Temperature measuring device, temperature measuring method, and program

Abstract

A temperature measuring device, a temperature measuring method, and a program are provided that allow freedom in the wavelength of light used to measure the temperature of an object to be measured. [Solution] For the spectral irradiance of a reference light source whose temperature is known, first light intensity information is received for each of multiple amounts known as the amount of absorber, including two adjacent wavelengths, a first wavelength of light included in a first wavelength range whose center wavelength is between 900 nm and 1000 nm, and a second wavelength of light included in another wavelength range, and for the spectral irradiance of the test object, second light intensity information on the first light received when the absorber is present in an actual amount and third light intensity information on the second light, and the temperature of the test object that is not affected by the amount of absorber is identified from the ratio of the sensor received light intensities when no absorber is actually present at one and the other of two adjacent wavelengths in two-color thermometry.

Description

[Technical field]

[0001] The present invention relates to a temperature measuring device, a temperature measuring method, and a program that can accurately measure the temperature of a test object even if an absorber is present on the test object or in the light receiving path from the test object. [Background technology]

[0002] As a temperature measurement device for measuring the temperature of a test object, a two-color thermometer, which is based on the two-color temperature measurement method and converts the temperature from the ratio of radiance using two different wavelengths that are close to each other, is used in various fields because it can measure the temperature of the test object without contact. In addition, a two-color temperature camera, which uses the measurement principle of the two-color thermometer and a two-dimensional sensor for the detection part, is known as a temperature measurement device that can measure the temperature distribution of the test object without contact.

[0003] Here, when a substance that absorbs light, such as water or water vapor, is present in the optical path, it is generally difficult to measure using a two-color thermometer or two-color temperature camera. However, for example, Patent Document 1 discloses a temperature measurement technology that uses two wavelengths that have the same spectral absorption coefficient. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7024644 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, there is a restriction on the wavelength of light used to measure the temperature of the test object, and it has been desired to have a degree of freedom in the wavelength of light used to measure the temperature of the test object.

[0006] An object of the present invention is to provide a temperature measuring device, a temperature measuring method, and a program that allow freedom in the wavelength of light used to measure the temperature of an object to be measured. [Means for solving the problem]

[0007] In order to achieve the above object, a temperature measuring device according to the present invention is a temperature measuring device that measures the temperature of a test object based on a ratio of light intensities when radiant energy for two wavelengths close to each other is received with respect to the spectral radiant energy of the test object, and has a correction unit that converts a measurement value that is affected by the amount of absorber present on the test object or in the optical path from the test object into an original measurement value that is not affected by the amount of absorber present, and the correction unit defines first light as light included in a first wavelength range having a central wavelength of 900 nm to 1000 nm, which is light of a wavelength that is absorbed by the absorber and whose light intensity changes greatly when received in accordance with the amount of absorber present, and defines a second wavelength range having a central wavelength of 650 nm to 900 nm, a third wavelength range having a central wavelength of 1000 nm to 1080 nm, and a fourth wavelength range having a central wavelength of 1220 nm to 1290 nm, which is light of a wavelength that is less absorbed by the absorber and whose light intensity changes little when received in accordance with the amount of absorber present, as compared to the first light. the second light is light included in at least one of a fourth wavelength range, the first light is light intensity information received for each of a plurality of amounts known as the amount of the absorber, the first light is light intensity information received for the spectral radiant energy of a reference light source having a known temperature, the first light is light intensity information received when the absorber is present in an actual amount for the first light wavelength, the second light is light intensity information received when the absorber is present in an actual amount for the first light wavelength, the third light is light intensity information received when the absorber is present in an actual amount for the second light wavelength, the third light is light intensity information received when the absorber is present in an actual amount for the second light wavelength, the third light is light intensity information received when the absorber is present in an actual amount for the second light wavelength, the third light is light intensity information received when the absorber is present in an actual amount for the first ...

