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ASTM E2175-01(2021)

(Practice)

Standard Practice for Specifying the Geometry of Multiangle Spectrophotometers

Standard Practice for Specifying the Geometry of Multiangle Spectrophotometers

SIGNIFICANCE AND USE
4.1 This practice is for the use of manufacturers and users of instruments to measure the appearance of gonioapparent materials, those writing standard specifications for such instruments, and others who wish to specify precisely the geometric conditions of multiangle spectrophotometry. A prominent example of industrial usage is the routine application of such measurements by material suppliers and automobile manufacturers to measure the colors of metallic paints and plastics.
SCOPE
1.1 This practice provides a way of specifying the angular and spatial conditions of measurement and angular selectivity of a method of measuring the spectral reflectance factors of opaque gonioapparent materials, for a small number of sets of geometric conditions.  
1.2 Measurements to characterize the appearance of retroreflective materials are of such a special nature that they are treated in other ASTM documents and are not included in the scope of this standard.  
1.3 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.  
1.4 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.

General Information

Status
Published
Publication Date
30-Sep-2021
ICS
17.180.30 - Optical measuring instruments
Technical Committee
E12 - Color and Appearance
Drafting Committee
E12.03 - Geometry
Current Stage
Ref Project

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ASTM E2175-01(2021) - Standard Practice for Specifying the Geometry of Multiangle SpectrophotometersASTM E2175-01(2021) - Standard Practice for Specifying the Geometry of Multiangle Spectrophotometers
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ASTM E2175-01(2021) - Standard Practice for Specifying the Geometry of Multiangle Spectrophotometers
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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:E2175 −01 (Reapproved 2021)
Standard Practice for
1
Specifying the Geometry of Multiangle Spectrophotometers
This standard is issued under the fixed designation E2175; 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.
INTRODUCTION
The appearance of metallic coatings and plastics usually depends on the directions of illumination
and viewing, a phenomenon called “gonioappearance.” This phenomenon is also observed with other
materials, such as lustrous textiles and materials containing pearlescent or interference pigments. The
characteristic appearance of most such materials is accentuated by directional illumination, such as
that provided by the sun on a clear day or a small lamp at night. The variation in color, as a function
of geometry, is usually measured by spectrophotometry with several specified sets of geometric
conditions. Measurement of this kind, at a few selected angles, is called “multiangle
spectrophotometry,” as distinguished from measurement over a broad range of angles, which is called
“goniospectrophotometry.” Spectrophotometric aspects of these measurements, including spectral
resolution and linearity of photometric scales, are treated in other standards, including Practice E308
and Practice E1164. Practice E1767 provides practice for specifying the geometry of measurements.
Retroreflectors exhibit a special kind of gonioappearance, which is treated in otherASTM documents.
The present document provides standard practice for specifying influx and efflux angles, angular
selectivity, spatial distributions of illuminators and receivers, and angular aspects of standardizing the
photometric scale, that are peculiar to multiangle spectrophotometry. Directional illumination
emphasizes the gonioappearance of most materials, but when interference pigments are used, such as
those used in ink to mark paper currency, the effect is observed with diffuse illumination and varying
angles of viewing, so these materials are also measured with diffuse illumination.
1. Scope ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
1.1 This practice provides a way of specifying the angular
mendations issued by the World Trade Organization Technical
and spatial conditions of measurement and angular selectivity
Barriers to Trade (TBT) Committee.
of a method of measuring the spectral reflectance factors of
opaque gonioapparent materials, for a small number of sets of
2. Referenced Documents
geometric conditions.
2
2.1 ASTM Standards:
1.2 Measurements to characterize the appearance of retrore-
E284 Terminology of Appearance
flective materials are of such a special nature that they are
E308 PracticeforComputingtheColorsofObjectsbyUsing
treated in other ASTM documents and are not included in the
the CIE System
scope of this standard.
E1164 PracticeforObtainingSpectrometricDataforObject-
1.3 This standard does not purport to address all of the Color Evaluation
safety concerns, if any, associated with its use. It is the E1767 Practice for Specifying the Geometries of Observa-
responsibility of the user of this standard to establish appro- tion and Measurement to Characterize the Appearance of
priate safety, health, and environmental practices and deter- Materials
mine the applicability of regulatory limitations prior to use.
3. Terminology
1.4 This international standard was developed in accor-
3.1 Fordefinitionsofappearancetermsusedinthispractice,
dance with internationally recognized principles on standard-
refer to Terminology E284.
1
This practice is under the jurisdiction of ASTM 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 Oct. 1, 2021. Published October 2021. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2001. Last previous edition approved in 2013 as E2175 – 01 (2013). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/E2175-01R21. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
E2175−01 (2021)
4. Significance and Use Angles subtended at the origin and measured from that normal
are called “anorma
...

