1、Designation: E1341 06 (Reapproved 2011)1Standard Practice forObtaining Spectroradiometric Data from Radiant Sourcesfor Colorimetry1This standard is issued under the fixed designation E1341; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEReference to CIE Publication 015:2004 was corrected editorially throughout in November 2011.INTRODUCTIONTh
3、e fundamental procedure for characterizing the color and absolute luminance of radiant sourcesis to obtain the spectroradiometric data under specified measurement conditions, and from these datato compute CIE chromaticity coordinates and luminance values based on the CIE 1931 StandardObserver. The c
4、onsiderations involved and the procedures to be used to obtain precision spectrora-diometric data for this purpose are contained in this practice. The values and procedures for computingCIE chromaticity coordinates are contained in Practice E308. This practice includes minor modifi-cations to the pr
5、ocedures given in Practice E308 that are necessary for computing the absoluteluminance of radiant sources.1. Scope1.1 This practice prescribes the instrumental measurementrequirements, calibration procedures, and physical standardsneeded for precise spectroradiometric data for characterizingthe colo
6、r and luminance of radiant sources.1.2 This practice lists the parameters that must be specifiedwhen spectroradiometric measurements are required in specificmethods, practices, or specifications.1.3 This practice describes the unique calculation proce-dures required to determine basic colorimetric d
7、ata of luminoussources.1.4 This practice is general in scope rather than specific asto instrument, object, or material.1.5 The values stated in SI units are to be regarded as thestandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is t
8、heresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E275 Practice for Describing and Measuring Performanceof Ultraviolet and Visible Spec
9、trophotometersE284 Terminology of AppearanceE308 Practice for Computing the Colors of Objects byUsing the CIE SystemE387 Test Method for Estimating Stray Radiant PowerRatio of Dispersive Spectrophotometers by the OpaqueFilter MethodE925 Practice for Monitoring the Calibration of Ultraviolet-Visible
10、Spectrophotometers whose Spectral Bandwidthdoes not Exceed 2 nmE958 Practice for Measuring Practical Spectral Bandwidthof Ultraviolet-Visible Spectrophotometers2.2 NIST Publications:NIST Technical Note 594-1 Fundamental Principles of Ab-solute Radiometry and the Philosophy of the NBS Pro-gram (19681
11、971)31This practice is under the jurisdiction of ASTM Committee E12 on Color andAppearance and is the direct responsibility of Subcommittee E12.06 on ImageBased Color Measurement.Current edition approved Nov. 1, 2011. Published November 2011. Originallyapproved in 1991. Last previous edition approve
12、d in 2006 as E1341 06. DOI:10.1520/E1341-06R11E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available
13、from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http:/www.nist.gov.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NIST Technical Note 594-3 Photometric Calibration P
14、roce-dures32.3 CIE Publications:CIE Publication 015:2004 Colorimetry, 3rd ed.4CIE Publication No. 38 Radiometric and PhotometricCharacteristics of Materials and their Measurement, 19774CIE Publication No. 63 Spectroradiometric Measurement ofLight Sources, 198442.4 IES Standard:IES Guide to Spectrora
15、diometric Measurements, 198352.5 ANSI Standard:ANSI/IES RP-16-1980 Nomenclature and Definitions forIlluminating Engineering53. Terminology3.1 Definitions:3.1.1 The definitions of appearance terms in TerminologyE284 are applicable to this practice.4. Summary of Practice4.1 Procedures are given for se
16、lecting the types and oper-ating parameters of spectroradiometers used to produce datafor the calculation of CIE tristimulus values and other colorcoordinates to describe the colors of radiant sources. Theimportant steps of the calibration of such instruments, and thestandards required for these ste
17、ps, are described. Parametersare identified that must be specified when spectroradiometricmeasurements are required in specific methods or other docu-ments. Modifications to Practice E308 are described in order toaccount for the differences between objects and radiantsources.5. Significance and Use5
18、.1 The fundamental method for obtaining CIE tristimulusvalues or other color coordinates for describing the colors ofradiant sources is by the use of spectroradiometric measure-ments. These measurements are used by summation togetherwith numerical values representing the CIE 1931 StandardObserver (C
