ASTM E2387-19
(Practice)Standard Practice for Goniometric Optical Scatter Measurements
Standard Practice for Goniometric Optical Scatter Measurements
SIGNIFICANCE AND USE
4.1 The angular distribution of scatter is a property of surfaces that may have direct consequences on an intermediate or final application of that surface. Scatter defines many visual appearance attributes of materials, and specification of the distribution and wavelength dependence is critical to the marketability of consumer products, such as automobiles, cosmetics, and electronics. Optically diffusive materials are used in information display applications to spread light from display elements to the viewer, and the performance of such displays relies on specification of the distribution of scatter. Stray-light reduction elements, such as baffles and walls, rely on absorbing coatings that have low diffuse reflectances. Scatter from mirrors, lenses, filters, windows, and other components can limit resolution and contrast in optical systems, such as telescopes, ring laser gyros, and microscopes.
4.2 The microstructure associated with a material affects the angular distribution of scatter, and specific properties can often be inferred from measurements of that scatter. For example, roughness, material inhomogeneity, and particles on smooth surfaces contribute to optical scatter, and optical scatter can be used to detect the presence of such defects.
4.3 The angular distribution of scattered light can be used to simulate or render the appearance of materials. Quality of rendering relies heavily upon accurate measurement of the light scattering properties of the materials being rendered.
SCOPE
1.1 This practice describes procedures for determining the amount and angular distribution of optical scatter from a surface. In particular it focuses on measurement of the bidirectional scattering distribution function (BSDF). BSDF is a convenient and well accepted means of expressing optical scatter levels for many purposes. It is often referred to as the bidirectional reflectance distribution function (BRDF) when considering reflective scatter or the bidirectional transmittance distribution function (BTDF) when considering transmissive scatter.
1.2 The BSDF is a fundamental description of the appearance of a sample, and many other appearance attributes (such as gloss, haze, and color) can be represented in terms of integrals of the BSDF over specific geometric and spectral conditions.
1.3 This practice also presents alternative ways of presenting angle-resolved optical scatter results, including directional reflectance factor, directional transmittance factor, and differential scattering function.
1.4 This practice applies to BSDF measurements on opaque, translucent, or transparent samples.
1.5 The wavelengths for which this practice applies include the ultraviolet, visible, and infrared regions. Difficulty in obtaining appropriate sources, detectors, and low scatter optics complicates its practical application at wavelengths less than about 0.2 µm (200 nm). Diffraction effects start to become important for wavelengths greater than 15 µm (15 000 nm), which complicate its practical application at longer wavelengths. Measurements pertaining to visual appearance are restricted to the visible wavelength region.
1.6 This practice does not apply to materials exhibiting significant fluorescence.
1.7 This practice applies to flat or curved samples of arbitrary shape. However, only a flat sample is addressed in the discussion and examples. It is the user’s responsibility to define an appropriate sample coordinate system to specify the measurement location on the sample surface and appropriate beam properties for samples that are not flat.
1.8 This practice does not provide a method for ascribing the measured BSDF to any scattering mechanism or source.
1.9 This practice does not provide a method to extrapolate data from one wavelength, scattering geometry, sample location, or polarization to any other wavelength, scattering geometry, sample location, or polarization. The user must ...
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E2387 − 19
Standard Practice for
1
Goniometric Optical Scatter Measurements
This standard is issued under the fixed designation E2387; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope an appropriate sample coordinate system to specify the mea-
surement location on the sample surface and appropriate beam
1.1 This practice describes procedures for determining the
properties for samples that are not flat.
amount and angular distribution of optical scatter from a
surface. In particular it focuses on measurement of the bidi- 1.8 This practice does not provide a method for ascribing
rectional scattering distribution function (BSDF). BSDF is a the measured BSDF to any scattering mechanism or source.
convenient and well accepted means of expressing optical
1.9 This practice does not provide a method to extrapolate
scatter levels for many purposes. It is often referred to as the
data from one wavelength, scattering geometry, sample
bidirectional reflectance distribution function (BRDF) when
location, or polarization to any other wavelength, scattering
considering reflective scatter or the bidirectional transmittance
geometry,samplelocation,orpolarization.Theusermustmake
distribution function (BTDF) when considering transmissive
measurements at the wavelengths, scattering geometries,
scatter.
sample locations, and polarizations that are of interest to his or
1.2 The BSDF is a fundamental description of the appear- her application.
ance of a sample, and many other appearance attributes (such
1.10 Any parameter can be varied in a measurement se-
as gloss, haze, and color) can be represented in terms of
quence.Parametersthatremainconstantduringameasurement
integrals of the BSDF over specific geometric and spectral
sequence are reported as either header information in the
conditions.
tabulated data set or in an associated document.
1.3 This practice also presents alternative ways of present-
1.11 Theapparatusandmeasurementprocedurearegeneric,
ing angle-resolved optical scatter results, including directional
sothatspecificinstrumentsareneitherexcludednorimpliedin
reflectance factor, directional transmittance factor, and differ-
the use of this practice.
ential scattering function.