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ASTM E1767-11(2022)(Practice)
Standard Practice for Specifying the Geometries of Observation and Measurement to Characterize the Appearance of Materials

SIGNIFICANCE AND USE
5.1 This practice is for the use of manufacturers and users of equipment for visual appraisal or measurement of appearance, those writing standards related to such equipment, and others who wish to specify precisely conditions of viewing or measuring attributes of appearance. The use of this practice makes such specifications concise and unambiguous. The functional notation facilitates direct comparisons of the geometric specifications of viewing situations and measuring instruments.
SCOPE
1.1 This practice describes the geometry of illuminating and viewing specimens and the corresponding geometry of optical measurements to characterize the appearance of materials. It establishes terms, symbols, a coordinate system, and functional notation to describe the geometric orientation of a specimen, the geometry of the illumination (or optical irradiation) of a specimen, and the geometry of collection of flux reflected or transmitted by the specimen, by a measurement standard, or by the open sampling aperture.  
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4.1 This practice is commonly used by vehicle service personnel to determine the freezing point, in degrees Celsius or Fahrenheit, of aqueous solutions of commercial ethylene and propylene glycol-based coolant. A durable hand-held refractometer is available that reads the freezing point, directly, in degrees Celsius or Fahrenheit, when a few drops of engine coolant are properly placed on the temperature-compensated prism surface of the refractometer. This refractometer is for glycol and water solutions, and is not suitable for other coolant solutions.  
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5.1 Cryo-TEM is a technique used to record high resolution images of samples that are frozen and embedded in a thin layer of vitrified, amorphous ice (2-5). Because vitrification occurs so rapidly, the resultant specimen is almost instantly frozen, yielding a very accurate representation of the specimen at the moment of freezing, without the distortions typically associated with air drying delicate wet samples. Once frozen, images of the specimen are recorded at low temperature using a specially designed electron microscope equipped with a cryo-holder capable of operating under low dose conditions in order to prevent beam induced structural damage to the specimen. The cryo-TEM technique is the consensus choice to directly observe, analyze and accurately measure liposomes suspended in aqueous solutions. Fig. 1 illustrates this by comparing an electron micrograph from an air-dried negatively stained liposomal preparation with an electron micrograph of the same solution imaged by cryo-TEM.
FIG. 1 Left—An Electron Micrograph of an Air-Dried Liposomal Preparation that has been Negatively Stained with 2 % Uranyl Acetate for Contrast; Right—An Electron Micrograph of the Same Liposomal Preparation Prepared as a Frozen Vitrified Specimen for Cryo-TEM
Note 1: Both images are shown to the same scale; scale bar is 200 nm.  
5.1.1 Fig. 1 demonstrates that liposomes may become distorted and are difficult to measure and analyze when they are air-dried, while the same liposomal preparation is clearly easier to analyze when the specimen is near-instantly preserved by vitrification.  
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SCOPE
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Standard Practice for Describing Photomultiplier Detectors in Emission and Absorption Spectrometry