[0008] Further, a temperature measurement method according to the present invention is a temperature measurement method for measuring the temperature of a test object based on a ratio of light intensities when radiant energy for two wavelengths close to each other is received with respect to the spectral radiant energy of the test object, the temperature measurement method having a correction step for converting a measurement value affected by the amount of absorber present on the test object or in the optical path from the test object into an original measurement value that is not affected by the amount of absorber present, the correction step including the steps of: defining light included in a first wavelength range having a center wavelength between 900 nm and 1000 nm as the first light, the first light being light of a wavelength that is absorbed by the absorber and whose light intensity when received changes greatly depending on the amount of absorber present; The second light is light having a wavelength that is less absorbed by the absorber and has a small change in light intensity when received according to the amount of the absorber, and is included in at least one of a second wavelength range having a center wavelength of 650 nm to 900 nm, a third wavelength range having a center wavelength of 1000 nm to 1080 nm, and a fourth wavelength range having a center wavelength of 1220 nm to 1290 nm, and the second light is light having a wavelength that is less absorbed by the absorber and has a small change in light intensity when received according to the amount of the absorber. The first light is light having a wavelength that is less absorbed by the absorber and has a small change in light intensity when received according to the amount of the absorber, and the second light is light having a wavelength that is less absorbed by the absorber and has a small change in light intensity when received according to the amount of the absorber. the first light intensity information being light intensity information received when the absorber is present in an actual amount for the first light wavelength with respect to the spectral radiant energy of the test object, and the third light intensity information being light intensity information received when the absorber is present in an actual amount for the second light wavelength with respect to the spectral radiant energy of the test object, the third light intensity information being light intensity information received when the absorber is present in an actual amount for the second light wavelength with respect to the spectral radiant energy of the test object, the first light intensity information, the second light intensity information, and the third light intensity information being light intensity information received when the absorber is not present for one and the other of the two adjacent wavelengths, respectively, are identified based on the first light intensity information, the second light intensity information, and the third light intensity information, and the temperature of the test object is identified based on a ratio of the identified light intensities.

[0009] The present invention also provides a program for causing a computer to function as each of the means of the temperature measuring device. Effect of the Invention

[0010] The present invention allows for flexibility in the wavelength of light used to measure the temperature of the object to be inspected. This makes it possible to prevent the measured value from being affected by the presence of an absorber on the test object or in the optical path from the test object, even when light of a wavelength with a different spectral absorption coefficient is used. [Brief description of the drawings]

[0011] [Figure 1] 4 is a flowchart commonly related to the first and second embodiments of the present invention. [Diagram 2] FIG. 1 shows the absorption spectra of water and water vapor. [Diagram 3] FIG. 1 shows the light intensity distribution of light emitted from a reference light source at approximately 1500° C. after passing through the optical path in the cases where there is no water vapor as an absorber in the optical path, where water vapor is present at a low concentration, and where water vapor is present at a medium concentration. [Figure 4] Regarding the first embodiment, FIG. 3 is a diagram additionally showing a measurement example of the sensor received light intensity at wavelengths λ1 to λ4 when a test object is set as a measurement target. [Diagram 5] 11 is a diagram for explaining how a reference light source for a provisional temperature is specified from the sensor received light intensities at λ1, λ2, and λ4 in relation to the first embodiment. FIG. [Figure 6] Regarding the first embodiment, a corrected intensity distribution was calculated taking into account the amount of water vapor, and this was added to FIG. [Figure 7] 5. FIG. 5 is a diagram illustrating a corrected intensity distribution obtained after performing a calculation of identification of a reference light source with a provisional temperature and correction based on the amount of water vapor multiple times in the first embodiment. [Figure 8] FIG. 13 is an explanatory diagram of a case where the intensity ratio between wavelengths λ2 and λ3 is used to identify the amount of absorber present. [Figure 9]FIG. 1 shows the light intensity distribution of light emitted from a reference light source at approximately 500° C. after passing through the optical path in the cases where there is no water vapor as an absorber in the optical path, where water vapor is present at a low concentration, and where water vapor is present at a medium concentration. [Figure 10] Regarding the first embodiment, FIG. 9 is a diagram additionally showing a measurement example of the sensor received light intensity at wavelengths λ1 to λ4 when a test object is set as a measurement target. [Figure 11] This figure shows the light intensity distribution of light emitted from a reference light source at approximately 1500°C after passing through the optical path in the following cases: when there is no water vapor as an absorber in the optical path, when only water vapor is present, and when water vapor mixed with industrial oil is present. [Figure 12] FIG. 1 shows the light intensity distribution of light emitted from a reference light source at approximately 300° C. after passing through the optical path in the cases where there is no water vapor as an absorber in the optical path, where water vapor is present at a low concentration, and where water vapor is present at a medium concentration. [Figure 13] FIG. 12 is a diagram additionally showing a measurement example of the sensor received light intensity at wavelengths λ2 to λ5 when a test object is set as the measurement target. [Figure 14] FIG. 1 is a diagram showing an example of a four-branch optical system as a spectroscopic optical system. [Figure 15] FIG. 1 is a diagram showing an example of a five-branch optical system as a spectroscopic optical system. [Figure 16] FIG. 1 is a system diagram in which a measurement terminal and a server are connected via the Internet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention can be implemented in many different forms, and should not be interpreted as being limited to the description of the present embodiment. Note that the same elements are designated by the same numbers throughout the embodiments.

[0013] (First embodiment) Prior to a specific description of this embodiment, the two-color temperature measurement method will first be described.

