JP7114930B2 - Apparatus, measuring apparatus and method of manufacturing apparatus - Google Patents

Description

The present application relates to devices, measuring devices , and methods of making devices .

A temperature distribution measuring device (DTS: Distributed Temperature Sensor) that uses a detection device equipped with an optical fiber as a temperature sensor is used in boilers and the like as a means for measuring temperature distribution over a long distance (see, for example, Patent Document 1. ). The optical fiber provided in the detection device has a structure in which the surface of optical fiber glass (core and clad) is covered with a coating material. With this configuration, the bending resistance of the optical fiber is improved, and breakage of the optical fiber can be suppressed.

However, the heat-resistant temperature of the coating material is lower than the heat-resistant temperature of the optical fiber glass (for example, about 1000° C.). For example, a coating material used for practical optical fibers with high heat resistance is polyimide. The heat resistance temperature of polyimide is about 300.degree. When such detectors are exposed to high temperatures, the coating material is destroyed by combustion, volatilization, or the like. In this case, the bending resistance of the optical fiber is lowered, and there is a possibility that the optical fiber may break.

In power plants, chemical plants, etc., there is a demand for monitoring the temperature of equipment that exceeds the heat-resistant temperature of the coating material of the optical fiber. In particular, DTS is effective when an infrared camera cannot be used, such as in an explosion-proof environment, or when the object to be measured is hidden by a protective material or the like. Therefore, the development of detection devices that can be used at high temperatures is underway.

JP 2016-42005 A

However, a detection device that can be used at high temperatures has not yet been developed.

In one aspect, the object of the present invention is to provide a device that can be used at high temperatures, a measuring device that includes the device, and a method for manufacturing the device .

In one aspect, the apparatus includes an optical fiber core wire, a ceramic braid covering the optical fiber core wire in a circumferential direction of the optical fiber core wire, a flexible ceramic braid covering the optical fiber core wire, and having flexibility. a core wire and a metal tube that is not fixed to the ceramic braid.

In one aspect, the measuring device comprises the above-mentioned device , a light source that injects light into the optical fiber core wire, and the temperature at each measurement point of the optical fiber core wire based on backscattered light from the optical fiber core wire. and a temperature measuring unit that measures the

In one aspect, a method of manufacturing an apparatus comprises: a first step of covering the optical fiber core wire in a circumferential direction of the optical fiber core wire with a ceramic braid; and a second step of inserting a ceramic braid into a flexible metal tube, wherein the metal tube is not fixed to the optical fiber core wire and the ceramic braid.

It is possible to provide a device that can be used at high temperatures, a measuring device that includes the device, and a method for manufacturing the device .

It is a schematic diagram showing the whole structure of a temperature distribution measuring device. It is a figure showing the component of backscattered light. (a) is a diagram illustrating the relationship between the elapsed time after light pulse emission and the light intensity of a Stokes component and an anti-Stokes component, and (b) is a temperature calculated using the detection result of (a). . (a) is a schematic diagram showing the overall configuration of the detection device, and (b) is a cross-sectional view of the detection device. (a) to (d) are diagrams illustrating the stress on the optical fiber core wire. (a) to (c) are diagrams illustrating joints. It is a flow figure showing a manufacturing method of a detecting device. It is a figure which illustrates a string making machine. (a) to (d) are diagrams illustrating the relationship between the bending of the optical fiber and the intensity of the returned light.

Hereinafter, embodiments will be described with reference to the drawings.

(embodiment)
FIG. 1 is a schematic diagram showing the overall configuration of a temperature distribution measuring device 100. As shown in FIG. As illustrated in FIG. 1, the temperature distribution measuring device 100 includes a measuring device 10, a control section 20, a detecting device 30, and the like. The measuring instrument 10 includes a laser 11, a beam splitter 12, an optical switch 13, a filter 14, a plurality of detectors 15a and 15b, and the like. The control unit 20 includes an instruction unit 21, a temperature measurement unit 22, a storage unit 23, and the like.

