Research On The Size-of-source Effect And Influencing Factors In Calibration Of Radiation Thermometer

Temperature is the physical quantity which characterized the hot and colddegree of objects. And it is one of the seven basic physical quantities in theinternational system of units (SI).As one of the temperature measuring systems, notonly Radiation temperature measurement is not interfere with the temperature fielddistribution, but also has fast,safe,pollution-free characteristics, which widely used infood, medicine aerospace and other fields. For example, during the period of SARS, itis extremely significant to monitor body temperature changes for epidemicprevention.However, because of non-contact temperature measurement, it is vulnerable tothe influences of objective conditions. Such as size-of-source effect, emissivity,environmental condition and etc. Lots of factors make temperature measurement notaccuracy, which limit the application of radiation thermometer. At the same time, withthe radiation temperature measurement expand to medium-and-low temperature andlong wave direction. The influence of the reflected radiation caused by thesurrounding can’t be ignored. It may become one of the main error sources in theindustrial measurement.This article has carried on the radiation thermometer accurate temperaturemeasurement theory, through theoretical and experimental research of the influencesof radiation thermometer calibration, such as reflected radiation, radiation of detector,emissivity. As for some certain conditions, it gives the correct instance.In this paper, the hardware system of SSE coefficient measurement is designed.For different radiation thermometers and measuring points, we have all measured andanalyzed the singularity problem under certain condition.The software is designed tocalculate SSE coefficient automatically, data storage, display and other functions. TheSSE coefficient measurement uncertainty is evaluated. On this basis, a temperaturecorrection formula is deduced by using micro ring temperature measuring model. And give the correct instances as well. The formula has certain value for industrialmeasurement.Finally, some influencing factors in radiation thermometer calibration arestudied. A method of determining measurement distance is proposed, which isaccording to the maximization and minimization principles of measurement signals. Itillustrates the application of additional aperture on the thermometer calibration. Thetheory of blackbody cavity effective temperature is studied. We analyze thedifferences of two aiming methods through the axial temperature distributionexperiment. Moreover, we have compared two methods. It has been showed that themethod of aiming at the bottom of the cavity has better accuracy and reliability.