System and method to make optical fiber to be sensor using simple method

Abstract

To perform wiring of an optical fiber using a simple method for sensing.SOLUTION: A system according to the present disclosure comprises: a sensor that is composed of an optical fiber 20 which is inserted to extend in a predetermined direction to an optical fiber coating 30 having a coating part 31 being formed into a flat plate shape extending in a predetermined direction and being deformable, and the coating part 31; and an optical sensing device 10 that acquires light scattering characteristics in the optical fiber 20.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to fiber optic sensing technology. [Background technology]

[0002] Conventionally, optical fiber sensing methods have been known in which an optical fiber is wired in contact with an object to be measured and the state of the object is measured. For example, Non-Patent Document 1 discloses a technique for measuring the dynamic strain of an optical fiber by irradiating a test light into the optical fiber and measuring the time change in the backscattered light. By measuring the state of the optical fiber, the state of the object to be measured can be measured.

[0003] Furthermore, studies are being conducted on the possibility of treating communication optical fiber networks as sensors to measure environmental information around the cables. In particular, in order to reduce the effort and cost of laying new optical fiber for optical fiber sensing, the use of communication optical fiber already laid in the city for sensing purposes is being considered (see Non-Patent Document 2). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] “Advances in distributed vibration sensing for optical communication fiber state visualization”, Optical Fiber Technology, Vol.57, 102263. 2020 [Non-patent document 2] “Smart Engineering / Maintenance Approach Aiming for Operational Innovation”, Business Communication, 2022, Internet,<https: / / www.bcm.co.jp / site / 2022 / 04 / ntt-as / 2204-ntt-as-01-06.pdf> Summary of the Invention [Problem to be solved by the invention]

[0005] However, when wiring optical fibers for sensing, the measurement results and accuracy can vary significantly depending on how they are laid and how they are contacted during wiring. For this reason, advanced technology is required to wire optical fibers for sensing, and there has been a demand for a simpler method for wiring optical fibers for sensing.

[0006] Therefore, an object of the present disclosure is to provide a simple method for wiring optical fibers for sensing. [Means for solving the problem]

[0007] In order to achieve the above object, the sensor, system, and sensing method of the present disclosure employ a technique in which an optical fiber is inserted into a member formed in a flat plate shape extending in a predetermined direction.

[0008] Specifically, the sensor of the present disclosure comprises: a deformable flat plate portion formed in a flat plate shape extending in a predetermined direction; an optical fiber inserted through the flat plate portion so as to extend in the predetermined direction; Equipped with

[0009] This technology can suppress the degradation of optical sensing performance and accuracy that accompanies the wiring of optical fibers for optical fiber sensing, and can achieve a certain level of performance. In addition, any optical fiber already in the market, such as a communication fiber, can be turned into an optical sensor medium while maintaining a certain level of performance.

[0010] The flat plate portion may be provided with a pipe extending in the predetermined direction and into which the optical fiber is inserted.

[0011] This prevents stress from being applied directly to the optical fiber even when the pipe is deformed.

[0012] The pipe has an inner diameter larger than the diameter of the optical fiber, The optical fiber may be inserted into the pipe with a predetermined amount of play.

[0013] This prevents stress from being applied directly to the optical fiber even when the pipe is deformed.

[0014] The pipe may also be filled with a liquid or gel.

[0015] This prevents the space inside the pipe from becoming narrower, reduces friction between the inner wall of the pipe and the optical fiber, and further mechanically suppresses twisting of the optical fiber.

[0016] The flat plate portion can be wrapped around the object to be measured so that the pipe is aligned along the longitudinal direction of the object to be measured, The pipe may be deformable in response to a deformation of the measurement object.

[0017] According to this, the pipe into which the optical fiber is inserted deforms in response to bending or the like of the object to be measured, thereby making it possible to measure the shape of the object to be measured.

[0018] Specifically, the system of the present disclosure comprises: The above sensor; an optical sensing device for acquiring light scattering characteristics in an optical fiber; Equipped with.

