Fusion splicing device and fusion splicing method

Abstract

A fusion splicing device according to one embodiment of the present invention fusion-splices a pair of optical fibers to each other by electric discharge. This fusion splicing device comprises: a discharge electrode that generates an electric discharge; a microscope for observing an optical fiber; an end surface state analysis unit that analyzes the state of an end surface of the optical fiber from an image of the optical fiber acquired by the microscope; an end surface state determination unit that determines whether or not the state of the end surface is a predetermined specified state; and a shaping discharge unit that, when the end surface state determination unit determines that the state of the end surface is the predetermined specified state, causes the discharge electrode to perform, on the end surface, a shaping discharge that is an electric discharge for shaping the end surface.

Description

Fusion splicing device and fusion splicing method

[0001] This application claims priority to International Patent Cooperation Treaty Application PCT / JP2024 / 031622, filed September 3, 2024, and incorporates by reference the entire disclosure of said international application.

[0002] Patent Document 1 describes a welding apparatus for thermally welding the ends of two optical waveguide fibers. The welding apparatus includes a pair of holding devices for holding optical waveguides, a pair of flexible couplers, an image processing system for observing the ends of the two optical waveguide fibers, and a control device electrically connected to the image processing system. The welding apparatus performs a rounding heat treatment to round the end faces of the pair of optical waveguide fibers. In the rounding heat treatment, the end faces of the pair of optical waveguide fibers are heated and melted, and are rounded by the surface tension of the glass that has been turned into a viscous liquid. This rounding heat treatment straightens and smooths the end faces of the pair of optical waveguide fibers. Even if the end faces of the pair of optical waveguide fibers have scratches, irregularities, rough surfaces, or other inhomogeneities, these are removed by the rounding heat treatment.

[0003] Japanese Patent Application Publication No. 10-206670

[0004] A fusion splicing device according to the present disclosure fusion-splices a pair of optical fibers together by electrical discharge, and includes a discharge electrode that generates an electrical discharge, a microscope for observing the optical fibers, an end face condition analysis unit that analyzes the condition of the end face of the optical fiber from an image of the optical fiber acquired by the microscope, an end face condition determination unit that determines whether the end face condition is a predetermined specific condition, and a shaping discharge unit that causes the discharge electrode to generate a shaping discharge on the end face, which is an electrical discharge for shaping the end face, when the end face condition determination unit determines that the end face condition is the specific condition.

[0005] FIG. 1 is a perspective view showing an example of a fusion splicer. FIG. 2 is a perspective view showing the internal structure of the fusion splicer of FIG. 1. FIG. 3 is a block diagram showing the functions of a fusion splicing device according to an embodiment. FIG. 4 is a diagram showing an example of an analysis mode performed by an end face condition analysis unit of the fusion splicing device of FIG. 3. FIG. 5 is a diagram showing an example of an analysis mode performed by the end face condition analysis unit of the fusion splicing device of FIG. 3. FIG. 6 is a diagram showing an example of an analysis mode performed by the end face condition analysis unit of the fusion splicing device of FIG. 3. FIG. 7 is a diagram schematically showing the positions of the end faces of a pair of optical fibers during fusion splicing and during shaping discharge. FIG. 8 is a diagram schematically showing the shapes of the end faces of a pair of optical fibers before and after performing shaping discharge. FIG. 9 is a flowchart showing an example of steps of a fusion splicing method according to an embodiment.

[0006] However, even if the end faces of a pair of optical fibers are heated before fusion splicing the pair of optical fibers by electric discharge, the end faces of the optical fibers may not be in a state where fusion splicing is appropriate, for example, due to insufficient symmetry at the end faces of the optical fibers. Therefore, it is necessary to prepare the end faces of the pair of optical fibers in an appropriate state before fusion splicing.

[0007] An object of the present disclosure is to provide a fusion splicing device and a fusion splicing method that can prepare the end faces of optical fibers in an appropriate state before fusion splicing.

[0008] [Description of Embodiments of the Present Invention] First, embodiments of a fusion splicing apparatus and a fusion splicing method according to the present disclosure will be listed and described. (1) A fusion splicing apparatus according to the present embodiments fusion splices a pair of optical fibers together by electric discharge. The fusion splicing apparatus includes a discharge electrode that generates an electric discharge, a microscope for observing the optical fibers, an end face condition analysis unit that analyzes the condition of the end face of the optical fiber from an image of the optical fiber acquired by the microscope, an end face condition determination unit that determines whether the condition of the end face is a predetermined specific condition, and a shaping discharge unit that causes the discharge electrode to generate a shaping discharge on the end face, which is an electric discharge for shaping the end face, when the end face condition determination unit determines that the condition of the end face is a specific condition.

[0009] This fusion splicing device has a discharge electrode, a microscope, and an end face condition analysis unit, and the end face condition analysis unit analyzes the condition of the end face of the optical fiber from an image of the optical fiber acquired by the microscope. The fusion splicing device also has an end face condition determination unit and a shaping discharge unit. The end face condition determination unit determines whether the end face condition is a predetermined specific state. When the end face condition determination unit determines that the end face condition is a specific state, the shaping discharge unit causes the discharge electrode to perform shaping discharge to shape the end face. Before performing shaping discharge, the end face condition analysis unit performs analysis of the end face and the end face determination unit performs judgment of the end face, thereby enabling the condition of the end faces of the pair of optical fibers to be grasped with higher accuracy. Then, when the end face condition is determined to be a specific state, the shaping discharge unit performs shaping discharge, thereby enabling the end faces to be shaped as necessary. By performing shaping discharge as necessary before fusion splicing, the end faces of the optical fibers can be brought into an appropriate state before fusion splicing.

[0010] (2) In the above (1), the end face condition analysis unit may calculate a value indicating the defect state of the end face based on the image, and the end face condition determination unit may determine whether the state of the end face is in a specific state based on the magnitude relationship between the value indicating the defect state and a threshold. In this case, the defect state of the end face is calculated as a value, and whether the state of the end face is in a specific state is determined based on the magnitude relationship between the calculated value and a predetermined threshold. Therefore, the state of the end face of the optical fiber can be grasped with higher accuracy.

[0011] (3) In (2) above, the value indicating the state of the defect may be a value based on the length of the defect portion of the end face determined based on the image.