[0014] (Two-color thermometry) The concept of two-color temperature measurement is explained below. In order to measure the temperature of high-temperature workpieces over 300°C without contact, the electromagnetic radiation emitted from the measurement object is measured and the temperature is calculated from its intensity. This method is commercialized in radiation thermometers that obtain temperature from visible or infrared light, and thermography that measures temperature distribution. Measurement objects are generally non-black bodies, and in order to obtain the true temperature from a radiation thermometer or from a thermograph, correction must be made using the emissivity, which is the ratio of the amount of radiation to that of a black body. However, the emissivity of a non-black body generally differs depending on its material, shape, and temperature, making it difficult to obtain an accurate temperature.

[0015] For this reason, the two-color thermometry method is used. The two-color thermometry method focuses on the fact that the emissivity of radiation at two adjacent wavelengths is the same, and since the ratio of the radiation amounts at the two wavelengths is in a functional relationship with the true temperature, it measures the radiation amounts at the two wavelengths and calculates the true temperature. This can be explained using the formula below.

[0016] The radiation utilization at wavelength λ is given by Planck's radiation formula:

[0017]

number

[0018] If the emissivity of the object is ε and the transmittance from the object to the measurement system is τ, then

[0019]

number

[0020] Applying Woorn's approximation formula, if the radiant energies at two wavelengths λ1 and λ2 are M1 and M2, the emissivities ε1 and ε2, the transmittances τ1 and τ2, and the conversion efficiencies of the sensors, etc. β1 and β2, the two-wavelength ratio R at wavelengths λ1 and λ2 is given as follows.

[0021]

number

[0022] If we take the logarithm, this can be expressed by the following formula:

[0023]

number

[0024] If there is no absorber (such as water, water vapor or steam, or a mixture mainly composed of water vapor) on the test object or in the optical path from the test object, the following occurs:

[0025] In other words, by bringing the two wavelengths of radiation close together, the emissivities ε1 = ε2, τ1 = τ2, and β1 = β2 become true, and the emissivity ε, transmittance τ, and conversion efficiency β are eliminated, and it is known that the ratio of the amounts of radiation is a function of the temperature.

[0026]

number

[0027] Even if the emissivity at two wavelengths or the transmittance of an inclusion are different, if the ratio does not change with temperature, the true temperature of an object whose temperature changes can be determined by correcting the ratio with a black body.

[0028] However, if an absorber (such as water, water vapor or steam, or a mixture mainly composed of water vapor) is present on the object to be measured or in the optical path from the object to be measured, then τ1 does not equal τ2 even if emissivity ε1=ε2 and β1=β2. The intensities of light received by the sensor at the two wavelengths λ1 and λ2 are different, and each differs depending on the amount of absorber present.

[0029] (Temperature measuring device and temperature measuring method) In this embodiment, the temperature measurement method will be mainly described, but as will be apparent to those skilled in the art, the temperature measurement device may be an embodiment having a branching optical system and a plurality of two-dimensional image sensors using a two-color temperature measurement method. In this case, it is a prerequisite that the pixel positions of the plurality of two-dimensional image sensors are aligned.

[0030] The temperature measuring device according to this embodiment includes a spectroscopic optical system, a measuring unit including a two-dimensional image sensor having sensitivity in the near-infrared region, and a correcting unit that performs sensor output processing.

[0031] (Correction section) The correction unit in this embodiment converts a measurement value that is affected by the amount of absorber present on the test object or in the light path from the test object into an original measurement value that is not affected by the amount of absorber.

[0032] (1) Identifying the amount of absorber present In this embodiment, the light intensity of the wavelengths that absorb water or water vapor as an absorber and the wavelengths that are less absorbed (wavelengths corresponding to the background) are used to determine a value corresponding to the amount of water or water vapor present. At least one wavelength in the range of 900 nm to 1000 nm is used as the wavelengths that absorb water or water vapor. At least one wavelength in the range of 650 nm to 900 nm or 1000 nm to 1080 nm is used as the wavelengths that are less absorbed by water or water vapor.

[0033] Here, the first light intensity information, the second light intensity information, the third light intensity information, and the divider relationship are defined as follows, together with the first light, the second light, the first wavelength range, the second wavelength range, and the third wavelength range.

[0034] The first light is defined as light that is absorbed by an absorber and has a wavelength at which the sensor's received light intensity changes greatly depending on the amount of absorber present, and that is included in the first wavelength range with a center wavelength between 900 nm and 1000 nm. The first wavelength range is a wavelength range centered on 950 nm, and 950 nm corresponds to the wavelength at which the third overtone absorption of water or water vapor (described in detail later) appears.

[0035] The second light is defined as light having a wavelength that is less absorbed by the absorber and changes little in the sensor received light intensity depending on the amount of absorber present, the second light being light falling within a second wavelength range having a central wavelength of 650 nm to 900 nm or a third wavelength range having a central wavelength of 1000 nm to 1080 nm.