The laser 11 is a light source such as a semiconductor laser, and emits laser light within a predetermined wavelength range according to instructions from the instruction unit 21 . In this embodiment, the laser 11 emits light pulses (laser pulses) at predetermined time intervals. The beam splitter 12 causes the optical pulse emitted by the laser 11 to enter the optical switch 13 . The optical switch 13 is a switch that switches the emission destination (channel) of the incident optical pulse. In the double-ended method, the optical switch 13 causes light pulses to alternately enter the first end and the second end of the detection device 30 at regular intervals according to instructions from the instruction section 21 . In the single-ended method, the optical switch 13 causes the optical pulse to enter either the first end or the second end of the detection device 30 according to an instruction from the instruction section 21 . The detection device 30 has an optical fiber and is arranged along a predetermined path of a temperature measurement object.

A light pulse incident on the detection device 30 propagates through the optical fiber in the detection device 30 . The light pulse propagates through the optical fiber while gradually attenuating while generating forward scattered light traveling in the propagation direction and backscattered light (return light) traveling in the return direction. The backscattered light passes through the optical switch 13 and reenters the beam splitter 12 . Backscattered light incident on the beam splitter 12 is emitted to the filter 14 . The filter 14 is a WDM coupler or the like, and extracts a long wavelength component (a Stokes component to be described later) and a short wavelength component (an anti-Stokes component to be described later) from the backscattered light. The detectors 15a and 15b are light receiving elements. The detector 15 a converts the received light intensity of the short-wavelength component of the backscattered light into an electrical signal and transmits the electrical signal to the temperature measurement unit 22 . The detector 15 b converts the received light intensity of the long wavelength component of the backscattered light into an electrical signal and transmits the electrical signal to the temperature measurement unit 22 . The temperature measurement unit 22 measures the temperature distribution in the extension direction of the detection device 30 using the Stokes component and the anti-Stokes component. Storage unit 23 stores the temperature distribution measured by temperature measurement unit 22 .

FIG. 2 is a diagram showing components of backscattered light. As illustrated in FIG. 2, the backscattered light is roughly classified into three types. These three types of light are, in descending order of light intensity and closeness to the incident light wavelength, Rayleigh scattered light used for OTDR (optical pulse tester), Brillouin scattered light used for strain measurement, temperature measurement, etc. is the Raman scattered light used for Raman scattered light is generated by interference between light and lattice vibrations in the optical fiber that change with temperature. Constructive interference produces short wavelength components, called anti-Stokes components, and destructive interference produces long wavelength components, called Stokes components.

FIG. 3A is a diagram illustrating the relationship between the elapsed time after the laser 11 emits a light pulse and the light intensity of the Stokes component (long wavelength component) and the anti-Stokes component (short wavelength component). The elapsed time corresponds to the propagation distance in the optical fiber (position in the optical fiber). As illustrated in FIG. 3(a), the light intensity of both the Stokes component and the anti-Stokes component decrease with time. This is due to the light pulse propagating through the optical fiber gradually attenuating while generating forward and backscattered light.

As exemplified in FIG. 3A, the light intensity of the anti-Stokes component is stronger at the high temperature position in the optical fiber than the Stokes component, and at the low temperature position it is higher than the Stokes component. become weak. Therefore, by detecting both components with the detectors 15a and 15b and utilizing the characteristic difference between the two components, the temperature at each position within the optical fiber can be detected. In addition, in FIG. 3A, the area showing the maximum is a relatively high-temperature area, which is the location described as "hot air" in the example of FIG. Also, the area showing the minimum is a relatively low temperature area, which is indicated as "cold water" in FIG.

In this embodiment, the temperature measurement unit 22 measures the temperature from the Stokes component and the anti-Stokes component for each elapsed time. Thereby, the temperature at each position (each section) within the optical fiber can be measured. That is, the temperature distribution in the drawing direction of the optical fiber can be measured. Since the characteristic difference between the two components is used, the temperature can be measured with high accuracy even if the light intensity of both components is attenuated according to the distance. FIG. 3(b) shows temperatures calculated using the detection results of FIG. 3(a). The horizontal axis of FIG. 3B is the position in the optical fiber calculated based on the elapsed time. By detecting the Stokes and anti-Stokes components, as exemplified in FIG. 3(b), the temperature at each location within the optical fiber can be measured.

FIG. 4A is a schematic diagram showing the overall configuration of the detection device 30. FIG. 4(b) is a cross-sectional view taken along the line AA in FIG. 4(a), which is a cross-sectional view of the detection device 30. FIG. As illustrated in FIGS. 4A and 4B, the detection device 30 includes an optical fiber cable 40, a ceramic braid 50, a metal tube 60, and the like. In addition, in FIG. 4A, the ceramic braid 50 in the metal tube 60 is partially illustrated, and the optical fiber core wire 40 in the ceramic braid 50 is illustrated.

