JP2018151354A - Radiant temperature measurement apparatus and radiant temperature measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure a reflectance ratio of a moving transparent measuring object online to measure a surface temperature of the measuring object.SOLUTION: A radiant temperature measurement apparatus 1 comprises: a light source 2; an on/off control circuit 11; a coaxial incident optical system 3 arranged inclined with respect to a perpendicular L1 of a measuring surface of a measuring object S, and emitting incident light from the light source 2 to the measuring surface; a retroreflective plate 4 arranged in a position opposite the position of the coaxial incident optical system 3 across the perpendicular L1 in the incident surface so as to form an angle perpendicular to the incident light reflected on the measuring surface, and returning the incident light reflected on the measuring surface and radiant light incident through the measuring surface to the coaxial incident optical system 3; a radiant light detector 5 detecting luminance of the light incident to the coaxial incident optical system 3; and a signal processor 12 calculating surface temperature of the measuring surface from a luminance value of the light detected by the radiant light detector 5.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radiation temperature measuring device and a radiation temperature measuring method for measuring the surface temperature of a measurement object.

  There are various techniques for measuring the temperature of an object to be measured. Among them, the radiation temperature measurement technique is a technique for measuring the surface temperature of the measurement object in a non-contact manner using the radiated light from the measurement object, and is practically used as a radiation thermometer. The radiation thermometer includes a photoelectric conversion element and an optical filter, measures the radiant energy value of the measurement object in a predetermined wavelength band, and converts the measured radiant energy value into a temperature, thereby measuring the surface temperature of the measurement object. Measure.

  Because the radiant energy value of the measurement object is the value obtained by multiplying the radiant energy value from the ideal black body by the emissivity of the measurement object, measure the surface temperature of the measurement object using a radiation thermometer. In this case, the emissivity value of the measurement object is required. For this reason, in a monochromatic radiation thermometer that measures the radiant energy value of a predetermined wavelength, the emissivity value of the measurement object is measured in advance, and the surface temperature of the measurement object is measured using the pre-measured emissivity value. Is measuring.

  On the other hand, when the measurement object is an opaque object, the sum of the reflectance and the emissivity is 1 based on Kirchhoff's law. For this reason, if the technique which measures the reflectance of a measuring object is used, the emissivity of a measuring object can be calculated | required from the reflectance of a measuring object, and possibility that it can use for temperature measurement is considered. Specifically, in Patent Document 1, as a method for measuring the reflectance of a measurement object having high specularity, light is irradiated from a direction perpendicular to the surface of the measurement object, and the surface of the measurement object is irradiated. A technique for calculating the vertical reflectance of a measurement object from the luminance of light reflected in a direction perpendicular to the reference is described.

Japanese Patent No. 5318303 (see FIG. 1)

  However, according to studies by the inventors of the present invention, the technique described in Patent Document 1 has the following problems. Hereinafter, with reference to FIG. 12, the problem of the technique described in Patent Document 1 will be described. FIG. 12 shows an in-plane average value of the vertical reflectivity Rv when the inclination (gonio stage angle) of a rolled aluminum plate with high specularity (measured surface roughness Ra is less than 0.08 μm) is changed by θ degrees. It is a figure which shows an example of the change of (average reflectance) (incident light wavelength: 850 nm) and relative ratio Rv ((theta)) / Rv (0 degree). The relative ratio Rv (θ) / Rv (0 degree) is a value obtained by dividing the average reflectance when the inclination is θ degrees by the average reflectance when the inclination is 0 degrees.

  As shown in FIG. 12, the relative ratio Rv (θ) / Rv (0 degree) of the vertical reflectance is attenuated to 83 to 87% when the inclination θ is changed by ± 0.5 degrees, and the inclination θ is ±±. When it changes by 0.8 degrees, it attenuates to 63-74%. That is, the vertical reflectance measured by the technique described in Patent Document 1 is easily affected by the inclination θ of the measurement object. For this reason, in order to accurately measure the reflectance of the measurement object using the technique described in Patent Document 1, it is necessary to strictly control the inclination θ of the measurement object. Therefore, for example, a patent document for a process of measuring the reflectance of a moving opaque measuring object such as a steel plate moving on a continuous galvanizing line online and calculating the surface temperature of the measuring object from the measured reflectance It is difficult to apply the technique described in 1.