ABSTRACT
This practice describes the photomultiplier properties that are essential to their judicious selection and use of in emission and absorption spectrometry. The properties covered here include structural features, electrical properties, and characteristics involved in precautions and problems. The structural features covered are envelope configurations, window materials, electrical connections, and housing for the external structure, and the photocathode, dynodes and anode, and rigidness of structural components for the internal structure. Electrical properties, on the other hand, incorporate the following: optical-electronic characteristics of the photocathode including spectral response; current amplification including gain per stage, overall gain, gain control (voltage-divider bridge), linearity of response, and anode saturation; signal nature; dark current including cathode size, internal aperture, and refrigeration effects; noise nature including additivity of noise power, signal-to-noise ratio, equivalent noise input; and photomultiplier properties as a component in an electrical circuit including output impedance, response time, and signal gating and integration possibilities. Finally, the characteristics involved in precautions and problems cover fatigue and hysteresis effects, illumination of photocathode, and gas leakage.
SCOPE
1.1 This practice covers photomultiplier properties that are essential to their judicious selection and use in emission and absorption spectrometry. Descriptions of these properties can be found in the following sections:    
Section  
Structural Features  
4  
General  
4.1  
External Structure  
4.2  
Internal Structure  
4.3  
Electrical Properties  
5  
General  
5.1  
Optical-Electronic Characteristics of the Photocathode  
5.2  
Current Amplification  
5.3  
Signal Nature  
5.4  
Dark Current  
5.5  
Noise Nature  
5.6  
Photomultiplier as a Component in an Electrical Circuit  
5.7  
Precautions and Problems  
6  
General  
6.1  
Fatigue and Hysteresis Effects  
6.2  
Illumination of Photocathode  
6.3  
Gas Leakage  
6.4  
Recommendations on Important Selection Criteria  
7  
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FIG. 1 SRM 2241 Measured on Four Commercial Raman Spectrometers Utilizing 785 nm Excitation  
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SCOPE
1.1 This guide is designed to enable the user to correct a Raman spectrometer for its relative spectral-intensity response function using NIST Standard Reference Materials2 in the 224X series (currently SRMs 2241, 2242, 2243, 2244, 2245, 2246), or a calibrated irradiance source. This relative intensity correction procedure will enable the intercomparison of Raman spectra acquired from differing instruments, excitation wavelengths, and laboratories.  
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ASTM E1840-96(2022)(Guide)
Standard Guide for Raman Shift Standards for Spectrometer Calibration

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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.  
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ASTM E1172-22(Practice)
Standard Practice for Describing and Specifying a Wavelength Dispersive X-Ray Spectrometer

SIGNIFICANCE AND USE
4.1 This practice describes the essential components of a wavelength dispersive X-ray spectrometer. This description is presented so that the user may gain a general understanding of the structure of an X-ray spectrometer system. It also provides a means for comparing and evaluating different systems as well as understanding the capabilities and limitations of each instrument.  
4.2 A laboratory may implement this practice or an X-ray fluorescence method in partnership with a manufacturer of the analytical instrumentation. If a laboratory chooses to consult with an instrument manufacturer, then the following should be considered. The laboratory should know the alloy matrices to be analyzed, elements and mass fraction ranges to be determined, and the expected performance requirements for each of these elements. The laboratory should inform the instrument manufacturer of these requirements so an analytical method may be developed which meets the laboratory’s expectations. Typically, instrument manufacturers customize the instrument configuration to satisfy the end-user’s requirements for elemental coverage, elemental precision, and detection limits. Instrument manufacturer developed analytical methods may include specific parameters for sample excitation, wavelengths, inter-element interference corrections, calibration and regression, equipment configuration/installation, and sample preparation requirements. Laboratories should have a basic understanding of the parameters derived by the manufacturer.
SCOPE
1.1 This practice covers the components of a wavelength dispersive X-ray spectrometer that are basic to its operation and to the quality of its performance. It is not the intent of this practice to specify component tolerances or performance criteria, as these are unique for each instrument. However, the practice does attempt to identify which tolerances are critical and thus which should be specified.  
1.2 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. Specific safety hazard statements are given in Section 7.  
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ASTM E925-09(2022)(Practice)
Standard Practice for Monitoring the Calibration of Ultraviolet-Visible Spectrophotometers whose Spectral Bandwidth does not Exceed 2 nm