The optical fiber core wire 40 has a structure in which a linear optical fiber glass 41 is concentrically covered with a covering material 42 . The optical fiber glass 41 is a glass structure in which a core 41a is concentrically covered with a clad 41b. The covering material 42 is, but not limited to, carbon, an organic substance, or the like. In this embodiment, the coating material 42 includes, for example, a carbon layer 42a concentrically covering the optical fiber glass 41 and a polyimide layer 42b concentrically covering the carbon layer 42a. The thickness of the carbon layer 42a is, for example, 100 nm or less. The thickness of the polyimide layer 42b is, for example, 30 μm or less. Since the coating material 42 has higher flexibility and stretchability than the optical fiber glass 41 , the bending resistance of the optical fiber core wire 40 is improved by covering the optical fiber glass 41 with the coating material 42 . Thereby, disconnection of the optical fiber core wire 40 can be suppressed.

The ceramic braid 50 has a structure that covers the optical fiber core wire 40 in the circumferential direction. The ceramic braid 50 is obtained by braiding heat-resistant ceramic fibers into a braid. As the ceramic fiber, for example, glass fiber containing 60 mass % or more of SiO ₂ component (high silicate glass fiber), alumina fiber, or the like can be used.

The metal tube 60 has a structure that covers the ceramic braid 50 in the circumferential direction. The metal tube 60 has flexibility. For example, the metal tube 60 is a metal spiral tube, a metal braid, or the like. Since the metal pipe 60 does not have to be dense, it may have air permeability, liquid permeability, and the like.

According to this embodiment, since the metal tube 60 is flexible, even if expansion and contraction occur due to heat cycles, the stress on the optical fiber cable 40 can be suppressed. Thereby, disconnection of the optical fiber core wire 40 at high temperatures can be suppressed.

In addition, since the ceramic braid 50 is braided in a braided shape, stress on the optical fiber core wire 40 can be suppressed during heat cycles. For example, as exemplified in FIG. 5A, if a helical structure 51 is used instead of the ceramic braid 50, the stress in the helical direction of the helical structure 51 at the contact point with the optical fiber core 40 that is the inclusion is may be applied. In this case, as exemplified in FIG. 5(b), the stress from the helical structure (not shown) is partially concentrated on the optical fiber core wire 40, and the optical fiber core wire 40 may break. . On the other hand, in the ceramic braid 50, since the ceramic fiber is braided, as shown in FIG. , the resulting stresses weaken each other. In addition, in the braiding of ceramic fibers, stress itself is less likely to occur due to friction between fibers, protrusions on the surface, and the like. Therefore, as exemplified in FIG. 5D, stress concentration from the ceramic braid 50 to the optical fiber core wire 40 is suppressed, and breakage of the optical fiber core wire 40 at high temperatures can be suppressed. Further, since the thermal expansion coefficient of the ceramic braid 50 is smaller than that of the metal tube 60, even if the metal tube 60 thermally expands, the stress caused by the thermal expansion is transmitted to the optical fiber core wire 40. can be suppressed.

Furthermore, the optical fiber cable 40, the ceramic braid 50, and the metal tube 60 are not fixed to each other. Here, "not fixed to each other" means that the optical fiber cable 40, the ceramic braid 50, and the metal tube 60 are not fixed to each other by any fixtures, adhesives, or the like. However, the optical fiber cable 40, the ceramic braid 50, and the metal tube 60 may partially contact each other. For example, the ceramic braid 50 is not fixed to the optical fiber cable 40 and the metal tube 60 at both ends of the ceramic braid 50 . The metal tube 60 is not fixed to the ceramic braid 50 at both ends of the metal tube 60 . As a result, no stress is applied to the ends of the optical fiber core wires 40 even if differences in thermal expansion and contraction occur due to temperature changes. As a result, breakage of the optical fiber core wire 40 at high temperatures can be suppressed.

As described above, the detection device 30 according to the present embodiment can be used at high temperatures.

