Home>ASTM Standards>ASTM E1341-16(R2020) pdf free download

ASTM E1341-16(R2020) pdf free download

ASTM E1341-16(R2020) pdf free download.Standard Practice for Obtaining Spectroradiometric Data from Radiant Sources for Colorimetry
4. Summary of Practice
4.1 Procedures are given for selecting the types and oper- ating parameters of spectroradiometers used to produce data for the calculation of CIE tristimulus values and other color coordinates to describe the colors of radiant sources. The important steps of the calibration of such instruments, and the standards required for these steps, are described. Parameters are identified that must be specified when spectroradiometric measurements are required in specific methods or other docu- ments. Modifications to Practice E308 are described in order to account for the differences between objects and radiant sources.
5. Significance and Use
5.1 The fundamental method for obtaining CIE tristimulus values or other color coordinates for describing the colors of radiant sources is by the use of spectroradiometric measure- ments. These measurements are used by summation together with numerical values representing the CIE 1931 Standard Observer (CIE Publication 015:2004) and normalized to K m , the maximum spectral luminous efficacy function, with a value of 683 lm/W. 5.2 This practice provides a procedure for selecting the operating parameters of spectroradiometers used for providing the desired precision spectroradiometric data, for their calibration, and for the physical standards required for calibra- tion. 5.3 Special requirements for characterizing sources of light possessing narrow or discontinuous spectra are presented and discussed. Modifications to the procedures ofPractice E308 are given to correct for the unusual nature of narrow or discon- tinuous sources.
6. Requirements When Using Spectroradiometry
6.1 When describing the measurement of radiant sources by spectroradiometry, the following must be specified. 6.1.1 The radiometric quantity determined, such as the irradiance (W/m 2 ) or radiance (W/m 2 -sr), or the photometric quantity determined, such as illuminance (lm/m 2 ) or luminance (lm/m 2 -sr or cd/m 2 ). The use ofolder, less descriptive names or units such as phot, nit, stilb (see ANSI/IES RP-16-1980) is not recommended. 6.1.2 The geometry of the measurement conditions, includ- ing whether a diffuser was used and its material of construction, the distances from the source of irradiation to the entrance to the spectroradiometer, and the presence of any special intermediate optical devices such as integrating spheres. 6.1.3 The spectral parameters, including the spectral region, wavelength measurement interval, and spectral bandwidth. 6.1.4 The type of standard used to calibrate the system, a standard lamp, a calibrated source, or a calibrated detector, and the source of the calibration.
7. Apparatus
7.1 The basic instrument requirement is a spectroradiomet- ric system designed for the measurement of spectral radiance or irradiance of light sources. The basic elements of a spectro- radiometric system are calibration sources with their regulated power supplies, a light detector, electronics for measuring the photocurrents, a monochromator with control equipment for computer interfacing, receiving optics, and a computer as described in CIE Publication No. 63 and IES Guide to Spectroradiometric Measurements. The computer is listed as an integral part of the system since the required precision is unobtainable without automated control. The characteristics of each element are discussed in the following sections.7.2 Calibration Sources—The standard calibration lamp for spectroradiometry is a tungsten-filament lamp operated at a specified current. Such lamps are available from many stan- dardizing laboratories. Typical ofsuch standards is the tungsten filament, 1000 W, halogen cycle, quartz-envelope FEL-type lamp recommended by the National Institute of Standards and Technology (NIST). (See NIST Technical Note 594-1, and 594-3.) Uncertainties in the transfer of the scale of spectral radiance or irradiance are about 1 %. It is preferable to have more than one standard source to permit cross-checks and to allow calibration at a range ofilluminance levels. Such sources can be constructed from lamps operating at any color tempera- ture and spectral nature that have been characterized against a standard lamp. Monochromatic emission sources, such as a low-pressure mercury arc lamp or tunable laser, should also be available for use in calibrating the wavelength scale in accor- dance with Practice E925. Multiline lasers, such as continuous wave (cw) argon-ion and helium-neon, are preferred since they can be tuned to a small number of lines of well known wavelengths.

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