1、Designation: E1213 97 (Reapproved 2009)E1213 14Standard Test Method Practice forMinimum Resolvable Temperature Difference for ThermalImaging Systems1This standard is issued under the fixed designation E1213; the number immediately following the designation indicates the year oforiginal adoption or,
2、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 This test method covers the determination of the minimum resolvable temperature d
3、ifference (MRTD) capability of thecompound observer-thermal imaging system as a function of spatial frequency.1.2 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 safet
4、y and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E1316 Terminology for Nondestructive Examinations3. Terminology3.1 Definitions:3.1.1 differential blackbodyan apparatus for establishing two parallel isothermal pla
5、nar zones of different temperatures, andwith effective emissivities of 1.0.3.1.2 See also Terminology E1316.4. Summary of Test Method4.1 A standard four-bar target is used in conjunction with a differential blackbody that can establish one blackbody isothermaltemperature for the set of bars and anot
6、her blackbody isothermal temperature for the set of conjugate bars, which are formed bythe regions between the bars (see Fig. 1). The target is imaged onto the monochrome video monitor of a thermal imaging systemwhere the image is viewed by an observer. The temperature difference between the bars an
7、d their conjugates, initially zero, isincreased incrementally only until the observer can distinguish the four bars. This critical temperature difference is the MRTD.4.2 The spatial distribution of temperature of each target must be measured remotely at the critical temperature difference thatdeterm
8、ines the MRTD. The mean temperature of each bar must not differ from that of any other bar by more than the measuredMRTD. A similar requirement applies to the temperature of each conjugate bar. Otherwise the MRTD value is unacceptable.4.3 The background temperature and the spatial frequency of each
9、target must be specified together with the measured valueof MRTD.4.4 The probability of resolution must be specified together with the reported value of MRTD.5. Significance and Use5.1 This test relates to a thermal imaging systems effectiveness for discerning details in a scene.5.2 MRTD values prov
10、ide estimates of resolution capability and may be used to compare one system with another. (LowerMRTD values indicate better resolution.)1 This test method practice is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.10 onEme
11、rgingSpecialized NDT Methods.Current edition approved March 1, 2009Oct. 1, 2014. Published March 2009October 2014. Originally approved in 1987. Last previous edition approved in 20022009 asE1213 - 97(2002).(2009). DOI: 10.1520/E1213-97R09.10.1520/E1213-14.2 For referencedASTM standards, visit theAST
12、M 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 an ASTM standard and is intended only to provide the user of an ASTM standard an ind
13、ication 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. In all cases only the current versionof the standard as published by ASTM is to be
14、considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1NOTE 1Test values obtained under idealized laboratory conditions may or may not correlate directly with service performance.6. Apparatus6.1 The apparatus
15、 consists of the following:6.1.1 Test Charts (Targets), comprised of four periodic bars of aspect ratio (width:height) 1:7, as shown in Fig. 1.6.1.2 Differential Blackbody, temporally stable and controllable to within 0.1C.6.1.3 Infrared Spot Radiometer, calibrated with the aid of a blackbody source
16、 to an accuracy within 0.1C.NOTE 2Test charts may be fabricated by cutting slots in metal and coating with black paint of emissivity greater than 0.95. In this case the slots wouldconstitute the bars.7. Procedure7.1 Mount a test chart (target) onto the differential blackbody.NOTE 3Differential black
17、bodies may be used within an environmental isothermal temperature chamber. Then, at equilibrium the temperature of theconjugates approximately equals the temperature of the room, or ambient temperature.7.2 Optimally focus the thermal imaging system directly on the target or on an optical projection
18、of the target.7.3 Adjust the thermal imaging system for quasi-linear operation.7.4 Adjust the monochrome video monitor controls so that the presence of noise is barely perceivable by the observer.7.5 Make the display luminance and the laboratory ambient luminance mutually suitable for visual acuity
19、and viewing comfort.7.6 Instruct the observer to signal when he can perceive the appearance of four distinct bars on the monitor. Refrain from furtherconversation during the test which could conceivably influence or bias the observer.7.7 Record the distances that determine spatial frequency (see 8.1
20、), and set the nominal T (the nominal temperature of the barsminus the nominal temperature of the conjugate bars, zero or a positive number) equal to zero.7.8 Gradually increase the nominal T in increments not exceeding 0.1C until the observer signals.7.9 Measure the spatial distribution of temperat
21、ure of the targets with an infrared spot radiometer of accuracy better than 0.1C.Each bar and each conjugate must be measured in at least three locations that include the ends and centerpoint. If additionallocations are measured, all must be at regular intervals. The field of view must be confined t
22、o the bar or conjugate being measured.7.10 Calculate the mean temperature of each bar and intercompare the values, and calculate the mean temperature of eachconjugate bar and intercompare the values.7.11 Calculate the actual T (the average temperature of the bars minus the average temperature of the
23、 conjugate bars).Provisionally, this is the MRTD.7.12 Compare the largest difference in the mean temperatures of any two bars, or any two conjugate bars, with the MRTD. Ifthis difference exceeds the MRTD, the test results are unacceptable for this particular spatial frequency.7.13 Replace the test c
24、hart with another of different spatial frequency and repeat the test (7.2 7.12).7.14 Repeat 7.13 one or more times.7.15 Repeat the entire test (7.1 7.14) with a different observer.FIG. 1 Targets Used for MRTD DeterminationsE1213 1427.16 Repeat 7.15 one or more times.NOTE 4Observers must be free of e