SIGNIFICANCE AND USE
4.1 This practice permits an analyst to compare the performance of an instrument to the manufacturer's supplied performance specifications and to verify its suitability for continued routine use. It also provides generation of calibration monitoring data on a periodic basis, forming a base from which any changes in the performance of the instrument will be evident.
SCOPE
1.1 This practice covers the parameters of spectrophotometric performance that are critical for testing the adequacy of instrumentation for most routine tests and methods2 within the wavelength range of 200 nm to 700 nm and the absorbance range of 0 to 2. The recommended tests provide a measurement of the important parameters controlling results in spectrophotometric methods, but it is specifically not to be inferred that all factors in instrument performance are measured.  
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1.3 This practice should be performed on a periodic basis, the frequency of which depends on the physical environment within which the instrumentation is used. Thus, units handled roughly or used under adverse conditions (exposed to dust, chemical vapors, vibrations, or combinations thereof) should be tested more frequently than those not exposed to such conditions. This practice should also be performed after any significant repairs are made on a unit, such as those involving the optics, detector, or radiant energy source.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
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ASTM E387-04(2022)(Test Method)
Standard Test Method for Estimating Stray Radiant Power Ratio of Dispersive Spectrophotometers by the Opaque Filter Method

SIGNIFICANCE AND USE
5.1 Stray radiant power can be a significant source of error in spectrophotometric measurements. SRP usually increases with the passage of time; therefore, testing should be performed periodically. Moreover, the SRPR test is an excellent indicator of the overall condition of a spectrophotometer. A control-chart record of the results of routinely performed SRPR tests can be a useful indicator of need for corrective action or, at least, of the changing reliability of critical measurements.  
5.2 This test method provides a means of determining the stray radiant power ratio of a spectrophotometer at selected wavelengths in a spectral range, as determined by the SRP filter used, thereby revealing those wavelength regions where significant photometric errors might occur. It does not provide a means of calculating corrections to indicated absorbance (or transmittance) values. The test method must be used with care and understanding, as erroneous results can occur, especially with respect to some modern grating instruments that incorporate moderately narrow bandpass SRP-blocking filters. This test method does not provide a basis for comparing the performance of different spectrophotometers.
Note 8: Kaye (3) discusses correction methods of measured transmittances (absorbances) that sometimes can be used if sufficient information on the properties and performance of the instrument can be acquired. See also A1.2.5.  
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5.4 The SRPR indicated by this test method using SRP filters is almost always an underestimation of the true value (see 1.3). A value cited in a manufacturer’s li...
SCOPE
1.1 Stray radiant power (SRP) can be a significant source of error in spectrophotometric measurements, and the danger that such error exists is enhanced because its presence often is not suspected (1-4).2 This test method affords an estimate of the relative radiant power, that is, the Stray Radiant Power Ratio (SRPR), at wavelengths remote from those of the nominal bandpass transmitted through the monochromator of an absorption spectrophotometer. Test-filter materials are described that discriminate between the desired wavelengths and those that contribute most to SRP for conventional commercial spectrophotometers used in the ultraviolet, the visible, the near infrared, and the mid-infrared ranges. These procedures apply to instruments of conventional design, with usual sources, detectors, including array detectors, and optical arrangements. The vacuum ultraviolet and the far infrared present special problems that are not discussed herein.
Note 1: Research (3) has shown that particular care must be exercised in testing grating spectrophotometers that use moderately narrow bandpass SRP-blocking filters. Accurate calibration of the wavelength scale is critical when testing such instruments. Refer to Practice E275.  
1.2 These procedures are neither all-inclusive nor infallible. Because of the nature of readily available filter materials, with a few exceptions, the procedures are insensitive to SRP of very short wavelengths in the ultraviolet, or of lower frequencies in the infrared. Sharp cutoff longpass filters are available for testing for shorter wavelength SRP in the visible and the near infrared, and sharp cutoff shortpass filters are available for testing at longer visible wavelengths. The procedures are not necessarily valid for “spike” SRP nor for “nearby SRP.” (See Annexes for general discussion and definitions of these terms.) However, they are adequate in most cases and for typical applications. They do cover...

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