By the way, when the detecting device 30 is installed, the bending resistance effect of the coating material 42 can prevent the optical fiber cable 40 from breaking. The covering material 42 may disappear when the detection device 30 is exposed to temperatures higher than the heat resistance temperature of the covering material 42 . However, since the detection device 30 is exposed to high temperatures after the detection device 30 is laid, even if the coating material 42 is not effective in bending resistance, it does not pose a particular problem.

The metal tube 60 may have a structure in which a plurality of metal tube units are connected in the length direction. For example, as illustrated in FIG. 4( a ), the metal tube 60 may have a plurality of metal tube units connected by joints 70 . For example, FIG. 6A is a cross-sectional view of the vicinity of the joint at room temperature (20° C.) in the detection device of this embodiment. FIG. 6(b) is a cross-sectional view of the vicinity of the joint at high temperature (600° C.) in the detection device of this embodiment. 6A shows the positions of the first metal tube unit 60a, the second metal tube unit 60b and the ceramic braid 50 in the joint 70 through the joint 70. FIG. The same applies to FIG. 6(b).

As illustrated in FIG. 6(a), the joint 70 engages the end of the first metal tube unit 60a and the end of the second metal tube unit 60b. A gap is provided between the first metal tube unit 60a and the second metal tube unit 60b. The amount of insertion of the first metal tube unit 60a and the second metal tube unit 60b into the joint 70 can vary. That is, the joint 70 has play for absorbing the thermal expansion due to the temperature change of the first metal tube unit 60a and the second metal tube unit 60b. Connect the ends.

Here, the play for absorbing thermal expansion is, for example, the gap between the first metal tube unit 60a and the second metal tube unit 60b. The metal tube 60 has a larger coefficient of thermal expansion than the optical fiber core wire and the ceramic braid 50 (not shown). In addition, the detection device is not normally laid in a straight line in the entire section, but is in a deformed state, as typified by the detection device 30 in FIG. 1 and the optical fiber core wire 40 in FIG. and the ceramic braid 50 is partially in contact with the metal tube unit and the optical fiber core wire. At this time, when the measurement atmosphere is heated to a high temperature environment, the first metal tube unit 60a and the second metal tube unit 60b expand.

If no gap is provided between the first metal tube unit 60a and the second metal tube unit 60b, the metal tube unit will generate tensile stress on the optical fiber core wire via the ceramic braid, resulting in temperature measurement. There is a risk of affecting or breaking the optical fiber core wire.

However, as shown in FIG. 6(a), since the gap is provided between the first metal tube unit 60a and the second metal tube unit 60b, even in a high temperature environment, the Therefore, the first metal tube unit 60a and the second metal tube unit 60b are not in contact with each other and do not cause strong tensile stress to the optical fiber core wire. It is possible to prevent disconnection of the fiber core wire.

For example, as illustrated in FIG. 6B, when the first metal tube unit 60a and the second metal tube unit 60b expand in the length direction as the temperature increases, the first metal tube unit 60a and the second metal tube unit 60b The amount of insertion of the metal tube unit 60b into the joint 70 increases. For example, if the first metal tube unit 60a and the second metal tube unit 60b are helical tubes, by making threaded grooves on the inner wall of the joint 70, the first metal tube unit 60a and the second metal tube unit 60a The amount of insertion of 60b can be varied. In addition, the first metal tube unit 60a and the second metal tube unit 60b are arranged so that a gap can be obtained between the first metal tube unit 60a and the second metal tube unit 60b even at the upper limit of the operating temperature of the detection device 30. It is preferable to provide a gap between Moreover, it is preferable that the joint 70 is fixed with respect to the object to be laid, in that the first metal pipe unit 60 a and the second metal pipe unit 60 b can be smoothly inserted into the joint 70 . 6(a) and 6(b), two metal pipe units are connected, but by providing a plurality of joints 70, three or more metal pipe units can be connected. can be done.

Here, metals have a relatively large coefficient of linear expansion compared to glass and ceramics. Therefore, at high temperatures, the metal tube 60 expands significantly relative to the optical fiber cable 40 and the ceramic braid 50 . In this case, stress is likely to occur in the optical fiber core wire 40 . However, by providing the joint 70 , the thermal expansion of the metal pipe 60 is absorbed by the joint 70 . Thereby, the stress on the optical fiber core wire 40 can be suppressed. As described above, by providing the joint 70, it is possible to further suppress disconnection of the optical fiber core wire 40 at high temperatures. The distance between two adjacent joints 70 is preferably several meters to several tens of meters, for example.

