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National Metrology Technical Specification of the People's Republic of China JJF1187-2008
Calibration Specification for Thermal Imagers
Calibration Specification for Thermal Imagers Issued on 2008-01-31
Implementation on 2008-04-30
Issued by the General Administration of Quality Supervision, Inspection and Quarantine JJF1187—2008
Calibration Specification for
Thermal Imagers
JJF1187-
This specification was approved by the General Administration of Quality Supervision, Inspection and Quarantine on January 31, 2008, and came into effect on April 30, 2008.
Responsible unit: National Technical Committee on Temperature Metrology Main drafting unit: China National Institute of Metrology Participating drafting unit: Guangzhou Fengte Electric Power Infrared Technology Co., Ltd. This specification is interpreted by the National Technical Committee on Temperature Metrology Main drafters of this specification:
JJF1187—2008
Bai Chengyu (China National Institute of Metrology) Xing Bo (China National Institute of Metrology)
Yuan Zundong (China National Institute of Metrology) Participating drafter:
Wu Yigang (Guangzhou Fengte Electric Power Infrared Technology Co., Ltd.) 1
References……·
3Terms and measurement units·
Measurement units·
Metrological characteristics
Indication error,
Temperature measurement consistency
Calibration conditions||tt ||Environmental conditions
Standards and other equipment
Calibration items and calibration methods
Calibration items·
Calibration methods
Expression of calibration results
9 Recalibration time interval
JJF1187—2008
Appendix A Assessment of calibration uncertainty of indication error of thermal imager Appendix B Record format of calibration results
Appendix C Format of data page of thermal imager calibration certificate (1)
（2）
（5）
（6）
（9）
1 Scope
JJF1187-2008
Thermal imager calibration specification
This specification applies to the calibration of thermal imagers with temperature measurement function in the range of -20℃ to 2000℃. 2 References
This specification references the following documents:
SOOH DNIISTENG
JJF1001-—1998 "General Information
JJG1007—2007
GB/T19870
JJF1059-
Terms and Definitions"
"Terms and Definitions of Reduction Measurement"
S Industrial Building
Uncertainty of Remaining Quantity
When using this specification, attention should be paid to the use of
Terms and Measurement
3.1 Terms||tt ||3.1.2 Indication
Thermal imager shear
3.2 Measurement
Temperature unit
-2005 "T
errorofindi
The sampling error is the
degrees Celsius (℃) or K
Thermal imager can correct for factors such as object
and|body surface thermal radiation
Effective version
Infrared Thermal Imager" terms and definitions apply to this specification. The temperature distribution of the surface of the object is measured by measuring the temperature of the object surface through the measurement of the reflectivity, reflectivity and transmittance. According to the application mode, thermal imagers can be divided into offline and online types; according to the original mode, thermal imagers can be divided into optical scanning imaging type and staring type, and according to the working temperature of the device, they can be divided into cooling type and non-cooling type. A correction function is used to accurately measure the surface temperature of the object. The correction factors generally include the emissivity of the object being measured, the target distance, the ambient temperature, the attenuation of the thermal radiation of the atmospheric environment to the measured target, the ambient thermal radiation, the optical and electrical measurement system, etc. Thermal imagers generally have a variety of thermal image display modes, and have the functions of freezing, storing, analyzing and outputting video signals of the thermal image of the measured object.
5 Metrological characteristics
5.1 Appearance
5.1.1 The thermal imager's housing, mechanical adjustment components, exposed optical elements, buttons, electrical connectors, etc. should not have defects that affect the calibration of the thermal imager.
JJF1187-2008
5.1.2 The thermal imager should be marked with the manufacturer (or trademark), model, number and other identification. 5.2 Display
The display effect of the thermal imager should not have defects that affect the calibration. 5.3 Indication error
The temperature indication error of the thermal imager is determined under the conditions of the calibration laboratory. 5.4 Temperature measurement consistency
The consistency of temperature measurement results in different areas within the field of view of the thermal imager is the ability of the thermal imager to accurately reflect the surface temperature distribution of the measured object.
Calibration conditions
6.1 Environmental conditions
6.1.1 The ambient temperature of the calibration laboratory shall be (23 ± 5)°C, and the humidity shall not be greater than 85%RH (no condensation). 6.1.2 The environmental conditions of the calibration laboratory shall meet the requirements for the use of the calibration equipment and the thermal imager to be calibrated. 6.1.3 The calibration environment shall be free of strong ambient heat radiation. 6.2 Standards and other equipment
6.2.1 Standards
Ptrinitial resistance thermometers, thermocouples (with corresponding electrical measuring equipment) or radiation thermometers are usually used as standards to measure the temperature of blackbody radiation sources.