  The present invention has been made in view of the above problems, and its purpose is to provide a radiation temperature that can accurately measure the reflectance of a moving opaque measuring object on-line and measure the surface temperature of the measuring object. It is to provide a measuring apparatus and a radiation temperature measuring method.

  A radiation temperature measuring device according to the present invention includes a light source, an on / off control circuit for controlling on / off of the light source, and a light source from the light source, which is inclined with respect to a normal to a measurement surface of a measurement object. A coaxial incident optical system that irradiates the measurement surface with incident light, and a coaxial incident optical system that sandwiches the perpendicular in the incident surface so as to be at an angle perpendicular to the incident light reflected on the measurement surface. A retroreflector disposed at a position opposite to the position and returning the incident light reflected from the measurement surface and the radiation incident from the measurement surface to the coaxial incident optical system; and the coaxial incident optical system A synchrotron radiation detector for detecting the luminance of the light incident on the signal detector, and a signal processing device for calculating the surface temperature of the measurement surface from the luminance value of the light detected by the synchrotron radiation detector, the signal processing device Is said on-off The reflectance of the measurement surface is calculated from the luminance value of the light detected when the light source is turned on by the control circuit, and the luminance of the light detected when the light source is turned off by the on / off control circuit Then, the emissivity of the measurement surface is calculated from the reflectance, and the surface temperature of the measurement surface is calculated using the brightness of the light detected when the light source is turned off by the on / off control circuit and the emissivity. It is characterized by calculating.

  The radiation temperature measuring device according to the present invention is the above-mentioned invention, wherein the signal processing device has a reflectance calculated from a luminance value of light detected when the light source is turned on by the on / off control circuit. The reflectance of the measurement surface is calculated using a reference luminance value corresponding to the reference reflectance measured in advance in consideration of the square value of the reflectance of the surface, and the emissivity and reflectance. The emissivity of the measurement surface is calculated on the assumption that the sum of the values is 1.0.

  In the above-described invention, the radiation temperature measuring device according to the present invention is configured so that the luminance value corresponding to the surface temperature of the measurement surface is an effective luminance level in an A / D converter included in the radiation detector. A control circuit for adjusting the detection time of the photodetector is provided.

  The radiation temperature measuring apparatus according to the present invention is characterized in that, in the above invention, the radiation detector is constituted by a single light receiving element.

  The radiation temperature measuring device according to the present invention is the above-mentioned invention, wherein the radiation detector is constituted by a two-dimensional CCD monochrome camera, the light source is an infrared LED light source, and visible light is visible at the tip of the coaxial incident optical system. A cut filter is arranged.

  The radiation temperature measuring device according to the present invention is characterized in that, in the above invention, the radiation detector is constituted by a two-dimensional CCD color camera.

  The radiation temperature measurement method according to the present invention includes a light source, an on / off control circuit for controlling on / off of the light source, and an inclination from the light source, which is arranged to be inclined with respect to a normal to the measurement surface of the measurement object. A coaxial incident optical system that irradiates the measurement surface with incident light, and a coaxial incident optical system that sandwiches the perpendicular in the incident surface so as to be at an angle perpendicular to the incident light reflected on the measurement surface. A retroreflector disposed at a position opposite to the position and returning the incident light reflected from the measurement surface and the radiation incident from the measurement surface to the coaxial incident optical system; and the coaxial incident optical system A radiation temperature detector that detects the brightness of light incident on the light source, and a signal processing device that calculates the surface temperature of the measurement surface from the brightness value of the light detected by the radiation light detector. Radiant temperature used Calculating a reflectance of the measurement surface from a luminance value of light detected when the light source is turned on by the on / off control circuit, and the light source by the on / off control circuit. Calculating the emissivity of the measurement surface from the brightness of the light detected when the light source is turned off and the reflectance, and the brightness of the light detected when the light source is turned off by the on / off control circuit And calculating the surface temperature of the measurement surface using the emissivity.

