JP2001091362A - Surface temperature measuring method amd apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface temperature measuring method and its apparatus wherein a compact equipment structure, in which cooling in the vicinity of a measuring part is unnecessary, can be realized, flexibility is imparted to a light guide path for receiving and introducing a thermal radiation light from a material surface, and an apparatus including a detector is sufficiently isolated from the material surface to be a measuring surface and can be installed with a increased degree of freedom. SOLUTION: In the method for measuring the surface temperature of a material by detecting a thermal radiation light from the material, a light guide path for receiving a thermal radiation light from the material surface and transmitting the light to a detector, and a light receiving mechanism capable of realizing a state of high reflection and a state of low reflection to the thermal radiation light introduced through the light guide path, are installed between the detector detecting the thermal radiation light and the material surface. The thermal radiation light introduced through the light guide path is introduced to the detector through the light receiving mechanism. Thermal radiation intensities corresponding to the state of high reflection and the state of low reflection are detected. On the basis of the detected values, emissivity of the material is corrected and the surface temperature is obtained. As to the light guide path, it is preferable that the surface side of the material is constituted of heat resisting optical material and the detector side is constituted of a multi-core optical fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for measuring a surface temperature, and more particularly to an improvement in a method and an apparatus for measuring a surface temperature of a material by detecting heat radiation from the material.

[0002]

2. Description of the Related Art A radiation thermometer that measures the surface temperature of a material by detecting heat radiation from the material has the advantage that the temperature of the material can be measured in a non-contact state, but the optical constant of the material, There is a problem that the emissivity of the material changes due to factors such as surface roughness and surface contamination, and a measurement error occurs due to reflection of radiation from the surroundings on the material surface.

In order to solve this problem, for example, a hemispherical cavity having a high reflectivity by plating the inner surface with gold is brought close to the surface of the material, and a small hole is formed at the apex of the cavity. A method of measuring the thermal radiation intensity from the surface of the material by attaching a detector ("Temperature Measurement", edited by the Society of Instrument and Control Engineers, temperature measurement subcommittee, page 233),
The cylindrical cavity is brought close to the surface of the material, the inner surface of the cavity is made highly reflective to heat radiation from the surface of the material, and the opening on the top surface of the cavity is placed above the opening on the top surface of the cavity to reflect heat radiation from the material. A method in which a rotating sector having reflection characteristics and low reflection characteristics is provided, and the rotating sector is rotated to measure the heat radiation intensity in the high reflection state and the low reflection state to determine the surface temperature of the material (Japanese Patent Publication No. 52-7954) Gazette)
And so on.

These methods measure the intensity of thermal radiation emitted from the surface of a material, correct this value to determine the emissivity of the material, and calculate the accurate temperature of the surface of the material. In this case, the cavity must be close to the measurement surface, and therefore, when the measurement surface is high temperature, it is necessary to cool the cavity and the rotating sector in order to perform accurate measurement, and the device becomes large-scale. There are difficulties. When measuring the material temperature in a vacuum vessel or furnace,
Cooling measures are particularly difficult. Also, it is not easy to keep the cavity at a high reflectance, and a change in the reflectance causes an error in temperature measurement.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems in a radiation thermometer which measures heat radiation from a material and measures the surface temperature of the material. The purpose is to realize a compact device structure that does not require cooling in the vicinity of the measuring section, and to make the detector flexible by providing a flexible light guide path for receiving and introducing heat radiation from the material surface. It is an object of the present invention to provide a method and an apparatus for measuring a surface temperature, which make it possible to install an apparatus including the apparatus sufficiently away from the surface of the material to be measured and with an increased degree of freedom.

[0006]

According to a first aspect of the present invention, there is provided a method for measuring a surface temperature of a material by detecting heat radiation from the material. A light guide path for receiving heat radiation from the surface of the material and transmitting the light to the detector between the detector for detecting the heat radiation and the surface of the material; and heat radiation introduced through the light guide path A light receiving mechanism capable of realizing a high reflection state and a low reflection state is provided, and the heat radiation light introduced through the light guide path is guided to a detector via the light receiving mechanism to correspond to the high reflection state and the low reflection state. It is characterized in that the heat radiation intensity is detected, and the emissivity of the material is corrected based on the detected value to obtain the surface temperature.