[0036] Then, the first light intensity information is light intensity information received for each of a plurality of known amounts of absorber, which includes two mutually adjacent wavelengths for temperature measurement, the first light wavelength, and the second light wavelength, for the spectral radiant energy of the reference light source having a known temperature. The second light intensity information is light intensity information received when the absorber is present in an actual amount for the first light wavelength for the spectral radiant energy of the test object. The third light intensity information is light intensity information received when the absorber is present in an actual amount for the second light wavelength for the spectral radiant energy of the test object.

[0037] The divideive relationship relates to the proportion or ratio of the second light intensity information to the third light intensity information in which the change in the intensity of light received by the sensor is small depending on the amount of absorber present.

[0038] In this embodiment, light of a wavelength that absorbs water or water vapor (first light in a first wavelength range) and light of a wavelength that is less absorbed (second light in a second wavelength range or a third wavelength range) are used to identify the amount of water or water vapor present as an absorber between the temperature measuring device and the test object.

[0039] Figure 2 shows the absorption spectrum of water and water vapor, with central wavelengths λ1 and λ2 being wavelengths where water and water vapor absorb less light, wavelength λ3 being wavelengths where water and water vapor absorb more light, λ4 being wavelengths where water and water vapor absorb less light, and λ5 being wavelengths where water vapor absorbs less light. Specifically, the wavelengths λ1, λ2, λ3, λ4, and λ5 are 670 nm, 870 nm, 950 nm, 1040 nm, and 1250 nm, respectively.

[0040] In the following embodiment, four wavelengths are used, and the cases where λ1, λ2, λ3, and λ4 are used (FIGS. 3 to 11) and where wavelengths λ2, λ3, λ4, and λ5 are used (FIGS. 12 and 13) will be described in order. Here, in the cases where λ1, λ2, λ3, and λ4 are used (FIGS. 3 to 11), the absorber may be either water or water vapor, or may be a case where both are present, for example, where water vapor, steam, and water attached to the test object coexist.

[0041] In addition, when using wavelengths λ2, λ3, λ4, and λ5 (Figures 12 and 13), the absorber is assumed to be only water vapor, or water vapor is the main component with a small amount of steam or water mixed in. Specifically, wavelengths λ2, λ3, λ4, and λ5 can be used when 90% or more of the absorber is water vapor.

[0042] Fig. 3 shows the light intensity distribution of light emitted from a reference light source at about 1500°C after passing through the light path in the cases of no water vapor as an absorber in the light path, low concentration water vapor, and medium concentration water vapor. Fig. 4 shows an example of measurement of the sensor received light intensity at wavelengths λ1 to λ4 when a test object is used as a measurement target, added to Fig. 3, Fig. 5 explains how to specify a reference light source at a provisional temperature from the sensor received light intensity at λ1, λ2, and λ4, and Fig. 6 shows a corrected intensity distribution obtained by taking the amount of water vapor into consideration, added to Fig. 5.

[0043] In FIG. 5, the reference light source of the provisional temperature is identified from the sensor light receiving intensity at wavelengths λ1, λ2, and λ4 where absorption is low. Two wavelengths, λ2 and λ3, or two wavelengths, λ3 and λ4, can be used to identify the amount of absorber present. The amount of absorber present is identified as shown in FIG. 8. That is, for example, two wavelengths, λ2 and λ3, are used to confirm the agreement with the ratio A measured in advance for the reference light source for the ratio X=sensor light receiving intensity of λ3 / sensor light receiving intensity of λ2. If the ratio X is equal to Ai, the amount of absorber present is identified as Bi. If the ratio X is between Ai and Ai+1, the amount of absorber present is estimated by interpolation (a value obtained by interpolation between Bi and Bi+1).

[0044] Figure 7 is a diagram in which the corrected intensity distribution obtained after multiple calculations of identification of the reference light source of the provisional temperature and correction by the amount of water vapor are added to Figure 5. As shown in Figure 7, the corrected intensity distribution after multiple corrections is obtained as being close to the sensor received light intensity of the reference light source in which no absorber is present, and it is possible to identify the received light intensity without water vapor (true intensity distribution) at two adjacent wavelengths (e.g., λ1 and λ2) of the two-color temperature measurement method.

[0045] The ratio of the received light intensities at λ1 and λ2 without water vapor (true intensity distribution) is checked to see if it matches the brightness ratio of a black body measured in advance, and the black body temperature is taken as the temperature of the object being measured.

[0046] Fig. 9 is a diagram showing the light intensity distribution of light emitted from a reference light source at about 500°C after passing through the optical path in the cases of no water vapor as an absorber in the optical path, low concentration water vapor, and medium concentration water vapor, and Fig. 10 is a diagram in which a measurement example of the sensor received light intensity at wavelengths λ1 to λ4 when a test object is used as the measurement target is added to Fig. 9. In this case, the received light intensity without water vapor (true intensity distribution) can be identified by the same method as described above.