  According to the radiation temperature measuring apparatus and the radiation temperature measuring method according to the present invention, the reflectance of a moving opaque measuring object can be accurately measured online to measure the surface temperature of the measuring object.

FIG. 1 is a schematic diagram showing a configuration of a radiation temperature measuring apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram for explaining a radiation temperature measuring method according to an embodiment of the present invention. FIG. 3 is a diagram showing an example of changes in the average value of the reflectance and the relative ratio measured according to the present invention when the inclination of the rolled aluminum plate is changed. FIG. 4 shows an example of a result of calculating a temperature error between the case where the retroreflector has an ideal reflectance (100%) and the case where the reflectance becomes 90% with respect to the state. FIG. FIG. 5 is a diagram illustrating an example of the reflectance distribution and the surface temperature distribution. FIG. 6 is a diagram showing an example of the result of measuring the reflectance while changing the temperature of the aluminum sample. FIG. 7 is a diagram showing the surface temperature of the aluminum sample measured from the results shown in FIG. FIG. 8 is a diagram showing an example of the result of measuring the reflectance while changing the temperature of the steel plate plated with ceramic and a metal that does not oxidize. FIG. 9 is a diagram showing the surface temperature of a steel plate plated with a ceramic and a metal that is not oxidized, measured from the results shown in FIG. FIG. 10 is a diagram showing the measurement results of the reflectivity of the high reflectivity specular reflector using a spectrophotometer. FIG. 11 is a diagram illustrating an example of a blackbody furnace calibration formula. FIG. 12 is a diagram illustrating an example of changes in the average value of the vertical reflectance and the relative ratio when the inclination of the rolled aluminum plate is changed.

  Hereinafter, a configuration of a radiation temperature measuring apparatus according to an embodiment of the present invention and a radiation temperature measuring method using the radiation temperature measuring apparatus will be described with reference to the drawings.

[Configuration of radiation temperature measuring device]
FIG. 1 is a schematic diagram showing a configuration of a radiation temperature measuring apparatus according to an embodiment of the present invention. As shown in FIG. 1, the radiation temperature measuring apparatus 1 according to an embodiment of the present invention calculates the emissivity of a measurement object obtained by measuring the reflectance of a moving opaque measurement object S such as a steel plate. This is a device for measuring the surface temperature by using the light source 2, the coaxial incident optical system 3, the retroreflector 4, the radiation detector 5, the on / off control circuit 11, and the signal processing device 12 as main components. I have.

  The light source 2 is a device that generates incident light that irradiates the measurement object S according to a control signal from the on / off control circuit 11, and is configured by, for example, an LED (Light Emitting Diode) light source. When measuring the reflectance of the measuring object S in a relatively low temperature range of 350 to 550 ° C., use a CCD monochrome camera having a wavelength range of 700 to 1100 nm and an infrared LED light source (main wavelength 850 nm). Is desirable.

  The coaxial incident optical system 3 is an optical system in which the optical axis of the incident light irradiated onto the measurement object S and the optical axis of the light receiving optical system coincide with each other, and is configured by, for example, a coaxial incident telecentric lens. The coaxial incident optical system 3 is disposed so as to be inclined with respect to the normal L1 of the measurement surface of the measurement object S. The coaxial incident optical system 3 causes the incident light generated by the light source 2 to enter the measurement surface of the measurement object S and transmits the incident light from the outside to the radiation light detector 5. A visible light cut filter may be disposed at the tip of the coaxial incident optical system 3.

  The retroreflecting plate 4 is a plate-like member having a retroreflective characteristic that returns light from the measurement surface of the measurement object S in the light incident direction, and incident light reflected on the measurement surface of the measurement object S. Is arranged at a position opposite to the position of the coaxial incident optical system 3 across the perpendicular L1 of the measurement surface in the incident surface so as to be at an angle perpendicular to the incident surface. The retroreflector 4 returns the incident light reflected on the measurement surface of the measuring object S and the radiated light incident from the measurement surface to the coaxial incident optical system 3. In general, it is said that when the incident angle of light with respect to the retroreflecting plate 4 is within ± 30 degrees, the retroreflecting plate 4 returns incident light to almost 100% light emission position.