According to a second aspect of the present invention, in the first aspect, the light guide path is formed of a heat-resistant optical material on the surface side of the material and a multi-core optical fiber on the detector side. And

According to a third aspect of the present invention, there is provided a surface temperature measuring method according to the first and second aspects, wherein a high reflectance is provided between the light guide path and the detector with respect to heat radiation introduced through the light guide path. A rotating sector having a portion having a low reflectance and a portion having a low reflectance are provided, and a portion having a high reflectance and a portion having a low reflectance alternate with respect to the heat radiation introduced through the light guide path. It is characterized by appearing.

According to a fourth aspect of the present invention, there is provided an apparatus for measuring the surface temperature of a material by detecting heat radiation from the material, the apparatus comprising at least a device for receiving the heat radiation from the surface of the material. On the surface side of the material, a first light guide path made of a heat-resistant optical material, a light receiving mechanism capable of realizing a high reflection state and a low reflection state with respect to heat radiation introduced through the first light guide path, A second light guide path comprising a multi-core optical fiber for guiding emitted light from the light receiving mechanism to the detector; and a detector for detecting thermal emitted light introduced via the light receiving mechanism. The heat radiation intensity corresponding to the high reflection state and the low reflection state is detected by a detector, and the emissivity of the material is corrected based on the detected value to obtain the surface temperature.

The principle of the surface temperature measurement according to the present invention will be described. As shown in FIG. 1, a heat-resistant optical material such as quartz, sapphire, A rod 4A made of glass or the like is placed, and a multi-core optical fiber 4B is connected to the rod 4A to form a first light guide path 4 for receiving heat radiation from the surface S of the material M.

On the upper surface of the multi-core optical fiber 4B, for example, as shown in FIG. 2, as the light receiving mechanism 2, a surface (gold-plated surface) 6A having a high reflectance to heat radiation and a surface having a low reflectance are provided. A rotating sector 6 in which (black surface) 6B are alternately arranged in a fan shape is provided, and the rotating sector 6 is rotated by a motor 8. The material of the surface 6A having a high reflectivity is preferably gold, but any material having a high reflectivity such as aluminum can be applied.

The rod 4 is placed on the surface S of the material M being heated.
3, the light flux of the thermal radiation R from the surface S of the material M enters the rod 4 from the end face 4E1 of the rod 4, and the maximum light receiving angle θ determined by the refractive index of the rod 4, as shown in FIG.
The heat radiation in the range of max is taken into the rod 4. This incident light propagates in the rod 4 as shown in FIG. A small part of the heat radiation light in the rod 4 is scattered by impurities contained in the rod 4 and leaks out of the side wall of the rod 4 to the outside. It reaches the end face 4E2 on the rotating sector 6 side.

When the high-reflectance surface (gold-plated surface) 6A of the rotating sector 6 disposed close to the end surface 4E2 of the rod 4 comes on the end surface 4E2 of the rod 4, the light has propagated through the rod 4. Most of the thermal radiation light R is reflected, propagates again in the rod 4 and is projected onto the material surface S from the end surface 4E1 facing the surface S of the material M. However, the end surface 4E1 of the rod 4 and the material surface S Are close to each other, the light is reflected by the surface S, reenters the rod 4, and propagates through the rod 4. In the rod 4, the multiple reflection of the thermal radiation R is repeated, and the radiation intensity increases. I do.

On the other hand, when the low reflectivity surface (black surface) 6B of the rotating sector 6 comes on the end surface 4E2 of the rod 4, most of the heat radiation propagating in the rod 4 is absorbed,
Only a small amount of heat radiation is reflected, propagates again in the rod 4 and is projected on the surface S of the material M. A part of the emitted thermal radiation is reflected on the material surface S, propagates again in the rod 4, and repeats multiple reflections. However, the radiation intensity is extremely weak as compared with the case of the high reflectance surface.

As shown in FIGS. 1 and 2, the heat radiation in the rod 4 which repeats multiple reflections is transmitted from the multi-core optical fiber through a slit 7 formed at the center of each of the reflectance surfaces 6A and 6B of the rotating sector 6. Into the second light guide path 5 and the detector 3
Lead to. The detector 3 detects the heat radiation intensity corresponding to the high reflection state and the low reflection state and converts it into an electric signal. In FIG. 1, the first light guide path 4 and the second light guide path 5 constitute the light guide path 1.

