IEC TS 63144-1:2020

IEC TS 63144-1 ®
Edition 1.0 2020-04
TECHNICAL
SPECIFICATION
Industrial process control devices – Thermographic cameras –
Part 1: Metrological characterization
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IEC TS 63144-1 ®
Edition 1.0 2020-04
TECHNICAL
SPECIFICATION
Industrial process control devices – Thermographic cameras –

Part 1: Metrological characterization

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 17.200, 25.040.40  ISBN 978-2-8322-7969-4

– 2 – IEC TS 63144-1:2020 © IEC 2020
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 9
4 Symbols . 14
5 Abbreviated terms . 14
6 Determination of technical data . 15
6.1 General . 15
6.2 Measuring temperature range . 15
6.2.1 General . 15
6.2.2 Required parameters . 16
6.2.3 Examples of indications . 16
6.2.4 Test condition, method and procedure for measuring temperature range . 16
6.3 Noise equivalent temperature difference (NETD) . 16
6.3.1 General . 16
6.3.2 Required parameters . 16
6.3.3 Examples of indications . 16
6.3.4 Test condition, method and procedure for noise equivalent temperature
difference . 17
6.4 Measuring distance (d) . 18
6.4.1 General . 18
6.4.2 Required parameters . 18
6.4.3 Examples of indications . 18
6.4.4 Test condition, method and procedure for measuring distance . 18
6.5 Field of view (FOV) . 18
6.5.1 General . 18
6.5.2 Required parameters . 19
6.5.3 Examples of indications . 19
6.5.4 Test condition, method and procedure for field of view . 19
6.6 Number of image elements . 19
6.7 Detector format used (number of detector elements used) . 19
6.8 Instantaneous field of view (IFOV) . 20
6.8.1 General . 20
6.8.2 Required parameters . 20
6.8.3 Example of indications . 20
6.8.4 Test condition, method and procedure for instantaneous field of view . 20
6.9 Slit response function (SRF) . 20
6.9.1 General . 20
6.9.2 Required parameters . 21
6.9.3 Examples of indications . 21
6.9.4 Test condition, method and procedure for slit response function . 21
6.10 Minimum field of view for temperature measurement (MFOV ) . 22
T
6.10.1 General . 22
6.10.2 Required parameters . 23
6.10.3 Example of indications . 23

6.10.4 Test condition, method and procedure for minimum field of view for
temperature measurement . 23
6.11 Spectral range . 24
6.11.1 General . 24
6.11.2 Examples of indications . 24
6.11.3 Test condition, method and procedure for spectral range . 24
6.12 Emissivity setting . 24
6.12.1 General . 24
6.12.2 Examples of indications . 24
6.12.3 Test condition, method and procedure for emissivity setting . 24
6.13 Influence of the internal instrument temperature . 24
6.13.1 General . 24
6.13.2 Required parameters . 25
6.13.3 Examples of indications . 25
6.13.4 Test condition, method and procedure for influence of the internal
instrument temperature . 25
6.14 Influence of the humidity . 26
6.14.1 General . 26
6.14.2 Required parameters . 26
6.14.3 Example of indications . 26
6.14.4 Test condition, method and procedure for influence of the humidity . 26
6.15 Long-term stability . 26
6.15.1 General . 26
6.15.2 Required parameters . 26
6.15.3 Example of indication . 26
6.15.4 Test condition, method and procedure for long-term stability . 27
6.16 Short-term stability . 27
6.16.1 General . 27
6.16.2 Required parameters . 27
6.16.3 Example of indication . 28
6.16.4 Test condition, method and procedure for short-term stability . 28
6.17 Repeatability . 28
6.17.1 General . 28
6.17.2 Required parameters . 28
6.17.3 Example of indication . 29
6.17.4 Test condition, method and procedure for repeatability . 29
6.18 Interchangeability (spread of production) . 29
6.18.1 General . 29
6.18.2 Required parameters . 29
6.18.3 Example of indication . 30
6.18.4 Test condition, method and procedure for interchangeability (spread of

production) . 30
6.19 Response time . 30
6.19.1 General . 30
6.19.2 Required parameters . 34
6.19.3 Example of indication . 34
6.19.4 Test condition, method and procedure for response time . 34
6.20 Exposure time . 35
6.20.1 General . 35
6.20.2 Required parameters . 36