  Here, the retroreflecting plate 4 is arranged so as to be at an angle perpendicular to the reflected light from the measurement surface of the measuring object S, but it is necessary to arrange it at a strictly perpendicular angle. The reflection light from the measurement surface of the measuring object S may be within a range in which it can be returned to the coaxial incident optical system 3. In the present embodiment, the retroreflecting plate 4 is arranged at a height position substantially the same as the height position of the tip of the coaxial incident optical system 3. Can be appropriately changed according to the layout of the apparatus.

  The radiated light detector 5 is a device that detects the luminance of the light transmitted from the coaxial incident optical system 3, and includes a single light receiving element, a CCD monochrome camera, a CCD color camera, and the like. Note that the CCD monochrome camera can also measure in a high temperature range. However, since the color changes depending on the temperature of the measuring object S in the high temperature range, the CCD color depends on the measurement temperature range (for example, about 550 ° C. or more). It is desirable to use a camera. Further, it is desirable to adjust the detection time of the synchrotron radiation detector 5 so that the luminance value corresponding to the measurement temperature of the measuring object S becomes an effective luminance level by the A / D converter. When a CCD monochrome camera is used, it is desirable to use an infrared LED light source as the light source 2 and to arrange a visible light cut filter at the tip of the coaxial incident optical system 3.

  The on / off control circuit 11 is a circuit that controls the on / off operation of the light source 2 by outputting a control signal to the light source 2.

  The signal processing device 12 calculates the reflectance of the measurement object S based on the luminance of the light detected by the synchrotron radiation detector 5, and calculates the surface temperature of the measurement object S based on the calculated reflectance. It is a device and is constituted by an information processing device such as a personal computer.

  The radiation temperature measuring apparatus 1 having such a configuration measures on-line the reflectance of an opaque measurement object that moves by the following radiation temperature measurement method. Hereinafter, with reference to FIG. 2, operation | movement of the radiation temperature measuring apparatus 1 at the time of performing the radiation temperature measuring method which is one Embodiment of this invention is demonstrated.

[Radiation temperature measurement method]
FIG. 2 is a schematic diagram for explaining a radiation temperature measuring method according to an embodiment of the present invention. In the radiation temperature measurement method according to the embodiment of the present invention, first, the light source 2 is turned on by the on / off control circuit 11 outputting a control signal to the light source 2. As a result, as shown in FIG. 2A, the incident light L2 is incident on the measurement surface (X, Y) of the measurement object S at an angle + θ via the coaxial incident optical system 3, and the measurement surface (X , Y), the incident light L2 is specularly reflected, and the reflected light L3 enters the retroreflecting plate 4.

  Then, the reflected light L3 is reflected on the surface of the retroreflection plate 4, and the reflected light L4 is incident on the measurement surface (X, Y) of the measurement object S at an angle −θ, and the measurement surface (X, Y). Then, the reflected light L4 is reflected, and the reflected light L5 enters the radiated light detector 5 through the coaxial incident optical system 3. When a retroreflector 4 having a size of 55 × 35 mm is used at a distance of 110 mm, the angle θ can be within a range of 12 to 15 degrees from the geometrical arrangement, and the retroreflection The plate 4 can cover the apex angle in the range of about 12.5 degrees with respect to the vertical axis of the regular reflection light.

  Here, the intensity of the incident light L2 on the measurement surface (X, Y) is L0 (θ, X, Y), and the incident light L2 incident on the measurement surface (X, Y) of the measuring object S at an angle + θ is specularly reflected. When the reflectance reflected in the direction is R (θ, X, Y) (%), the intensity of the reflected light L3 is expressed as L0 (θ, X, Y) × R (θ, X, Y) / 100. Can do. At this time, the value of L0 (θ, X, Y) × R (θ, X, Y) / 100 is sufficiently larger than the emitted light (self-emitting emitted light) from the measurement surface (X, Y). A light source having a value of L0 (θ, X, Y) is used. Similarly, assuming that the reflectivity of the retroreflecting plate 4 is 100%, the intensity of the reflected light L5 is L0 (θ, X, Y) × R (θ, X, Y) × R (−θ, X, Y) / 10000. Since it can be assumed that the regular reflectance is not affected by the directivity if the angle θ is the same, the following formula (1) is established. In Equation (1), Rφ (X, Y) indicates the reflectance (%) of the measurement surface (X, Y).