1.12 For measurements performed for the semiconductor
1.4 ThispracticeappliestoBSDFmeasurementsonopaque,
industry, the operator should consult Guide SEMI ME 1392.
translucent, or transparent samples.
1.13 This standard does not purport to address all of the
1.5 The wavelengths for which this practice applies include
safety concerns, if any, associated with its use. It is the
the ultraviolet, visible, and infrared regions. Difficulty in
responsibility of the user of this standard to establish appro-
obtainingappropriatesources,detectors,andlowscatteroptics
priate safety, health, and environmental practices and deter-
complicates its practical application at wavelengths less than
mine the applicability of regulatory limitations prior to use.
about 0.2 µm (200 nm). Diffraction effects start to become
1.14 This international standard was developed in accor-
important for wavelengths greater than 15 µm (15000 nm),
dance with internationally recognized principles on standard-
which complicate its practical application at longer wave-
ization established in the Decision on Principles for the
lengths. Measurements pertaining to visual appearance are
Development of International Standards, Guides and Recom-
restricted to the visible wavelength region.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.6 This practice does not apply to materials exhibiting
significant fluorescence.
2. Referenced Documents
1.7 This practice applies to flat or curved samples of
2
2.1 ASTM Standards:
arbitraryshape.However,onlyaflatsampleisaddressedinthe
E284Terminology of Appearance
discussionandexamples.Itistheuser’sresponsibilitytodefine
E308PracticeforComputingtheColorsofObjectsbyUsing
the CIE System
1
This practice is under the jurisdiction ofASTM Committee E12 on Color and
2
Appearance and is the direct responsibility of Subcommittee E12.03 on Geometry. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2019. Published December 2019. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2005. Last previous edition approved in 2011 as E2387–05 (2011). Standar
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E2387 − 05 (Reapproved 2011) E2387 − 19
Standard Practice for
1
Goniometric Optical Scatter Measurements
This standard is issued under the fixed designation E2387; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice describes procedures for determining the amount and angular distribution of optical scatter from a surface. In
particular it focuses on measurement of the bidirectional scattering distribution function (BSDF). BSDF is a convenient and well
accepted means of expressing optical scatter levels for many purposes. It is often referred to as the bidirectional reflectance
distribution function (BRDF) when considering reflective scatter or the bidirectional transmittance distribution function (BTDF)
when considering transmissive scatter.
1.2 The BSDF is a fundamental description of the appearance of a sample, and many other appearance attributes (such as gloss,
haze, and color) can be represented in terms of integrals of the BSDF over specific geometric and spectral conditions.
1.3 This practice also presents alternative ways of presenting angle-resolved optical scatter results, including directional
reflectance factor, directional transmittance factor, and differential scattering function.
1.4 This practice applies to BSDF measurements on opaque, translucent, or transparent samples.
1.5 The wavelengths for which this practice applies include the ultraviolet, visible, and infrared regions. Difficulty in obtaining
appropriate sources, detectors, and low scatter optics complicates its practical application at wavelengths less than about 0.2 μm
(200 nm). Diffraction effects start to become important for wavelengths greater than 15 μm (15 000 nm), which complicate its
practical application at longer wavelengths. Measurements pertaining to visual appearance are restricted to the visible wavelength
region.
1.6 This practice does not apply to materials exhibiting significant fluorescence.
1.7 This practice applies to flat or curved samples of arbitrary shape. However, only a flat sample is addressed in the discussion
and examples. It is the user’s responsibility to define an appropriate sample coordinate system to specify the measurement location
on the sample surface and appropriate beam properties for samples that are not flat.
1.8 This practice does not provide a method for ascribing the measured BSDF to any scattering mechanism or source.
1.9 This practice does not provide a method to extrapolate data from one wavelength, scattering geometry, sample location, or
polarization to any other wavelength, scattering geometry, sample location, or polarization. The user must make measurements at
the wavelengths, scattering geometries, sample locations, and polarizations that are of interest to his or her application.
1.10 Any parameter can be varied in a measurement sequence. Parameters that remain constant during a measurement sequence
are reported as either header information in the tabulated data set or in an associated document.
1.11 The apparatus and measurement procedure are generic, so that specific instruments are neither excluded nor implied in the
use of this practice.
1.12 For measurements performed for the semiconductor industry, the operator should consult PracticeGuide SEMI ME 1392.
1.13 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.14 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
1
This practice is under the jurisdiction of ASTM Committee E12 on Color and Appearance and is the direct responsibility of Subcommittee E12.03 on Geometry.
Current edition approved July 1, 2011Nov. 1, 2019. Published July 2011December 2019. Originally approved in 2005. Last previous edition approved in 20052011 as
E2387 – 05.E2387 – 05 (2011). DOI: 10.1520/E2387-05R11.10.1520/E2387-19.
...
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