FIG.6(c) is a figure explaining the detection apparatus of other embodiment. FIG. 6(c) shows a cross section near the joint in the detection device of the modified example. 6A shows the positions of the first metal tube unit 60a, the second metal tube unit 60b and the ceramic braid 50 in the joint 70 through the joint 70. FIG.

In FIG. 6(c), the joint 70 is provided with screw holes 71a and 71b. The first metal tube unit 60a and the second metal tube unit 60b may be fixed by screwing male screws 72a and 72b into the screw holes 71a and 71b, respectively. The first metal tube unit 60a and the second metal tube unit 60b are locked to the joint 70 so that the first metal tube unit 60a and the second metal tube unit 60b are not disengaged from the joint 70 due to heat shrinkage. .

The joint 70 has a gap between the first metal tube unit 60a and the second metal tube unit 60b that absorbs thermal expansion due to temperature changes, and the first metal tube unit 60a and the second metal tube unit 60b are connected together. Since the ends of 60b are connected to each other, the first metal tube unit 60a and the second metal tube unit 60b do not come into contact with each other even in a high temperature environment, and a strong tensile stress is generated on the optical fiber. Therefore, it is possible to maintain the accuracy of temperature measurement and prevent disconnection of the optical fiber.

In FIG. 6(c), the joint 70 may be provided with a groove corresponding to the spiral shape of the first metal tube unit 60a and the second metal tube unit 60b as in FIG. 6(a).

Next, the effect of installing the detection device 30 will be described. First, as described above, since the flexibility and stretchability of the coating material 42 are higher than those of the optical fiber glass 41, the bending resistance of the optical fiber core wire 40 is improved. As a result, disconnection of the optical fiber cable 40 can be suppressed during laying.

Next, since the metal tube 60 has flexibility, even if the metal tube 60 is bent when laying the detection device 30, the stress on the optical fiber core wire 40 can be suppressed. As a result, disconnection of the optical fiber cable 40 can be suppressed during laying. If a metal braid is used, the inner diameter of the metal braid may become smaller due to tension when laying the detection device 30, and the optical fiber cable 40 and the ceramic braid 50 may be tightened. Therefore, it is preferable to adjust the stretchability of the metal braid in order to suppress the tightening. The stretchability of the metal braid can be adjusted by the coverage of the metal braid, the number of strokes, and the like. For example, it is preferable to set the number of hits to 24 or more. In addition, since the ceramic braid 50 is braided in a braided shape, stress on the optical fiber core wire 40 can be suppressed when the detection device 30 is laid.

In addition, if the inner diameter of the metal tube 60 is small, stress may be generated from the metal tube 60 to the optical fiber core wire 40 . Therefore, from the viewpoint of stress relaxation, it is preferable that the inner diameter of the metal tube 60 is large. However, if the inner diameter of the metal tube 60 is large, the distance between the object of temperature measurement and the optical fiber core wire 40 may become large. In this case, the responsiveness to temperature changes may deteriorate. Therefore, from the viewpoint of temperature measurement accuracy, it is preferable that the inner diameter of the metal tube 60 is small. For example, it is preferable to set the inner diameter of the metal tube 60 so that the stress on the optical fiber core wire 40 is reduced according to the bending radius at the time of laying, the thermal expansion displacement at the maximum operating temperature of the detection device 30, and the like.

When the optical fiber core wire and/or the internal ceramic braid is long and bent with respect to the metal spiral tube, by reducing the amount of insertion of the first metal tube unit 60a and the second metal tube unit 60b into the joint 70, the metal The length of the entire helical tube can be adjusted to eliminate deflection. The distance between two adjacent joints 70 is preferably, for example, several meters to several tens of meters, in order to easily eliminate deflection caused by bending during installation.

Next, a method for manufacturing the detection device 30 will be described. FIG. 7 is a flowchart showing a method for manufacturing the detection device 30. As shown in FIG. As illustrated in FIG. 7, first, a ceramic braid 50 is created so as to cover the optical fiber core wire 40 in the circumferential direction (step S1). FIG. 8 is a diagram illustrating a braiding device 80 for braiding the optical fiber core wire 40 with ceramic fibers. As illustrated in FIG. 8, the string making device 80 includes a plurality of bobbins 81 wound with ceramic fibers. By rotating these bobbins 81 by a turntable 82, the ceramic braid 50 is woven so as to cover the optical fiber core wire 40 in the circumferential direction. Note that the optical fiber cable 40 is likely to buckle due to the ceramic braid 50 . Therefore, it is preferable to wind the optical fiber core wire 40 around the bobbin 83 so that the optical fiber core wire 40 is not bent.