[0012] (4) In (2) above, the value indicating the defect state may be a value based on the area of ​​the defect portion of the end face obtained based on the image.

[0013] (5) In (2) above, the value indicating the defect state may be a value based on the volume of the defect portion of the end face determined based on the image.

[0014] (6) In any of the above (1) to (5), the end face condition determination unit may determine whether the end face is in a specific state based on a result of prior learning. In this case, the end face condition determination unit can determine whether the end face is in a specific state using the results of machine learning.

[0015] (7) In any of (1) to (6) above, the end face condition analysis unit may calculate a first defect amount, which is the defect amount of a portion located in a first direction that is a direction intersecting the axis as viewed from the axis of the optical fiber in the image, and a second defect amount, which is the defect amount of a portion located in a second direction that is the opposite direction to the first direction as viewed from the axis of the optical fiber in the image. The end face condition determination unit may determine whether the state of the end face is in a specific state from the first defect amount and the second defect amount.

[0016] (8) In any of (1) to (6) above, the end face condition analysis unit may calculate a symmetry degree indicating the symmetry between a portion located in a first direction, which is a direction intersecting the axis of the optical fiber in the image, as viewed from the axis of the optical fiber in the image, and a portion located in a second direction, which is a direction opposite to the first direction, as viewed from the axis of the optical fiber in the image. The end face condition determination unit may determine whether the state of the end face is in a specific state from the symmetry degree.

[0017] (9) In any of (1) to (8) above, the end face condition analysis unit may calculate a first length, which is the maximum length of defects on the end face located in a first direction, which is a direction intersecting the axis as viewed from the axis of the optical fiber in the image, and a second length, which is the maximum length of defects on the end face located in a second direction, which is the opposite direction to the first direction as viewed from the axis of the optical fiber in the image. The end face condition analysis unit may at least one of calculate the sum of the first length and the second length, and calculate the ratio of the first length to the second length or the ratio of the second length to the first length. The end face condition determination unit may determine the condition of the end face using at least one of the calculated sum and ratio as a value indicating the defect condition. In this case, the condition of the end face of the optical fiber can be determined with higher accuracy.

[0018] (10) In any of (1) to (8) above, the end face condition analysis unit may calculate a first area of ​​a defect portion of the end face located in a first direction, which is a direction intersecting the axis as viewed from the axis of the optical fiber in the image, and a second area of ​​a defect portion of the end face located in a second direction, which is the opposite direction to the first direction as viewed from the axis of the optical fiber in the image. The end face condition analysis unit may at least one of calculate the sum of the first area and the second area, and calculate the ratio of the first area to the second area or the ratio of the second area to the first area. The end face condition determination unit may determine the condition of the end face using at least one of the calculated sum and ratio as a value indicating the defect condition. In this case, the condition of the end face of the optical fiber can be determined with higher accuracy.

[0019] (11) In any of (1) to (8) above, the end face condition analysis unit may calculate a first volume of a defect portion of the end face located in a first direction, which is a direction intersecting the axis as viewed from the axis of the optical fiber in the image, and a second volume of a defect portion of the end face located in a second direction, which is the opposite direction to the first direction as viewed from the axis of the optical fiber in the image. The end face condition analysis unit may at least one of calculate the sum of the first volume and the second volume, and calculate the ratio of the first volume to the second volume or the ratio of the second volume to the first volume. The end face condition determination unit may determine the condition of the end face using at least one of the calculated sum and ratio as a value indicating the defect condition. In this case, the condition of the end face of the optical fiber can be grasped with higher accuracy.

[0020] (12) In any of the above (1) to (11), the shaping discharge unit may cause the discharge electrode to perform shaping discharge in a state in which the pair of optical fibers are spaced apart from each other more than during fusion splicing. In this case, the shaping discharge is performed in a state in which the distance between the pair of end faces is more appropriate, so that the pair of end faces can be in a more appropriate state before fusion splicing.

[0021] (13) In any of the above (1) to (11), the shaping discharge section may cause the discharge electrode to generate the shaping discharge in a state where the pair of optical fibers are closer to each other than in the case of fusion splicing.

[0022] (14) In any of the above (1) to (13), the heat quantity of the shaping discharge may be smaller than the heat quantity of the discharge during fusion splicing and larger than the heat quantity of the preliminary discharge carried out prior to fusion splicing.

[0023] (15) In any of the above (1) to (14), the heat quantity of the shaping discharge may be 10 times or more the heat quantity of the preliminary discharge carried out prior to fusion splicing.

[0024] (16) In any of the above (1) to (15), the duration of the shaping discharge may be longer than the duration of the preliminary discharge carried out prior to the fusion splicing.

[0025] (17) In any of the above (1) to (16), the duration of the shaped discharge may be 1.0 second or more and 2.0 seconds or less.

[0026] (18) In any one of the above (1) to (17), the shaping discharge unit may generate shaping discharge while changing the positions of the pair of optical fibers.

[0027] (19) In any of the above (1) to (18), the shaping discharge section may move the pair of optical fibers to a position where the radius of curvature of the rounded end faces is equal to or greater than a pre-stored lower limit value.

[0028] (20) A fusion splicing method according to the present disclosure includes a step of fusion-splicing a pair of optical fibers with a discharge electrode, the step of observing the optical fibers with a microscope, a step of analyzing the state of an end face of the optical fiber from an image of the optical fiber acquired by the microscope, a step of determining whether the state of the end face is a predetermined specific state, and a step of causing the discharge electrode to generate a shaping discharge on the end face, which is a discharge for shaping the end face, when it is determined that the state of the end face is the specific state.

[0029] In this fusion splicing method, the condition of the end faces of the optical fibers is analyzed from an image of the optical fibers acquired by a microscope, and it is determined whether the condition of the end faces is a predetermined specific state. If it is determined that the condition of the end faces is a specific state, a shaping discharge is generated by the discharge electrodes to shape the end faces. By analyzing and determining the end faces before the shaping discharge is generated, the condition of the end faces of the pair of optical fibers can be grasped with higher accuracy. If it is determined that the condition of the end faces is a specific state, a shaping discharge is generated, so that the end faces can be shaped as needed. By performing a shaping discharge as needed before fusion splicing, the end faces of the optical fibers can be brought into an appropriate state before fusion splicing.