6.2.2 Radiation sources
The temperature range of the blackbody radiation source shall meet the calibration requirements of the thermal imager to be calibrated. For the technical requirements of blackbody radiation sources, see Table 1.
Table 1 Technical requirements for radiation sources
Radiation source
Cavity blackbody
Radiation source
Surface radiation source
Indication error calibration
Temperature measurement consistency calibration
Temperature measurement consistency calibration
Temperature range
Below 100℃
100℃～1000℃
1000℃~2000℃
Below 100℃
Cavity effective emissivity
(Effective emissivity of target surface)
(0.99~1.00)±0.01
(0.99～1.00)±0.01
(0.99～1.00)±0.01
0.97±0.02
Temperature stability
±0.05℃
±0.05℃
The temperature of black body radiation source is usually measured by contact thermometer or radiation thermometer, such as platinum resistance thermometer or thermocouple (with corresponding electrical measuring equipment).
6.2.3 The external display showing the measurement results of the thermal imager shall meet the measurement signal output index requirements of the calibrated thermal imager (if the calibrated thermal imager requires an external display). 6.2.4 Instrument bracket required for thermal imager calibration. 2
7 Calibration items and calibration methods
7.1 Calibration items
7.1.1 Appearance
JJF1187-2008
Thermal imager housing, mechanical adjustment parts, exposed optical components, buttons, electrical connectors, etc. should not have defects that affect the measurement function of the thermal imager.
Thermal imager should be marked with manufacturer (or trademark), model, number and other identification. 7.1.2 Display
Thermal imager display effect should not have defects that affect normal use. 7.1.3 Indication errorwww.bzxz.net
Thermal imager indication error calibration should be carried out under laboratory environmental conditions. 7.1.4 Temperature measurement consistency
Thermal imager should be tested for temperature measurement consistency under laboratory environmental temperature and humidity conditions. 7.2 Calibration method
7.2.1 Appearance
Manual and visual inspection, the appearance of the calibrated thermal imager must meet the requirements of 7.1.1. 7.2.2 Display
Manual and visual inspection, the display device of the calibrated thermal imager must meet the requirements of 7.1.2. 7.2.3 Indication error
7.2.3.1 Selection of calibration temperature points.
The calibration temperature points are the upper and lower limits of the range and the middle value of the range. For thermal imagers with multiple ranges, in the temperature area where the ranges overlap, calibration should be selected at different ranges. The calibration temperature can also be set according to user requirements.
7.2.3.2 Clean the exposed optical components of the thermal imager according to the thermal imager instruction manual. 7.2.3.3 Install additional optical lenses or optical components such as attenuation plates according to user requirements. 7.2.3.4 Determine the measuring distance according to the user's requirements or the focusing range requirements, optical resolution and target diameter of the blackbody radiation source of the thermal imager. Adjust the position of the thermal imager so that the thermal imager is aimed at the target center of the blackbody radiation source to be measured along the axial direction of the blackbody radiation source, and the measured target is clearly imaged. 7.2.3.5 According to the requirements of the thermal imager manual, the thermal imager should be turned on for a certain time before measurement (if the calibrated thermal imager has requirements).
7.2.3.6 According to the requirements of the thermal imager manual, input the range and calibration condition data, such as ambient temperature, ambient humidity, and measurement distance parameters. During calibration, the emissivity parameter of the calibrated thermal imager is set to 1 or equal to the emissivity of the blackbody radiation source.
7.2.3.7 Before calibrating the indication error, other operations that affect the measurement results, such as zeroing, etc., as required by the thermal imager manual, should be completed (if the calibrated thermal imager has requirements). 3
JJF1187—2008
7.2.3.8 Refer to the instruction manual to set the calibrated thermal imager to the point temperature measurement mode and measure the target center temperature of the blackbody radiation source. At each calibration temperature point, perform no less than 4 measurements. During the measurement, simultaneously record the measurement value of the blackbody radiation source reference standard, the indication ti of the calibrated thermal imager and the current range of the calibrated thermal imager. The recording format for calibrating a thermal imager with an emissivity set to 1 using a blackbody radiation source with a platinum resistance thermometer as the standard is shown in Appendix B. 7.2.3.9 Calculate the average radiation temperature tBBi of the blackbody radiation source. tBBi
CNONHSTI
wherein: tBBi,j——the ith calibration temperature m——the number of measurements at the ith calibration temperature, m≥47.2.3.10
Calculate the average value of the calibrated thermal imager
values at the t
calibration temperature point and the measured value of the radiation source temperature at the calibrated temperature point;
Under the short range, at the ith calibration temperature point, the indication error of the calibrated thermal imager7.2.3.11
is calculated at
100℃ according to the actual use of the thermal imager.
