Find the most up-to-date version of ASTM E at Engineering ASTM E() E1 Standard Practice for Obtaining Spectrometric Data for Object-Color Evaluation [ASTM International] on *FREE*. ASTM E Standard Practice for Obtaining Spectrometric Data for Object- Color Evaluation. This practice covers the instrumental measurement.
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A number in parentheses indicates the year of last reapproval. The considerations involved and the procedures used to obtain precise spectrometric data are contained in this practice. The values and procedures for computing CIE tristimulus values from spectrometric data are contained in Practice E Considerations regarding the selection of appropriate illuminating and viewing geometries are contained in Guide E Exceptions to this applicability are noted.
This practice is general as to the materials to be characterized for color. Asgm other units of measurement are included in this standard. 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.
Current edition approved June 1, Originally approved in Last previous edition approved e116 as E — It exceeds unity if the system is such that the specimen causes more light to reach the receiver than would in its absence.
Summary of Practice 4. The important steps in the calibration of such instruments, and the material standards required for these steps, are described. Colorimetric data are obtained by combining object spectral data with data representing a CIE standard observer and a CIE standard illuminant, as described in Practice E It also provides for instrument calibration by means of material standards, and for selection of suitable specimens for obtaining precision in the measurements.
Requirements When Using Spectrometry 6. E — 09a 7. The spectrometer may be either a typical colorimetric spectrometer, designed speci?
Commonly used light sources include incandescent lamps, either operated without? More recently, discrete pseudo-monochromatic sources, such as light emitting diodes LED have also been used as sources in colorimetric spectrometers.
Considerations required when measuring? The use of pseudomonochromatic sources is not currently recommended by Subcommittee E The element should conform to the following requirements: Use of shorter wavelength ranges may result in reduced accuracy.
Each user must decide whether the loss of accuracy in his measurements is negligibly small for the purpose for which data are obtained. NOTE 1—Accuracy is here de?
If the spectral interval and bandpass are greater than 1 nm then it is recommended that the spectral data be interpolated and then deconvolved 21 down to the 1 nm interval before computing tristimulus values as recommended in Practice E However, the use of a wider interval can lead to signi?
However, for the measurement of? A still better method for characterizing? The detector may be a photoelectric device phototube or photomultipliera silicon photodiode or diode array, or another suitable photodetector. The detector must be stable with time and have adequate responsivity over the wavelength range used. NOTE 2—With the possible exception of the measurement of unusually structured or?
For example, the value of the re? In order to avoid implying unnecessary restrictions on instrumentation that can be used, when referencing this practice one should except in those cases of? See Practice E Use of a wider interval, such as 10 nm or 20 nm, will result in a signi?
The following paragraphs incorporate such a statement. The angle between the direction of viewing and the normal to the specimen surface should not exceed 0. The same restriction applies to the viewing beam. Detailed descriptions of these geometries can be found in the appropriate sections of Practice E NOTE 3—For certain applications of the The geometric arrangement of the viewing beam may be the same as that of the illuminating beam, or may differ, for example, by the use of a hemispherical receiver such as an integrating sphere.
The requirements for illuminating and viewing may be interchanged. NOTE 5—When a hemispherical receiver such as an integrating sphere is used, and the specimen is placed? When the specimen is placed in the transmission compartment as far away from the sphere port as possible, essentially regular transmittance factor is obtained.
In general, spectral re? Thus there is only one mode of measurement possible for the d: When all regularly that is, specularly re?
NOTE 4—Corrections for errors in the use of integrating spheres for the 8. Special precautions, outlined here, must be observed to minimize the effects of these characteristics; the use of special equipment beyond the scope of this practice may be required to eliminate the effects entirely. Tt and the measurement provides the total transmittance factor Tt. When the regularly transmitted beam is excluded, for example by the use of a light trap, the condition is designated 0: Td and the diffuse transmittance Td is obtained.
Details of the size, shape, and re? The results of diffuse measurements made on specimens having broad regular-transmittance factor peaks will depend importantly on the size of the re? It is essential that these portions impinge on areas of the sphere wall having the same re? If a white re?
Care must also be taken to avoid discoloring of either area due to prolonged radiation or dirt, or partial translucency due to insufficient thickness of the coating. In such cases, it is recommended 5 to use the substitution method of measurement rather than the comparison method 3.
Care must be taken to correct for this error 3, Test Method D NOTE 6—For all the conditions described in 8. See also Guide E and Practice E Geometric notations may be found in Practice E Special considerations for the interactions between an 5 instrument geometry and the specimen surface are cited in the following sections and will also apply to the formulation of product colors.
Use of most geometries will not allow complete separation of the surface effects from the color. The preferred geometry will be the one that minimizes the surface effects, thereby optimizing the separation. When the degree of directionality of the specimen is to be evaluated, uniplanar geometry should be used. The angles at which these readings occur should be noted in reference to the orientation of the specimen.
When information on directionality is not required, the several measurements may be averaged. When the specimen does not exhibit directionality, any of the bi-directional geometries may be used.
Some modern, high brightness, retrore? In these cases, it may be more appropriate to use larger cone angles, with appropriate tolerances.
Standard Practice for Obtaining Spectrometric Data for Object-Color Evaluation
When the specimens do not have these desired characteristics, departures should be noted. Care should be taken not to touch the area to be measured except for application of a suitable cleaning procedure. The condition of the specimens before and after measurement should be noted and reported. Standardization and Material Standards The instrument user must assume the responsibility for obtaining the necessary material standards. The CIE recommends that this ideal standard of re? Other standards calibrated to the perfect re?
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In other cases, use may be made of another white material, with assigned re? For transmittance measurement, the reading obtained in the absence of a specimen is regularly assigned the value Some national laboratories will accept user supplied white material standards and supply a calibration of the re? The same asm should be used to verify the zero reading in instruments that do not require such a calibration step.
The presence of surface contaminants will critically affect the atm of this standard. Dust, dirt and even? If the black-cavity traps light by utilizing asymmetric or off-axis black optics then a preferred orientation of the cavity relative to the optical axis should be identi?
Whenever the cavity is employed it should always be presented to the instrument in the indicated orientation. Blocking should be carried out by replacing the specimen with an opaque object of the same size and shape ee1164 the specimen, placed in the same position.
In such cases, verify the accuracy of the reading at the low end of the photometric scale by using a calibrated standard with re? While this method works? Keeping the surface clean is essential as errors in apparent re? Errors in the apparent re? If the instrument requires calibration with a Grey tile to evaluate the single-beam integrating-sphere photometric nonlinearity, the linearity veri? Examples of suitable veri?
It is highly recommended that instrumental readings be corrected for? This step does not apply to spectrocolorimeters. Precision and Bias