[0019] Specifically, the sensing method of the present disclosure includes: a step of embedding a pipe in a deformable flat plate portion formed in a flat plate shape extending in a predetermined direction, so as to extend along the predetermined direction; inserting an optical fiber into the pipe; Includes.

[0020] Also, a step of winding the flat plate portion around the pipe so that the pipe is aligned along the longitudinal direction of the object to be measured; obtaining light scattering characteristics in the optical fiber using an optical sensing device; may include:

[0021] The above disclosures can be combined as much as possible. [Effects of the Invention]

[0022] According to the present disclosure, optical fibers can be wired for sensing in a simple manner. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram illustrating an overview of an optical fiber sensing system according to a first embodiment of the present disclosure. [Figure 2] 10 is a diagram illustrating a state in which an optical fiber coating with an optical fiber inserted therein is wrapped around a measurement object. FIG. [Figure 3] 1A and 1B are diagrams illustrating the configuration of an optical fiber coating. [Figure 4] 1 is a cross-sectional view of an optical fiber coating. [Figure 5] 10 is a flowchart illustrating a process for wrapping an optical fiber coating into which an optical fiber is inserted around a measurement object. [Figure 6] FIG. 10 is a diagram illustrating an overview of an optical fiber sensing system according to a second embodiment of the present disclosure. [Figure 7] FIG. 1 is a diagram showing an example of a state of an optical fiber attached to a measurement object. [Figure 8] 10A and 10B are diagrams illustrating an optical fiber coating according to a modified example. [Figure 9] 1A and 1B are diagrams illustrating an application example of measuring the shape of a measurement object using an optical fiber. [Figure 10] FIG. 10 is a diagram illustrating an optical fiber storage pipe according to a third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below. These implementation examples are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Note that components with the same reference numerals in this specification and drawings indicate the same components.

[0025] [Outline of Optical Fiber Sensing] An optical fiber sensing system 500 according to a first embodiment of the present disclosure will be described with reference to Fig. 1 to Fig. 5. Fig. 1 provides an overview of optical fiber sensing using the optical fiber sensing system 500. The optical fiber sensing system 500 includes an optical fiber sensing device 10, an optical fiber 20, and an optical fiber coating 30 (see Fig. 2).

[0026] Specifically, the optical fiber sensing system 500 of the present disclosure includes: an optical fiber coating 30 through which the optical fiber 20 is inserted; an optical fiber sensing device 10; Equipped with.

[0027] In the optical fiber sensing system 500, an optical fiber sensing device 10 is used to input test light such as pulse or CW (Continuous Wave) into an optical fiber 20, and observe the backscattered light generated within the optical fiber 20. Based on the observation results of such backscattered light, the optical fiber sensing system 500 can measure the state of an object in contact with the optical fiber 20. The optical fiber sensing device 10 functions as an "optical sensing device."

[0028] Specifically, the state of the optical fiber 20 changes when a disturbance (bending, temperature change, strain, vibration, etc.) is applied, and the state of the backscattered light also changes in accordance with this state change. In other words, by observing the state change of the backscattered light, it is possible to observe the state change of the optical fiber 20, that is, the state of the disturbance applied to the optical fiber 20. For this reason, the optical fiber sensing system 500 uses a method in which the optical fiber 20 is regarded as a sensor and the backscattered light is observed to measure or estimate the disturbance applied to the optical fiber 20 (bending, temperature change, strain change, vibration, etc.). Here, the disturbance applied to the optical fiber 20 includes a disturbance caused by a change in the state of an object that is in direct or indirect contact with the optical fiber 20.

[0029] In this way, the optical fiber sensing system 500 estimates not only the state of the optical fiber cable itself containing the optical fiber 20, but also the state of the environment surrounding the optical fiber 20. It is expected that this information regarding the state of the environment surrounding the optical fiber 20 will be used for various purposes (see Non-Patent Document 2).

