JPS6058411B2 - radiation thermometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the true temperature of an object by removing the influence of emissivity, which is an error factor when measuring surface temperature using a radiation thermometer.

Conventional radiation thermometers include monochromatic thermometers that determine the temperature of an object from the amount of radiant energy from the object, and two-color thermometers that determine the object temperature from the ratio of spectral radiant energy of two different wavelengths. These radiation thermometers have a major drawback: they can only measure the true temperature of a black body in the case of a monochromatic thermometer, and only a gray body in the case of a two-color thermometer, and the influence of emissivity cannot be removed for ordinary objects. It was hot. In view of the above points, the purpose of this invention is to
It is an object of the present invention to provide a radiation thermometer that can measure the surface temperature of a general object by removing the influence of emissivity.

In order to achieve the above object, the present invention is configured as follows.

In other words, three or more spectral radiant energies consisting of certain different wavelengths are each converted into electrical signals, and each electric signal is calculated using all values proportional to the difference between these effective wavelengths, excluding the value that includes the effective wavelength. By raising the signal to a power and determining the ratio of the resulting signal values, the true temperature of the radiation source is obtained. The present invention will be explained below with reference to FIG. For ease of explanation, an example using three wavelengths will be described. The radiant energy flux emitted from the object to be measured (radiation source) 1 is focused by a condensing lens 2, and the spectral energy of three wavelengths is selected by a spectrometer 3 (filter, diffraction grating, etc.), and then sent to a detection element. 4 and is converted into an electrical signal. The signal is amplified by a preamplifier 5, subjected to impedance conversion, then logarithmically converted by a logarithmic converter 6, synchronously rectified by a synchronous signal from a spectrometer 3, and discriminated into signal values for each wavelength. Then the first wavelength λ
, the signal ln(λ,) is (λ.-λ3) at the second wavelength λ.
The signal ln(λ.) has a third wavelength λ3 (λ, −λ.).
The signal lnV(λ.) is amplified by amplifiers 7, 8, and 9 having an amplification factor proportional to (λ, -λ.), and then an adder/subtractor 10 performs the operation of 8nVλ λ λ Vλ λ−λ −C (7). V(λ
. xλ, -λ. ) (C is a constant).

This signal value has the influence of emissivity removed, and by reciprocating this signal using a reciprocal converter 11, the true temperature T of the radiation source can be obtained.

The principle of the above operation for carrying out the present invention will be explained as follows.

If the true temperature of the radiation source is TO (K) and the effective values of the selected wavelengths are λ1, λ2, λ3, then the spectral radiant energy E (λI
, TO) becomes as follows for the wavelength λi using Wien's law.

(Here, Cl and C2 are constants.) This means that when the radiation source is a black body, and its spectral emissivity is generally ε(λi), its spectral radiant energy E(λI, Ti) is as follows. .

When this signal is raised to the power of the difference in effective wavelengths excluding the effective wavelength, the following is obtained.

If we take the ratio of these signals alternately as the numerator and denominator and perform natural logarithmic transformation, we get the following.

In the above equation, even if there is a change in emissivity, the emissivity term remains, assuming that t(λi) is always Exp(AO+a1λi)*, and this term is removed.

Therefore, the true temperature TO is as follows. The above is the operating principle of a multicolor radiation thermometer using three wavelengths.

A similar ratio may be used for wavelengths longer than that. As mentioned above, this thermometer can eliminate the influence of emissivity, which was a weakness of radiation thermometers.

Moreover, the method of use is no different from that of conventional radiation thermometers, and it goes without saying that measurements are easy and maintenance and inspection are easy. Furthermore, from the true temperature TO and brightness temperatures Tl, T2, and T3 obtained from this thermometer, the spectral emissivity E(λ1) of the radiation source,
It is a matter of course that ε (λ2) and E (λ3) can be found.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention. 1... Radiation source, 2... Condensing lens, 3
...Spectrometer, 4...Detection element, 5...
...Preamplifier, 6 ... Logarithmic converter, 7,8,
9...Amplifier, 10...Adder/subtractor, 1
1... Reciprocal converter.

Claims (1)

[Claims] 1. A spectrometer that selects spectral radiant energy corresponding to three or more wavelengths from the radiant energy flux from the radiation source;
A detection element that inputs the spectral radiant energy selected by the spectrometer and converts it into an electrical signal, a preamplifier that amplifies the output signal of this detection element, and converts the output of the preamplifier into a signal for each of the selected wavelengths. a logarithmic converter that separates and performs logarithmic conversion; and an amplifier that powers the output of the logarithmic converter by all values proportional to the difference between the effective values of the selected wavelengths, excluding a value that includes the effective wavelength. , an adder/subtracter that adds and subtracts the output of the amplifier, and a reciprocal converter that converts the output of the adder/subtracter into a reciprocal number, and measures the temperature of a radiation source.