Radiation Thermometer Research Articles

High-dynamic-range radiation thermometer of flame based on multi-flux in parallel

High-dynamic-range radiation thermometer of flame based on multi-flux in parallel

Temporal Analysis of Temperature Distribution at a Laser Spot in Selective Laser Thermoregulation Using a High-Speed Radiation Thermometer

Temporal Analysis of Temperature Distribution at a Laser Spot in Selective Laser Thermoregulation Using a High-Speed Radiation Thermometer

Crop water stress index characterizes maize productivity under water and salt stress by using growth stage-specific non-water stress baselines

ContextThe use of non-destructive, continuous, and rapid canopy temperature (Tc) indices for crop stress diagnosis is of significant importance for improving crop water productivity (WP). However, the comprehensive applicability of the crop water stress index (CWSI), grounded in Tc, in diagnosing both single and combined water and salt stress, as well as characterizing physiological and growth traits, remains inadequately explored. ObjectiveWe aim to investigate the ability of CWSI to diagnose single and combined water and salt stress and to test whether a non-water stress baseline (NWSB) with or without growth stage and genotype differences influences CWSI to characterise maize leaf physiological and growth traits. MethodsHere, we measured the Tc using infrared radiation thermometers of two maize genotypes (XY335 and ZD958) under both single and combined water and salt stress over two growing seasons, compared the differences of NWSB in three growth stages, and established CWSI. Our analysis involved scrutinizing the differences in characterizing crop physiology and growth traits between CWSI calculated using NWSB with and without growth stage differentiations. ResultsOur findings indicated that Tc is modulated by an interplay of soil water content, VPD, and soil salinity. The NWSB exhibited variations with both growth stage (pslope < 0.001) and genotype (pslope or pintercept < 0.01). The CWSI can diagnose single and combined water and salt stress suffered by maize. Under no stress, and single and combined water and salt stress, CWSI was significantly correlated with stomatal conductance (R2 ≥ 0.31, p < 0.1) and net photosynthetic rate (R2 ≥ 0.38, p < 0.1), rather than with hydraulic traits. The mean CWSI across the entire growth period closely correlated with leaf area index (LAI), canopy photosynthetically active radiation interception, biomass, yield, and evapotranspiration across varying treatments (R2 ≥ 0.54, p < 0.1). Contrary to CWSI derived from NWSB without growth stage variations, utilizing CWSI with growth stage distinctions better characterized physiological traits, while the former was more suitable for delineating yield and WP. ImplicationsThis research underscores the efficacy of CWSI for stress diagnosis and the evaluation of gas exchange and productivity in maize under both single and combined soil water-salt stress. This investigation significantly propels forward the implementation of crop-centric irrigation strategies aimed at optimizing water utilization efficiency.

Direct observation of plateau progression in fixed-point blackbodies via X-ray imaging

In this study, we address the challenge of calibrating radiation thermometers using blackbody furnaces that employ a metal melting/freezing plateau. Here, we first present the observation results utilizing X-rays, enabling us to monitor the entire temperature cycle, from heating to cooling, during the calibration process. Through this approach, we directly observe the emergence of voids within deteriorating metal cells, which may give insights into the underlying mechanisms occurring within enclosed graphite cells.

TEMPERATURE CORRECTION METHOD OF RADIATION THERMOMETER BASED ON THE NONLINEAR MODEL FITTED FROM SPECTRAL EMISSIVITY MEASUREMENTS OF Ni-BASED ALLOY

Accurate temperature monitoring of heat transfer tube is crucial for safe and efficient operation of nuclear power plants, and radiation thermometer is a common method used for this purpose. This paper thoroughly introduces the measurement principle of the radiation thermometer with an operation wavelength range of 8-14 &amp;mu;m. The spectral emissivity of Ni-based alloy DD6 under argon condition is measured using an emissivity measurement setup equipped with a Fourier-transform infrared (FTIR) spectrometer. By integrating the spectral emissivity in the working wavelength range, the spectral band emissivity can be calculated to enhance the accuracy of calculation results obtained by radiation thermometer. And curve of the spectral band emissivity with temperature can be accurately described by the nonlinear model. The radiation and corrected temperatures are compared with the temperatures obtained by a K-type thermocouple to verify the availability of the spectral band emissivity obtained by fitting the nonlinear model. The temperature comparison results demonstrate that the corrected temperatures are closer to the true temperature than the radiation temperature, with a maximum temperature deviation of only 4.38&amp;deg;C. The combined relative uncertainty of true temperature measurement by the radiation thermometer at temperatures of 200, 300, 400, and 500&amp;deg;C is less than 3.60&amp;#37;.