– 4 – IEC TS 63144-1:2020 © IEC 2020
6.20.3 Example of indication . 36
6.20.4 Test condition, method and procedure for exposure time . 36
6.21 Warm-up time . 37
6.21.1 General . 37
6.21.2 Required parameters . 37
6.21.3 Examples of indication . 37
6.21.4 Test condition, method and procedure for warm-up time . 37
6.22 Integration time setting range. 38
6.22.1 General . 38
6.22.2 Required parameters . 38
6.22.3 Example of indication . 38
6.23 Refresh rate . 38
6.23.1 General . 38
6.23.2 Example of indication . 39
6.23.3 Test condition, method and procedure for refresh rate . 39
6.24 Non-uniformity (inhomogeneity of detector responsivity) . 39
6.24.1 General . 39
6.24.2 Required parameters . 39
6.24.3 Example of indication . 39
6.24.4 Test condition, method and procedure for non-uniformity . 39
6.25 Inhomogeneity equivalent temperature difference (IETD) . 40
6.25.1 General . 40
6.25.2 Required parameters . 40
6.25.3 Examples of indications . 40
6.25.4 Test condition, method and procedure for inhomogeneity equivalent
temperature difference . 40
6.26 Operating temperature range and air humidity range . 41
6.26.1 General . 41
6.26.2 Example of indication . 41
6.26.3 Test condition, method and procedure for operating temperature range
and air humidity range . 41
6.27 Size-of-source effect (SSE) . 41
6.27.1 General . 41
6.27.2 Required parameters . 41
6.27.3 Examples of indications . 42
6.27.4 Test condition, method and procedure for size-of-source effect . 42
Annex A (informative) Change in the indicated temperature caused by a 1 % change
in the radiative interchange . 43
Bibliography . 44

Figure 1 – Schematic measuring setup . 15
Figure 2 – Slit response function . 21
Figure 3 – Minimum size of a measuring spot for temperature measurement . 22
Figure 4 – Synchronous signal acquisition for a quantum detector . 31
Figure 5 – Asynchronous signal acquisition for a quantum detector . 32
Figure 6 – Asynchronous signal acquisition for a thermal detector (best case) . 33
Figure 7 – Asynchronous signal acquisition for a thermal detector (worst case) . 34
Figure 8 – Example of the measurement of the warm-up time . 38

Table 1 – Symbols . 14
Table A.1 – Change in the indicated temperature . 43

– 6 – IEC TS 63144-1:2020 © IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL PROCESS CONTROL DEVICES –
THERMOGRAPHIC CAMERAS –
Part 1: Metrological characterization

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. In exceptional
circumstances, a technical committee may propose the publication of a Technical Specification
when
• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• the subject is still under technical development or where, for any other reason, there is the
future but no immediate possibility of an agreement on an International Standard.
Technical Specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC TS 63144-1, which is a Technical Specification, has been prepared by subcommittee 65B:
Measurement and control devices, of IEC technical committee 65: Industrial-process
measurement, control and automation.

The text of this Technical Specification is based on the following documents:
Draft TS Report on voting
65B/1129/DTS 65B/1159/RVDTS
Full information on the voting for the approval of this Technical Specification can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 63144 series, published under the general title Industrial process
control devices – Thermographic cameras, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 8 – IEC TS 63144-1:2020 © IEC 2020
INTRODUCTION
Thermographic cameras (also called "thermographic imagers" or "infrared cameras") are being
increasingly used for spatially and temporally resolved, non-contact radiation temperature
measurement. Tracing the temperature values indicated by these instruments to the
International Temperature Scale (ITS-90) is gaining in importance for the comparability of
measurements. The precondition for their calibration and metrological application with low
uncertainties is to accurately describe and determine the essential metrological data of
thermographic cameras. Whereas there are international regulations to determine the technical
specifications for radiation thermometers – namely IEC TS 62492-1 and IEC TS 62492-2 –
there is a lack of such regulations for thermographic cameras in such a detailed form.
This document is Part 1 of a series of technical specifications for thermographic cameras. It is
intended to improve comparability and testability of the essential metrological technical data of
thermographic cameras. To this end, unambiguous procedures are laid down for the indication
and the determination of this technical data. Future IEC TS 63144-2 is intended to specifically
address the absolute calibration procedures and the corresponding uncertainties for
thermographic cameras in more depth and detail.

