In the experiment of measuring the emissivity distribution characteristics by integrating sphere reflection method, the laser output power stability is an important guarantee for the accurate emissivity measurement. However, there is a lack of research on the influence of laser power stability on measurement results. Therefore, a measurement system for the infrared radiation source emissivity distribution characteristics is designed and built based on the complete hemispherical laser integrated reflection scheme in this paper. The stability of the laser light source subsystem is evaluated, and the laser power drift is corrected by means of a alternating measurement sequence. The experiment of measuring the flat plate radiation source emissivity distribution characteristics is carried out with a laser power of 3 W. The results show that the laser power shows a periodic drift and one period is about 70 s. The macroscopic power of the laser increases linearly throughout the measurement process. After correcting the laser power drift, the relative standard deviation of the flat plate radiation source is 0.56%, and the volatility is 2.99%. After drift correction, the measurement accuracy is improved by 28.2%.
KEYWORDS: Black bodies, Temperature metrology, Infrared radiation, Monte Carlo methods, Measurement devices, Computer simulations, Thermography, Mouth, Integrated modeling, Ray tracing
With the efficient use of energy, the study of emissivity is considered to be of great importance. In industrial production, temperature measurement technology, and many other fields, emissivity research is performed an important role. The emissivity is considered to be an important quantitative parameter for the infrared radiation characteristics of high-temperature coatings. Although the experimental measurement technique for high-temperature infrared spectral emissivity by the integrated blackbody method has been studied, little research has been reported on the integrated blackbody temperature field measurement and the simulation study of the emissivity of the integrated blackbody cavity. Therefore, in this paper, the temperature distribution of integrated blackbody cavity with the graphite cavity bottom is measured at 800°C, 1000°C. Besides, the above results are adopted, and the effective emissivity of the integrated blackbody is numerically simulated, based on the measurement results and the Monte-Carlo ray-tracing method. Thus, the feasibility of integrating the blackbody is demonstrated, the infrared radiation properties of integrated blackbodies are also studied as influenced by the temperature of the blackbody cavity.
Accurate measurement of the true surface temperature of high-temperature materials is very important in many fields, such as modern industrial systems, solar heat utilization and metrology. At present, passive radiation thermometry is mainly used to measure the real surface temperature of high-temperature materials. This technology cannot get rid of the influence of emissivity on temperature measurement accuracy. The active laser infrared radiation thermometry is a new emissive-free temperature measurement technology. Based on the active thermometry of dual-wavelength infrared laser, with the condition of environmental reflection interference and unknown emissivity, the true surface temperature of high-temperature material is precisely measured and studied. Based on the theoretical model of active dual-wavelength infrared laser thermometry, an active laser thermometry system was built and upgraded in this study. The active temperature measurement experiments of changing laser power were carried out to analyze the influence of laser power on the accuracy of active temperature measurement. Then the active temperature measurement experiments were carried out by changing the laser modulation frequency to analyze the influence of the laser modulation frequency on the active temperature measurement accuracy. The results show that the reasonable selection of laser parameters(laser power and laser modulation frequency) is the key to carrying out precision temperature measurement based on active laser infrared radiation thermometry.
In this paper, the dual laser induced measurement of thermal conductivity of solids is studied based on the laser-induced technique. Perfected the principle of dual-wavelength infrared laser-induced measurement of thermal conductivity of solids, and built an experimental system. According to the principle of measuring the thermal conductivity of solid with dualwavelength infrared laser, an experimental system was built. Taking the fully oxidized 304 stainless steel as an example, the feasibility of the method and the stability of the system are verified; the relationship between thermal conductivity and temperature of 304 stainless steel is obtained; and the influence of the temperature inconsistency between the reference sample and the sample to be tested on the measurement results of the correction factor is analyzed. The results show that the experimental system for measuring the thermal conductivity of solids has good stability, and the stability is within 2% in the range of 873k ~ 1173k; the relationship between thermal conductivity and temperature of 304 stainless steel is K304=0.0144T+14.455; when the temperature is 973K and 1073K, the temperature deviation of the two samples is within 1K, the effect of temperature inconsistency is within 1.3%.
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