PRINCIPLE AND APPLICATION OF THE PYROMETRY BY USE OF FUNCTION FITTINGMETHOD TO THERMAL-RADIATION SPECTRA

It is not difficult to observe spectra of thermal radiation emitted fr om a hot surface. It is very interesting to develop the pyrometry to d etermine the temperature on the basis of thermal radiation spectra. Th ere is not yet sufficient theoretical analysis for the pyrometry, whic h was termed the spectrum method in this paper. This method also will not be free from the so called emissivity problem. For solving this pr oblem, this method assumed a linear wavenumber-dependence of the emiss ivity. The theoretical analysis predicted that there was the particula r linearity that led to no temperature determination. The present work described the requirements for permissible linearity. The conventiona l two-color method assuming constant emissivity was applied to the spe ctrum data and the determination errors due to the deviation from the constant were estimated. A temperature-emissivity diagram was made to show the applicability arrangement of the spectrum and the two-color m ethods in the spectrum pyrometry. It was found that these methods were able to play complementary roles to determine temperatures. This diag ram was useful for predicting the feasibility of temperature measureme nt. A temperature measurement technique combining both methods was pro posed and applied to silicon carbide tube and platinum ribbon heaters. This technique proved to be useful, although it still needs more accu mulation of empirical knowledge about how to choose wavenumber range.