Next, the ceramic braid 50 containing the optical fiber core wire 40 is inserted through the metal tube 60 (step S2). Thereby, the detection device 30 is completed. The optical fiber cable 40, the ceramic braid 50, and the metal tube 60 are not fixed to each other.

Here, it is theoretically possible to insert the optical fiber core wire 40 into the ceramic braid 50 after inserting the ceramic braid 50 into the metal tube 60 . However, the longer the detection device 30 is, the more difficult it is to insert the optical fiber cable 40 into the ceramic braid 50 . In contrast, according to the manufacturing method of the detection device 30 according to the present embodiment, the optical fiber core wire 40 is inserted into the ceramic braid 50 while the ceramic fibers are braided, so that the optical fiber core wire 40 can be easily It can be inserted through the ceramic braid 50 . Next, since the ceramic braid 50 is inserted into the metal tube 60 with the optical fiber core wire 40 enclosed therein, bending of the optical fiber core wire 40 is suppressed. Thereby, disconnection of the optical fiber core wire 40 can be suppressed.

The inner diameter of the ceramic braid 50 is larger than the outer diameter of the optical fiber cable 40 . Thereby, the optical fiber core wire 40 can be moved relative to the ceramic braid 50 . For example, when passing the ceramic braid 50 through the metal tube 60, even if the diameter of the ceramic braid 50 is reduced by extending the ceramic braid 50, a gap remains between the ceramic braid 50 and the optical fiber core wire 40. It is preferable to adjust the stretchability of the ceramic braid 50 . The stretchability of the ceramic braid 50 can be adjusted by the coverage of the ceramic braid 50, the number of strokes, and the like. Further, since the ceramic braid 50 slightly shrinks and solidifies at high temperatures, it is preferable to increase the difference between the inner diameter of the ceramic braid 50 and the outer diameter of the optical fiber core 40 .

Further, when the ceramic braid is applied to the optical fiber core wire 40 , the expansion and contraction of the ceramic braid 50 may cause a difference in length between the optical fiber core wire 40 and the ceramic braid 50 . In this case, as illustrated in FIG. 9A, the optical fiber cable 40 may be bent. In this case, non-uniform lateral pressure is applied from the ceramic braid 50 to the optical fiber core wire 40 , causing microbend loss in the optical fiber core wire 40 . As a result, as illustrated in FIG. 9B, the return light intensity is greatly attenuated along with the distance. In this case, the temperature measurement accuracy of the temperature distribution measuring device 100 may deteriorate.

Therefore, it is preferable to eliminate the bending of the optical fiber cable 40 as illustrated in FIG. 9(c). When the bending of the optical fiber core wire 40 is eliminated, the lateral pressure on the optical fiber core wire 40 is suppressed. Thereby, attenuation of the return light intensity can be suppressed as illustrated in FIG. 9(d).

Moreover, when inserting the ceramic braid 50 into the metal pipe 60, the ceramic braid 50 may also bend. If the ceramic braid 50 is bent, the optical fiber core wire 40 is compressed by the bending, which may cause microbend loss. Therefore, it is preferable to eliminate the bending of the ceramic braid 50 as well.

It is preferable to pull out the optical fiber cable 40 and the ceramic braid 50 from the metal tube 60 in order to eliminate the bending. However, the greater the sensing device 30 distance, the greater the friction. In this case, the optical fiber cable 40 may be broken. In addition, the friction reduces the inner diameter of the ceramic braid 50, and as a result, the optical fiber cable 40 may be broken. Therefore, it is preferable to use the joint 70 described in FIGS. 6(a) and 6(b).

For example, the ceramic braid 50 containing the optical fiber cable 40 is inserted through the first metal tube unit 60a. At this stage, the optical fiber core wire 40 and the ceramic braid 50 are pulled. In this case, since the first metal tube unit 60a is shorter than the metal tube 60, friction is reduced. Thereby, disconnection of the optical fiber core wire 40 can be suppressed.