  Further, as shown in the following mathematical formula (2), the reflectance R obtained based on the luminance of the reflected light L5 from the retroreflecting plate 4 detected by the radiation light detector 5 is the measurement surface (X, Y ) Is the square value of the reflectance Rφ (X, Y). Therefore, the reflectance Rφ (X, Y) of the measurement surface (X, Y) can be obtained by substituting the reflectance R into the following formula (3). Specifically, the reflectance R is calculated from the reference luminance value corresponding to the reference reflectance measured in advance and the luminance value detected by the radiated light detector 5, and the calculated reflectance R is calculated as follows. By substituting into Equation (3), the reflectance Rφ (X, Y) of the measurement surface (X, Y) is calculated. In this way, the reflectance Rφ (X, Y) of the measurement surface (X, Y) from the luminance of the reflected light L5 from the retroreflection plate 4 detected by the radiation detector 5 when the light source 2 is turned on. Can be calculated.

  Next, the on / off control circuit 11 turns off the light source 2 by stopping the output of the control signal to the light source 2. As a result, as shown in FIG. 2B, radiated light (self-emitting radiated light) L6 radiated from the measurement surface (X, Y) in the direction of the angle + θ is radiated light detector via the coaxial incident optical system 3. 5 is incident. Further, the radiated light L7 radiated from the measurement surface (X, Y) in the angle −θ direction is incident on the retroreflecting plate 4, and the radiated light L7 is reflected on the surface of the retroreflecting plate 4, and the reflected light L8 is reflected. Incident to the measurement surface (X, Y) of the measurement object S at an angle −θ. Then, the reflected light L8 is reflected on the measurement surface (X, Y), and the reflected light L9 enters the radiated light detector 5 via the coaxial incident optical system 3.

Here, the light quantity Ra ^* _ε1 (X, Y) of the radiated light L6 is the Ra ^* ₀ (X, Y: T ° C., ε = 1.0) when the emissivity is 1.0. ), It can be expressed as the following formula (4). Similarly, the light amount Ra ^* _ε2 (X, Y) of the _radiated light L7 can be expressed as the following formula (5). Further, the light amount Ra ^* _ε3 (X, Y) of the reflected light L9 can be expressed as the following formula (6), where D is the reflectance of the retroreflecting plate 4.

  In addition, the regular reflectance is not affected by the directionality when the angle θ is the same (Equation (1) established), and the direction of the emissivity ε is the same when the angle is the same as shown in the following Equation (7). It is assumed that the sum of the reflectance Rφ (X, Y) / 100 and the emissivity εφ (X, Y) is 1 as shown in the following formula (8). Note that εφ (X, Y) indicates the emissivity on the measurement surface (X, Y).

Thereby, the sum Ra ^* sum (X, Y) of the luminances of the radiated light L6 and the reflected light L9 is expressed as the following mathematical formulas (9) to (11). In addition, ε (X, Y) in the formula (11) is an emissivity of double reflection, and is expressed as the following formula (12).

The luminance sum Ra ^* sum (X, Y) shown in Equation (10) is a luminance value detected by the synchrotron radiation detector 5. Accordingly, the emissivity ε (X, Y) obtained by substituting the luminance sum Ra ^* sum (X, Y) and the reflectance Rφ (X, Y) into the equation (12) is expressed in the equation (11). By substituting, it is possible to calculate an emissivity-corrected radiance value Ra ^* ₀ (X, Y: T ° C., ε = 1.0). Thus, the blackbody furnace calibration formula shown in the following formula (13) is the logarithmic value V (X, Y) of the emissivity-corrected radiance value Ra ^* ₀ (X, Y: T ° C., ε = 1.0). By substituting into, the surface temperature TEMP (X, Y) of the measurement surface (X, Y) can be calculated. Note that parameters A, B, and C in Equation (13) indicate coefficients.

