included. The measured area shall be a
circle with area 6.5 cm ; otherwise multiple measurements
shall be made and averaged to achieve an equivalent specimen
area (see 8.2.3).
6.1.3 The spectral responsivity of the illuminator-filter-
receiver combination shall match that of the CIE spectral
luminous efficiency function V (l) when combined with CIE
standard illuminant C if a filter-type reflectometer is used. Use
of spectrophotometric apparatus is allowable if it fulfils the
geometric requirements of 6.1.2.
6.2 Calibration Standards, either supplied by the manufac-
turer or obtained separately. The standards, one white and one
black, must be flat, opaque, glossy ceramic glass or porcelain
enamel plaques at least 75 by 75 mm.
6.2.1 White Reflecting Tile or Standard (Mandatory)—This
instrument standard shall be calibrated by use of 30/t geometry
against barium su
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