[0030] [Details of the Embodiments of the Present Invention] Specific examples of a fusion splicing apparatus and a fusion splicing method according to embodiments of the present disclosure will be described below with reference to the drawings. The present disclosure is not limited to the examples below, but is defined by the claims, and is intended to include all modifications within the scope of equivalents to the claims. In the description of the drawings, identical or corresponding elements are given the same reference numerals, and redundant description will be omitted as appropriate. For ease of understanding, some parts of the drawings may be simplified or exaggerated, and dimensional proportions and the like are not limited to those shown in the drawings.

[0031] FIG. 1 is a perspective view of an example fusion splicer 1. The fusion splicer 1 has a windshield cover 2. FIG. 2 is a perspective view showing the fusion splicer 1 with the windshield cover 2 open. As shown in FIGS. 1 and 2 , the fusion splicer 1 includes a housing 3. The fusion splicer 1 includes a fusion splicing unit 4 that fusion splices optical fibers together, and a heater 5 that heats and shrinks a fiber reinforcement sleeve that covers the spliced ​​optical fibers at the fusion splicing unit 4. The windshield cover 2 is provided to prevent wind from entering the fusion splicing unit 4. The fusion splicer 1 also includes a monitor 7 that displays the state of the fusion splicing of the optical fibers, as photographed by a microscope 6 (see FIG. 3 ) located inside the housing 3. The fusion splicer 1 also includes a power switch 8 that turns the power of the fusion splicer 1 on and off, and a splicing start switch 9 that fusion splices the optical fibers.

[0032] The fusion splicing unit 4 includes a pair of optical fiber holders 4b, a pair of fiber positioning units 4c, and a discharge electrode 4d that generates an electric discharge. Each of the pair of optical fibers to be fusion spliced ​​is placed on the fiber positioning units 4c. The fiber positioning units 4c are disposed between the pair of optical fiber holders 4b. The fusion splicing unit 4 also includes a pair of discharge electrodes 4d. The pair of discharge electrodes 4d are disposed between the pair of fiber positioning units 4c. The discharge electrodes 4d are electrodes that fusion splice the tips of the optical fibers together by arc discharge.

[0033] FIG. 3 is a functional block diagram showing an exemplary configuration of a fusion splicing apparatus 10 according to this embodiment. The fusion splicing apparatus 10 fusion-splices a pair of optical fibers together by electrical discharge. As shown in FIG. 3 , the fusion splicing apparatus 10 includes the fusion splicer 1 described above, a server 11, and an information terminal 20. The fusion splicer 1 is capable of communicating with the server 11 and the information terminal 20 via, for example, wireless communication. The information terminal 20 is, for example, a terminal owned by a manager of a construction project using the fusion splicer 1. The information terminal 20 may be a mobile terminal such as a smartphone or tablet, or a fixed terminal such as a personal computer. The server 11 is, for example, a management server or a data processing server that oversees multiple construction projects. The server 11 is, for example, a computer that can communicate with the fusion splicer 1 and the information terminal 20 via an information communication network such as the Internet. The fusion splicer 1 and the information terminal 20 are, for example, located in different locations from the server 11.

[0034] The fusion splicer 1 may include a computer including hardware such as a CPU, RAM, ROM, input device, wireless communication module, auxiliary storage device, and output device. These components may operate according to a program or the like to perform each function of the fusion splicer 1. As described above, the fusion splicer 1 includes the fusion splicer 4, the microscope 6, and the monitor 7. The microscope 6 observes the optical fibers. The microscope 6 captures images of the end faces and side faces of a pair of optical fibers to be fusion spliced, with the pair of optical fibers positioned facing each other, and generates image data. The "end face" refers to the surface of the optical fiber located at the end of the optical fiber in the direction in which the optical fiber extends. In this embodiment, the "end face" may refer not only to the end face itself but also to a certain region of the optical fiber including the end face. The fusion splicer 1 includes, as functional components, an end face condition analyzer 12, an end face condition determiner 13, a shaping discharger 14, and a discharger 15.

[0035] The server 11 is configured to include a computer equipped with hardware such as a CPU, RAM, ROM, a communication module, and an auxiliary storage device. These components operate according to programs or the like to execute the various functions of the server 11. The server 11 may include, as functional components, an end face condition analysis unit 12 and an end face condition determination unit 13.

[0036] The information terminal 20 is configured to include a computer equipped with hardware such as a CPU, RAM, ROM, a communication module, and an auxiliary storage device. These components operate according to programs or the like to execute the various functions of the information terminal 20. The information terminal 20 may include, as functional components, an end face condition analysis unit 12 and an end face condition determination unit 13.

[0037] In the following, an example will be described in which the fusion splicer 1 includes an end face condition analysis unit 12 and an end face condition determination unit 13. However, instead of the end face condition analysis unit 12 and the end face condition determination unit 13 of the fusion splicer 1, the server 11 or the information terminal 20 may be provided with the end face condition analysis unit and the end face condition determination unit. An apparatus other than the fusion splicer 1, the server 11, or the information terminal 20 (for example, an observation apparatus or inspection apparatus that observes the end face of an optical fiber) may be provided with the end face condition analysis unit and the end face condition determination unit. A portion of each of the end face condition analysis unit and the end face condition determination unit may be provided separately in multiple apparatuses.

[0038] The end face condition analysis unit 12 analyzes the condition of the end face of the optical fiber from an image of the optical fiber acquired by the microscope 6. For example, the end face condition analysis unit 12 calculates a value indicating the defect condition of the end face in the image. The "defect condition" indicates the state of defects occurring on the end face of the optical fiber. The "defect condition" indicates, for example, a state in which the end face of the optical fiber is not smooth. The "defect" indicates a defect occurring on the end face of the optical fiber. The "defect" is, for example, an irregularity occurring on the end face of the optical fiber. As a specific example, the "defect" is a crack or chip occurring on the end face of the optical fiber, or a foreign object adhering to the end face of the optical fiber. The end face condition analysis unit 12 analyzes the condition of the end face of the optical fiber from the image of the optical fiber, for example, by various methods. Various examples of end face analysis methods by the end face condition analysis unit 12 are described below.