The signal mg corresponding to the high-reflection state and the signal mb corresponding to the low-reflection state are expressed by the following equations (1) and (2), respectively.
It is expressed by an equation. These signals mg and mb are calculated based on the material surface S
The heat radiation directly entering the detector 3, reflected once by the rotating sector 6, returns to the material surface S, re-reflected and enters the detector 3, reflected twice by the rotating sector 6, and the material surface Returning to S, the sum of the signals for the heat radiation reflected back and entering the detector 3, the heat radiation reflected four times, the heat radiation reflected four times, and the heat radiation reflected five to infinite times is obtained. mg = εL (t) + ερg (1-ε) L (t) + ερg 2 (1-ε) 2 L (t) + --- = ε / {1-ρg (1-ε)} × L (t) (1) mb = ε / {1-ρb (1-ε)} × L (t) (2) t is the temperature of the material M, L (t) is the radiation intensity from the blackbody furnace at the temperature t, and ε is The emissivity of the material M, ρg is the reflectance of the high reflectance surface 6A of the rotating sector 6 (≒ 1.0), and ρb is the reflectance of the low reflectance surface 6B of the rotating sector 6 (≒ 0.0).

The ratio between the expressions (1) and (2) is as follows. mb / mg = {1-ρg (1-ε)} / {1-ρb (1-ε)} (3) When the equation (3) is rearranged by the emissivity ε, the equation (4) is obtained. ε = {(1−ρg) mg− (1−ρb) mb} / (ρbmb−ρgmg) (4) In equation (4), ρb and ρg are known parameters measured in advance, and radiation intensities mb and mg Is a measured value.

As an example, FIG. 4 shows the relationship between the emissivity ε on the horizontal axis and the radiation intensity ratio (mb / mg) on the vertical axis. In this case, ρb = 0.02, ρg =
0.7. Substituting ε thus obtained into equation (1) to obtain L (t), L (t) = mg {1-ρg (1-ε)} / ε (5) L (t) is It indicates the blackbody radiation intensity at the temperature t, and the relationship between the two can be obtained in advance using a blackbody furnace or the like. Therefore, the temperature can be obtained from the measured value of the radiation intensity mg as t = L ^-1 [mg {1-ρg (1-ε)} / ε] (6). In the equation (6), L ^-1 [] indicates a function in which the radiation intensity mg is an independent variable and the temperature t is a dependent variable. Specifically, using the relationship between the temperature measured in a blackbody furnace and the radiation intensity, It means to calculate the temperature from the radiation intensity.

The reflectances ρg and ρb are determined as follows. First, emissivity is measured in advance by a radiation thermometer using a material sample to which a thermocouple is attached. In this case, the following equation (7) holds. ε = m / L (t) (7) m is the measurement signal of the radiation thermometer, and L (t) is the radiation intensity from the black body furnace corresponding to the material temperature measured by the thermocouple.

Then, the reflectances ρg and ρ are calculated using the equations (8) and (9) obtained by modifying the equations (1) and (2).
Determine b. ρg = (1−εL (t) / mg) / (1−ε) (8) ρb = (1−εL (t) / mb) / (1−ε) (9) Before the measurement, the reflectances ρg and ρb is determined, and these values are constant unless the optical characteristics of the rod 4 and the rotating sector 6 change. Therefore, these values are substituted into the expressions (4) and (6) and measured. Signals mg and m
From b, the emissivity ε of the material surface and the temperature t are obtained.

[0021]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, a surface S of a material M is used.
Out of the first light guide path 4 that guides the received heat radiation light to the light receiving mechanism 2 capable of realizing a high reflection state and a low reflection state with respect to the heat radiation light. The portion located on the surface S side is preferably formed of a heat-resistant optical material. As the heat-resistant optical material, quartz, sapphire, heat-resistant glass, or the like can be applied, and these can be formed into a rod to form a light guide path. Among them, a quartz rod is most preferably used. By using a rod made of a heat-resistant optical material, accurate measurement can be performed without the need for cooling even when the measurement surface is at a high temperature, and attachment to the apparatus is simplified. In FIG. 1, the multi-core optical fiber 4B is connected to the rod 4A to form the first light guide path 1. However, the multi-core optical fiber is used to make the light guide path flexible. The first light guide path 4 may be constituted by only the rod 4A.