  FIG. 3 shows the reflectivity Rφ measured according to the present invention when the inclination (gonio stage angle) of a rolled aluminum plate with high specularity (measured surface roughness Ra is less than 0.08 μm) is changed by θ degrees. It is a figure which shows an example of the change of an average value (average reflectance) (incident light wavelength: 850 nm) and relative ratio R (phi) ((theta)) / R (phi) (0 degree). The relative ratio Rφ (θ) / Rφ (0 degree) is a value obtained by dividing the average reflectance when the inclination is θ degrees by the average reflectance when the inclination is 0 degrees.

  As shown in FIG. 3, if the inclination angle θ is within ± 3 degrees with respect to 0 degree, the reflectance Rφ is stable at 86 to 100%, and the inclination angle θ exceeds 4 degrees. For the first time, the reflectance Rφ begins to decrease. As described above, in the conventional reflectance measurement method (see FIG. 12), the relative ratio Rv (θ) / Rv (0 degree) of the reflectance Rv is 83 only by changing the slope θ by ± 0.5 degrees. Attenuates to -87%, and attenuates to 63-74% when the slope θ changes ± 0.8 degrees. Therefore, according to the present invention, the influence of the inclination θ of the measurement object when measuring the reflectance Rφ can be greatly reduced. For this reason, according to the present invention, for example, the reflectance of a moving opaque measuring object such as a steel plate moving on a continuous galvanizing line can be measured online to measure the surface temperature of the measuring object.

  Here, the error given to the temperature measurement when the reflectance of the retroreflector 4 is reduced to 90% of the ideal case will be described. FIG. 4 shows the case where the retroreflector 4 has an ideal reflectivity (100) when a sample at a temperature of 450 ° C. with a reflectivity Rφ (X, Y) of the measurement surface of 80% to 10% every 10% is measured. %) Is a diagram illustrating a result of calculating a temperature error between (1.0) having a (%) and (0.9) having a reflectivity of 90% with respect to the state. As shown in FIG. 4, it can be seen that even if the reflectance is 80%, which is most likely to cause the temperature error, the temperature error is within about 10 ° C. at most.

  FIG. 5 is a diagram showing an example of the reflectance distribution and the surface temperature distribution when the mirror surface portion of the aluminum sample measured according to the present invention and the rough surface portion of roughness # 30 are set to 450 ° C. with an aluminum nitride heater. It is. The boundary between the mirror surface and the rough surface is created at the center of an aluminum plate 50 mm × 25 mm, and the average value of the center 11 pixels of 8 mm × 2 mm (1000 × 250 pixels) at the center is shown. From the graph shown in FIG. 5, it can be seen that the surface temperature shows almost the same temperature while the reflectance distribution changes greatly at the boundary. As a result of calculating the surface temperature distribution, since the flat surface roughened with the abrasive grain of roughness # 30 is quite rough, the temperature distribution on the mirror surface is almost uniform, but the temperature distribution varies greatly in the plane. You can see that Moreover, since the radiation heat transfer loss from a rough surface is large, it turns out that the average temperature of the rough surface side is about 5 degreeC low.

  Moreover, the result of having measured the reflectance while changing the temperature of the aluminum sample of roughness # 30 and roughness # 320 is shown in FIG. In FIG. 6, the reflectance Rφ (S1) of the mirror surface portion, the reflectance Rφ (S5) of the rough surface portion, and the difference Rφ (S1−S5) are shown. As shown in FIG. 6, it was confirmed that both the roughness # 30 and the roughness # 320 have a tendency that the reflectance increases as the temperature increases. FIG. 7 shows the surface temperature of the aluminum sample calculated from the results shown in FIG. As shown in FIG. 7, it can be seen that the surface temperatures of the mirror surface portion and the rough surface portion are in good agreement. Further, the difference between the heater set value and the temperature of the mirror surface portion was different between the aluminum samples having roughness # 30 and roughness # 320. This is presumably because the surface temperature of the aluminum sample with roughness # 30 is rough and the surface temperature of the aluminum sample with high emissivity is low due to large thermal radiation. Similar data for steel plates plated with ceramics and non-oxidized metals are shown in FIGS. Similar results were obtained for these.

