ASTM E1213-14(2022)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1213 − 14 (Reapproved 2022)
Standard Practice for
Minimum Resolvable Temperature Difference for Thermal
Imaging Systems
This standard is issued under the fixed designation E1213; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Summary of Practice
1.1 This practice covers the determination of the minimum
4.1 A standard four-bar target is used in conjunction with a
resolvable temperature difference (MRTD) capability of the differential blackbody that can establish one blackbody isother-
compound observer-thermal imaging system as a function of
mal temperature for the set of bars and another blackbody
spatial frequency. isothermal temperature for the set of conjugate bars, which are
formed by the regions between the bars (see Fig. 1). The target
1.2 The values stated in SI units are to be regarded as
is imaged onto the monochrome video monitor of a thermal
standard. No other units of measurement are included in this
imaging system where the image is viewed by an observer.The
standard.
temperature difference between the bars and their conjugates,
1.3 This standard does not purport to address all of the
initially zero, is increased incrementally only until the observer
safety concerns, if any, associated with its use. It is the
can distinguish the four bars. This critical temperature differ-
responsibility of the user of this standard to establish appro-
ence is the MRTD.
priate safety, health, and environmental practices and deter-
4.2 The spatial distribution of temperature of each target
mine the applicability of regulatory limitations prior to use.
must be measured remotely at the critical temperature differ-
1.4 This international standard was developed in accor-
encethatdeterminestheMRTD.Themeantemperatureofeach
dance with internationally recognized principles on standard-
bar must not differ from that of any other bar by more than the
ization established in the Decision on Principles for the
measured MRTD. A similar requirement applies to the tem-
Development of International Standards, Guides and Recom-
perature of each conjugate bar. Otherwise the MRTD value is
mendations issued by the World Trade Organization Technical
unacceptable.
Barriers to Trade (TBT) Committee.
4.3 The background temperature and the spatial frequency
2. Referenced Documents
of each target must be specified together with the measured
2 value of MRTD.
2.1 ASTM Standards:
E1316 Terminology for Nondestructive Examinations
4.4 The probability of resolution must be specified together
with the reported value of MRTD.
3. Terminology
5. Significance and Use
3.1 Definitions:
3.1.1 differential blackbody—an apparatus for establishing
5.1 This practice relates to a thermal imaging system’s
two parallel isothermal planar zones of different temperatures,
effectiveness for discerning details in a scene.
and with effective emissivities of 1.0.
5.2 MRTD values provide estimates of resolution capability
3.1.2 See also Terminology E1316.
and may be used to compare one system with another. (Lower
MRTD values indicate better resolution.)
5.3 Due to the partially subjective nature of the procedure,
This practice is under the jurisdiction of ASTM Committee E07 on Nonde-
repeatability and reproducibility are apt to be poor and MRTD
structive Testing and is the direct responsibility of Subcommittee E07.10 on
differences less than 0.2 °C are considered to be insignificant.
Specialized NDT Methods.
Current edition approved Dec. 1, 2022. Published December 2022. Originally
NOTE 1—Values obtained under idealized laboratory conditions may or
approved in 1987. Last previous edition approved in 2018 as E1213 – 14(2018).
may not correlate directly with service performance.
DOI: 10.1520/E1213-14R22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6. Apparatus
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 6.1 The apparatus consists of the following:
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1213 − 14 (2022)
FIG. 1 Targets Used for MRTD Determinations
6.1.1 Comparison Charts (Targets), comprised of four pe- 7.9 Measure the spatial distribution of temperature of the
riodic bars of aspect ratio (width:height) 1:7, as shown in Fig. targets with an infrared spot radiometer of accuracy better than
1. 0.1 °C. Each bar and each conjugate must be measured in at
6.1.2 Differential Blackbody, temporally stable and control- least three locations that include the ends and centerpoint. If
lable to within 0.1 °C. additional locations are measured, all must be at regular
6.1.3 Infrared Spot Radiometer, calibrated with the aid of a intervals. The field of view must be confined
...