As the light receiving mechanism 2 capable of realizing a high reflection state and a low reflection state with respect to the heat radiation light received and introduced through the first light guide path 4, the rotating sector 6 shown in FIGS. Used to enable accurate temperature measurement.
In the present invention, in addition to the rotating sector 6 as the light receiving mechanism 2, as shown in FIGS.
A light receiving mechanism consisting of zeros can also be used. That is, as shown in FIG. 6, the high reflection portion 11 and the slit 13 are arranged side by side in an interdigitated manner, particularly as shown in FIG. 6, on the upper surface of the end surface 4E2 of the rod 4 forming the first light guide path, and the measurement is performed at the center. Fixing the slit member 9 provided with the opening 14 for
A slit member 10 having the same configuration is arranged between the slit member 9 and the end surface 4E2 of the rod 4, and the slit member 10 is vibrated in a lateral direction using a tuning fork, as shown in FIGS. The state where the high reflection portion 12 of the slit member 10 comes to the position of the slit 13 of the slit member 9 and the entire surface becomes a high reflection surface (FIG. 7), and the high reflection portion 1 of the slit members 9 and 10
This realizes a state (FIG. 6) in which the reflective surfaces 1 and 12 overlap to form a half high reflection surface. According to this configuration, the modulation of the thermal radiation light intensity can be realized at a high speed, so that the response of the device is improved, and there is an advantage that the device can be downsized and the durability can be improved.

As shown in FIG. 8, the reflectance can be changed by using a liquid crystal shutter. That is, a high-reflection surface 15 which gives high reflection characteristics to heat radiation light by gold plating is disposed above the end surface 4E2 of the rod 4, and a liquid crystal shutter 16 is interposed between the high-reflection surface 15 and the end surface 4E2 of the rod 4. When the liquid crystal shutter 16 is opened, a high reflection state is obtained, and when the liquid crystal shutter 16 is closed, a low reflection state is obtained. The detector 3 detects the heat radiation intensity corresponding to the high reflection state and the low reflection state. The high reflection surface 15 and the liquid crystal shutter 16 are provided with an opening for measurement at the center. According to this method, a light receiving mechanism having no mechanical driving portion and having high speed and excellent durability is configured. However, the wavelength range in which the liquid crystal shutter functions is limited to the visible region, so that the range of use is limited.

It is desirable that the light guide path for guiding the heat radiation light to the light receiving mechanism 2 is constituted by a flexible multi-core optical fiber, and the heat radiation light is directly introduced from the light receiving mechanism 2 to the detector 3. Alternatively, a second light guide path 5 for guiding the light from the light receiving mechanism 2 to the detector 3 may be provided, and the second light guide path 5 may be formed of a flexible multi-core optical fiber. The use of a flexible multi-core optical fiber allows flexibility in the installation of the apparatus, and allows the apparatus to be provided sufficiently away from the high-temperature measurement surface. The heat radiation signals corresponding to the high reflection state and the low reflection state detected by the detector 3 are processed according to a normal method, for example, by a signal processing device, and then the emissivity ε of the material surface and the temperature are processed via an arithmetic device. t is calculated, and these values are displayed on the display device.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, and effects thereof will be demonstrated based on the embodiments. It should be noted that these examples are for describing a preferred embodiment of the present invention, and the present invention is not limited thereto.

Example 1 An example of measuring the surface temperature of a silicon wafer in a vacuum furnace according to the present invention will be described. It is known that the emissivity of a silicon wafer changes depending on the temperature and the type and thickness of the film on the surface. As shown in FIG. 9, a heater 19 is arranged at the upper part in the vacuum furnace 18, and the silicon wafer 17 is heated from the upper part. The surface temperature of the silicon wafer 17 is measured from the lower surface of the silicon wafer 17.

A quartz rod 4A having a diameter of 12 mm and a length of 200 mm is fixed via a vacuum holder 20 so as to approach the lower surface of the silicon wafer 17. The distance between the end surface of the quartz rod 4A and the lower surface of the silicon wafer 17 was set to 5 mm.
The quartz rod 4A can easily maintain a vacuum by being fixed in the vacuum holder 20 via packing. The heat radiation light condensed by the quartz rod 4A passes through the multi-core optical fiber 4B from the quartz rod 4A, and the light receiving mechanism 2
It is led to.

