JPH0462013B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a radiation temperature measurement method.

2. Description of the Related Art Conventionally, as a non-contact method for measuring the temperature of a sample, a radiation temperature measurement method is known in which the amount of radiant energy radiated from the sample is measured.
This method uses a spectrometer to measure the intensity of thermal radiation at specific wavelengths, and uses the measured value and emissivity to determine the temperature of the sample using Planck's formula.
In this case, knowing the emissivity is an essential condition. However, since the emissivity varies depending on the material, temperature, oxidation state, surface roughness, wavelength, etc. of the sample, accurate temperature measurements cannot be made unless the emissivity is corrected. Generally, to correct emissivity, a complicated method is used, such as installing a black body with which accurate emissivity can be known along with the sample, and then determining the emissivity of the sample by knowing the emissivity of the black body, and the limitations of installing a black body. In addition, there is a drawback that the temperature of the sample cannot be measured at any location, making it impractical.

In order to avoid such troublesome emissivity correction, the thermal radiation of the sample is measured at two wavelengths and the two-wavelength method (two-color measurement method) is used to reduce the influence of emissivity. Methods such as changing the wavelength to a shorter wavelength have been proposed, but in the former method, the emissivity measured at the two wavelengths is erased as the same value, or the ratio of the emissivity of the two wavelengths is assumed to be constant during the measurement. However, since the ratio of this emissivity is used as the measurement constant, there is a large error if the emissivity changes during measurement, and the latter method uses a short wavelength, which is inconvenient as it cannot measure temperature in low-temperature regions where thermal radiation is small. There is.

The purpose of the present invention is to propose a radiation temperature measurement method that does not have the above-mentioned drawbacks and inconveniences. Assuming a linear approximation formula for the spectral thermal emissivity at the wavelength, the approximate spectral thermal emissivity of the wavelengths of three of the wavelengths in the linear approximation formula and the spectral thermal emissivity of the measurement corresponding to the three colors. The temperature is determined from the radiation, and the approximate spectral thermal emissivity of the wavelengths of three colors including the remaining colors among the four colors in the linear approximation formula, and the values corresponding to the three colors including the remaining colors. The method is characterized in that the temperature is determined from the measured spectral heat radiation, and the temperature at which the respective determined temperatures match is determined as the temperature of the sample.

An embodiment of the present invention is shown in a vacuum container 1 as shown in the first diagram.
A case will be explained in which the temperature of the sample 2 housed inside is measured with an external radiation thermometer 4 through the vacuum window 3.
The radiation thermometer 4 includes a spectrometer 5 that separates the thermal radiation of the sample 2 into a plurality of wavelengths, a detector 6 that detects the amount of the spectroscopic thermal radiation, and a computer such as a microprocessor that calculates the detected value. The spectrometer 5 separates thermal radiation into four color wavelengths or more wavelengths, and each spectral thermal radiation is simultaneously measured by a detector 6 having a light-receiving section corresponding to the number of spectral wavelengths. Each measured value is subjected to calculation in the microprocessor 7 to determine the temperature of the sample 2.

In the example, it is assumed that the temperature of the sample 2 is T, the thermal emissivity is ε, and the thermal radiation is L. Of these, the temperature T and thermal emissivity ε are unknown quantities, and the thermal radiation L is spectrally divided into four or more color wavelengths λ ₁ , λ ₂ , ... λ _o , and the spectral thermal radiation ₁ , L ₂ at the wavelength of the husband is ,...L _o is the radiation thermometer 4
It is measured by

On the other hand, the spectral thermal emissivity ε ₁ at each wavelength λ ₁ ...λ _o ,
ε ₂ , ... ε _o cannot be determined without knowing the thermal radiation to be compared, such as the thermal radiation of a black body, but it is known that it changes along a certain curve, and the 2 As shown in the figure, the spectral thermal emissivity ε ₁ , ε ₂ , ... ε _o
A linear approximation equation ε _c of the spectral thermal emissivity passing through each point or the vicinity of each point can be assumed. This approximate formula ε _c
can be expressed as a linear expression of wavelength λ as follows.

ε _c aλ + b ... [] The measured spectral thermal radiation L _o is, if the spectral thermal radiation from the black body is L _o ^* , then L _o = ε _c・L _o ^* = (aλ _o + b)・L _o ^* ... …[] becomes. This L _o ^* is obtained from Planck's formula as L _o ^* = C ₁ /λ ⁵ _o・1/exP(C ₂ /λ _o T)−1...[
] In this, C ₁ is 1.19196×10 ^-16
(W·m ² ), C ₂ is a constant expressed as 0.014388 (m·K).