[0039] FIG. 4 is a diagram illustrating an example of the analysis of the end face F1 of the optical fiber F by the end face condition analysis unit 12. The end face condition determination unit 13 determines whether the state of the end face F1 is a predetermined specific state. In this embodiment, "the end face is in a specific state" refers to a state in which the end face of the optical fiber is in an inappropriate state. "The end face is in an inappropriate state" refers to a state in which the end face of the optical fiber is not in an appropriate state for fusion splicing, such as when the symmetry of the end face of the optical fiber is insufficient. "Symmetry at the end face" refers to, for example, the symmetry of the shape of the end face relative to the center of the end face. Higher symmetry at the end face enables more appropriate fusion splicing. For example, "symmetry at the end face" may refer to the vertical symmetry between the shape of the end face F1 in the first region R1 and the shape of the end face F1 in the second region R2 in the image M. Higher symmetry at the end face F1 allows the optical fiber F to melt more uniformly during fusion splicing, reducing the possibility that the cladding of the molten optical fiber F will flow into a defect due to surface tension. As a result, it is possible to prevent the end face F1 from being curved when making a connection, thereby preventing the occurrence of poor appearance and an increase in connection loss.

[0040] An example will be described below in which the defect is a chip that is recessed in the end face F1 of the optical fiber F along the extending direction D3 of the optical fiber F. The end face condition analysis unit 12 analyzes the image M acquired by the microscope 6. The end face condition analysis unit 12 calculates a first defect amount W1, which is the defect amount of a portion located in a first direction D1 that intersects with the axis A of the optical fiber F in the image M as viewed from the axis A of the optical fiber F, and a second defect amount W2, which is the defect amount of a portion located in a second direction D2 that is the opposite direction to the first direction D1 as viewed from the axis A of the optical fiber F in the image M. The end face condition determination unit 13 determines whether the state of the end face F1 is a specific state based on the first defect amount W1 and the second defect amount W2. For example, the end face condition determination unit 13 determines that the end face F1 is in a specific state when the sum of the first missing amount W1 and the second missing amount W2 is equal to or greater than a predetermined value, and determines that the end face F1 is not in a specific state when the sum of the first missing amount W1 and the second missing amount W2 is not equal to or greater than the predetermined value.

[0041] The end face condition analysis unit 12 may calculate a symmetry value indicating the symmetry between a portion of the image M located in a first direction D1 intersecting the axis A of the optical fiber F as viewed from the axis A of the optical fiber F and a portion of the image M located in a second direction D2 opposite the first direction D1 as viewed from the axis A of the optical fiber F. The "symmetry value" is, for example, an index indicating the degree of symmetry between a line on the image M of the end face F1 located in the first direction D1 of the axis A and a line on the image M of the end face F1 located in the second direction D2 of the axis A. The end face condition determination unit 13 may determine whether the state of the end face F1 is in a specific state based on the symmetry value. For example, the end face condition determination unit 13 determines that the end face F1 is in a specific state when the symmetry value is equal to or less than a predetermined value, and determines that the end face F1 is not in a specific state when the symmetry value is greater than the predetermined value. Further specific examples of the analysis of the end face condition by the end face condition analysis unit 12 and the determination of the end face condition by the end face condition determination unit 13 are described below.

[0042] The end face condition analyzer 12 calculates, for example, a value indicating the defect state of the end face F1 in the image M as the length L of the defect portion of the end face F1 in the image M. In the example of FIG. 4 , the value indicating the defect state is a value based on the length L. The length L is, for example, the length in the direction D3 from the portion F2 of the end face F1 that protrudes most along the direction D3 to the portion of the end face F1 that is recessed along the direction D3. The length L includes a first length L1 that is the maximum length of the defect in the end face F1 located in the first direction D1, which is a direction intersecting the axis A as viewed from the axis A of the optical fiber F in the image M, and a second length L2 that is the maximum length of the defect in the end face F1 located in the second direction D2, which is the opposite direction to the first direction D1 as viewed from the axis A in the image M. For example, the first length L1 may be the maximum length of the first defect amount W1 in the direction D3, and the second length L2 may be the maximum length of the second defect amount W2 in the direction D3.

[0043] The end face condition analysis unit 12 calculates a first length L1 and a second length L2. Hereinafter, a portion of the image M of the optical fiber F located in a first direction D1 from the axis A will be referred to as a first region R1, and a portion of the image M of the optical fiber F located in a second direction D2 from the axis A will be referred to as a second region R2. For example, the first length L1 is the maximum value of the length L in the first region R1, and the second length L2 is the maximum value of the length L in the second region R2. The end face condition analysis unit 12 calculates, for example, the sum of the first length L1 and the second length L2. Furthermore, the end face condition analysis unit 12 calculates the ratio of the first length L1 to the second length L2 or the ratio of the second length L2 to the first length L1. For example, the ratio of the first length L1 to the second length L2 may be the degree of symmetry described above.

[0044] The end face condition determination unit 13 determines whether the state of the end face F1 is a specific state. For example, the end face condition determination unit 13 determines whether the state of the end face F1 is a specific state based on the magnitude relationship between the value indicating the defect state and a predetermined threshold. In this embodiment, the "threshold" is a value that is compared with the value indicating the defect state. For example, when the value indicating the defect state is equal to or greater than the threshold (or is greater than the threshold), the end face condition determination unit 13 determines that the end face F1 is in a specific state, and when the value indicating the defect state is less than the threshold (or is equal to or less than the threshold), the end face condition determination unit 13 determines that the end face F1 is not in a specific state.

[0045] The end face condition determination unit 13 determines the condition of the end face F1 using at least one of the sum and ratio described above as a value indicating the defect state. For example, the end face condition determination unit 13 determines the condition of the end face F1 from the sum of the first length L1 and the second length L2 calculated by the end face condition analysis unit 12. For example, the end face condition determination unit 13 determines that the end face F1 is in a specific state when the sum of the first length L1 and the second length L2 is equal to or greater than a threshold, and determines that the end face F1 is not in a specific state when the sum of the first length L1 and the second length L2 is less than the threshold.