In the light receiving mechanism 2, the multi-core optical fiber 4
As shown in FIG. 2, a rotating sector (not shown) in which a high-reflection surface and a low-reflection surface are alternately realized is rotated at 3000 revolutions per minute near the end surface of B, The emitted light is introduced into the detector 3, and the thermal radiation intensity is measured by the detector 3. As shown in FIG. 10, in the radiation signal measured by the detector 3, a signal mg measured in a high reflection state and a signal mb measured in a low reflection state appear alternately. Using the synchronizing signal shown in FIG. 10, mg and mb are separated, and then the above equation (4) and (6) are calculated by an arithmetic unit (not shown).
The emissivity ε and the temperature t are calculated using the equations. FIG. 11 shows the change over time of the temperature t and the emissivity ε of the silicon wafer measured as described above. When the temperature t increases with time, the emissivity ε slightly decreases, but as the temperature t decreases, the emissivity ε approaches the original value.

In the conventional radiation temperature measuring method using a hemispherical cavity or a cylindrical cavity, it is necessary to cool the cavity and the measuring part for accurate temperature measurement, and therefore, the temperature measurement target silicon There is a problem that the wafer is locally cooled, which complicates the mounting and adjustment to the apparatus.In the present invention, sufficiently accurate temperature measurement can be performed without cooling the quartz rod. In addition, since the device can be installed far away from the measurement location by the multi-core optical fiber 4B having flexibility, the above-described problem is avoided, and it is advantageous that the device is easily mounted and takes up little space. can get. Further, since the measurement point and the detector are connected by a quartz rod or an optical fiber, they are not affected by electromagnetic noise generated during sputtering or plasma etching. Since the light-collecting efficiency of a rod made of a heat-resistant optical material such as a quartz rod is high, a high modulation ratio (radiation intensity ratio) between a high reflection state and a low reflection state can be obtained, and highly accurate measurement can be performed.

Example 2 After a paint is applied to the surface of a steel sheet, the steel sheet is passed through a drying oven, and in a paint baking step of baking the paint, the surface temperature of the coated steel sheet is measured according to the present invention. The baking temperature is an important control item because it affects the adhesion and corrosion resistance of the coating film in the coating baking process, but the emissivity of the coated steel sheet is determined by the type of paint and the type of steel sheet used as the substrate, Conventionally, accurate temperature measurement has not been performed because the temperature greatly changes depending on the surface state.

Conventionally, for measuring the surface temperature of a coated steel sheet, a method of intermittently measuring the temperature by bringing a contact-type thermocouple thermometer into contact with the steel sheet has been commonly used. This method has drawbacks in that, in addition to scratching the surface of the steel sheet, intermittent measurement is not sufficiently useful for detecting an operation abnormality.

As shown in FIG. 12, a quartz rod 4A covered with a stainless steel pipe 22 is disposed close to the surface of a coated steel plate 21, and an air purge hood 23 is attached to the tip of the quartz rod 4A. To perform a strong air purge on the surface of the coated steel plate 21. In the paint baking step, since the volatile component of the coating film evaporates and contaminates the end surface of the rod facing the surface of the coated steel plate 21, the temperature measurement surface of the coated steel plate 21 is subjected to air purge to thereby reduce the end surface of the rod. To prevent dirt.

The heat radiation light from the coated steel plate 21 condensed by the quartz rod 4A is received by a light receiving mechanism 2 (FIG. 2) consisting of a rotating sector arranged close to the upper end of the quartz rod 4A.
Is guided to the detector 3 through a light guide path 5 composed of a multi-core optical fiber. The light receiving mechanism 2 may adopt a structure in which cooling is performed through cooling water as needed. The radiation signal measured by the detector 3 is processed in the same manner as in the first embodiment, and the surface temperature t and the emissivity ε of the coated steel plate 21 are displayed. FIG. 13 shows the change over time of the temperature t obtained by the present invention and the temperature t ′ actually measured by a conventional contact-type thermocouple thermometer. According to FIG. 13, it was recognized that the two were in excellent agreement, and the accuracy of the temperature measurement according to the present invention was confirmed.

[0034]

According to the present invention, the following effects can be expected. (1) Since at least the light guide path on the measurement surface side among the light guide paths for condensing thermal radiation from the high-temperature measurement surface is made of a heat-resistant optical material, accurate measurement can be performed without cooling. Since it is possible, it can be easily attached to the device and a compact structure can be realized. Furthermore, the problem of cooling the measuring surface and causing errors in the measuring temperature is avoided. (2) By using a multi-core optical fiber for a part of the light guide path, a flexible light guide path is formed, and the degree of freedom of installation of the device can be increased. (3) The light condensing degree can be increased by appropriately selecting the material of the rod forming the light guide path, and the modulation ratio (radiation intensity ratio) of the radiation intensity in the high reflection state and the low reflection state can be increased. Therefore, accurate temperature measurement can be performed. (4) When measuring the surface temperature of a material in a vacuum furnace or an atmosphere furnace, when the rod is inserted into the furnace, the atmosphere can be easily maintained by, for example, fixing by packing, so that measurement should be performed without difficulty. Can be. (5) It is not affected by electromagnetic noise.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of an apparatus configuration for measuring a surface temperature according to the present invention.

