JPH03287028A - Radiation thermometer - Google Patents

Abstract

PURPOSE:To accurately measure temperature and emissivity at the same time with two spectral radiation brightness signals including information on real temperature and real emissivity by performing arithmetic processing based upon an emissivity characteristic function inherent to a body to be measured which is found previously by experimentation. CONSTITUTION:A photodetector 2 diffracts radiation brightness from the body 1 to be measured into N with >=2 different wavelength ranges and a polarizer 3 detects respective polarized components to obtain N polarized spectral radiation brightness signal sequences 4. A selecting circuit 5 selects the best combination of wavelength and polarization for the body 1 to be measured among 2N sequences, and a parameter showing the relation between two known spectral emissivity values corresponding to the two selected spectral radiation conditions and the parameter of a black body furnace calibration function showing the relation between the spectral radiation brightness signal and real temperature are inputted from an input part 6 to an arithmetic part 7. The arithmetic part 7 finds the real emissivity on the emissivity characteristic function from the relational equation inherent to the body 1 to be measured between the two corresponding spectral emissivity values according to the two selected spectral radiation brightness signals, thereby finding the real temperature at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a radiation thermometer that simultaneously measures the temperature and emissivity of an object whose emissivity changes during the manufacturing process of ferrous and non-ferrous metals.

[Conventional technology]

Conventional radiation temperature measurement requires the emissivity of the object to be measured to be known, but in the manufacturing process of ferrous and non-ferrous metals,
At present, the emissivity of the object to be measured may change, and for this reason, conventional radiation thermometers are not sufficiently reliable.

Various improvement measures have been proposed to deal with this emissivity fluctuation problem, but all of them require complicated measurement equipment,
Currently, its application is limited to very specific fields because it is subject to various constraints when put into practical use, such as the need to perform complex calculations.

[Problem to be solved by the invention]

Emissivity is determined by the conditions defined by the measurement system, such as the wavelength, and the material conditions of the object, such as the material. Therefore, even if we consider only the conditions of the measurement system, the wavelength, directionality (angle)
, it is possible to define an infinite number of emissivities with different polarization components, and if the effects of the material to be measured, processing conditions, surface roughness, degree of redox, thermal history, temperature, etc. are taken into account, the emissivity can be varied. Determined by parameters. In other words, it is not easy to set the emissivity, and it is extremely difficult to set the emissivity when the emissivity changes due to changes in the physical conditions of the object to be measured. Among the conditions defined in the measurement system, the relationship between two spectral emissivities that differ in terms of wavelength or polarization component is unique to the physical conditions of the object being measured. By focusing on the relationship between the two spectral emissivities and experimentally determining the relationship between the two spectral emissivities, we can accurately measure temperature and emissivity at the same time based on two spectral radiance signals that include information on true temperature and true emissivity. The purpose is to know.

[Means for Solving the Problems] The radiation thermometer of the present invention is a means for detecting two or more thermal radiations that differ from each other in at least one condition among the wavelength and the measurement angle among the thermal radiations that tend to be measured from an object to be measured. , a means for separating and detecting the detected thermal radiation into two linearly polarized components, and a means for selecting two arbitrary different spectral radiation conditions (wavelength, polarization, measurement angle) from the plurality of obtained spectral radiance signals. and a means for inputting a parameter defining a relational expression specific to the object to be measured between the two spectral emissivities corresponding to the two selected spectral radiance conditions, Based on the means for inputting parameters that determine the relational expression between the two spectral emissivities and two arbitrarily selected spectral radiance signals, the relational expression unique to the measured object between the two spectral emissivities is determined. The present invention is characterized by comprising calculation means for calculating temperature and emissivity at the same time.

0 Effect] The effect of the present invention will be specifically explained below. Let us now assume that two different spectral emissivities are Ex and EY, and that the relationship between the two spectral emissivities is experimentally known and can be expressed as shown in FIG.

This relationship is expressed as the emissivity ratio of material A by the following equation (1).

Ey = f (Ex) (
1) The subscripts X and Y represent measurement conditions with different wavelengths, measurement angles, or polarization components, and their combinations include, for example, two-wavelength type, polarization type, and two-wavelength polarization type.The features of the present invention are as follows: By detecting the polarization components of thermal radiation with different wavelengths or measurement angle conditions, and selecting an arbitrary combination from among them, temperature and radiation The purpose is to find the ratio, and the process will be explained below. First, when the radiometer is calibrated in a blackbody furnace, the relationship between the true temperature and the radiometer output is shown in FIG. 4 and can be expressed by equations (2) and (3).

That is, parameters A, B, and C are determined by calibration.

To; true temperature 1. x, 1. Y; Radiometer output C2;
Second radiation constants A, B, C, blackbody furnace calibration numerical parameter E XOI
Evo; true emissivity Figure 5 is unknown true temperature T. and true emissivity EX.

The output of the radiometer containing information on both EYo and y is
4) It can be expressed by equation (5').

Lx −Ex0' Lb(λ,,To) (
4) Lv=Eyo・Lb(λY, To)
(5) Although the true temperature and emissivity are unknown at this point, the assumed temperature T is given and the apparent radiance, ', t, y' is determined from equation (2). Therefore, the apparent emissivity can be determined from equations (6) and (7).

Lx Lb(λX+1) The second feature of the present invention is to calculate the apparent emissivity Ex with reference to the emissivity characteristic number f that is held as prior knowledge.