In addition, the formula [] was determined by actual measurement as follows: L ₁ = (aλ ₁ + b)・L ₁ ^* L ₂ = (aλ ₂ + b)・L ₂ ^* L ₃ = (aλ ₃ + b)・L ₃ ^* L ₄ = (aλ ₄ + b) )・L ₄ ^* [], and if the coefficients a and b are eliminated using the above formula [] regarding the wavelengths of the three colors λ ₁ , λ ₂ , λ ₃ , L ₁ /L ₁ ^* (λ ₃ −λ ₂ )+L ₂ /L ₂ ^* (λ ₁ −λ ₃ ) +L ₃ /L ₃ ^* (λ ₂ −λ ₁ )=0 ……[V]. In this case, the thermal radiation L _o ^* from the blackbody is given by the formula [], so the formula [] is y=L ₁ λ ⁵ ₁ [exp(C ₂ /λ ₁ T)−1]・(λ ₃ − λ ₂ ) +L ₂ λ ⁵ ₂ [exp(C ₂ /λ ₂ T)−1]・(λ ₁ −λ ₃ ) +L ₃ λ ⁵ ₃ [exp(C ₂ /λ ₃ T)−1]・(λ ₂ −λ ₁ )=
0...[], and when this y is plotted against the temperature T using the microprocessor 7, two solutions are obtained as shown in the third figure.
T _A and T _B can be found. Therefore, it is not possible to determine which of T _A and T _B is the temperature of the sample (2), so the remaining colors of the measurement wavelengths, that is, three colors including λ ₄ , for example, λ ₂ and λ ₃ , λ ₄ from the above formula [], and get y=L ₂ λ ⁵ ₂ [exp(C ₂ /λ ₂ T)−1]・(λ ₄ −λ ₃ ) +L ₃ λ ⁵ ₃ [exp (C ₂ / λ ₃ T) − 1]・(λ ₂ − λ ₄ ) +L ₄ λ ⁵ ₄ [exp (C ₂ / λ ₄ T) − 1]・(λ ₃ −λ ₂ )=
0...[] by plotting the temperature T to obtain two solutions T _C and T _D as shown in the fourth diagram.

As a result, if T _A = T _C and T _B ≠ T _D , it can be determined that T _A is the temperature of sample (2).

Even if you plot the equation [][] at temperature T, there may be no solution and it may have a minimum value as shown in Figure 5, but in that case, if y at T _E is close to zero, then T _E
can be determined to be the approximate temperature of sample (2). Further, as shown in FIG. 6, there may be cases where there is neither a solution nor a minimum value, but in this case, it is possible to measure and calculate the thermal radiation by changing the wavelength λ to obtain the temperature T or an approximate temperature.

The wavelength λ may be four or more colors. For example, in the case of six colors, the thermal radiation of the sample (2) is spectroscopically measured at wavelengths λ ₁ ... λ ₆ , and λ ₁ ... λ ₃ and λ ₄ ... λ ₆ It can be calculated separately.

As described above, according to the present invention, the thermal radiation of a sample is spectroscopically measured in four or more colors, and the temperature of the sample is determined by applying three colors each from the linear approximation formula of the spectral thermal emissivity and the measured spectral thermal radiation. Since it is calculated in this way, there is no need to particularly set up a comparison object such as a black body, and there is no need to make corrections for emissivity, so there are effects such as the ability to easily measure radiation temperature.

[Brief explanation of the drawing]

Fig. 1 is a diagram of one example of the measuring method of the present invention, Fig. 2 is a diagram of an example of the measuring method of the present invention;
The figure is a diagram showing the relationship between spectral thermal emissivity and a linear approximation formula, and FIGS. 3 to 6 are curve diagrams obtained by plotting y against temperature T.

Claims (1)

[Claims] 1. While spectroscopically measuring the spectral thermal radiation of four or more color wavelengths by spectroscopy of the thermal radiation from the sample, a linear approximation formula for the spectral thermal emissivity at each wavelength is assumed, and the wavelength in the linear approximation formula is The temperature is determined from the approximate spectral thermal emissivity of the wavelengths of three of the colors and the measured spectral thermal radiation corresponding to the three colors, and the remaining wavelengths of the four or more colors in the linear approximation formula are calculated. 3 including colors
The temperature is determined from the approximate spectral thermal emissivity of the wavelength of the color and the measured spectral thermal radiation corresponding to the three colors including the remaining colors, and the temperature at which the respective determined temperatures match is determined as the temperature of the sample. Characteristic radiation temperature measurement method.