INDUSTRIAL PROCESS CONTROL DEVICES –
THERMOGRAPHIC CAMERAS –
Part 1: Metrological characterization

1 Scope
This part of IEC 63144 applies, in the field of metrology, to the statement and testing of technical
data in datasheets and instruction manuals for thermographic cameras that are used to measure
the temperature of surfaces. This includes, unless otherwise stated, both two-dimensional and
one-dimensional (line cameras or line scanners) temperature measuring instruments,
independently of the scanning principle (fixed multi-element detector or scanning camera
system).
This document describes standard test methods to determine relevant metrological data of
thermographic cameras. Manufacturers and sellers can choose relevant data and can state that
the data shall be compliant with this Technical Specification.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
NOTE The term “uncertainty” used in this document is precisely derived from the above databases and more
specifically from ISO/IEC Guide 98-3:2008 [3].
3.1
blackbody radiator
radiator that emits radiation in a very good approximation of Planck's radiation law
Note 1 to entry: A blackbody radiator is a source of thermal radiation with an effective emissivity close to 1.
3.2
coverage factor
numerical factor used as a multiplier of the combined standard uncertainty in order to obtain an
expanded uncertainty
Note 1 to entry: Coverage factor, k, is a number larger than one and, typically, in the range from 2 to 3.
3.3
detector format used
number of detector elements (detector pixels) that have actually been used to record the image
Note 1 to entry: The term "pixel", which is frequently used, will not be used in this document since it can refer both
to the detector (detector element) and to the image (image element).

– 10 – IEC TS 63144-1:2020 © IEC 2020
3.4
exposure time
minimum period of time during which the input quantity (measurement temperature or
measurement radiation) is applied in the event of abrupt changes in order for the output signal
of the thermographic camera to reach a pre-defined value
3.5
emissivity setting range
range within which the emissivity of the target can be set at the thermographic camera
3.6
field of view
FOV
horizontal and vertical angle of the maximum realizable image section of the thermographic
camera, with specified optics
Note 1 to entry: The field of view is the angular extent of the observable world that is seen at any given moment.
3.7
influence of air humidity
parameter which gives the additional uncertainty of the measured temperature value of a target
depending on the deviation of the actual humidity from the humidity at calibration referring to a
defined measuring range
[SOURCE: IEC TS 62492-1:2008, 3.1.11, modified – "depending on the relative air humidity at
a defined ambient temperature" replaced with "of a target depending.measuring range".]
3.8
influence of the internal instrument temperature
parameter which gives the additional uncertainty of the measured temperature value of a target
depending on the deviation of the actual internal temperature of the thermographic camera from
the internal temperature at calibration referring to a defined measuring range
[SOURCE: IEC TS 62492-1:2008, 3.1.10, modified – "depending on the deviation of the
temperature.ambient conditions" replaced with "of a target depending.measuring range".]
3.9
inhomogeneity equivalent temperature difference
IETD
smallest resolvable temperature difference that corresponds to the noise distributed over the
surface of the image elements in an image
Note 1 to entry: "Noise distributed over the surface" means the position-dependent deviation of the indicated value
of an image element from the mean value of all elements without the influence of time-dependent noise at a
homogeneous radiance of the source.
3.10
instantaneous field of view
IFOV
horizontal and vertical angle resulting from the computation of the section of the field of view
detected by a single detector element of the thermographic camera with aberration-free optics
with a specified focal length
3.11
integration time
time span in which a quantum detector converts the incident radiation into an output signal
Note 1 to entry: The measurement signal is also integrated when using thermal detectors, but in this case, the
integration time is not representative for the description of the time-dependent behaviour.

3.12
integration time setting range
range in which the time span for the conversion of the radiation signal into an output signal can
be set (for thermographic cameras with a quantum detector)
3.13
interchangeability
half the maximum deviation between the measurement results of two thermographic cameras
of the same type that are operated under identical conditions
[SOURCE: IEC TS 62492-1:2008, 3.1.15, modified – Definition revised.]
3.14
internal instrument temperature
internal temperature which is determined by the manufacturer at one or several representative
points and is provided to the user in order to monitor the admissible operating temperatures
and to indicate additional components in the measurement uncertainty
3.15
long-term stability
reproducibility of measurements repeated over a period of at least three months
[SOURCE: IEC TS 62492-1:2008, 3.1.12, modified – "over a long time" replaced with "a period
of at least three months".]
3.16
measurement accuracy
closeness of agreement between a measured quantity value and a true quantity value of a
measurand
Note 1 to entry: The concept “measurement accuracy” is not a quantity and is not given a numerical quantity value.
A measurement is said to be more accurate when it offers a smaller measurement error.
3.17
measurement uncertainty
parameter, associated with the result of a measurement, that characterizes the dispersion of
the values that could reasonably be attributed to the measurand
EXAMPLE The half-width of an interval having a stated coverage probability.
Note 1 to entry: "Measurement uncertainty" and "measurement accuracy" are not synonyms.
[SOURCE: ISO/IEC Guide 98-3:2008, 2.2.3, modified – Notes replaced with the example and
note to entry.]
3.18
measuring distance
distance or distance range between the thermographic camera and the target for which the
thermographic camera is designed and in which a focussed imaging of the target is possible
[SOURCE: IEC TS 62492-1:2008, 3.1.4, modified – "radiation thermometer" replaced with
"thermographic camera" and "and in which a focussed imaging of the target is possible" added.]
3.19
measuring temperature range
temperature range, with respect to the blackbody, for measurements in which the thermographic
camera is designed
Note 1 to entry: For this temperature range, the measurement uncertainty remains within defined limits.