[0030] Note that the disturbances that can be measured depend on the measurement method and the type of scattered light being observed. For example, the optical fiber sensing device 10 may be an OTDR (Optical Time-Domain Reflectometer) that inputs an optical pulse into the optical fiber 20 and extracts the scattered light. Furthermore, the measurement method for optical fiber sensing may be an OFDR (Optical Frequency Domain Reflectometry) that uses the coherence of laser light, or a BOTDR (Brilouin Optical Time Domain Reflectometry) that receives and analyzes Brillouin scattered light to continuously measure the strain of the optical fiber.

[0031] Furthermore, the optical fiber sensing system 500 may be a DAS (Distributed Antenna System) that expands the communicable area by distributing radio waves arriving from a base station via optical cables.

[0032] Furthermore, the scattered light to be observed may be any of Rayleigh scattered light, Brillouin scattered light, Raman scattered light, etc. In particular, the optical fiber sensing device 10 may be a Raman OTDR.

[0033] [Optical fiber coating wrapping pattern] Next, the manner in which the optical fiber coating 30 is wrapped around the measurement object 40 will be described with reference to Fig. 2. The measurement object assumed in this embodiment is an optical cable, a pipe, etc. As described above, the optical fiber sensing system 500 includes the optical fiber sensing device 10, the optical fiber 20, and the optical fiber coating 30.

[0034] In this embodiment, an optical fiber coating 30 for optical fiber sensing is applied by a predetermined method around a measurement object 40 such as a communication cable, wire rope, or pipe. The coating for optical fiber sensing is applied. This enables optical fiber sensing with standardized specifications for any measurement object 40. As will be described in detail later, in this embodiment, by standardizing the structure of the optical fiber coating 30 and fixing the optical fiber 20 to the optical fiber coating 30, it is possible to create a sensor for any shape of measurement object 40 using the same method. The optical fiber coating 30 with the optical fiber 20 inserted therethrough functions as a "sensor."

[0035] As a result, in this embodiment, it is possible to suppress the degradation of optical sensing performance and accuracy that accompanies wiring of optical fibers for optical fiber sensing, and to achieve a certain level of performance. Also, any optical fiber already in the market, such as a communication fiber, can be made into an optical sensor medium while maintaining a certain level of performance. This will be explained in detail below.

[0036] As shown in Fig. 2, an optical fiber coating 30 in which a sensing optical fiber 20 used only for sensing is embedded is wrapped around a measurement object 40. Specifically, the optical fiber coating 30 is wrapped around and fixed to the measurement object 40 in a straight, enveloping manner. This prevents unnecessary force from being applied to the optical fiber 20 compared to when the optical fiber coating 30 is wrapped around the measurement object 40 in a spiral shape, thereby suppressing deterioration in optical sensing performance and accuracy due to wiring and achieving a certain level of performance. Note that an optical fiber for communication may be embedded in the optical fiber coating 30.

[0037] According to this embodiment, optical fiber sensing of the measurement object can be achieved in a post-process (ex-post process) of wrapping the optical fiber coating 30 in which the optical fiber 20 is embedded around the measurement object 40. Furthermore, by standardizing the method of wrapping the optical fiber coating 30 around the measurement object 40, the wiring characteristics between the optical fibers become the same, and optical fiber sensing that is standardized according to predetermined measurement specifications becomes possible. There are no limitations on the physical quantities that can be measured by optical fiber sensing (temperature, strain, vibration, etc.).

[0038] Although details will be described later, any method for embedding the optical fiber 20 in the optical fiber coating 30 can be used as long as it does not apply stress to the optical fiber coating 30 to the fiber. This makes it possible to embed optical fibers in a variety of forms, such as bare wires and ribbon-type new wires, in the optical fiber coating 30.

[0039] [Example of optical fiber coating configuration] Next, an example of the configuration of the optical fiber coating 30 will be described with reference to Fig. 3. The optical fiber coating 30 has a coating portion 31 and an optical fiber storage pipe 32.