19、IE Publication 015:2004) and normalized to Km,the maximum spectral luminous efficacy function, with a valueof 683 lm/W.5.2 This practice provides a procedure for selecting theoperating parameters of spectroradiometers used for providingthe desired precision spectroradiometric data, for their calibra
20、-tion, and for the physical standards required for calibration.5.3 Special requirements for characterizing sources of lightpossessing narrow or discontinuous spectra are presented anddiscussed. Modifications to the procedures of Practice E308 aregiven to correct for the unusual nature of narrow or d
21、iscon-tinuous sources.6. Requirements When Using Spectroradiometry6.1 When describing the measurement of radiant sources byspectroradiometry, the following must be specified.6.1.1 The radiometric quantity determined, such as theirradiance (W/m2) or radiance (W/m2-sr), or the photometricquantity dete
22、rmined, such as illuminance (lm/m2) or luminance(lm/m2-sr or cd/m2). The use of older, less descriptive namesor units such as phot, nit, stilb (see ANSI/IES RP-16-1980)isnot recommended.6.1.2 The geometry of the measurement conditions, includ-ing whether a diffuser was used and its material of const
23、ruc-tion, the distances from the source of irradiation to the entranceto the spectroradiometer, and the presence of any specialintermediate optical devices such as integrating spheres.6.1.3 The spectral parameters, including the spectral region,wavelength measurement interval, and spectral bandwidth
24、.6.1.4 The type of standard used to calibrate the system, astandard lamp, a calibrated source, or a calibrated detector, andthe source of the calibration.7. Apparatus7.1 The basic instrument requirement is a spectroradiomet-ric system designed for the measurement of spectral radianceor irradiance of
25、 light sources. The basic elements of a spectro-radiometric system are calibration sources with their regulatedpower supplies, a light detector, electronics for measuring thephotocurrents, a monochromator with control equipment forcomputer interfacing, receiving optics, and a computer asdescribed in
26、 CIE Publication No. 63 and IES Guide toSpectroradiometric Measurements. The computer is listed asan integral part of the system since the required precision isunobtainable without automated control. The characteristics ofeach element are discussed in the following sections.7.2 Calibration SourcesTh
27、e standard calibration lamp forspectroradiometry is a tungsten-filament lamp operated at aspecified current. Such lamps are available from many stan-dardizing laboratories.Typical of such standards is the tungstenfilament, 1000 W, halogen cycle, quartz-envelope FEL-typelamp recommended by the Nation
28、al Institute of Standards andTechnology (NIST). (See NIST Technical Note 594-1, and594-3.) Uncertainties in the transfer of the scale of spectralradiance or irradiance are about 1 %. It is preferable to havemore than one standard source to permit cross-checks and toallow calibration at a range of il
29、luminance levels. Such sourcescan be constructed from lamps operating at any color tempera-ture and spectral nature that have been characterized against astandard lamp. Monochromatic emission sources, such as alow-pressure mercury arc lamp or tunable laser, should also beavailable for use in calibra
30、ting the wavelength scale in accor-dance with Practice E925. Multiline lasers, such as continuouswave (cw) argon-ion and helium-neon, are preferred since theycan be tuned to a small number of lines of well knownwavelengths.7.2.1 Calibration Source Power SuppliesThe electricalsupplies for the calibra
31、tion sources should be of the constantcurrent type. The supply should be linear and not a switchingsupply. Current regulation should be maintained to better than0.1 %. This level of regulation is required to maintain aconstant flux across the entrance to the spectroradiometer.4Available from U.S. Na
32、tional Committee of the CIE (International Commissionon Illumination), C/o Thomas M. Lemons, TLA-Lighting Consultants, Inc., 7 PondSt., Salem, MA 01970, http:/www.cie-usnc.org.5Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.o
33、rg.E1341 06 (2011)127.2.2 A standard for the measurement of length (such as ahigh-quality metric rule) should also be available since abso-lute irradiance calibrations must be performed at exact dis-tances from the filament of the standard lamp.7.3 Detectors:7.3.1 Photomultiplier TubesPhotomultiplie
34、r tubes are thetraditional detectors in spectroradiometers. This is due to theirsuperior performance in low-light-level conditions such as areencountered at the exit slit of a low-efficiency monochromator.The photocathodes of photomultipliers are sensitive to tem-perature, polarization, and magnetic