– 12 – IEC TS 63144-1:2020 © IEC 2020
[SOURCE: IEC TS 62492-1:2008, 3.1.1, modified – "radiation thermometer" replaced with
"thermographic camera", "with respect to the blackbody, for measurements in which" and note
added.]
3.20
minimum field of view for temperature measurement

MFOV
T
field of view of the circular target with the smallest possible diameter, which, when measured
proportionally to the radiance, does not result in a decrease compared to the reference value
larger than that specified
3.21
noise equivalent temperature difference
NETD
contribution to the measurement uncertainty, indicated in K or in °C, which occurs due to time-
dependent instrument noise
[SOURCE: IEC TS 62492-1:2008, 3.1.3, modified – Definition revised.]
3.22
non-uniformity
inhomogeneity of detector responsivity
maximum difference between the indicated temperature values in an image when viewing an
image-filling, homogeneous radiance of the measurement object and neglecting the time-
dependent intrinsic noise of the instrument
3.23
number of image elements
number of single values of which the image provided by the thermographic camera consists,
horizontally and vertically
3.24
operating humidity range
admissible humidity range within which the thermographic camera may be operated
[SOURCE: IEC TS 62492-1:2008, 3.1.19, modified – "permissible" replaced with "admissible"
and "radiation thermometer" replaced with "thermographic camera".]
3.25
operating temperature range
admissible temperature range within which the thermographic camera may be operated
[SOURCE: IEC TS 62492-1: 2008, 3.1.19, modified – "permissible" replaced with "admissible"
and "radiation thermometer" replaced with "thermographic camera".]
3.26
image element
image pixel
smallest independent thermographic detector cell of a thermographic camera
Note 1 to entry: The term "pixel", which is frequently used, will not be used in this document since it can refer both
to the detector (detector element) and to the image (image element).
3.27
Planck's radiator
idealized thermal radiation source, which emits radiation with a characteristic spectrum that
only depends on the temperature and is fully described by Planck's law

3.28
reference radiator
radiating source for the metrological characterization of a thermographic camera whose
radiating surface has a sufficient size, temperature homogeneity and spectral emissivity that is
sufficiently stable and sufficiently well-known for its application
Note 1 to entry: The requirements on the reference radiator result from the technical specifications of the
thermographic camera to be characterized and the intended uncertainty of its characterization.
3.29
refresh rate
number of output images in the specified resolution (number of image elements) per second
3.30
repeatability
twice the standard deviation of measurements repeated under the same conditions within a time
span of at least three minutes
[SOURCE: IEC TS 62492-1:2008, 3.1.14, modified – "very short time span (several minutes)"
replaced with "a time span of at least three minutes".]
3.31
response time
time interval between the instant of an abrupt change in the value of the input parameter
(measurement temperature or measurement radiation) between two constant values and the
instant from which the measured value of the thermographic camera remains within specified
limits of its final value
[SOURCE: IEC TS 62492-1:2008, 3.1.16, modified – "object" replaced with "measurement",
"between two constant values" added and "radiation thermometer" replaced with
"thermographic camera".]
3.32
short-term stability
reproducibility of measurements repeated over a period of at least three hours
[SOURCE: IEC TS 62492-1:2008, 3.1.13, modified – "a short time period (several hours)"
replaced with "a period of at least three hours".]
3.33
size-of-source effect
SSE
change in the radiation value or temperature value indicated by the thermographic camera when
viewing the centre of a radiating surface with a homogeneous temperature when the area of the
radiation surface is enlarged
3.34
slit response function
SRF
relative change in the value measured at the centre of the slit, in radiance-proportional quantity
while reducing the width of a slit-shaped aperture oriented horizontally and/or vertically with
respect to the detector and positioned in front of a homogeneously temperature-stabilized
radiator
3.35
spectral range
parameter that gives the lower and upper limits of the wavelength range over which the
thermographic camera detects radiation from the target