[0047] (Type of absorbent) Representative examples of absorbers include water, water vapor or steam, and mixtures mainly composed of water vapor. FIG. 11 shows the light intensity distribution of light emitted from a reference light source at about 1500°C after passing through the light path in the cases where there is no water vapor as an absorber in the light path, only water vapor is present, and water vapor mixed with industrial oil is present. Industrial oil is mainly composed of hydrocarbons, and it is known that absorption appears around 920nm to 930nm and around 1010nm to 1030nm, and FIG. 11 shows the light intensity distribution that reflects this. FIG. 11 shows that detailed analysis of the light intensities of λ2 to λ4 may provide information on whether industrial oil is present or not.

[0048] (Used wavelength) The wavelengths used are wavelength P, which is used to identify the amount of absorber present, and wavelength Q, which is used to measure the temperature of the test object using two-color thermometry.

[0049] 8 described above, the wavelengths λ2 and λ3 are used as the used wavelength P, and the wavelengths λ1 and λ2 can be used as the used wavelength Q. However, the present invention is not limited to this.

[0050] 1) Wavelength P used (wavelength for identifying the amount of absorbent) In the examples shown in Figs. 3 to 11 in which four wavelengths λ1 to λ4 are used as a whole, the wavelengths λ2 and λ3, or the wavelengths λ4 and λ3, can be used as the used wavelength P.

[0051] In addition, three wavelengths, λ2, λ3, and λ4, can be used as the wavelength P. The central wavelengths λ2, λ3, and λ4 are 870 nm, 950 nm, and 1040 nm, respectively, and the bandwidth is 25 nm, but the central wavelength and bandwidth can be changed as long as they are consistent with the technical concept of the present invention. When the absorption of water or water vapor is large (when there is a lot of water or water vapor in the optical path), the bandwidth of λ3, for example, can be widened.

[0052] As described above, the amount of water or water vapor present in the optical path is determined mainly by using the sensor light receiving intensity ratio of λ2 and λ3. However, instead, the amount of water or water vapor can also be determined from the sensor intensities of the three wavelengths having central wavelengths λ2, λ3, and λ4.

[0053] It is preferable to obtain standard data in advance using a standard light source with a known temperature in an experimental system in which the amount of water or water vapor in the light path is controlled, and to specify the amount of water or water vapor present by comparing it with this. This standard data is obtained by photographing a standard light source (temperature standard) with a known temperature in advance through a known amount of water and / or water vapor. In other words, the temperature range to be measured is photographed at certain intervals, and the amount of water or water vapor present is also photographed at certain intervals.

[0054] In the present invention, instead of the wavelengths λ1 to λ4 shown in Figs. 3 to 11, the wavelengths λ2 to λ5 can be used as the four wavelengths as shown in Figs. 12 and 13. λ5 is a wavelength in the wavelength range of 1220 nm to 1290 nm, and an example of the central wavelength is 1250 nm. In this case, the wavelength P used can be one of the three central wavelengths λ2, λ3, and λ4, as described above. The central wavelengths λ2, λ3, and λ4 are 870 nm, 950 nm, and 1040 nm, respectively, and the bandwidth is 25 nm, but the central wavelength and the bandwidth can be changed as long as they are consistent with the technical concept of the present invention. When the absorption of water or water vapor is large (when there is a lot of water or water vapor in the optical path), for example, the bandwidth of λ3 can be widened.

[0055] Furthermore, as the wavelength P to be used, at least one of the central wavelengths λ2, λ4, and λ5, and the central wavelength λ3 can also be used.

[0056] 2) Wavelength Q (wavelength for measuring the temperature of the test object using the two-color temperature measurement method) When using four wavelengths in total, in the case of using the wavelengths λ1 to λ4 shown in Figures 3 to 11, for the wavelength Q to be used, two wavelengths (λ1 and λ2) of 900 nm or less can be used for measuring high temperatures of 1000°C or higher, and at least one wavelength exceeding 1000 nm can be used for measuring temperatures in the range of 500°C to 1200°C (for example, λ4 and λ2).

[0057] When the wavelengths λ2 to λ5 are used as the four wavelengths as shown in FIG. 12 and FIG. 13, λ4 and λ5 can be used for measuring temperatures in the range of 300°C to 1000°C.

[0058] The three wavelengths λ1, λ2, and λ4 in the embodiments shown in Figures 3 to 11, and the three wavelengths λ2, λ4, and λ5 in the embodiments shown in Figures 12 and 13, are also background wavelengths for estimating the amount of water or water vapor. The wavelengths used for temperature measurement and the background wavelengths used to obtain values ​​corresponding to the amount of water or water vapor can be the same wavelengths, and by using the same wavelengths, the number of wavelengths used can be reduced, thereby reducing the load of measurement and analysis.