25、ye disease, have good eyesight, and be familiar with viewing thermal imagery.NOTE 5Only one observer at a time shall be present during the testing.8. Calculation8.1 Calculate the spatial frequency, F, of the test charts as follows:F 51023 Ds Fcyclesmrad G (1)where:F = spatial frequency,D = distance
26、from target to thermal imaging system, m,s = center line to center line separation of bars, m, and D s.8.2 Calculate the probability of resolution as shown by the following illustration: For a given test chart, the MRTD resultsobtained with three different observers are 0.5C, 0.6C, and 1.0C. The obs
27、erver who resolved 0.5C would also be capable ofresolving 0.6C and 1.0C; similarly the observer who resolved 0.6C would also be capable of resolving 1.0C. Therefore, therespective probabilities of resolution are: for 0.5C, 13 = 33 %; for 0.6C, 23 = 67 %; for 1.0C, 33 = 100 %.9. Report9.1 Report the
28、following information:9.1.1 Spatial frequency,9.1.2 MRTD,9.1.3 Probability of resolution, and9.1.4 Background temperature.9.2 MRTD values must relate to a probability of resolution of at least 50 %.9.3 Only a single probability of resolution must be used throughout.NOTE 6A graph of MRTD versus spati
29、al frequency is a convenient form of reporting the data.10. Precision and Bias10.1 Insufficient data are available on which to base a precision and bias statement. Notwithstanding, owing to the partiallysubjective nature of the test, repeatability and reproducibility are apt to be poor and MRTD diff
30、erences less than 0.2C areconsidered to be insignificant.11. Keywords11.1 infrared imaging systems; minimum resolvable temperature difference; nondestructive testing; thermal imaging systems;thermography; infraredASTM International takes no position respecting the validity of any patent rights asser
31、ted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by
32、the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive
33、 careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM Interna
34、tional, 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 serviceastm.org (e-mail); or through
35、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:/ Scope*1.1 This practice covers the determination of the minimum resolvable temperature difference (MR
36、TD) capability of thecompound observer-thermal imaging system as a function of spatial frequency.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if
37、any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.E1213 1432. Referenced Documents2.1 ASTM Standards:2E1316 Terminology for Nondestructive Exami
38、nations3. Terminology3.1 Definitions:3.1.1 differential blackbodyan apparatus for establishing two parallel isothermal planar zones of different temperatures, andwith effective emissivities of 1.0.3.1.2 See also Terminology E1316.4. Summary of Practice4.1 A standard four-bar target is used in conjun
39、ction with a differential blackbody that can establish one blackbody isothermaltemperature for the set of bars and another blackbody isothermal temperature for the set of conjugate bars, which are formed bythe regions between the bars (see Fig. 1). The target is imaged onto the monochrome video moni
40、tor of a thermal imaging systemwhere the image is viewed by an observer. The temperature difference between the bars and their conjugates, initially zero, isincreased incrementally only until the observer can distinguish the four bars. This critical temperature difference is the MRTD.4.2 The spatial
41、 distribution of temperature of each target must be measured remotely at the critical temperature difference thatdetermines the MRTD. The mean temperature of each bar must not differ from that of any other bar by more than the measuredMRTD. A similar requirement applies to the temperature of each co
42、njugate bar. Otherwise the MRTD value is unacceptable.4.3 The background temperature and the spatial frequency of each target must be specified together with the measured valueof MRTD.4.4 The probability of resolution must be specified together with the reported value of MRTD.5. Significance and Use
43、5.1 This practice relates to a thermal imaging systems effectiveness for discerning details in a scene.5.2 MRTD values provide estimates of resolution capability and may be used to compare one system with another. (LowerMRTD values indicate better resolution.)5.3 Due to the partially subjective natu
44、re of the procedure, repeatability and reproducibility are apt to be poor and MRTDdifferences less than 0.2C are considered to be insignificant.NOTE 1Values obtained under idealized laboratory conditions may or may not correlate directly with service performance.6. Apparatus6.1 The apparatus consist
45、s of the following:6.1.1 Comparison Charts (Targets), comprised of four periodic bars of aspect ratio (width:height) 1:7, as shown in Fig. 1.6.1.2 Differential Blackbody, temporally stable and controllable to within 0.1C.6.1.3 Infrared Spot Radiometer, calibrated with the aid of a blackbody source t
46、o an accuracy within 0.1C.NOTE 2Comparison charts may be fabricated by cutting slots in metal and coating with black paint of emissivity greater than 0.95. In this case theslots would constitute the bars.7. Procedure7.1 Mount a comparison chart (target) onto the differential blackbody.NOTE 3Differen
47、tial blackbodies may be used within an environmental isothermal temperature chamber. Then, at equilibrium the temperature of theconjugates approximately equals the temperature of the room, or ambient temperature.7.2 Optimally focus the thermal imaging system directly on the target or on an optical p
48、rojection of the target.7.3 Adjust the thermal imaging system for quasi-linear operation.7.4 Adjust the monochrome video monitor controls so that the presence of noise is barely perceivable by the observer.7.5 Make the display luminance and the laboratory ambient luminance mutually suitable for visu
49、al acuity and viewing comfort.7.6 Instruct the observer to signal when he can perceive the appearance of four distinct bars on the monitor. Refrain from furtherconversation during the test which could conceivably influence or bias the observer.7.7 Record the distances that determine spatial frequency (see 8.1), and set the nominal T (the nominal temperature of the barsminus the nominal temperature of the conjugate bars, zero or a positive number) equal to zero.7.8 Gradually increase the nominal T in increments not
