1、Designation: E 1341 06Standard Practice forObtaining Spectroradiometric Data from Radiant Sourcesfor Colorimetry1This standard is issued under the fixed designation E 1341; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe fundamental procedure for characterizing the color and absolute luminance of radiant sourcesis to obtain the sp
3、ectroradiometric data under specified measurement conditions, and from these datato compute CIE chromaticity coordinates and luminance values based on the CIE 1931 StandardObserver. The considerations involved and the procedures to be used to obtain precision spectrora-diometric data for this purpos
4、e are contained in this practice. The values and procedures for computingCIE chromaticity coordinates are contained in Practice E 308. This practice includes minormodifications to the procedures given in Practice E 308 that are necessary for computing the absoluteluminance of radiant sources.1. Scop
5、e1.1 This practice prescribes the instrumental measurementrequirements, calibration procedures, and physical standardsneeded for precise spectroradiometric data for characterizingthe color and luminance of radiant sources.1.2 This practice lists the parameters that must be specifiedwhen spectroradio
6、metric measurements are required in specificmethods, practices, or specifications.1.3 This practice describes the unique calculation proce-dures required to determine basic colorimetric data of luminoussources.1.4 This practice is general in scope rather than specific asto instrument, object, or mat
7、erial.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 theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine
8、 the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 275 Practice for Describing and Measuring Performanceof Ultraviolet, Visible, and Near-Infrared Spectrophotom-etersE 284 Terminology of AppearanceE 308 Practice for Computing the Colors of Objects
9、 byUsing the CIE SystemE 387 Test Method for Estimating Stray Radiant PowerRatio of Dispersive Spectrophotometers by the OpaqueFilter MethodE 925 Practice for Monitoring the Calibration ofUltraviolet-Visible Spectrophotometers whose SpectralSlit Width does not Exceed 2 nmE 958 Practice for Measuring
10、 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 (19681971)3NIST Technical Note 594-3 Photometric Calibration Proce-dures32.3 CIE Publications:CI
11、E Publication 15:2004 Colorimetry, 3rd ed.4CIE Publication No. 38 Radiometric and PhotometricCharacteristics of Materials and their Measurement, 19774CIE Publication No. 63 Spectroradiometric Measurement ofLight Sources, 198441This practice is under the jurisdiction of ASTM Committee E12 on Color an
12、dAppearance and is the direct responsibility of Subcommittee E12.06 on ImageBased Color Measurement.Current edition approved July 1, 2006. Published July 2006. Originally approvedin 1991. Last previous edition approved in 2001 as E 1341 96 (2001).2For referenced ASTM standards, visit the ASTM websit
13、e, 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 from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 3460, Gaithersburg, MD
14、20899-3460.4Available from U.S. National Committee of the CIE (International Commissionon Illumination), C/o Thomas M. Lemons, TLA-Lighting Consultants, Inc., 7 PondSt., Salem, MA 01970.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States
15、.2.4 IES Standard:IES Guide to Spectroradiometric 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 TerminologyE 284 are applicable to this practice.4. Summary o
16、f Practice4.1 Procedures are given for selecting 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
17、, and thestandards required for these steps, are described. Parametersare identified that must be specified when spectroradiometricmeasurements are required in specific methods or other docu-ments. Modifications to Practice E 308 are described in orderto account for the differences between objects a
18、nd radiantsources.5. Significance and Use5.1 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 rep
19、resenting the CIE 1931 StandardObserver (CIE Publication 15:2004) and normalized to Km, themaximum spectral luminous efficacy function, with a value of683 lm/W.5.2 This practice provides a procedure for selecting theoperating parameters of spectroradiometers used for providingthe desired precision s
20、pectroradiometric data, for their calibra-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 E 308are given to cor
21、rect for the unusual nature of narrow ordiscontinuous 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
22、/m2-sr), or the photometricquantity determined, 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 dif
23、fuser was used and its material of construc-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 meas
24、urement interval, and spectral bandwidth.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 measurem
25、ent of spectral radianceor irradiance of 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, receivi
26、ng optics, and a computer asdescribed in 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 foll
27、owing sections.7.2 Calibration SourcesThe 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-envelop
28、e FEL-typelamp recommended by the National Institute of Standards andTechnology (NIST). (See NIST Tech Note 594-1, and 594-3.)Uncertainties in the transfer of the scale of spectral radiance orirradiance are about 1 %. It is preferable to have more than onestandard source to permit cross-checks and t
29、o allow calibrationat a range of illuminance levels. Such sources can be con-structed from lamps operating at any color temperature andspectral nature that have been characterized against a standardlamp. Monochromatic emission sources, such as a low-pressure mercury arc lamp or tunable laser, should
30、 also beavailable for use in calibrating the wavelength scale in accor-dance with Practice E 925. 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 SuppliesT
31、he electricalsupplies for the calibration 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 spec
32、troradiometer.7.2.2 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 TubesPhotomultiplier tube
33、s 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 field
34、s. Light levels on the5Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.E1341062photocathode 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
35、 of the multipliertube is controlled by the voltage across the dynodes.7.3.2 Silicon PhotodiodesRecently, silicon photodiodeshave superseded photomultiplier tubes in radiometric instru-ments. Photodiodes are less sensitive to temperature, polariza-tion, and magnetic fields than photomultipliers, but
36、 care shouldstill be taken to control these variables. Two silicon photodiodebased detectors used in instrumentation 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 them
37、onochromator should be 360 to 830 nm for highest accuracy,but a region of 380 to 780 nm should suffice for mostcharacterizations. 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
38、1.0 nm bandwidth and measurement interval forhighest accuracy, and suggests 2.0 nm as a compromise forcharacterizing 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 accurac
39、y of better than 0.5 nm. The size and shape ofthe entrance and exit slits of the monochromator should bechosen 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 b
40、e constructed and used for specific applicationswhere the instrument can depart from the above guidelines. Forexample, 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
41、MonochromatorsThe newer technologyof holographically reproduced gratings has made possible theproduction of single- 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 lon
42、g-pass filter. A drive mechanism andposition encoder should be attached to the scanning monochro-mator drive 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
43、slit width must bechanged as a function of the wavelength to maintain constantbandwidth.7.4.2 PolychromatorsPhotodiode 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 spec
44、trograph. The guidelinesgiven above should be followed for the diode array instrumentas well.7.5 Receiving OpticsTo 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 min
45、imum. In extended diffusesources, only a set of limiting apertures may be needed. Forsmall sources a diffusing 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 assemb
46、ly. Care should betaken to use a magnification that will adequately fill theentrance slit when viewing both the 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 firs
47、t the calibration source andthen to view the test source. Since the efficiency of integratingspheres tend to 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. Thep
48、rogram should control or monitor as many of the instrumentparameters as possible. Included in the computer system 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 au
49、torang-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 abuilt-in current to voltage amplifier is recommended since thephotocurrents are very small and can be affected by strayelectromagnetic fields and capacitances. Amplification andconversion to voltage
