Physics/7. Optics
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
where
Given
the assumption that the emission ratio is linear in the range of
Where
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
For convenience
let us choose
Then (6) could be
rewritten as
And after the
substitution of
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.