V. Poryev, S. Kushnir
National Technical University of Ukraine “Kyiv Polytechnic Institute”
The Method to Determine Multispectral Temperature
In the modern pyrometry a multiple conventional temperatures, such as the radiation temperature, brightness temperature and the temperature of spectral ratio. At the same time the true temperature at the surface’s body is the thermodynamic temperature specific to the state of the surface. We propose the new method to determine the thermodynamic temperature based on using the multispectral television evaluation tool (ET).
In generalized form the spectral signal of the ET could be written as
the assumption that the emission ratio is linear in the range of
Writing ET signal for the three different wavelengths in accordance with (2) we get:
Introducing the substitution
Then the (3) system could be rewritten as
We shall find
let us choose
Then (6) could be rewritten as
And after the
In the (10) system we shall use Planck formula for brightness function, then we get the following:
The specific of this formula is that it contains the relation between spectral signals and SC values for the chosen wavelengths. Therefore, one could choose any triplet of the wavelengths and get the values for the temperature independent of the chosen wavelengths.
Evaluation of the temperature according to this method opens new possibilities for metrology and simplifies the calibration of the existing pyrometers in the lab.