[0040] Specifically, the sensor of the present disclosure comprises: an optical fiber coating 30 formed in a flat plate shape extending in a predetermined direction and having a deformable coating portion 31; The optical fiber 20 is inserted into the coating 31 so as to extend in a predetermined direction.

[0041] Here, the optical fiber coating 30 is subjected to various stresses because it is wrapped around and fixed to the measurement target 40 having any shape and size. For this reason, it is necessary to embed the optical fiber 20 in the optical fiber coating 30 so that the optical fiber 20 embedded in the optical fiber coating 30 is not subjected to such stresses. Below, an example of the configuration of the optical fiber coating 30 that suppresses the optical fiber 20 from being subjected to stresses will be described.

[0042] The covering portion 31 has a certain thickness and is formed into a plate shape extending in a predetermined direction. In this embodiment, the covering portion 31 extends in the left-right direction of the figure. In other words, the left-right direction of the figure is an example of the "predetermined direction" in this disclosure. The covering portion 31 can be wrapped around or fixed to any measurement object 40. The covering portion 31 may have any structure, and may be made of, for example, PVC (Polyvinyl Chloride), PE (Polyethylene), FEP (Fluorinated Ethylene Propylene, Teflon (registered trademark)), etc. The covering portion 31 may also be formed in a mesh-like shape. Forming the covering portion 31 in this mesh-like shape makes it easier to fix the optical fiber storage pipe 32 to the covering portion 31 and makes it easier to wrap around and fix the covering portion 31 to any shape of measurement object 40. The covering portion 31 functions as a "flat plate portion."

[0043] The optical fiber storage pipe 32 is a cylindrical pipe extending in a predetermined direction and fixed to the coating 31. One or more optical fibers 20 can be placed in the hollow portion of the optical fiber storage pipe 32. The optical fiber storage pipe 32 is bendable while maintaining its hollow portion. Any configuration can be used to make the optical fiber storage pipe 32 bendable, for example, by making part of the material of the optical fiber storage pipe 32 flexible or by making it bellows-shaped. The optical fiber 20 is inserted into the optical fiber storage pipe 32 with a certain amount of play, without being fixed. In other words, the optical fiber storage pipe 32 has an inner diameter larger than the diameter of the optical fiber 20. This prevents stress from being applied to the optical fiber 20 even when the optical fiber storage pipe 32 is deformed. The optical fiber storage pipe 32 functions as a "pipe."

[0044] The optical fiber storage pipe 32 may be made of a material having a certain rigidity. By making the optical fiber storage pipe 32 of a material having a certain rigidity in this way, not only can stress be prevented from being applied to the optical fiber 20 when the optical fiber coating 30 is fixed to the measurement object 40, but also bending of the optical fiber 20 beyond a certain level can be prevented.

[0045] 4, a groove 31a filled with adhesive may be formed in the coating portion 31. The coating portion 31 may be designed so that when the optical fiber coating 30 is wrapped around the measurement object 40, the adhesive flows out of the groove 31a and into the gap between the side surface of the measurement object 40 and the optical fiber coating 30, thereby fixing the measurement object 40 and the optical fiber coating 30 together.

[0046] [Workflow] Next, with reference to the flowchart of FIG. 5, a process for wrapping the optical fiber coating 30 with the optical fiber 20 inserted therein around the measurement object 40 will be described.

[0047] Specifically, the sensing method of the present disclosure includes: a step of embedding an optical fiber storage pipe 32 along a predetermined direction in a deformable covering portion 31 formed in a flat plate shape extending in a predetermined direction; inserting the optical fiber 20 into the optical fiber storage pipe 32; a step of wrapping the coating 31 around the measurement target 40 so that the optical fiber storage pipe 32 is aligned along the longitudinal direction of the measurement target 40; a step of acquiring light scattering characteristics in an optical fiber 20 using an optical fiber sensing device 10; Includes:

[0048] First, the user embeds the optical fiber storage pipe 32 in the coating portion 31 to create the optical fiber coating 30. Then, the user inserts the optical fiber 20 into the optical fiber storage pipe 32 (step S1).