According to the user's manual, install additional optics. According ... 6. Determine the test distance based on user requirements or the focusing range diameter of the machine object. Adjust the thermal imager's azimuth, resolution, and blackbody radiation source target
system optical axis to coincide with the axial direction of the blackbody radiation source (when using a surface radiation source for calibration, the optical axis of the thermal imager's optical system should coincide with the normal through the center of the surface radiation source), and make the measured target clearly imaged. When performing temperature measurement consistency tests, the digital zoom function of the thermal imager is not allowed.
7.2.4.7 Before performing temperature measurement consistency calibration, other operations that may affect the measurement results as required by the thermal imager's instruction manual should be completed, such as zeroing, etc. (if required by the thermal imager being calibrated). 7.2.4.8 As shown in Figure 1, divide the display screen of the thermal imager being calibrated into equal parts. 9 areas, mark the center points of the 9 areas respectively. If the user requires, additional marking points can be added. 4
7.2.4.9 In the experimental conditions
JJF1187—2008
Consistency experiment
When the size of the blackbody radiation source cannot completely cover the field of view of the potential imager, use method
When the size of the blackbody radiation source cannot completely cover the field of view of the potential imager, use method
Method 1 to perform temperature measurement consistency test;
Method 2 to perform temperature measurement,
Method—:
Test experiment.
Decomposition of blackbody radiation
Adjust the thermal imager to reduce the amount of blackbody radiation source
Measure blackbody radiation
2,….，9,
Method 2
Adjust the thermal imager to reduce the amount of blackbody radiation source
2,, 9,
Where: The center temperature of the surface radiation source or the black body radiation source is measured and the thermal imager is calibrated to measure the temperature of the point. When the thermal imager indicates that the temperature of the point is completely visible, the center of the square is imaged at the marked point. The measurement sequence of the thermal imager is as follows: 5-→i→5(i -1,
jin imaging, set the thermal imager emissivity parameter to r5
measurement sequence as shown
9,5)
mean.
5→i→5(i-1,
according to the standard shrink nest a process property clear for the disease treatment for the energy cell TROL calibration results should be reflected in the calibration certificate or calibration report. The calibrated thermal imager effective settings that affect the results, including filters, lenses, measurement distance, etc.
For indication error calibration, the calibration temperature point, the calibrated thermal imager measurement value, range and calibration uncertainty should be clearly stated in the calibration result.
For temperature measurement consistency calibration, the calibration temperature point, temperature measurement consistency value, marking point distribution conditions and range should be noted in the calibration result. The format of the calibration certificate data page is shown in Appendix C. In addition to the calibration result information above, the calibration result certificate or report shall also include (but not limited to) the following information: a) Title, such as "Calibration Certificate" or "Calibration Report" b) Name and address of the laboratory; c) Location where the calibration was performed (if the calibration was not performed in the laboratory); d) Unique identification of the certificate or report (such as certificate number), page number and total number of pages; e) Name and address of the unit sending the calibration; f) Description and clear identification of the object being calibrated; g) Date of calibration, if relevant to the validity and application of the calibration results; h) If it is related to the validity and application of the calibration results, the sampling procedure should be explained; i) The identification of the technical specification on which the calibration is based, including the name and code; i) The traceability and validity of the measurement standard used in this calibration; k) Description of the calibration environment;
1) Description of the calibration result and its measurement uncertainty; m) The signature, position or equivalent identification of the issuer of the calibration certificate or report, and the date of issue; n) A statement that the calibration result is only valid for the calibrated object; o) A statement that the calibration certificate or report shall not be partially copied without the written approval of the laboratory. Recalibration time interval
The recalibration time interval is determined by the user based on the usage. It is recommended to be 1 year. It should be shortened appropriately when it is used frequently. 6
Appendix A
JJF1187—2008
Uncertainty assessment of calibration of thermal imager indication error A.1 Uncertainty analysis of calibration of thermal imager indication error A.1.1 Mathematical model of calibration
The calibration of thermal imager indication error is carried out using a cavity blackbody radiation source. The mathematical model of thermal imager indication error calibration is (i=1,2,.,n)
At,=t-tBBt
Where: At-the ith calibration temperature point, the indication error of the calibrated thermal imager; t—the ith calibration temperature point, the indication of the calibrated thermal imager tBB——blackbody temperature.