The purpose is to find a solution by performing an operation in which EY matches the true emissivity E XO, E y6. To explain this with Fig. 6, the apparent emissivity (E , On the other hand, since Exo y Evo, which the true emissivity can take, is on the f curve, the intersection with the 0 curve is the true emissivity determined, and the temperature T assumed at that time becomes the true temperature T0. The 0 curve and the f-function curve are the true temperature T. Even if they are the same, if the true emissivity is different, they will intersect at different positions.

Here, the combination of different measurement conditions that is optimal for the object to be measured means that the 0 curve and the f curve intersect stably. 7th
As shown in the figure, as the slopes of the 0 curve and the f curve become closer, the intersection becomes unstable due to changes in emissivity, and the accuracy deteriorates. Therefore, by optimally selecting a combination of measurement conditions that differ depending on the object to be measured, it is possible to always obtain a stable solution.

In this way, in the radiation thermometer of the present invention, by optimally selecting a combination of different measurement conditions among a plurality of spectral radiances from the detector, the optimal emissivity characteristic function for the object to be measured can be obtained and accurate Temperature measurement becomes possible.

〔Example〕

Hereinafter, the features of the present invention will be specifically explained based on examples with reference to the drawings. Fig. 1 shows the configuration of the present invention, where 1 is an object to be measured, 2 is a photodetector, and 3 is a photodetector that separates the radiance from the object to be measured into N parts in two or more different wavelength ranges.
Detects the polarization component of each wavelength detected by the polarizer. Therefore, 2N polarized spectral radiance signal sequences 4 are obtained. Reference numeral 5 denotes a circuit for selecting a combination of two spectral radiation conditions (wavelength, polarization) optimal for the object to be measured from among the obtained 2N spectral radiance signals. 6 parameter input section 6. Now, parameters of a relational expression representing the relationship between two known spectral emissivities specific to the object to be measured corresponding to the two selected spectral radiation conditions are input. On the other hand, in the parameter input section 6□, parameters (ABC three constants) of a blackbody furnace calibration function representing the relationship between the spectral radiance signal of the detector and the true temperature corresponding to the two selected spectral radiation conditions are input. These parameters are stored internally in advance,
It is also possible to automatically set the number when a combination of spectral radiation conditions is selected. In the calculation section 7, based on the two selected spectral radiance signals, the true emissivity on the emissivity characteristic function, which is the relational expression between the two corresponding spectral emissivities, is calculated, and the true emissivity is calculated at the same time. Find the temperature.

FIG. 2 schematically shows an embodiment of the calculation section. As input data, two arbitrarily selected spectral radiance signals LX, L, which are optimal for one measured object, and a signal unique to the measured object corresponding to the two selected spectral radiation conditions (wavelength, polarization) are input. A parameter 12 of a relational expression representing the relationship between two known spectral emissivities and a blackbody furnace calibration parameter 13 representing the relationship between the spectral radiance signal and true temperature are required. Parameter 12
, 13 may be input using a keyboard or the like, or stored internally and automatically retrieved when selecting any two spectral radiation conditions that are optimal for the object to be measured. By giving the assumed temperature T of 8. Find it as ε′a. On the other hand, the emissivity characteristic equation 19, which expresses the relationship unique to the measured object between the two spectral emissivities corresponding to the spectral radiation conditions, is the true emissivity (ε8°, εa).

) is a possible combination of curves f in 21 two-dimensional planes.
It is indicated by. That is, the assumed temperature T at which the true emissivity that exists on this curve can be taken indicates the true temperature T0. Therefore, while changing the assumed temperature T at 20, the true temperature T is determined at 22 by finding the assumed temperature at which the apparent emissivity matches the true emissivity on the curve f. is obtained.

Further, in FIG. 1, by providing a plurality of photodetectors 2 with different measurement angles, it is possible to obtain spectral radiance signals with different measurement angle conditions, and the range of selection of measurement conditions is expanded accordingly.

〔Effect of the invention〕

As described above, according to the present invention, the true temperature and emissivity can be reasonably determined because the calculation is performed based on the emissivity characteristic function unique to the object to be measured, which has been determined experimentally in advance. Furthermore, by combining three different spectral radiation conditions (measurement angle, wavelength, and polarization), it is possible to select the optimum number of emissivity characteristics that matches the emissivity change process of the object to be measured, allowing accurate temperature measurement.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the general configuration of the present invention, and Fig. 2 is the actual structure! A diagram schematically explaining one example, and FIGS. 3 to 7 are diagrams for explaining the present invention in detail. In the figure, 1... object to be measured, 4... spectral radiance signal sequence. True temperature 0 EX Diagram EX 185-

Claims (1)

[Claims] 1. Means for detecting two or more thermal radiations from an object to be measured that differ in at least one condition among wavelength and measurement angle, and separating and detecting the detected thermal radiation into two linearly polarized components. means for selecting any two different spectral radiation conditions (wavelength, polarization, measurement angle) from the plurality of obtained spectral radiance signals; A means for inputting parameters defining a relational expression specific to the object to be measured between the spectral emissivity and a means for inputting parameters defining a relational expression between the true temperature and the two selected spectral radiance signals; and calculation means for simultaneously calculating the temperature and emissivity of the object to be measured from a relational expression specific to the object to be measured between the two spectral emissivities based on the two spectral radiance signals obtained. A characteristic radiation thermometer.