[0046] The end face condition determination unit 13 may determine the condition of the end face F1 based on the ratio between the first length L1 and the second length L2. For example, the end face condition determination unit 13 may determine that the end face F1 is in a specific state when the ratio between the first length L1 and the second length L2 is greater than or equal to 0 and less than X1, or greater than or equal to X2 (X1 is a positive real number less than 1, and X2 is a positive real number greater than 1), and may determine that the end face F1 is not in a specific state when the ratio is greater than X1 and less than X2. For example, the end face condition determination unit 13 may determine that the end face F1 is in a specific state when 0≦L1 / L2≦X1<1, or 1<X2≦L1 / L2. Alternatively, the end face condition determination unit 13 may determine that the end face F1 is in a specific state when 0<X7≦|L1-L2| is satisfied. The value of X7 is, for example, 8 μm. Alternatively, the value of X7 is 6 μm. Alternatively, the value of X7 is 4 μm.

[0047] For example, a "specific state" indicates a state in which the degree of symmetry is equal to or less than a predetermined value, i.e., the vertical symmetry of the optical fiber F in the image M with respect to the axis A is not good. A "not specific state" indicates a state in which the degree of symmetry is greater than a predetermined value, i.e., the vertical symmetry is good. Note that the values ​​of X1 and X2 may be changeable. The end face state determination unit 13 may determine the state of the end face F1 using the ratio between the second length L2 and the first length L1. Furthermore, the end face state determination unit 13 may determine the state of the end face F1 using both the sum and ratio of the lengths described above.

[0048] 5 is a diagram illustrating another example of analysis of the end face F1 by the end face condition analysis unit 12. The end face condition analysis unit 12 calculates, for example, a value indicating the defect state of the end face F1 in the image M as the area T of the defect portion of the end face F1 in the image M. In this case, the value indicating the defect state is a value based on the area T. The area T is, for example, the area of ​​a region in the image M that is surrounded by a first virtual line M1 that passes through the portion F2 of the end face F1 that protrudes most along the direction D3 and is perpendicular to the direction D3, a second virtual line M2 that extends from the upper end of the optical fiber F along the direction D3, a third virtual line M3 that extends from the lower end of the optical fiber F along the direction D3, and the end face F1. The area T includes a first area T1, which is the area of ​​a defect portion of the end face F1 located in the first direction D1 as viewed from the axis A of the optical fiber F in the image M, and a second area T2, which is the area of ​​a defect portion of the end face F1 located in the second direction D2 as viewed from the axis A of the optical fiber F in the image M. The end face condition analysis unit 12 calculates the first area T1 and the second area T2. For example, the first area T1 is the area of ​​the defect in the first region R1, and the second area T2 is the area of ​​the defect in the second region R2. The first area T1 may be the area of ​​the first defect amount W1, and the second area T2 may be the area of ​​the second defect amount W2. The end face condition analysis unit 12 calculates, for example, the sum of the first area T1 and the second area T2. Furthermore, the end face condition analysis unit 12 calculates the ratio of the first area T1 to the second area T2 or the ratio of the second area T2 to the first area T1. For example, the ratio between the first area T1 and the second area T2 may be the degree of symmetry described above.

[0049] The end face condition determination unit 13 determines the condition of the end face F1, for example, from the sum of the first area T1 and the second area T2 calculated by the end face condition analysis unit 12. For example, the end face condition determination unit 13 determines that the end face F1 is in a specific state when the sum of the first area T1 and the second area T2 is equal to or greater than a threshold, and determines that the end face F1 is not in a specific state when the sum of the first area T1 and the second area T2 is less than or equal to the threshold. The end face condition determination unit 13 may also determine the condition of the end face F1 from the ratio of the first area T1 to the second area T2. For example, the end face condition determination unit 13 may determine that the end face F1 is in a specific state when the ratio of the first area T1 to the second area T2 is equal to or greater than 0 and equal to or less than X3, or equal to or greater than X4 (where X3 is a positive real number less than 1 and X4 is a positive real number greater than 1), and may determine that the end face F1 is not in a specific state when the ratio is greater than X3 and less than X4. For example, the end face condition determining unit 13 may determine that the end face F1 is in a specific state when 0≦T1 / T2≦X3<1 or 1<X4≦T1 / T2. The end face condition determining unit 13 may also determine that the end face F1 is in a specific state when 0<X8≦|T1-T2| is satisfied. The value of X8 is, for example, 30 μm ２ Or the value of X8 is 20 μm ２ Or the value of X8 is 10 μm ２ is.

[0050] The end face condition determination unit 13 may determine the condition of the end face F1 using the ratio of the second area T2 to the first area T1. As an example, the end face condition determination unit 13 may determine that the condition of the end face F1 is in a specific state when the ratio of the smaller of the first area T1 and the second area T2 to the larger one is 0.5 or less. Furthermore, the end face condition determination unit 13 may determine the condition of the end face F1 using both the sum and ratio of the areas described above.

[0051] 6 is a diagram illustrating yet another example of analysis of the end face F1 by the end face condition analysis unit 12. For example, the end face condition analysis unit 12 calculates a value indicating the loss state of the end face F1 in the image M as the volume V of the lost portion of the end face F1. In this case, the value indicating the loss state is a value based on the volume V. An example of a method by which the end face condition analysis unit 12 calculates the volume V will be described below.

[0052] First, in a shape F4 obtained by approximating the cross section of the optical fiber F to a polygonal shape, the end face condition analyzer 12 divides each of the first region R1 and the second region R2 into N blocks B (N is a natural number equal to or greater than 2). An example in which the multiple blocks B are a first block B1, a second block B2, and a third block B3 (N is 3) will be described below. In the first region R1, the first block B1, the second block B2, and the third block B3 are lined up in this order along the first direction D1, and in the second region R2, the first block B1, the second block B2, and the third block B3 are lined up in this order along the second direction D2.

[0053] The end face condition analysis unit 12 calculates the area of ​​the first block B1 in the image M, the area of ​​the second block B2 in the image M, and the area of ​​the third block B3 in the image M. The end face condition analysis unit 12 calculates the distance K1 from the end face F1 to the first virtual line M1 on the axis A of the image M, and the distance K2 from the end face F1 to the first virtual line M1 at the boundary line between the first block B1 and the second block B2 in the image M. The end face condition analysis unit 12 calculates the distance K3 from the end face F1 to the first virtual line M1 at the boundary line between the second block B2 and the third block B3 in the image M, and the distance K4 from the end face F1 to the first virtual line M1 on a straight line extending from the lower end (or upper end) of the optical fiber F in the image M along the direction D3.

