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ASTM E2387-05

(Practice)

Standard Practice for Goniometric Optical Scatter Measurements

Standard Practice for Goniometric Optical Scatter Measurements

SIGNIFICANCE AND USE
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.
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.
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
p>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 m (200 nm). Diffraction effects start to become important for wavelengths greater than 15 m (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 users 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 wavele...

General Information

Status
Historical
Publication Date
31-Dec-2004
ICS
17.180.30 - Optical measuring instruments
Technical Committee
E12 - Color and Appearance
Drafting Committee
E12.03 - Geometry
Current Stage
Ref Project

Relations

Replaced By
ASTM E2387-05(2011) - Standard Practice for Goniometric Optical Scatter Measurements
Effective Date
01-Jul-2011

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ASTM E2387-05 - Standard Practice for Goniometric Optical Scatter Measurements
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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: E2387 – 05
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 surement location on the sample surface and appropriate beam
properties for samples that are not flat.
1.1 This practice describes procedures for determining the
1.8 This practice does not provide a method for ascribing
amount and angular distribution of optical scatter from a
the measured BSDF to any scattering mechanism or source.
surface. In particular it focuses on measurement of the bidi-
1.9 This practice does not provide a method to extrapolate
rectional scattering distribution function (BSDF). BSDF is a
data from one wavelength, scattering geometry, sample loca-
convenient and well accepted means of expressing optical
tion, or polarization to any other wavelength, scattering geom-
scatter levels for many purposes. It is often referred to as the
etry, sample location, or polarization. The user must make
bidirectional reflectance distribution function (BRDF) when
measurements at the wavelengths, scattering geometries,
considering reflective scatter or the bidirectional transmittance
sample locations, and polarizations that are of interest to his or
distribution function (BTDF) when considering transmissive
her application.
scatter.
1.10 Any parameter can be varied in a measurement se-
1.2 The BSDF is a fundamental description of the appear-
quence.Parametersthatremainconstantduringameasurement
ance of a sample, and many other appearance attributes (such
sequence are reported as either header information in the
as gloss, haze, and color) can be represented in terms of
tabulated data set or in an associated document.
integrals of the BSDF over specific geometric and spectral
1.11 Theapparatusandmeasurementprocedurearegeneric,
conditions.
sothatspecificinstrumentsareneitherexcludednorimpliedin
1.3 This practice also presents alternative ways of present-
the use of this practice.
ing angle-resolved optical scatter results, including directional
1.12 For measurements performed for the semiconductor
reflectance factor, directional transmittance factor, and differ-
industry, the operator should consult Practice SEMI ME1392.
ential scattering function.
1.13 This standard does not purport to address all of the
1.4 ThispracticeappliestoBSDFmeasurementsonopaque,
safety concerns, if any, associated with its use. It is the
translucent, or transparent samples.
responsibility of the user of this standard to establish appro-
1.5 The wavelengths for which this practice applies include
priate safety and health practices and determine the applica-
the ultraviolet, visible, and infrared regions. Difficulty in
bility of regulatory limitations prior to use.
obtaining appropriate sources, detectors, and low scatter optics
complicates its practical application at wavelengths less than
2. Referenced Documents
about 0.2 µm (200 nm). Diffraction effects start to become
2
2.1 ASTM Standards:
important for wavelengths greater than 15 µm (15000 nm),
E284 Terminology of Appearance
which complicate its practical application at longer wave-
E308 Practice for Computing the Colors of Objects by
lengths. Measurements pertaining to visual appearance are
Using the CIE System
restricted to the visible wavelength region.
E1331 Test Method for Reflectance Factor and Color by
1.6 This practice does not apply to materials exhibiting
Spectrophotometry Using Hemispherical Geometry
significant fluorescence.
2.2 ISO Standard:
1.7 This practice applies to flat or curved samples of
ISO 13696 Optics and Optical Instruments—Test Methods
arbitraryshape.However,onlyaflatsampleisaddressedinthe
3
for Radiation Scattered by Optical Components
discussionandexamples.Itistheuser’sresponsibilitytodefine
an appropriate sample coordinate system to specify the mea-
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
1
This practice is under the jurisdiction ofASTM Committee E12 on Color and Standards volume information, refer to the standard’s Document Summary page on
Appearance and is the direct responsibility of Subcommittee E12.03 on Geometry. the ASTM website.
3
Current edition approved Jan. 1, 2005. Published February 2005. DOI: 10.1520/
Available from International Organization for Standardization (ISO), 1 rue de
E2387-05. Varembé, Case postale 56, CH-1211, Geneva 20, Switzerland.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
...

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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.  
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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.  
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Section  
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4  
General  
4.1  
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4.2  
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5.1  
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5.2  
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5.7  
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6.1  
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6.2  
Illumination of Photocathode  
6.3  
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FIG. 1 SRM 2241 Measured on Four Commercial Raman Spectrometers Utilizing 785 nm Excitation  
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Standard Guide for Raman Shift Standards for Spectrometer Calibration

SIGNIFICANCE AND USE
4.1 Wavenumber calibration is an important part of Raman analysis. The calibration of a Raman spectrometer is performed or checked frequently in the course of normal operation and even more often when working at high resolution. To date, the most common source of wavenumber values is either emission lines from low-pressure discharge lamps (for example, mercury, argon, or neon) or from the non-lasing plasma lines of the laser. There are several good compilations of these well-established values (1-8).3 The disadvantages of using emission lines are that it can be difficult to align lamps properly in the sample position and the laser wavelength must be known accurately. With argon, krypton, and other ion lasers commonly used for Raman the latter is not a problem because lasing wavelengths are well known. With the advent of diode lasers and other wavelength-tunable lasers, it is now often the case that the exact laser wavelength is not known and may be difficult or time-consuming to determine. In these situations it is more convenient to use samples of known relative wavenumber shift for calibration. Unfortunately, accurate wavenumber shifts have been established for only a few chemicals. This guide provides the Raman spectroscopist with average shift values determined in seven laboratories for seven pure compounds and one liquid mixture.
SCOPE
1.1 This guide covers Raman shift values for common liquid and solid chemicals that can be used for wavenumber calibration of Raman spectrometers. The guide does not include procedures for calibrating Raman instruments. Instead, this guide provides reliable Raman shift values that can be used as a complement to low-pressure arc lamp emission lines which have been established with a high degree of accuracy and precision.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 Some of the chemicals specified in this guide may be hazardous. It is the responsibility of the user of this guide to consult material safety data sheets and other pertinent information to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to their use.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 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.

  • Guide
    11 pages
    English language
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