  In this example, the surface temperature was measured by performing pre-processing for reflectance calibration and pre-processing for measuring the surface temperature of the measurement object. In this embodiment, the sensitivity curve of the CCD monochrome camera is set to γ = 1.0, and an image luminance value proportional to the input light intensity is obtained.

  In the pretreatment, first, a quasi-black body with zero reflected light was prepared. This is a cylinder with an internal diameter of 50 mm, a height of 90 mm, and a member having a cone having a vertex angle of 60 degrees at the bottom of the cylinder, which are joined together by screwing, and is called a black calibration cylinder. The material of the cylindrical and conical bottom portions was aluminum, and the surface thereof was used with a matte black alumite treatment. As the reflectance calibration plate, a high reflectance mirror reflector is commercially available. The high-reflectance specular reflector is expensive and easily damaged, so it is used as an official standard, and a low-reflectance quasi-white body priced with that standard is made in the form of a white calibration cylinder in the same way as the quasi-black body. It was used as a regular standard reflector having a low reflectance of about 0.3% (the value is determined by calibration). The white calibration cylinder is different from the black calibration cylinder in that the apex angle is as large as 175 degrees and the matte white alumite treatment is applied.

  Next, the reflectance of the white calibration cylinder was calibrated with a high reflectance mirror reflector. The shutter time was determined in a range where the brightness count value when the reflectance of the white calibration cylinder was measured was not saturated. The A / D conversion of the CCD monochrome camera is 16 bits and exceeds 65000 counts (gradation). In this embodiment, the gain is determined so that the LED light source is stable, and the shutter time is set to 0.2 msec. Therefore, the reflectance of the white calibration cylinder was measured, and then the reflectance of the black calibration cylinder was measured. The reflectance of the virtual white calibration cylinder at this time was temporarily input as 0.300. The white count was 36366.8, the black count was 35980.2, and the difference was 386.6.

  Next, the reflectivity of the high reflectivity specular reflector was measured. FIG. 10 shows the measurement results of the reflectance of the high-reflectance specular reflector with a spectrophotometer. The reflectivity of the highly reflective specular reflector with respect to incident light having a wavelength of 850 nm was 86%. After confirming that the luminance value of the high-reflectivity specular reflector was not saturated, the shutter time was set to 0.01 msec. Next, the luminance value of the black calibration cylinder was measured with the same shutter time, and subtracted from the luminance value of the high reflectance specular reflector. On the other hand, the brightness value of the white calibration cylinder was 386.6 counts when the shutter time was 0.2 msec. Therefore, this count value was converted when measured at 0.01 msec, and 386.6 × 0.01 / 0. .2 = 19.33. A calibration value of 0.300% of the white calibration cylinder was determined so that the reflectance of the high-reflectance specular reflector was 86% when calculated with this coefficient, and was registered as the reference reflectance of the white calibration cylinder.

  When measuring the surface temperature of the measurement object, first, the reflectance of the reference reflectance calibration plate was measured. When the measurement of the reflectance of the reference reflectance calibration plate was completed, the blackbody furnace calibration formula was set. Next, two items of preparation measurement for reflectance measurement and surface temperature measurement are required. First, the shutter time that does not saturate the reflection luminance value of the measurement object is selected. Then, a quasi-black body is set on the front surface of the coaxial incident optical system, the LED light source is first turned on, and the internal noise luminance value of the optical system is stored as two-dimensional image data with a determined shutter time. Next, black body measurement for radiance measurement was performed. The above is preparation.

  Next, the quasi-black body was removed, and the reflectance of the measurement object being heated was measured. Next, the radiation temperature of the measurement object was measured. Thereafter, the surface temperature of the measurement surface (X, Y) was calculated by substituting the logarithmic value of the radiance value corrected for emissivity into the blackbody furnace calibration formula. An example of the blackbody furnace calibration formula is shown in FIG.