[0054] The end face condition analysis unit 12 calculates the length W of each block B in the first direction D1 (or the second direction D2) on the end face F1 from the diameter D of the optical fiber F. The diameter D may be calculated by the end face condition analysis unit 12, or may be stored in advance. The end face condition analysis unit 12 calculates the length W as the value obtained by dividing the diameter D by twice the number N of blocks B. That is, the end face condition analysis unit 12 calculates the length W using equation (1): W=D / (N×2) (1) The length W is the same for multiple blocks B.

[0055] The end face condition analysis unit 12 calculates the lengths S1, S2, and S3 of each block B on the end face F1 in the direction D4 perpendicular to the first direction D1 (or the second direction D2) from the diameter D. The end face condition analysis unit 12 calculates the length S1 of the first block B1 in the direction D4 using equation (2): S1=D (2) The end face condition analysis unit 12 calculates the length S2 of the second block B2 in the direction D4 using equation (3): S2=D×(N-1) / N (3) The end face condition analysis unit 12 calculates the length S3 of the third block B3 in the direction D4 using equation (4): S3=D×(N-2) / N (4)

[0056] The volume V of the missing portion of the end face F1 includes a volume V11 of the missing portion of the first block B1, a volume V12 of the missing portion of the second block B2, and a volume V13 of the missing portion of the third block B3. The end face condition analysis unit 12 calculates the volume V11 as the product of the area of ​​the missing portion of the first block B1 and the length S1 of the first block B1 in direction D4. That is, the end face condition analysis unit 12 calculates the volume V11 using equation (5): V11 = ((K1 + K2) × W / 2) × S1 (5) The end face condition analysis unit 12 calculates the volume V12 using equation (6): V12 = ((K2 + K3) × W / 2) × S2 (6) The end face condition analysis unit 12 calculates the volume V13 using equation (7). V13=((K3+K4)×W / 2)×S3...(7)

[0057] The end face condition analysis unit 12 calculates the volumes V11, V12, and V13 for the first region R1 and the second region R2. The end face condition analysis unit 12 calculates a first volume V1, which is the volume of a defect in the end face F1 located in the first direction D1 as viewed from the axis A of the optical fiber F in the image M, and a second volume V2, which is the volume of a defect in the end face F1 located in the second direction D2 as viewed from the axis A of the optical fiber F in the image M. For example, the first volume V1 may be the volume of the first defect amount W1, and the second volume V2 may be the volume of the second defect amount W2. The end face condition analysis unit 12 calculates the first volume V1 as the sum of the volumes V11, V12, and V13 in the first region R1, and calculates the second volume V2 as the sum of the volumes V11, V12, and V13 in the second region R2. The end face condition analysis unit 12 calculates, for example, the sum of the first volume V1 and the second volume V2. Furthermore, the end face condition analysis unit 12 calculates the ratio of the first volume V1 to the second volume V2 or the ratio of the second volume V2 to the first volume V1. For example, the ratio of the first volume V1 to the second volume V2 or the ratio of the second volume V2 to the first volume V1 may be the degree of symmetry described above.

[0058] The end face condition determination unit 13 determines the condition of the end face F1, for example, from the sum of the first volume V1 and the second volume V2 calculated by the end face condition analysis unit 12. For example, the end face condition determination unit 13 determines that the end face F1 is in a specific state when the sum of the first volume V1 and the second volume V2 is equal to or greater than a threshold, and determines that the end face F1 is not in a specific state when the sum of the first volume V1 and the second volume V2 is not equal to or greater than the threshold. The end face condition determination unit 13 may also determine the condition of the end face F1 from the ratio of the first volume V1 to the second volume V2. For example, the end face condition determination unit 13 may determine that the end face F1 is in a specific state when the ratio of the first volume V1 to the second volume V2 is equal to or greater than 0 and equal to or less than X5, or equal to or greater than X6 (where X5 is a positive real number less than 1 and X6 is a positive real number greater than 1), and may determine that the end face F1 is not in a specific state when the ratio is greater than X5 and less than X6. For example, the end face condition determining unit 13 may determine that the end face F1 is in a specific state when 0≦V1 / V2≦X5<1 or 1<X6≦V1 / V2. The end face condition determining unit 13 may also determine that the end face F1 is in a specific state when 0<X9≦|V1-V2| is satisfied. The value of X9 is, for example, 800 μm ３ Alternatively, the value of X9 is 500 μm ３ Alternatively, the value of X9 is 100 μm ３ The end face condition determination unit 13 may determine the condition of the end face F1 using the ratio between the second volume V2 and the first volume V1. Furthermore, the end face condition determination unit 13 may determine the condition of the end face F1 using both the sum and ratio of the volumes described above.

[0059] The above describes various examples of the analysis of defects on the end face F1 by the end face condition analysis unit 12 and the determination of the end face F1 by the end face condition determination unit 13. However, the methods of the analysis of defects on the end face F1 by the end face condition analysis unit 12 and the determination of the end face F1 by the end face condition determination unit 13 are not limited to the above examples and can be further modified. The end face condition determination unit 13 may determine whether the state of the end face F1 is a specific state based on the results of pre-learning. The "pre-learning results" may be, for example, pre-stored learning results of the state of the end face F1. The "pre-learning results" may be images of the end face F1 determined to be in a specific state and images of the end face F1 determined not to be in a specific state. The end face condition determination unit 13 may be a determination AI (artificial intelligence) that determines whether the state of the end face F1 is in a specific state. Furthermore, the end face condition determination unit 13 may limit a specific area of ​​the image M, attempt to detect the core of the optical fiber F in that area, and when the core is detected, perform fusion splicing of the optical fiber F under pre-stored conditions, and output a message indicating that an error has occurred when the core is not detected.