FIG. 2 is a plan view showing one embodiment of a light receiving mechanism used for measuring a surface temperature according to the present invention.

FIG. 3 is a side view showing details of the relationship among the material surface, the light guide path, and the light receiving mechanism in the surface temperature measurement of the present invention.

FIG. 4 is a diagram showing a relationship between emissivity and radiation intensity.

FIG. 5 is a plan view showing another embodiment of the light receiving mechanism used for measuring the surface temperature of the present invention.

FIG. 6 is a plan view showing a slit member of the light receiving mechanism of FIG.

FIG. 7 is a plan view showing a state in which a slit member of the light receiving mechanism of FIG. 5 overlaps to form a high reflection surface.

FIG. 8 is a plan view showing still another embodiment of the light receiving mechanism used for measuring the surface temperature according to the present invention.

FIG. 9 is a diagram in which the surface temperature measuring method according to the present invention is applied to surface temperature measurement of a silicon wafer heated in a vacuum furnace.

FIG. 10 is a diagram showing a temperature signal measured according to FIG. 9;

FIG. 11 is a diagram showing changes with time of the temperature t and the emissivity ε measured according to FIG. 9;

FIG. 12 is a diagram in which the surface temperature measuring method according to the present invention is applied to the surface temperature measurement of a coated steel sheet heated in a paint baking step.

FIG. 13 is a diagram showing a change over time of a temperature t measured by FIG. 12 and a temperature t ′ actually measured by a conventional contact-type thermocouple thermometer.

[Explanation of symbols]

 Reference Signs List 1 light guide path 2 light receiving mechanism 3 detector 4 first light guide path 4A rod 4B multi-core optical fiber 5 second light guide path 6 rotating sector 6A high reflectivity surface 6B low reflectivity surface 7 slit 8 motor 9 slit Member 10 Slit member 11 High reflection part 12 High reflection part 13 Slit 14 Opening 15 High reflection surface 16 Liquid crystal shutter 17 Silicon wafer 18 Vacuum furnace 19 Heater 20 Vacuum holder 21 Painted steel plate 22 Stainless steel tube 23 Air purge hood M Material S Surface

Claims (4)

[Claims] 1. A method for measuring surface temperature of a material by detecting heat radiation from the material, wherein the heat radiation from the surface of the material is disposed between a detector for detecting the heat radiation and the surface of the material. And a light receiving mechanism capable of realizing a high-reflection state and a low-reflection state with respect to the heat radiation light introduced through the light guide path, and introduced through the light guide path. The heat radiation light is guided to the detector via the light receiving mechanism,
A method for measuring a surface temperature, comprising detecting heat radiation intensities corresponding to the high reflection state and the low reflection state, and correcting the emissivity of the material based on the detected value to obtain a surface temperature. 2. The surface temperature measuring method according to claim 1, wherein the light guide path is made of a heat-resistant optical material on the surface side of the material and a multi-core optical fiber on the detector side. 3. A rotating sector having a portion having a high reflectivity and a portion having a low reflectivity for thermal radiation introduced through the light guide passage is interposed between the light guide passage and the detector. And the heat radiation introduced through the light guide path,
3. A part having a high reflectance and a part having a low reflectance alternately appear.
The described surface temperature measuring method. 4. An apparatus for measuring surface temperature of a material by detecting heat radiation from the material, wherein at least the surface side of the material for receiving the heat radiation from the surface of the material comprises a heat-resistant optical material. A light guide path, a light receiving mechanism capable of realizing a high reflection state and a low reflection state with respect to the heat radiation light introduced through the first light guide path, and a light guide mechanism for guiding the heat radiation light from the light receiving mechanism to the detector. A second light guide path made of a multi-core optical fiber, and a detector for detecting heat radiation light introduced through the light receiving mechanism, the detector detects the high reflection state and the low reflection state. A surface temperature measuring device configured to detect a corresponding heat radiation intensity and to correct a material emissivity based on the detected value to obtain a surface temperature.