Final report for CCT comparison of ITS-90 realisations above the silver point using two transfer radiation thermometers and a set of high temperature fixed-point blackbody cells

Main textThis report outlines the equipment, measurement method, results and uncertainties associated with the participant measurements for the Consultative Committee of Thermometry Key Comparison K10 (CCT-K10), "ITS-90 realisations above the silver point using two transfer radiation thermometers and a set of high temperature fixed-point blackbody cells", over the period from around summer 2014 to the final measurements made during January 2020. The report presents differences of the participant data from the KCRV values for both the radiation thermometer and HTFP measurements. Note: this interim report excludes the measurement data of VNIIM, Russia - see explanation at the end of Section 6.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Data reduction and uncertainty assessment of the direct pulse heating technique with both contact and radiance temperature measurements

This work presents a data reduction procedure of the direct pulse heating technique with both contact and radiance temperature measurements. The technique is applied for the measurement of thermophysical properties of electroconductive solids over a wide temperature range, i.e., from room temperature up to about 2300°C. Absolute and radiance temperatures of a tested material are measured by thermocouple and radiation thermometer, respectively and these and other experimental data are then reduced to the values of specific heat, specific electrical resistivity, hemispherical total emissivity and normal spectral emissivity of the tested material. The related data reduction and corresponding uncertainty assessment for each property is described in detail. An example of uncertainty assessment is given for the recent measurement of specific heat, specific electrical resistivity, hemispherical total emissivity and normal spectral emissivity at 900 nm of molybdenum alloy TZM specimens.

InAsSb Photodiode Fibre Optic Thermometry for High-Speed, near-Ambient Temperature Measurements

Infrared radiation thermometers (IRTs) overcome many of the limitations of thermocouples, particularly responsiveness and calibration drift. The main challenge with radiation thermometry is the fast and reliable measurement of temperatures close to room temperature. A new IRT which is sensitive to wavelengths between 3 μm and 11 μm was developed and tested in a laboratory setting. It is based on an uncooled indium arsenide antimony (InAsSb) photodiode, a transimpedance amplifier, and a silver halogenide fibre optic cable transmissive in the mid- to long-wave infrared region. The prototype IRT was capable of measuring temperatures between 35 °C and 100 °C at an integration time of 5 ms and a temperature range between 40 °C and 100 °C at an integration time of 1 ms, with a root mean square (RMS) noise level of less than 0.5 °C. The thermometer was calibrated against Planck’s law using a five-point calibration, leading to a measurement uncertainty within ±1.5 °C over the aforementioned temperature range. The thermometer was tested against a thermocouple during drilling operations of polyether ether ketone (PEEK) plastic to measure the temperature of the drill bit during the material removal process. Future versions of the thermometer are intended to be used as a thermocouple replacement in high-speed, near-ambient temperature measurement applications, such as electric motor condition monitoring; battery protection; and machining of polymers and composite materials, such as carbon-fibre-reinforced plastic (CFRP).

Optimization of the electrical transport properties of La0.7Ca0.3MnO3 films by sintering temperature adjustment

With the development of the radiation thermometers, perovskite manganites have been fallen into the focus of highly sensitive infrared bolometers due to its metal-insulator transition properties. In this study, La0.7Ca0.3MnO3 (LCMO) films were prepared on (l00) LaAlO3 substrates using sol-gel spin-coating technology by adjusting different sintering temperatures (Ts, 1000 °C ≤ Ts ≤ 1400 °C). The analysis of the microstructure, surface morphology, ion valence state, and electrical transport properties revealed that the crystalline quality enhanced and the concentration of Mn4+ increased with the increasing of sintering temperature, promoting the DE effect and improving the electrical properties of the LCMO films. At Ts = 1200 °C, the temperature coefficient of resistivity (TCR) value of the LCMO film reached the maximum value (22.95% K−1) and corresponding peak TCR temperature of 246.85 K indicating that the LCMO film has great potential in infrared bolometers.