[0059] If it is possible to change the exposure time of the sensor for each of the above wavelengths, this method can also be used. However, the measurement target generally has time fluctuations, and in such cases, the method of changing the exposure time is not desirable. This also means that a time-division spectrometer or a time-division hyperspectral camera is not suitable for measuring the four colors shown in Figure 12.

[0060] (The third overtone absorption wavelength of water and water vapor) It is known that water and water vapor exhibit main absorption at a wavelength of about 3 μm, with its overtone absorption at a wavelength of about 1.95 μm, its second overtone absorption at a wavelength of about 1.45 μm, and its third overtone absorption at a wavelength of about 0.95 μm, as shown in Figure 2. The intensity of the absorption decreases as the wavelength becomes shorter, and there is a difference of about three orders of magnitude between the main absorption and the third overtone absorption.

[0061] For various reasons, water absorption occurs to a certain extent in any wavelength region longer than 1.1 μm. The absorption peak wavelengths of water and water vapor are not the same. In terms of third overtone absorption, water is about 0.96 μm (960 nm), while water vapor is about 0.94 μm (940 nm).

[0062] Although the third overtone absorption of water and water vapor is relatively small, this wavelength is also suitable for identifying the amount of water or water vapor present in the optical path. The reasons for this are as follows:

[0063] The first reason is that the background wavelengths where absorption by water or water vapor is small are close to the third overtone absorption, and this can be utilized.

[0064] The second reason is that, although it is common to use "two wavelengths with a wavelength difference of about 200 nm" to cancel the effect of emissivity when measuring temperature using two-color thermometry, if the background wavelength mentioned above, which has low absorption by water and water vapor, is used, a wide temperature range from about 300°C to about 2500°C can be measured. Note that, although light scattering increases as the wavelength becomes shorter, the effect is negligible if the wavelength difference is about 200nm to 400nm.

[0065] In addition, when using a two-dimensional sensor for the measurement section, if the wavelength range from 650 nm to 1290 nm is targeted, a general-purpose sensor such as black silicon can be used, and a general-purpose lens with small chromatic aberration and distortion can also be used. This is also the reason why the third overtone absorption of water and water vapor is targeted for measurement. In particular, to obtain a temperature distribution image with high spatial resolution, the selection of the above sensor and lens is important in addition to the prism spectroscopic optical system described below.

[0066] (Spectroscopic optical system) In order to improve the accuracy of temperature measurement and obtain a temperature distribution image with high spatial resolution, it is preferable to use prism spectroscopy and multiple two-dimensional sensors. Figure 12 shows an example of a spectroscopic optical system when detecting the four colors shown in Figure 4 with a two-dimensional sensor.

[0067] The combined prism in the spectroscopic optical system shown in Figure 14 is made up of multiple prism units combined together, with an optical thin film formed on the adhesive surface. The ratio of transmitted light (T) to reflected light (R) in the optical thin film is 1:1. A typical thin film used in beam splitters can be used for this optical thin film. The typical configuration is to place an objective lens and a relay lens on the incident side of this prism, and a relay lens and a two-dimensional sensor on the exit side.

[0068] The prism is generally made of synthetic quartz, which has high transmission characteristics, but is not limited to this and can be made of any material that has consistent transmission characteristics in the wavelength range from 650 nm to 1290 nm.

[0069] (Sensor) As mentioned above, when using a two-dimensional image sensor in the measurement section, a general-purpose sensor such as black silicon can be used as long as it targets the wavelength range of 650 nm to 1290 nm shown in Fig. 4. In this embodiment, the use of a two-dimensional image sensor makes it possible to grasp the entire view of the test object without contact, and the adoption of a two-color temperature measurement method makes it possible to measure the temperature of all pixels or multiple measurement points without the need for emissivity correction.

[0070] As described above, the first embodiment of the present invention relates to two-color temperature measurement using two closely spaced wavelengths λ1 and λ2, and the amount of absorber present is measured using the intensity ratio between wavelengths λ2 and λ3 to obtain a temperature that is not influenced by the absorber. The outline of this method is as follows.

[0071] 1) Measurement of the temperature of the object being inspected using the two-color temperature measurement method using two closely spaced wavelengths λ1 and λ2 If the luminance of the test object at wavelength λ1 is R1 and the luminance of the test object at wavelength λ2 is R2, the luminance ratio of the test object is calculated as Y = R1 / R2.Then, the blackbody temperature that matches the luminance ratio of the blackbody measured in advance is determined as the temperature of the test object.