  The embodiment to which the invention made by the present inventors is applied has been described above, but the present invention is not limited by the description and the drawings that constitute a part of the disclosure of the present invention. That is, other embodiments, examples, operational techniques, and the like made by those skilled in the art based on this embodiment are all included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Radiation temperature measuring apparatus 2 Light source 3 Coaxial incident optical system 4 Retroreflecting plate 5 Synchrotron radiation detector 11 On-off control circuit 12 Signal processing apparatus S Measurement object

Claims (7)

A light source;
An on / off control circuit for controlling on / off of the light source;
A coaxial incident optical system for irradiating the measurement surface with incident light from the light source, which is disposed to be inclined with respect to a normal to the measurement surface of the measurement object;
The measurement surface disposed at a position opposite to the position of the coaxial incident optical system across the perpendicular in the incident surface so as to have an angle perpendicular to the incident light reflected on the measurement surface. A retroreflector that returns the incident light reflected at and the radiation incident from the measurement surface to the coaxial incident optical system;
A synchrotron radiation detector for detecting the brightness of light incident on the coaxial incident optical system;
A signal processing device that calculates the surface temperature of the measurement surface from the luminance value of the light detected by the synchrotron radiation detector,
The signal processing device calculates a reflectance of the measurement surface from a luminance value of light detected when the light source is turned on by the on / off control circuit, and turns off the light source by the on / off control circuit. The emissivity of the measurement surface is calculated from the brightness and reflectance of the light detected when the light source is turned on, and the brightness and the emissivity of the light detected when the light source is turned off by the on / off control circuit A surface temperature of the measurement surface is calculated using a radiation temperature measuring device.   The signal processing device takes into account that the reflectance obtained from the luminance value of the light detected when the light source is turned on by the on / off control circuit is a square value of the reflectance of the measurement surface. The reflectance of the measurement surface is calculated using a reference luminance value corresponding to the reference reflectance measured in advance, and the sum of the emissivity and the reflectance is assumed to be 1.0. The radiation temperature measuring device according to claim 1, wherein the emissivity is calculated.   A control circuit that adjusts the detection time of the radiation detector so that the luminance value corresponding to the surface temperature of the measurement surface becomes an effective luminance level in the A / D converter included in the radiation detector; The radiation temperature measuring device according to claim 1, wherein   The radiation temperature measuring device according to any one of claims 1 to 3, wherein the radiation detector is configured by a single light receiving element.   The radiated light detector is constituted by a two-dimensional CCD monochrome camera, the light source is an infrared LED light source, and a visible light cut filter is disposed at a tip of the coaxial incident optical system. The radiation temperature measuring device according to any one of 1 to 3.   The radiation temperature measuring device according to any one of claims 1 to 3, wherein the radiation detector is constituted by a two-dimensional CCD color camera. A light source, an on / off control circuit that controls on / off of the light source, and a coaxial that illuminates the measurement surface with incident light from the light source that is inclined with respect to the normal of the measurement surface of the measurement object The epi-illumination optical system is disposed at a position opposite to the position of the coaxial epi-illumination optical system across the perpendicular in the incidence plane so as to be perpendicular to the incident light reflected on the measurement surface. A retroreflector that returns the incident light reflected on the measurement surface and radiation incident from the measurement surface to the coaxial incident optical system, and radiation that detects the luminance of the light incident on the coaxial incident optical system. A radiation temperature measurement method using a radiation temperature measurement device comprising: a light detector; and a signal processing device that calculates a surface temperature of the measurement surface from a luminance value of light detected by the radiation light detector,
Calculating the reflectance of the measurement surface from the luminance value of the light detected when the light source is turned on by the on / off control circuit;
Calculating the emissivity of the measurement surface from the brightness and reflectance of the light detected when the light source is turned off by the on / off control circuit;
Calculating the surface temperature of the measurement surface using the brightness and emissivity of light detected when the light source is turned off by the on / off control circuit;
A radiation temperature measurement method comprising: