1、Designation: E1897 97 (Reapproved 2010)E1897 14Standard Test Methods Practice forMeasuring and Compensating for Transmittance of anAttenuating Medium Using Infrared Imaging Radiometers1This standard is issued under the fixed designation E1897; the number immediately following the designation indicat
2、es the year oforiginal adoption or, in the case of revision, 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.1. Scope1.1 These test methods cover procedures for measu
3、ring and compensating for transmittance when using an infrared imagingradiometer to measure the temperature of a specimen through an attenuating medium, such as a window, filter or atmosphere.1.2 The values stated in SI units are to be regarded as the standard.1.3 These test methods may involve use
4、of equipment and materials in the presence of heated or electrically-energizedequipment, or both.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health
5、practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E1316 Terminology for Nondestructive Examinations3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 attenuating mediuma semi-transparent solid, liquid or gas
6、, such as a window, filter, external optics or an atmosphere thatattenuates radiation.3.1.2 blackbody simulatora device with an emissivity close to 1.00 that can be heated or cooled to a stable temperature.3.1.3 filtera semi-transparent material that attenuates certain wavelengths of radiation.3.1.4
7、 infrared thermographerthe person using an infrared imaging radiometer.3.1.5 reflected temperaturethe temperature of the energy incident upon and reflected by the measurement surface of thespecimen.3.1.6 windowa semi-transparent material that separates conditioned and unconditioned atmospheres and a
8、ttenuates certainwavelengths of radiation.3.2 See also Terminology E1316.4. Summary of Test Method4.1 Using the computer built into an infrared imaging radiometer, a method is given for measuring the transmittance of anattenuating medium.4.2 Using the computer built into an infrared imaging radiomet
9、er, a method is given for compensating for errors whenmeasuring the temperature of a specimen through an attenuating medium when the emissivity of the specimen and thetransmittance of the attenuating medium are known.1 These test methods are This practice is under the jurisdiction ofASTM Committee E
10、07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.10on Specialized NDT Methods.Current edition approved June 15, 2010Dec. 1, 2014. Published November 2010December 2014. Originally approved 1997. Last previous edition approved 2002 in 2010as E1897 97 (2002)(2010).1. DO
11、I: 10.1520/E1897-97R10.10.1520/E1897-14.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not
12、an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate.
13、 In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.3 Using the computer built into an infrared imaging radiometer, a m
14、ethod is given for measuring and compensating forunknown transmittance and emissivity errors when the specimen temperature is known.5. Significance and Use5.1 The transmittance of an attenuating medium can cause errors for an infrared thermographer using an infrared imagingradiometer to measure the
15、temperature of a specimen through the medium. Three test methods are given for measuring andcompensating for this error source.5.1.1 A test method is given for measuring the transmittance of an attenuating medium.5.1.2 A test method is given for compensating for errors when measuring the temperature
16、 of a specimen having a knownemissivity through an attenuating medium with a known transmittance.5.1.3 A test method is given for measuring and compensating for transmittance and emissivity errors when the specimentemperature is known.5.2 These test methods can be used in the field or laboratory usi
17、ng commonly available materials.5.3 These test methods can be used with any infrared radiometers that have the required computer capabilities.6. Interferences6.1 Test Method for Measuring the Transmittance of an Attenuating Medium:6.1.1 This test method requires a blackbody simulator with an emissiv
18、ity of 0.95 or greater that is at least 20C warmer thanambient temperature. Potential errors can be minimized by ensuring the stability of the temperature difference between the sourceand the ambient temperature during the test. Also, the transmittance measurement accuracy can be increased by increa
19、sing thistemperature difference.6.1.2 Errors can be minimized by ensuring that the temperature of the attenuating medium is as close as possible to the reflectedtemperature incident upon the specimen.6.1.3 The compositions and thicknesses of attenuating media can vary within the same specimen. Error
20、s can be minimized bymeasuring through the same portion of the specimen every time.6.2 Test Method for Compensating for Unknown Errors When Measuring the Temperature of a Specimen With a KnownEmissivity Through an Attenuating Medium Having a Known Transmittance:6.2.1 Errors can be minimized by ensur
21、ing that the temperature of the attenuating medium is as close as possible to the reflectedtemperature incident upon the specimen.6.3 The transmittance of an attenuating medium may be specific to the temperature of the medium and the spectral wavebandof the radiometer used to make the measurement. T
22、herefore, the temperature of the measured specimen and the spectral wavebandof the radiometer used should be noted with the measured transmittance value.6.4 The use of these test methods to compensate for the transmittance of an attenuating medium is valid only when measuringthe temperatures of spec
23、imens that are opaque in the waveband of the infrared imaging radiometer.7. Apparatus7.1 A calibrated infrared imaging radiometer with a built-in computer that allows the infrared thermographer to input reflectedtemperatures and emissivity values.7.2 The test method for measuring the transmittance o
24、f an attenuating medium requires a tripod or device to support the infraredimaging radiometer.7.3 The test method for measuring the transmittance of an attenuating medium requires a high-emissivity source that is heatedto a stable temperature at least 20C above ambient temperature.7.4 The test metho
25、d for measuring and compensating for unknown transmittance and emissivity errors when the specimentemperature is known requires a calibrated thermometer to measure the temperature of the specimen.8. Procedure8.1 To measure the transmittance of an attenuating medium, use the following sequential step
26、s:8.1.1 Place the infrared imaging radiometer on the tripod or support device at the desired location and distance from theblackbody simulator.8.1.2 Point the infrared imaging radiometer at the blackbody simulator and focus on a portion that has an emissivity of 0.95 orgreater. Make sure that the bl
27、ackbody simulator is at a stable temperature at least 20C above the ambient temperature.8.1.3 Use an appropriate infrared imaging radiometer measurement function (such as spot temperature, crosshairs or isotherm)to measure and compensate for the reflected temperature error incident upon the blackbod
28、y simulator.8.1.4 With the imagers computer emittance control still set to 1.00, measure and record the apparent temperature of this sameportion of the blackbody simulator.E1897 1428.1.5 Position the attenuating medium between the imagers detector or lens and the blackbody simulator.8.1.6 Without mo
29、ving the imager, adjust its computers emissivity control until the imagers computer indicates the sametemperature recorded in 8.1.4. The indicated “emissivity” value is the transmittance of the attenuating medium, at this blackbodysimulator temperature and radiometers spectral waveband.8.1.7 Repeat
30、8.1.1 through 8.1.6 a minimum of three times and average the transmittance values to yield an averagetransmittance.8.2 To measure the temperature of a specimen having a known emissivity through an attenuating medium having a knowntransmittance, use the following sequential steps.8.2.1 Point the infr
31、ared imaging radiometer at the specimen and focus on the portion where the temperature is to be measured.Place the attenuating medium having a known transmittance between the imagers detector or lens and the specimen.8.2.2 Instead of 1.00, enter the measured transmittance percentage of the attenuati
32、ng medium under the imagers emissivityinput (sometime referred to as “emittance” or “E”). Use an appropriate infrared imaging radiometer function (such as spottemperature, crosshairs or isotherm) to measure and compensate for the reflected temperature error incident upon the specimen.8.2.3 Calculate
33、 the combined emissivity and transmittance correction value by multiplying the known emissivity of thespecimen times the known transmittance of the attenuating medium. Record this combined correction value.8.2.4 Repeat 8.2.1 through 8.2.3 a minimum of three times and average the values to yield an a
34、verage combined correctionvalue.8.2.5 Compensate for emissivity and transmittance errors by entering the combined correction value recorded in 8.2.3 in theinfrared radiometric imagers computer under the “emissivity” input.8.3 To measure and compensate for unknown transmittance and emissivity errors
35、when the specimen temperature is known, usethe following sequential steps. Use an appropriate infrared imaging radiometer function (such as spot temperature, crosshairs orisotherm) to measure and compensate for the reflected temperature error incident upon the specimen.8.3.1 Point the imager at the
36、specimen and the portion of the specimen having an unknown emissivity. Place the attenuatingmedium(s) with an unknown transmittance(s) between the imagers detector or lens and the specimen.8.3.2 With another thermometer, measure and record the temperature of the portion of the specimen delineated wi
37、th the infraredimaging radiometers measurement function.8.3.3 With the imager still focused on the same portion of the specimen, adjust the imagers computer emissivity control untilthe indicated temperature is the same as the temperature just recorded in 8.3.2. Record this “emissivity” value which i
38、s thecombined correction value for errors produced by the transmittance of the attenuating medium and the emissivity of the specimen,at this medium temperature and radiometers spectral waveband.8.3.4 Repeat 8.3.1 through 8.3.3 a minimum of three times and average the emissivity values to yield an av
39、erage combinedcorrection value.8.3.5 Enter this average combined correction value in the imager computer under the emissivity input to compensate for errorsproduced by this attenuating medium when measuring a specimen with the same emissivity.9. Precision and Bias9.1 PrecisionA measure of the precis
40、ion of these test methods can be inferred from the results of the replicate tests specifiedin 8.1.7, 8.2.4, and 8.3.4.9.2 BiasThe bias cannot be determined by these test methods because the values of transmittance are defined only in termsof the test methods.10. Keywords10.1 attenuating medium; blac
41、kbody simulator; emissivity; filter; imaging, infrared; infrared examination; infrared testing;infrared thermography; nondestructive testing; radiometry; reflected temperature; temperature compensation; transmittance;temperature measurement; windowASTM International takes no position respecting the
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45、dard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or se
46、rviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 1431. Scope*1.1 This practice covers procedures for measuring and
47、compensating for transmittance when using an infrared imagingradiometer to measure the temperature of a specimen through an attenuating medium, such as a window, filter or atmosphere.21.2 The values stated in SI units are to be regarded as the standard.1.3 These procedures may involve use of equipme
48、nt and materials in the presence of heated or electrically-energized equipment,or both.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices
49、and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3E1316 Terminology for Nondestructive Examinations3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 attenuating mediuma semi-transparent solid, liquid or gas, such as a window, filter, external optics or an atmosphere thatattenuates radiation.3.1.2 blackbody simulatora device with an emissivity close to 1.00 that can be heated or cooled to a stable temperature.3.1.3 filtera semi-transparent materi