Large-area Fe–C eutectic fixed-points for radiation and contact thermometry

Abstract High-quality metal (carbide)–carbon eutectic materials based on high-temperature fixed points (HTFPs) are widely used in radiometry and thermometry as reference standards. HTFPs on the base of iron–carbon (Fe–C) binary eutectic alloys, with a nominal melting temperature of about 1154 °C (just above the copper freezing point of 1084.62 °C), are one of the promising candidates among the eutectic materials. To establish new HTFPs as reference metrological tools for high-temperature thermometry, their performance should be thoroughly investigated regarding reproducibility and stability. In this work, two large-area (8 mm aperture, 107 mm cavity/thermowell length) Fe–C fixed-point cells were constructed and studied in detail using a radiation thermometer and two different thermocouples (TCs). Three different furnaces were used to explore the thermal behaviors of the cells at various furnace gradients and furnace offsets. The melting temperature at the inflections point of the melting curves of the cells studied across extensive measurement campaigns demonstrated good performance with repeatability of less than 9 mK (assessed from four successive runs) and reproducibility—less than 100 mK (at different furnaces and furnace offsets). The melting temperature agreement between both cells in the same experimental conditions was better than 30 mK. In addition, the equivalence of the developed large-area cells and a small-area radiometric cell (3 mm cavity aperture, and 35 mm cavity length) were comparatively examined in the same experimental conditions. The coherence of the obtained results for the melting temperature of large-area Fe–C cells indicates the feasibility of using large-volume cells for precise calibration of both radiation thermometers and TCs.

A novel PZT-based high-power piezoelectric vibrator for ultrasonic motors: properties enhanced by Yb institution

PurposeThe electrical properties of piezoelectric vibrators have a crucial influence on the operating state of ultrasonic motors. In order to solve the problem that the current piezoelectric vibrator generates a large amount of heat during vibration to degrade its performance, which in turn affects the normal operation of ultrasonic motors, this paper prepares a novel piezoelectric vibrator and tests its maximum vibration velocity under the working condition, which is more than twice as much as that of the current commercial PZT-8.Design/methodology/approachThe crystal structures of the samples were analyzed by using an X-ray diffractometer. For microstructure observation, samples were observed by scanning electron microscope (SEM). The quasi-static piezoelectric coefficient meter (ZJ-3AN) was used for piezoelectric measurement. Dielectric properties were measured by utilizing an impedance analyzer (Agilent 4294A) with a laboratory heating unit. Ferroelectric hysteresis loops were obtained using a ferroelectric analyzer (Radiant, Multiferroic 100). A Doppler laser vibrometer (Polytec PSV-300F, Germany) and a power amplifier were used for piezoelectric vibration measurements, during which the temperature rise was determined by an infrared radiation thermometer (Victor 303, China).FindingsThe ceramics exhibit enhanced piezoelectric performance at 0.1–0.4 mol% of Yb doping contents. The ceramic of 0.4 mol% Yb reaches the maximal internal bias field and presents a larger mechanical quality factor of 1,692 compared with that of 0.2 mol% Yb-doped ceramic, in spite of a slightly decreased dielectric constant of 439 pC/N, the unit of the piezoelectric constant, which is the ratio of the local charge (pC) to the frontal force (N) and electromechanical coupling coefficient of 0.63. The vibrator with this large mechanical quality factor ceramic displays a vibration velocity of up to 0.81 m/s under the constraint of 20 °C temperature rising, which is much higher than commercial high-power piezoelectric ceramics PZT-8.Originality/valueThe enhanced high-power properties of the piezoelectric vibrator by Yb doping may provide a potential application for the high-performance USM and offer the possibility of long-term stable operation under high power for special equipment like USM. In the subsequent phase of research, the novel PZT-based high-power piezoelectric vibrator can be utilized in the USM, and the motor's performance will be evaluated under aerospace conditions to objectively assess the reliability of the piezoelectric vibrator.

Development and characterization of a high-emissivity reference blackbody radiation source with V-grooves and large aperture at low-temperature