[0049] The user wraps and fixes the optical fiber coating 30, into which the optical fiber 20 has been inserted, around the measurement target 40 (step S2).

[0050] The user uses the optical fiber 20 and the optical fiber sensing device 10 to perform desired optical fiber sensing (step S3).

[0051] [Second embodiment] Next, an optical fiber sensing system 501 according to the second embodiment will be described with reference to Fig. 6 to Fig. 9. As shown in Fig. 6, the optical fiber sensing system 501 includes a calculation processing device 50 in addition to the components included in the optical fiber sensing system 500 according to the first embodiment. The optical fiber sensing system 501 measures the shape of the measurement target 40 using an optical fiber 20. The calculation processing device 50 is configured to be able to calculate various physical quantities using the results of the shape measurement.

[0052] In general, an optical fiber sensing system can measure the expansion and contraction of an optical fiber as a physical quantity. Therefore, in the present disclosure, the optical fiber 20 is wired along the object 40 to be measured so that when strain occurs in the object 40, that is, when expansion and contraction occurs on the surface, the optical fiber 20 also expands and contracts by the same amount. In other words, the optical fiber is wired along the object 40 to integrate the expansion and contraction of the optical fiber 20 with the expansion and contraction of the object 40 to be measured. In this embodiment, the shape of the object 40 can be measured via the expansion and contraction of the optical fiber 20.

[0053] Specifically, as shown in Fig. 7, when the measurement object 40 is bent or distorted, the optical fiber 20 should move in the same manner as the measurement object 40. For simplicity, Fig. 6 does not show the optical fiber 20 inserted into the optical fiber storage pipe 32 of the optical fiber coating 30. In reality, the optical fiber 20 is inserted into the optical fiber storage pipe 32 as described above.

[0054] For example, if the optical fiber 20 is routed along the measurement object 40, when the measurement object 40 is bent, the portion of the optical fiber 20 corresponding to the bent portion will stretch. In this embodiment, the shape of the measurement object 40 can be measured based on the axial deformation of the optical fiber 20 corresponding to the bending of the measurement object 40.

[0055] In this embodiment, the optical fiber storage pipe 32 into which the optical fiber 20 is inserted is deformed in response to bending or the like of the measurement object 40, thereby making it possible to measure the shape of the measurement object 40.

[0056] Specifically, the covering portion 31 can be wrapped around the measurement object 40 so that the optical fiber storage pipe 32 is aligned along the longitudinal direction of the measurement object 40, The optical fiber housing pipe 32 is deformable in response to the deformation of the measurement object 40 .

[0057] Here, when measuring the shape of the measurement object 40 using the above-described method, it is necessary that the optical fiber 20 can move freely in its longitudinal direction to a certain extent and that twisting of the optical fiber 20 is suppressed. In this embodiment, the optical fiber 20 is not fixed, but is inserted into the optical fiber storage pipe 32 with a certain amount of play. Therefore, the optical fiber 20 can move freely in its longitudinal direction without being restrained. Furthermore, the optical fiber 20 can rotate freely within the optical fiber storage pipe 32. Therefore, twisting of the optical fiber 20 is also suppressed. Note that although twisting of the optical fiber 20 is suppressed, twisting of the measurement object 40 can be measured.

[0058] In a specific shape sensing of the measurement target 40, the optical fiber sensing device 10 inputs light into the optical fiber 20 and receives scattered light from the optical fiber 20, thereby acquiring the light scattering characteristics at each position in the longitudinal direction of the optical fiber 20. The arithmetic processing device 50 performs shape sensing of the optical fiber 20 using the light scattering characteristics obtained by the optical fiber sensing device 10. Then, the arithmetic processing device 50 measures the overall deformation of the measurement target 40.