[0072] If there is no absorber between the test object and the sensor, Y = R1 / R2 = V1 / V2, where V1 is the sensor received light intensity at wavelength λ1 for the test object, and V2 is the sensor received light intensity at wavelength λ2 for the test object.

[0073] 2) Identifying the amount of absorber present If there is an absorber in the optical path from the test object to the sensor, its amount is determined by specifying the reference light source S and then using the ratio X=V3 / V2, where V3 is the sensor-received light intensity at wavelength λ3 for the test object, and V2 is the sensor-received light intensity at wavelength λ2 for the test object.

[0074] 3) Identify the temperature that is not affected by the absorber by the ratio of the corrected intensities at two adjacent wavelengths (e.g., λ1 and λ2) when no absorber is present. Once the reference light source S and the amount of absorber present are specified, the ratio of corrected intensities at two adjacent wavelengths (e.g., λ1 and λ2) can be specified from the sensor light receiving intensity distribution (curve) that is separately calculated in advance according to the amount of absorber present. Then, the blackbody temperature that matches the luminance ratio of the blackbody measured in advance is determined as the temperature of the test object.

[0075] Second Embodiment In the first embodiment, the ratio of the sensor received light intensities of two adjacent wavelengths used in the two-color thermometry was determined based on the divider-like relationship between the first light intensity information and the second and third light intensity information. In the present embodiment, however, the ratio of the sensor received light intensities of two adjacent wavelengths used in the two-color thermometry is determined based on the additive relationship between the first light intensity information and the second and third light intensity information.

[0076] The additive relationship means that the second light intensity information and the third light intensity information are combined (connected), so that the similarity with the first light intensity information can be determined.

[0077] In this embodiment, the relative values ​​of the light intensity at each of wavelengths λ1 to λ3 normalized by the light intensity at λ4 are plotted on the vertical axis, and the relative values ​​are plotted at each of wavelengths λ1 to λ4. The coincidence between the shape of the envelope connecting the four plotted positions and the shape of a known envelope connecting the four plotted positions that have been stored in advance as corresponding to each reference temperature and each amount of absorber present is determined (pattern matching).

[0078] In this embodiment, the amount of absorber present and the temperature of the test object can be simultaneously identified based on pattern matching.

[0079] FIG. 1 shows a flowchart according to the present invention common to the first and second embodiments. In step S1, temperature is measured based on the ratio of the sensor received light intensities at two adjacent wavelengths. In step S2, first light intensity information is stored when the reference light source is the measurement target in the presence of an absorber. In step S3, second and third light intensity information is acquired when the test object is the measurement target in the presence of an absorber. In step S4, the temperature is determined based on the ratio of the corrected sensor received light intensities at two adjacent wavelengths.

[0080] As described above, according to the present invention, unlike Patent Document 1, which has restrictions on the wavelength used, it is possible to give freedom to the wavelength used. Then, by processing with the two-color temperature measurement method, highly accurate temperature data can be obtained, and the temperature of the product being processed or heat-treated can be measured through water or water vapor, making it possible to manufacture products with stable quality. In addition, it contributes to cost reduction and energy saving, such as reducing defective products and unnecessary heating.

[0081] (Modification) Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, it is possible to combine the first and second embodiments. In addition, the number of wavelengths used is not limited to four, and it is also possible to use five wavelengths, for example, λ1 to λ5. In this case, a five-branch optical system as shown in FIG. 15 can be used.

[0082] In addition to the case where the measurement unit and the correction unit are provided in a housing as a temperature measurement device, a measurement terminal 1 (one or more) equipped with a measurement unit may be connected to a server 2 equipped with a correction unit via the Internet as shown in Fig. 16. The server 2 executes the flowchart shown in Fig. 1, and the temperature measurement result can be displayed on the display surface of the measurement terminal 1 using characters, sounds, colors, images, etc.

[0083] Furthermore, the present invention can be configured as a temperature measuring device, a temperature measuring method, and also as a program for causing a computer to function as each of the means of the above-mentioned temperature measuring device.

[0084] (Modification) [Explanation of symbols]