A high-emissivity blackbody radiation source can improve the measurement level of infrared radiation temperature, which is critical for applications in high-value industries and human health monitoring. In this study, a new high-emissivity blackbody source with V-grooves and large aperture was redesigned and developed, which can be used as a radiation temperature reference source for the calibration of secondary blackbody sources and precision radiation thermometers in the temperature range from −10 ℃ to 100 ℃, including the temperature range of human body infrared radiation considered in the study of people exhibiting fever symptoms. The wavelengths of the infrared spectral radiation temperatures involved in the study were in the range of 8–14 μm. The blackbody source consisted of a blackbody cavity, a jet-stirred precision constant-temperature bath, a standard platinum resistance thermometer, a high-precision digital multimeter, a frost-proof cover, and an auxiliary test frame. The cavity was cylindrical and conical with a diameter of 60 mm, a conical top angle of 120°, and a total length of 300 mm. The V-grooves with an angle of 50° on the inner wall were coated with high-emissivity coatings. The cavity was then completely immersed in a thermostatic bath. The radiation temperature of the blackbody source was traced to the International Temperature Scale of 1990 using a standard platinum resistance thermometer, which was calibrated at fixed-points of the Ar, Hg, H2O, Sn, and Zn. The experimental results revealed that the normal effective emissivity of the blackbody measured by the thermal cavity reflectometer method was 0.999 751, which is consistent with the theoretical calculation results based on the Monte Carlo method using optical ray tracing technology. In addition, the accuracy of the radiation temperature was verified by comparing it with a reference blackbody source from the National Institute of Metrology (NIM), China. The temperature stability of the blackbody source did not exceed 0.005 ℃ within 30 min, the axial temperature uniformity of the blackbody cavity did not exceed 0.048 ℃, and the temperature uniformity at the bottom of the cavity was better than 0.053 ℃. The combined standard uncertainty of the radiation temperature of the blackbody radiation source was evaluated from 0.010 ℃ to 0.032 ℃. The novel design with 50° V-grooves allowed for the blackbody source to provide the combination of a large aperture and high emissivity, which improved radiance temperature measurements. The reliability of the new design was experimentally verified. This design provides a novel method and experimental basis for the future design of compact light-weight blackbody sources, which is useful for the development of compact spaceborne blackbody sources.

Design, construction and modeling of a small-scale high temperature field rotor test rig

In-field validation of radiation thermometer performance is time consuming and expensive, especially when prototype experiments are performed. This study focuses on the development of a novel small-scale high temperature field simulation test rig for measuring turbine blade surface temperatures under changing environmental conditions. When developing and testing a radiation thermometer, the testing is typically performed directly on a test rig that can simultaneously provide a standardized environment and compare temperature data. This apparatus allows for static and dynamic temperature testing in a hostile environment by combining temperature, particle, and atmospheric effects. In the present study, a test rig will be utilized to analyze and validate the radiation thermometer, which will be subjected to harsh combined environmental variables with a temperature range of up to 2000K. Notably, the rotating head structure of the two materials allows for the application of a vast range of temperature measurements (700–2000 K), which is a distinctive characteristic of the design. The requirements of the test rig are defined based on the specimens to be tested. The necessity for the combined complete test setup, as well as its design and functionality, are discussed in this paper. Finally, validation experiments are conducted to demonstrate the test rig's accuracy in measuring turbine blade surface temperature, which is 0.25%.

Laboratory evaluation of forehead infrared radiation thermometers (FIRTs) used for core body temperature measurements

Laboratory evaluation of forehead infrared radiation thermometers (FIRTs) used for core body temperature measurements

Adjustable Trifunctional Mid-Infrared Metamaterial Absorber Based on Phase Transition Material VO2.

In this paper, we demonstrate an adjustable trifunctional absorber that can achieve the conversion of broadband, narrowband and superimposed absorption based on the phase transition material vanadium dioxide (VO2) in the mid-infrared domain. The absorber can achieve the switching of multiple absorption modes by modulating the temperature to regulate the conductivity of VO2. When the VO2 film is adjusted to the metallic state, the absorber serves as a bidirectional perfect absorber with switching capability of wideband and narrowband absorption. The superposed absorptance can be generated while the VO2 layer is converted to the insulating state. Then, we introduced the impedance matching principle to explain the inner mechanism of the absorber. Our designed metamaterial system with a phase transition material is promising for sensing, radiation thermometer and switching devices.

The Effect of the Conversion Coefficients of Platinum-Based Resistance Thermometers on the Uncertainty Estimation

Different types of thermometers (resistance thermometers, thermocouples, liquid in glass thermometers, radiation thermometers, etc.) are used in temperature measurements. Resistance thermometers are among the most reliable types of sensors used for sensitive temperature measurements. The traceability, accuracy and precision of the measurement results are important for the reliability of the measurements. There are many parameters that affect the uncertainty estimation in measurements made with resistance thermometers. One of the parameters to be considered in the uncertainty estimation is the interpolation error in converting the resistance value to temperature. Different methods (ITS-90, Calendar Van Dusen CVD, Polynomial equation) can be used to convert the resistance value to temperature. The problem is that there are differences in the temperature values read using the coefficients obtained by different methods. In this study, the effect of errors from CVD and polynomial equation methods on measurement uncertainty was investigated.