– 14 – IEC TS 63144-1:2020 © IEC 2020
[SOURCE: IEC TS 62492-1:2008, 3.1.9, modified – "radiation thermometer operates" replaced
with "the thermographic camera detects radiation from the target".]
3.36
warm-up time
maximum time period needed by the thermographic camera after switching on to operate
according to its specification
[SOURCE: IEC TS 62492-1:2008, 3.1.18, modified – "maximum" added and "radiation
thermometer" replaced with "thermographic camera".]
4 Symbols
For the purposes of this document, the symbols listed in Table 1 below are used:
Table 1 – Symbols
Symbol Description Unit
U Expanded measurement uncertainty
M Measurement result
k Coverage factor 1
FOV Horizontal field of view °

h
FOV Vertical field of view °
v
IFOV
Horizontal instantaneous field of view mrad
h
IFOV Vertical instantaneous field of view mrad
v
MFOV Minimum field of view for temperature measurement mrad

T
n Horizontal image element number 1
h
n
Vertical image element number 1
v
χ Idealized measurement field mm

Ideal
d Measuring distance m
f Optical factor 1
Optic
λ Wavelength µm
Mean temperature difference K
ΔT
t Time s
t
Warm-up time s
W
f Refresh rate Hz
B
t Integration time s
M
NETD Noise equivalent temperature difference °C

5 Abbreviated terms
For the purposes of this document, the abbreviated terms listed below are used:
IETD inhomogeneity equivalent temperature difference
SRF slit response function
FWHM full width at half maximum

NUC non-uniformity correction
6 Determination of technical data
6.1 General
A typical setup for the determination of characteristics of thermographic camera is shown in
Figure 1. The following test conditions apply for all measurements, if not stated otherwise:
1) ambient temperature range in the laboratory: 18 °C to 28 °C;
2) thermographic camera to be connected to a power supply in accordance with the
manufacturer’s instructions;
3) positioning system which allows linear and angular alignment of the thermographic camera
in respect of the optical axis of the reference radiator;
4) compliance with the warm-up time specified by the manufacturer;
5) use of a reference radiator;
6) presupposition that, if the measuring distance is indicated in accordance with the
measurement provisions, the objective of the thermographic camera is focussed on this
distance.
NOTE The reference radiator is, if possible, a cavity blackbody radiator that is a good approximation of Planck's
radiator, or a large-area surface radiator with a good temperature homogeneity and a coating characterized by a
homogeneous and high emissivity (> 0,95 if T ≤ 150 °C and > 0,90 if T > 150 °C).
If detector elements are faulty, which the manufacturer most of the time replaces by special
algorithms, this shall not influence the measurements; if needed, the manufacturer shall be
asked to provide these algorithms or the measurements shall be repeated at different positions.

Figure 1 – Schematic measuring setup
6.2 Measuring temperature range
6.2.1 General
The temperature range for which the thermographic camera is designed and in which the
measurement uncertainty lies, within the given specification, always refers to the blackbody.
Besides the specified measuring temperature range, a temperature indication range may be
given. Within the limits of this range, the thermographic camera indicates measured values
without necessarily complying with the specified measurement uncertainty.

– 16 – IEC TS 63144-1:2020 © IEC 2020
6.2.2 Required parameters
In the case of interchangeable objectives, spectral filters or diaphragms, the arrangement used
shall be indicated. If wider measuring temperature ranges are divided into several manually or
automatically adjustable individual ranges, this division shall also be indicated.
6.2.3 Examples of indications
a) Measuring temperature range: −20 °C to 300 °C
b) Measuring temperature ranges: (1) −20 °C to 120 °C and (2) 0 °C to 600 °C
6.2.4 Test condition, method and procedure for measuring temperature range
The measuring temperature range is closely linked to the measurement uncertainty (3.17) and
can therefore be fully determined in connection with the latter only.
To determine the temperature indication range, the thermographic camera is placed centrally
in front of a reference radiator of known temperature and emissivity. The temperature of the
reference radiator is progressively brought closer to the specified minimum and maximum
temperatures of the respective temperature indication range. Taking the specified measurement
uncertainty of the thermographic camera and the uncertainty of the reference radiator used into
account, the indication of the lowest and of the highest temperature in the thermographic image
is recorded and compared with the manufacturer's declarations.
6.3 Noise equivalent temperature difference (NETD)
6.3.1 General
The noise equivalent temperature difference indicates the contribution to the measurement
uncertainty which is caused by high-frequency temporal instrument noise. It corresponds to the
temperature difference of a blackbody where the signal-to-noise ratio of the thermographic
camera is 1. In the case of t
...