A1.2 Uncertainty assessment of calibration
The input quantities that affect the uncertainty of the thermal imager calibration result are the indication of the calibrated thermal imager and the blackbody radiation temperature tBBi. The two input quantities are independent of each other, and the combined standard uncertainty u of the indication error of the thermal imager is ue=yui +u=eu(t)+cu(tBBi)
wherein: ut.—
standard uncertainty component introduced by the input quantity; ute
u(tBBr)
standard uncertainty component introduced by the input quantity tBBs; the sensitivity coefficient of the input quantity t determined by the measurement mathematical model, according to formula (A.1), C
a(At:)
the sensitivity coefficient of the input quantity tsB determined by the measurement mathematical model, according to formula (A.1) Get Ctgei
--the standard uncertainty of the input quantity;
a(At,)
--the standard uncertainty of the input quantity tBB.
A.2 Example 11 of uncertainty assessment of calibration of thermal imager indication error
Take the use of cavity heat pipe blackbody radiation source to calibrate the thermal imager as an example, the experimental conditions are as follows: Ambient temperature: 25℃
Calibration temperature: 100℃
Blackbody radiation source: At the calibration temperature point, the cavity effective emissivity is 0.9985±0.0015, and the temperature control stability is 0.1C/10min.
Standard: Precision platinum resistance thermometer, measuring the temperature of the radiation source. Calibrated thermal imager: The response band is 8μm~14um, the indication resolution is 1℃ at the calibration temperature point, and the measurement repeatability is 1.0℃.
A.2.1 Evaluation of standard uncertainty of each input quantity A.2.1.1 Evaluation of standard uncertainty u (tBBi) of input quantity tBB:① Standard uncertainty component u1 caused by unstable temperature control of blackbody radiation source The temperature control stability of blackbody radiation source is 0.1℃/10min. Based on uniform distribution, u,=0.06℃. 7
JJF1187—2008
② Standard uncertainty component u2 caused by emissivity correction of blackbody radiation source At 100℃, the emissivity of blackbody radiation source is 0.9985±0.0015. With 0.9985 as the reference value, the indication of the calibrated thermal imager is corrected due to the deviation of the emissivity of the radiation source from 1. The uncertainty of the radiation source emissivity of 0.0015 causes the uncertainty of the radiation temperature of the blackbody radiation source to be 0.1℃. Based on uniform distribution, the standard uncertainty component u2 caused by the emissivity of the blackbody radiation source is 0.06℃. ③ Uncertainty component u3 introduced by reference standard transfer According to the calibration certificate, the standard uncertainty component u3 introduced by the precision platinum resistance thermometer is 0.04℃. ④ Standard uncertainty component o2℃ introduced by electrical measuring equipment Using digital multimeter and standard resistance transfer meter to measure the resistance of standard thermometer, taking Keithley2000 as an example, the standard uncertainty component o2℃ introduced by electrical measuring equipment. ③ The uncertainty caused by the temperature difference between the radiation source target surface temperature and the measurement point of the isolator u
The maximum temperature difference between the radiation source target surface temperature and the isolator measurement point and the standard instrument measurement point is us=0.05//30.03
Then the input quantity tBB is the standard uncertainty of the input quantity u
V0.062+0.06
① The standard thermal imager introduced by the thermal imager measurement is repeated
/4)℃, where the measurement is repeated ② The thermal imager indication is divided into 4 measurements in the experiment When the maximum
is 4, the range coefficient
standard
of the avoidance force is 1℃, and the Pai Ya uncertainty u (A.2.2 synthetic standard uncertainty
value is 100
temperature field characteristics are considered, and the standard deviation and
distribution of the uncertainty components of the radiation source target surface temperature are considered, u=（1/2/3）℃,
According to formula (A.2), the synthetic standard uncertainty u of the indication reading difference is
expanded uncertainty U
, take k=2, then U=0.9℃.
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