35、 fields. Light levels on thephotocathode should never be allowed to generate photocur-rents in excess of 106A. The high-voltage supply should bestabilized to better than 0.01 % since the gain of the multipliertube is controlled by the voltage across the dynodes.7.3.2 Silicon PhotodiodesRecently, sil
36、icon photodiodeshave superseded photomultiplier tubes in radiometric instru-ments. Photodiodes are less sensitive to temperature, polariza-tion, and magnetic fields than photomultipliers, but care shouldstill be taken to control these variables. Two silicon photodiodebased detectors used in instrume
37、ntation are Charge CoupledDevises (CCD) and Complimentary Metal Oxide Silicon(CMOS).7.4 MonochromatorsThe monochromator is the wave-length dispersive element in the system. The region of themonochromator should be 360 to 830 nm for highest accuracy,but a region of 380 to 780 nm should suffice for mo
38、stcharacterizations. The bandwidth should be kept constantacross the region of measurement at between 85 and 100 % ofthe measurement interval, but no greater than 5.0 nm. The CIErecommends a 1.0 nm bandwidth and measurement interval forhighest accuracy, and suggests 2.0 nm as a compromise forcharact
39、erizing radiation sources with spectra that contain bothcontinuous and line emissions (CIE Publication No. 63). Theprecision of the wavelength setting should be 0.1 nm with anabsolute accuracy of better than 0.5 nm. The size and shape ofthe entrance and exit slits of the monochromator should bechose
40、n to provide a symmetric bandshape, preferably triangu-lar. The entrance slit should be completely and uniformly filledwith light. Specialized versions of the general spectroradiom-eter may be constructed and used for specific applicationswhere the instrument can depart from the above guidelines. Fo
41、rexample, a source with little or no radiant energy in the far redend of the visible spectrum may be correctly characterized bymeasurements to 700 or 710 nm rather than 780 nm.7.4.1 Scanning MonochromatorsThe newer technologyof holographically reproduced gratings has made possible theproduction of s
42、ingle- and double-grating monochromators withvery high throughputs and very low stray-light levels. Second-order spectra need to be eliminated through the use of either apredisperser or a long-pass filter. A drive mechanism andposition encoder should be attached to the scanning monochro-mator drive
43、to allow the monochromator to scan the wave-length region under control of a computer. Prism-based scan-ning monochromators can also be used though the drivemechanism is more complex and the slit width must bechanged as a function of the wavelength to maintain constantbandwidth.7.4.2 PolychromatorsP
44、hotodiode arrays are used in flat-field spectrographic radiometers. The bandwidth and samplinginterval are determined by the pitch of the array and thereciprocal linear dispersion of the spectrograph. The guidelinesgiven above should be followed for the diode array instrumentas well.7.5 Receiving Op
45、ticsTo maximize the light throughput,the number of optical surfaces between the source of light(either a calibration or test source) and the monochromatorentrance slit should be kept to a minimum. In extended diffusesources, only a set of limiting apertures may be needed. Forsmall sources a diffusin
46、g element may be required, such as aPTFE-fluorocarbon cap or integrating sphere. In some in-stances, it may be desirable to image the source with anintermediate focusing lens or mirror assembly. Care should betaken to use a magnification that will adequately fill theentrance slit when viewing both t
47、he calibration and test source.The CIE recommends the use of a rotatable integrating sphereas the input optics (CIE Publication No. 63). The entrance portof the sphere is rotated to view first the calibration source andthen to view the test source. Since the efficiency of integratingspheres tend to
48、be rather low, this method is only useful forbright sources.7.6 Computer System:7.6.1 There are no special requirements for the computer.Any minicomputer or microcomputer should suffice. Theprogram should control or monitor as many of the instrumentparameters as possible. Included in the computer sy
49、stem is theanalog to digital conversion process, which changes the pho-tocurrents to voltages, amplifies the voltages, and digitizes thevoltages into computer-readable signals. A 312 digit autorang-ing digital ammeter with a computer interface is suitable forthis purpose. Alternatively, an autoranging electrometer with acomputer interface can be used, but shielding and guarding ofthe low level signals becomes more critical. This is equivalentto a twelve bit ADC (analog to digital converter) with variablegains on the input signal. The use of a detector housing with