Measurement of Exothermic Values of Casting-sleeve Materials Using an Ice Calorimeter

Defects, which are a major problem in casting, can affect the integrity of products. The processes used to reduce defects are often complex and increase manufacturing cost. Simulations are used to predict casting defects by analyzing the flow and solidification of the metal. However, simulation results often differ from actual casting results because appropriate values for the physical properties have not yet been experimentally obtained. Thus, in this study, an ice calorimeter was developed to measure the exothermic value of sleeve materials under rapid heating conditions. In the case where a thermocouple or radiation thermometer is used to determine the heater temperature, heat loss due to the lead wires or hole for temperature measurement cannot be avoided. Therefore, in this study, the heater resistance was obtained using current and voltage, and the temperature was determined using the resistance value. Although some variations were observed, the average measured exothermic values of all exothermic sleeve materials (1.2 kJ/g) matched approximately with those predicted by computer simulation using known thermophysical properties and experimentally obtained distributions of shrinkage cavities. Therefore, the exothermic values obtained in this study are considered valid.

A Traceable Spectral Radiation Model of Radiation Thermometry

Despite great technical capabilities, the theory of non-contact temperature measurement is usually not fully applicable to the use of measuring instruments in practice. While black body calibrations and black body radiation thermometry (BBRT) are in practice well established and easy to accomplish, this calibration protocol is never fully applicable to measurements of real objects under real conditions. Currently, the best approximation to real-world radiation thermometry is grey body radiation thermometry (GBRT), which is supported by most measuring instruments to date. Nevertheless, the metrological requirements necessitate traceability; therefore, real body radiation thermometry (RBRT) method is required for temperature measurements of real bodies. This article documents the current state of temperature calculation algorithms for radiation thermometers and the creation of a traceable model for radiation thermometry of real bodies that uses an inverse model of the system of measurement to compensate for the loss of data caused by spectral integration, which occurs when thermal radiation is absorbed on the active surface of the sensor. To solve this problem, a hybrid model is proposed in which the spectral input parameters are converted to scalar inputs of a traditional scalar inverse model for GBRT. The method for calculating effective parameters, which corresponds to a system of measurement, is proposed and verified with the theoretical simulation model of non-contact thermometry. The sum of effective instrumental parameters is presented for different temperatures to show that the rule of GBRT, according to which the sum of instrumental emissivity and instrumental reflectivity is equal to 1, does not apply to RBRT. Using the derived models of radiation thermometry, the uncertainty of radiation thermometry due to the uncertainty of spectral emissivity was analysed by simulated worst-case measurements through temperature ranges of various radiation thermometers. This newly developed model for RBRT with known uncertainty of measurement enables traceable measurements using radiation thermometry under any conditions.

Geometrical and thermal optimization of cylinder-conical blackbody cavities to uniform radiance temperature profiles in the infrared

Large-area blackbody cylinder conical cavities are generally used as primary radiation sources for calibrating and characterizing radiation thermometers and quantitative thermal imagers in the infrared, both in metrology laboratories or for industrial applications. The radiation temperature of the emitted radiation depends on effective emissivity and surface (contact) temperature. The instrument’s field of view generally only covers the cavity bottom since this is where contact temperature is best measured. A non-uniform effective emissivity profile at the bottom poses a problem if instruments with a different field of view have to be calibrated with the same blackbody. Spatial uniformity depends principally on the cone angle and temperature gradient along the cavity. In this paper, we analyse blackbody optimization in terms of uniform radiance temperature profiles as a function on geometric parameters and temperature. For the isothermal case, we conclude that angles between 160° and 170° are the optimum, depending on intrinsic emissivity and length-to-diameter ratio of the cavity. For non-isothermal cavities, the effect of the temperature gradient on uniformity is relatively small, with only the temperature near the bottom proving significant. The use of multi-zone maintenance furnaces would allow temperature gradients to be designed that can improve uniformity in addition to geometric optimization.

CONFORMITY ASSESSMENT IN INFRARED EAR THERMOMETER CALIBRATION

Body temperature is a basic physiological measurement used primarily for observation and diagnosis during surgery, pandemic diseases, intensive care, recovery or treatment. Various thermometers are clinically used for these measurements and can be divided into two categories, contact or non-contact. To have maximum confidence in the clinical performance of the temperature measuring instrument, it is important to calibrate the instrument traceable to the 1990 International Temperature Scale (ITS-90). The absence of traceable calibrations accredited to ISO/IEC 17025 can lead to insecurity in temperature measurement and in some cases can have a detrimental effect on patient care.Infrared or radiation thermometers are preferred in many different sectors from health to food, from automotive to agriculture, from iron and steel industry to chemistry due to their fast measuring capabilities, reasonable prices, wide measuring ranges and ease of use. In this study, ear thermometer calibration and measurement uncertainty calculations are investigated by using the traceability method via contact thermometer. Considering the maximum permissible error value of the device, conformity assessment is made according to the measurement result.