Next, the ceramic braid 50 is inserted through the second metal tube unit 60b. The ends of the first metal tube unit 60a and the second metal tube unit 60b are jointed 70 with play for absorbing thermal expansion due to temperature changes in the first metal tube unit 60a and the second metal tube unit 60b. Connect by At this stage, the optical fiber core wire 40 and the ceramic braid 50 are pulled. In this case, since the second metal tube unit 60b is shorter than the metal tube 60, friction is reduced. Thereby, disconnection of the optical fiber core wire 40 can be suppressed. In this way, by pulling the optical fiber core wire 40 and the ceramic braid 50 in the process of sequentially connecting the metal tube units using the joint 70, it is possible to suppress the breakage of the optical fiber core wire 40 and eliminate the deflection. can.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations can be made within the scope of the gist of the present invention described in the scope of claims. Change is possible.

REFERENCE SIGNS LIST 10 measuring instrument 11 laser 12 beam splitter 13 optical switch 14 filter 15a, 15b detector 20 control unit 21 instruction unit 22 temperature measurement unit 23 storage unit 30 detector 40 optical fiber cable 41 optical fiber glass 41a core 41b clad 42a carbon layer 42b Polyimide layer 42 Coating material 50 Ceramic braid 60 Metal tube 70 Joint 71 Screw hole 72 Male screw 80 String device 81 Bobbin 82 Turntable 83 Bobbin 100 Temperature distribution measuring device

Claims (9)

an optical fiber core;
a ceramic braid covering the optical fiber core wire in the circumferential direction of the optical fiber core wire;
and a flexible metal tube that covers the ceramic braid and is not fixed to the optical fiber core wire and the ceramic braid. The metal pipe comprises a first pipe, a second pipe, and a joint connecting the first pipe and the second pipe,
2. The device of claim 1, wherein a gap is provided between said first tube and said second tube. The metal pipe comprises a first pipe, a second pipe, and a joint connecting the first pipe and the second pipe,
each of the first tube and the second tube is a helical tube;
The joint includes a first connection port connected to the first pipe, first grooves each provided inside the first connection port and having a shape corresponding to the shape of the first pipe, and the second pipe. A second connection port to be connected, and a second groove having a helical shape corresponding to the helical shape of the second pipe, which is provided inside the second connection port, and
The claim, wherein the first tube is rotatably threaded into the first groove, and the second tube is rotatably threaded into the second groove. Item 1. The device according to item 1. The optical fiber core wire has an optical fiber glass and a coating material that concentrically coats the optical fiber glass,
A device according to any preceding claim, wherein the covering material comprises a carbon layer and a polyimide layer. 5. Apparatus according to any one of claims 1, 2, 4, wherein the metal tube is a metal spiral tube or a metal braid. a device according to any one of claims 1 to 5;
a light source for injecting light into the optical fiber core wire;
and a temperature measuring unit that measures the temperature at each measurement point of the optical fiber core wire based on the backscattered light from the optical fiber core wire. a first step of covering the optical fiber core wire in the circumferential direction of the optical fiber core wire with a ceramic braid;
After the first step, a second step of inserting the ceramic braid covering the optical fiber core wire into a flexible metal tube,
A method of manufacturing an apparatus, wherein the metal tube is not fixed to the optical fiber core wire and the ceramic braid. The metal tube has a first tube and a second tube,
In the second step, inserting the ceramic braid through the first tube, inserting the ceramic braid through the second tube,
8. The method of manufacturing a device according to claim 7, further comprising, after the second step, a third step of connecting the ends of the first tube and the second tube with a joint with a gap therebetween. The metal pipe comprises a first pipe, a second pipe, and a joint connecting the first pipe and the second pipe,
each of the first tube and the second tube is a helical tube;
The joint includes a first connection port connected to the first pipe, first grooves each provided inside the first connection port and having a shape corresponding to the shape of the first pipe, and the second pipe. A second connection port to be connected, and a second groove having a helical shape corresponding to the helical shape of the second pipe, which is provided inside the second connection port, and
inserting the ceramic braid through the first tube and inserting the ceramic braid through the second tube in the second step;
After the second step, by relatively rotating the joint and the first tube, the first tube is screwed into the first groove, and the joint and the second tube are relatively rotated. 8. A method according to claim 7, including a fourth step of threading said second tube into said second groove by rotating it through.

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