Abstract
The accurate measurement of temperature is very important in the control of the production process. The thermocouple that requires physical contact with an object is usually used, but the radiation thermometer has made remarkable progress in various fields such as steel industry. The radiation thermometer put into practice now is one that uses infrared rays as the measuring wavelength and it is reported that the radiation thermometry has lead to noticeable error if emissivity of an object is not accurately known.
According to Planck's law of radiation, it is evident that the effect of temperature on spectral radiance is greater at the shorter wavelength. In the present paper, the temperature measurement by UV (ultra-violet) thermal radiation has been discussed. In the experiment, stainless steel (SUS304) and iron have been melted in a reducing atmosphere by the levitation melting method, and the melting points of metals have been measured with CCD camera, image intensifier and UV-filter (spectral range : 0.35μm) .
As a result, it is made clear that the melting point of SUS304 have been measured in error 60 K-70 K and iron in 40 K-50 K by the proposal UV thermal method, without correcting the emissivity as the infrared thermometer. UV sensor made it possible to detect the temperature thermal image and to observe the temperature distribution in melting process.