[0085] 1. Measurement terminal, 2. Server

Claims

1. A temperature measuring device for measuring a temperature of a test object based on a ratio of light intensities when receiving radiant energy for two wavelengths close to each other with respect to the spectral radiant energy of the test object, comprising: a correction unit for correcting a measurement value influenced by the amount of absorber present on the test object or in the light path from the test object to an original measurement value not influenced by the amount of absorber present, The correction unit is The first light is light having a wavelength that is absorbed by the absorber and has a large change in light intensity when received depending on the amount of the absorber, and the first light is light having a center wavelength in a first wavelength range between 900 nm and 1000 nm; The second light is light having a wavelength that is less absorbed by the absorber and exhibits a small change in light intensity when received in accordance with the amount of the absorber present, compared to the first light, and is included in at least one of a second wavelength range having a central wavelength of 650 nm to 900 nm, a third wavelength range having a central wavelength of 1000 nm to 1080 nm, and a fourth wavelength range having a central wavelength of 1220 nm to 1290 nm; Regarding the spectral irradiance of a reference light source having a known temperature, light intensity information received for each of a plurality of amounts of the absorber known in advance is defined as first light intensity information, so as to include the two adjacent wavelengths, the first light wavelength, and the second light wavelength; Regarding the spectral irradiance of the test object, light intensity information received when the absorber is present in an actual amount for the wavelength of the first light is defined as second light intensity information; Regarding the spectral irradiance of the test object, light intensity information received when the absorber is present in an actual amount for the wavelength of the second light is defined as third light intensity information, Based on the first light intensity information, the second light intensity information, and the third light intensity information, A temperature measuring device characterized by identifying the received light intensity when the absorber is not present at one and the other of the two adjacent wavelengths, and identifying the temperature of the test object based on the ratio of the identified light intensities.

2. determining a provisional temperature based on the third light intensity information; identifying an amount of the absorber based on the first light intensity information and a divide-and-convert relationship between the second light intensity information and the third light intensity information; 2. The temperature measuring device according to claim 1, wherein the received light intensity in the absence of the absorber is determined for one and the other of the two adjacent wavelengths, and the temperature of the test object is determined based on the ratio of the determined light intensities.

3. 2. The temperature measuring device according to claim 1, further comprising: a pattern matching process for comparing the first light intensity information with the second light intensity information and the third light intensity information based on an additive relationship between the information and the third light intensity information to identify the amount of the absorber present; and a process for identifying received light intensities in the case where the absorber is not actually present at one and the other of the two adjacent wavelengths; and a temperature of the test object is identified based on a ratio of the identified light intensities.

4. When the absorbent is either water or water vapor, or when the absorbent contains both water and water vapor, 2. The temperature measuring device according to claim 1, characterized in that the first light includes one type of wavelength within the first wavelength range, the second light includes two types of wavelengths within the second wavelength range, and the second light includes one type of wavelength within the third wavelength range.

5. When 90% or more of the absorbent is water vapor, 2. The temperature measuring device according to claim 1, characterized in that the first light has one type of wavelength included in the first wavelength range, the second light has one type of wavelength included in the second wavelength range, the second light has one type of wavelength included in the third wavelength range, and the second light has one type of wavelength included in the fourth wavelength range.

6. 2. The temperature measuring device according to claim 1, wherein at least one of the two wavelengths close to each other is the same as the wavelength of at least one of the first light and the second light.

7. 2. The temperature measuring device according to claim 1, wherein the absorbent is water, water vapor, steam, or a mixture containing water vapor as a main component.

8. 2. The temperature measuring device according to claim 1, wherein the spectral radiant energies of the test object and the reference light source are received by a sensor via a spectroscopic optical system including a prism.

9. A temperature measuring method for measuring a temperature of a test object based on a ratio of light intensities when radiant energy having two wavelengths close to each other is received with respect to the spectral radiant energy of the test object, the method comprising: a correction step of correcting a measurement value affected by the amount of absorber present on the test object or in a light path from the test object to an original measurement value not affected by the amount of absorber present, The correction step includes: The first light is light having a wavelength that is absorbed by the absorber and has a large change in light intensity when received depending on the amount of the absorber, and the first light is light having a center wavelength in a first wavelength range between 900 nm and 1000 nm; The second light is light having a wavelength that is less absorbed by the absorber and exhibits a small change in light intensity when received in accordance with the amount of the absorber present, compared to the first light, and is included in at least one of a second wavelength range having a central wavelength of 650 nm to 900 nm, a third wavelength range having a central wavelength of 1000 nm to 1080 nm, and a fourth wavelength range having a central wavelength of 1220 nm to 1290 nm; Regarding the spectral irradiance of a reference light source having a known temperature, light intensity information received for each of a plurality of amounts of the absorber known in advance is defined as first light intensity information, so as to include the two adjacent wavelengths, the first light wavelength, and the second light wavelength; Regarding the spectral irradiance of the test object, light intensity information received when the absorber is present in an actual amount for the wavelength of the first light is defined as second light intensity information; Regarding the spectral irradiance of the test object, light intensity information received when the absorber is present in an actual amount for the wavelength of the second light is defined as third light intensity information, Based on the first light intensity information, the second light intensity information, and the third light intensity information, A temperature measurement method characterized by identifying the received light intensities in the absence of the absorber at one and the other of the two closely spaced wavelengths, and identifying the temperature of the test object based on the ratio of the identified light intensities.

10. A program for causing a computer to function as each of the means of the temperature measuring device according to any one of claims 1 to 8.

Images