[0059] Note that a multicore fiber may be used to sense the shape of the measurement object 40. Specifically, the degree of distortion of each core in the cross section of the multicore fiber is compared, and it can be determined that the object is bent in the direction of greater distortion by the greater amount of distortion.

[0060] The shape of the optical fiber 20 can be measured by a similar method even when a plurality of single-core fibers are used, without using a multi-core fiber. For example, the shape of the optical fiber 20 may be measured using an optical fiber coating 30A shown in Fig. 8 that includes a plurality of optical fiber storage pipes 32 into which the optical fibers 20 are inserted.

[0061] 9 shows an application example of the measurement results of measuring the shape of the measurement object 40 using the optical fiber 20. First, the optical fiber sensing system 501 measures the shape of the optical fiber 20 attached along the shape of the measurement object 40 (step S11). The arithmetic processing device 50 may calculate the deformation of the measurement object 40 using the shape of the optical fiber 20 (step S12). The arithmetic processing device 50 may also calculate the stress distribution on the measurement object 40 based on the deformation of the measurement object 40 (step S13). Furthermore, the arithmetic processing device 50 may detect stress concentration on the measurement object 40 and identify the stress concentration location (step S14).

[0062] [Third embodiment] Next, an optical fiber storage pipe 32 according to a third embodiment of the present disclosure will be described with reference to Fig. 10. As shown in Fig. 10, in this embodiment, the optical fiber storage pipe 32 is filled with a liquid 33. The liquid 33 may be a gel.

[0063] This prevents the space inside the optical fiber storage pipe 32 from becoming narrower, reduces friction between the inner wall of the optical fiber storage pipe 32 and the optical fiber 20, and further mechanically suppresses twisting of the optical fiber 20. Any configuration may be used to prevent the liquid 33 from leaking out from the end of the optical fiber storage pipe 32. A liquid or gel-like anti-friction layer may be formed on the inner wall surface of the optical fiber storage pipe 32 to reduce friction with the optical fiber 20. The optical fiber storage pipe 32 may be designed to be rigid enough to prevent twisting of the optical fiber 20.

[0064] The device of the present invention can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network. The program of the present disclosure is a program for causing a computer to realize each function of the device according to the present disclosure, and a program for causing a computer to execute each procedure of the method executed by the device according to the present disclosure. [Explanation of symbols]

[0065] 10: Optical fiber sensing device 20: Optical fiber 30, 30A: Optical fiber coating 31: Covering part 31a: Groove 32: Optical fiber storage pipe 40: Measurement target 50: Processing unit 500, 501: Optical fiber sensing system

Claims

1. a deformable flat plate portion formed in a flat plate shape extending in a predetermined direction; an optical fiber inserted through the flat plate portion so as to extend in the predetermined direction; Equipped with Sensor.

2. The flat plate portion is provided with a pipe extending in the predetermined direction and into which the optical fiber is inserted. The sensor of claim 1 .

3. the pipe has an inner diameter larger than the diameter of the optical fiber; The optical fiber is inserted into the pipe with a predetermined play. The sensor of claim 2 .

4. The pipe is filled with a liquid or gel. The sensor of claim 3 .

5. the flat plate portion can be wrapped around the object to be measured so that the pipe is aligned along the longitudinal direction of the object to be measured, The pipe is deformable in response to deformation of the measurement object. The sensor of claim 3 .

6. A sensor according to any one of claims 1 to 5; an optical sensing device for acquiring light scattering characteristics in an optical fiber; Equipped with system.

7. a step of embedding a pipe in a deformable flat plate portion formed in a flat plate shape extending in a predetermined direction, so as to extend along the predetermined direction; inserting an optical fiber into the pipe; Including, Sensing method.

8. a step of winding the flat plate portion around the pipe so that the pipe is aligned along the longitudinal direction of the object to be measured; obtaining light scattering characteristics in the optical fiber using an optical sensing device; Including, The sensing method according to claim 7 .

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