[0060] When the end face condition determination unit 13 determines that the state of the end face F1 is a specific state, the shaping discharge unit 14 performs a shaping discharge on the end face F1, which is a discharge for shaping the end face F1. "Shaping" refers to removing defects on the end face of the optical fiber to an extent that allows appropriate fusion splicing. "Shaping" refers, for example, to reducing irregularities occurring on the end face F1 to flatten the end face F1. "Shaping" refers, for example, to removing defects on the end face F1 to increase the symmetry of the end face F1. "Shaping discharge" is a discharge for shaping. The end face F1 is shaped by the shaping discharge. For example, the heat quantity of the shaping discharge is smaller than the heat quantity of the discharge during fusion splicing and greater than the heat quantity of the preliminary discharge performed prior to fusion splicing. For example, such preliminary discharge may be a discharge to soften the end faces F1 of the pair of optical fibers F in advance. The heat quantity of the shaping discharge is greater than the heat quantity of such preliminary discharge. For example, the heat quantity of the shaped discharge is 10 times or more the heat quantity of the preliminary discharge. As an example, the heat quantity of the shaped discharge may be 20 times or more the heat quantity of the preliminary discharge. Also, the time of the shaped discharge may be longer than the time of the preliminary discharge. As an example, the time of the preliminary discharge is 0.1 seconds, and the time of the shaped discharge is 1.0 seconds or more and 2.0 seconds or less.

[0061] As shown in Figures 7 and 8, the shaping discharge unit 14 places the pair of optical fibers F farther apart from each other than in fusion splicing. The shaping discharge unit 14 causes the discharge electrode 4d to perform shaping discharge with the pair of optical fibers F farther apart from each other than in fusion splicing. In shaping discharge, the end face F1 may become rounded F3. When shaping discharge is performed with the pair of optical fibers F farther apart from each other than in fusion splicing, it is possible to prevent the roundness F3 of the end face F1 from becoming sharper. The shaping discharge unit 14 may also cause the discharge electrode 4d to perform shaping discharge with the pair of optical fibers F closer to each other than in fusion splicing. When the shaping discharge unit 14 causes the discharge electrode 4d to perform shaping discharge with the pair of optical fibers F closer to each other, the heat quantity of the shaping discharge is reduced compared to when the pair of optical fibers F are not close to each other.

[0062] The distance Z between the pair of optical fibers F when the shaping discharge is performed is, for example, 10 μm. This distance Z may be the same value each time the shaping discharge is performed, or it may be a different value. Furthermore, the shaping discharge unit 14 may perform the shaping discharge while changing the position of the pair of optical fibers F. The closer the distance Z between the pair of optical fibers F is, the tighter the roundness F3 becomes, but the more effective it is at removing defects from the end surface F1. For example, the lower limit of the radius of curvature of the roundness F3 and the position of the pair of optical fibers F when this lower limit is obtained may be stored in advance. In this case, the shaping discharge unit 14 may move the pair of optical fibers F to a position where the radius of curvature of the roundness F3 is equal to or greater than this lower limit. For example, this lower limit is 62.5 μm.

[0063] For example, the fusion splicer 1 may perform preliminary discharge to clean the end faces F1 of the pair of optical fibers F prior to fusion splicing. The duration of this preliminary discharge is shorter than the duration of shaping discharge. As an example, the duration of preliminary discharge is 0.1 seconds or more and 0.2 seconds or less. For example, the distance between the pair of optical fibers F when preliminary discharge is performed is shorter than the distance Z between the pair of optical fibers F when shaping discharge is performed, but is longer than the distance between the pair of optical fibers F during fusion splicing. The distance Z is, for example, approximately 290 μm longer than the distance between the pair of optical fibers F during fusion splicing, and approximately 210 μm longer than the distance between the pair of optical fibers F when preliminary discharge is performed. For example, the amount of heat imparted to the optical fibers F by the shaping discharge is greater than the amount of heat imparted to the optical fibers F by preliminary discharge, but is equal to or less than the amount of heat imparted to the optical fibers F by discharge during fusion splicing. For example, the heat quantity of the shaping discharge is 50% to 100% of the heat quantity of the discharge during fusion splicing, and the heat quantity of the pre-discharge is 5% to 10% of the heat quantity of the discharge during fusion splicing. In this case, the heat quantity of the shaping discharge is 10 times to 20 times the heat quantity of the pre-discharge.

[0064] The discharge unit 15 causes the discharge electrode 4d to generate a discharge for fusion-splicing the pair of optical fibers F. The discharge unit 15 causes the discharge electrode 4d to generate a discharge, thereby fusion-splicing the pair of optical fibers F to each other.

[0065] Next, a fusion splicing method according to this embodiment will be described with reference to the flowchart in Fig. 9. In the fusion splicing method, a pair of optical fibers F are fusion-spliced ​​to each other using the discharge electrode 4d. An example of fusion-splicing a pair of optical fibers F to each other using the fusion splicing device 10 described above will be described below. First, the pair of optical fibers F are arranged in a pair of optical fiber holders 4b so as to be aligned in a straight line, and the microscope 6 acquires an image of the end faces F1 of the pair of optical fibers F (step S1).

[0066] The optical fiber F is observed with the microscope 6 (observation step). Then, the end face condition analysis unit 12 analyzes the state of the end face F1 of the optical fiber F and calculates the state of defects on the end face F1 (analysis step, step S2). The end face condition analysis unit 12 calculates a value indicating the state of defects on the end face F1 in the image M acquired by the microscope 6. As described above, the value indicating the state of defects may be a value based on the length L, a value based on the area T, or a value based on the volume V.

[0067] Next, the end face condition determination unit 13 determines whether the state of the end face F1 is a specific state (determining step). For example, the end face condition determination unit 13 determines whether the value indicating the defect state is equal to or greater than a threshold value (step S3). If the end face condition determination unit 13 determines that the value indicating the defect state is not equal to or greater than the threshold value, the state of the end face F1 is determined to be not a specific state, and the discharge unit 15 causes the discharge electrode 4d to discharge and fusion splice the pair of optical fibers F (step S8). After that, the series of steps is completed.

[0068] If the end face condition determination unit 13 determines that the value indicating the defect state is equal to or greater than the threshold value (YES in step S3), for example, the end face condition determination unit 13 determines whether the value indicating the defect state is equal to or less than an upper threshold value, which is the upper limit of the shaping threshold value (step S4). If the value indicating the defect state exceeds the upper threshold value, the condition of the end face F1 may not be appropriate even if shaping discharge is performed. Therefore, if the end face condition determination unit 13 determines that the value indicating the defect state is not equal to or less than the upper threshold value, an error message is displayed (step S9), and the series of processes is completed.

[0069] If the end face condition determination unit 13 determines that the value indicating the defect state is equal to or less than the upper threshold (YES in step S4), the shaping discharge unit 14 moves the pair of optical fibers F (step S5). For example, the shaping discharge unit 14 moves the pair of optical fibers F farther apart than during fusion splicing. Then, the shaping discharge unit 14 causes the discharge electrode 4d to perform shaping discharge (step of causing the discharge electrode to perform shaping discharge, step S6). After the shaping discharge, the end face condition determination unit 13 determines whether the value indicating the defect state is less than the threshold (step S7). If the end face condition determination unit 13 determines that the value indicating the defect state is not less than the threshold, the process proceeds to step S6, where the shaping discharge unit 14 performs shaping discharge again. In this way, the shaping discharge unit 14 may perform shaping discharge multiple times. If the end face condition determination unit 13 determines that the value indicating the defect state is less than the threshold value (YES in step S7), the discharge unit 15 causes the discharge electrode 4d to discharge, thereby fusion splicing the pair of optical fibers F (step S8). After that, the series of steps is completed.

[0070] Next, the effects obtained by the fusion splicing apparatus 10 and fusion splicing method according to this embodiment will be described. The fusion splicing apparatus 10 and fusion splicing method according to this embodiment include a discharge electrode 4d, a microscope 6, and an end face condition analysis unit 12. The end face condition analysis unit 12 analyzes the condition of the end face F1 of the optical fiber F from the image M of the optical fiber F acquired by the microscope 6. The fusion splicing apparatus 10 also includes an end face condition determination unit 13 and a shaping discharge unit 14. The end face condition determination unit 13 determines whether the state of the end face F1 is a predetermined specific state. If the end face condition determination unit 13 determines that the state of the end face F1 is a specific state, the shaping discharge unit 14 causes the discharge electrode 4d to perform shaping discharge to shape the end face F1. The end face condition analysis unit 12 and the end face condition determination unit 13 determine the end face F1 before performing shaping discharge, thereby enabling the condition of the end face F1 of the pair of optical fibers F to be grasped with higher accuracy. When the state of the end face F1 is determined to be a specific state, the shaping discharge unit 14 performs shaping discharge, thereby shaping the end face F1 as needed. By performing shaping discharge as needed before fusion splicing, the end face F1 of the optical fiber F can be brought into an appropriate state before fusion splicing.

[0071] As described above, the end face condition analysis unit 12 may calculate a value indicating the defect state of the end face F1 based on the image M, and the end face condition determination unit 13 may determine whether the state of the end face F1 is in a specific state based on the magnitude relationship between the value indicating the defect state and a threshold value. In this case, the defect state of the end face F1 is calculated as a value, and whether the state of the end face F1 is in a specific state is determined based on the magnitude relationship between the calculated value and a predetermined threshold value. Therefore, the state of the end face F1 of the optical fiber F can be grasped with higher accuracy.

[0072] As described above, the value indicating the defect state may be a value based on the length L of the defect portion of the end face F1 calculated based on the image M. The value indicating the defect state may also be a value based on the area T of the defect portion of the end face F1 calculated based on the image M. In this case, the defect state of the end face F1 can be grasped with higher accuracy. Furthermore, the value indicating the defect state may also be a value based on the volume V of the defect portion of the end face F1 calculated based on the image M. In this case, the defect state of the end face F1 can be grasped with even higher accuracy.

[0073] As described above, the end face condition determination unit 13 may determine whether the state of the end face F1 is a specific state based on the results of prior learning. In this case, the end face condition determination unit 13 can determine whether the state of the end face F1 is a specific state using the results of machine learning.

[0074] As described above, the end face condition analysis unit 12 may calculate a first length L1, which is the maximum length L of the defect on the end face F1 located in a first direction D1, which is a direction intersecting the axis A as viewed from the axis A of the optical fiber F in the image M, and a second length L2, which is the maximum length L of the defect on the end face F1 located in a second direction D2, which is the opposite direction to the first direction D1 as viewed from the axis A of the optical fiber F in the image M. The end face condition analysis unit 12 may calculate at least one of the sum of the first length L1 and the second length L2, and the ratio of the first length L1 to the second length L2 or the ratio of the second length L2 to the first length. The end face condition determination unit 13 may determine the condition of the end face F1 using at least one of the calculated sum and ratio as a value indicating the defect condition. In this case, the condition of the end face F1 of the optical fiber F can be determined with higher accuracy.

[0075] As described above, the end face condition analysis unit 12 may calculate a first area T1 of a defect portion of the end face F1 located in the first direction D1 as viewed from the axis A of the optical fiber F in the image M, and a second area T2 of a defect portion of the end face F1 located in the second direction D2 as viewed from the axis A of the optical fiber F in the image M. The end face condition analysis unit 12 may calculate at least one of the sum of the first area T1 and the second area T2, and the ratio of the first area T1 to the second area T2 or the ratio of the second area T2 to the first area T1. The end face condition determination unit 13 may determine the condition of the end face F1 using at least one of the calculated sum and ratio as a value indicating the defect condition. In this case, the condition of the end face F1 of the optical fiber F can be determined with higher accuracy.

[0076] As described above, the end face condition analysis unit 12 may calculate a first volume V1 of a defect portion of the end face F1 located in the first direction D1 as viewed from the axis A of the optical fiber F in the image M, and a second volume V2 of a defect portion of the end face F1 located in the second direction D2 as viewed from the axis A of the optical fiber F in the image M. The end face condition analysis unit 12 may calculate at least one of the following: the sum of the first volume V1 and the second volume V2, and the ratio of the first volume V1 to the second volume V2 or the ratio of the second volume V2 to the first volume V1. The end face condition determination unit 13 may determine the condition of the end face F1 using at least one of the calculated sum and ratio as a value indicating the defect condition. In this case, the condition of the end face F1 of the optical fiber F can be grasped with higher accuracy.

[0077] As described above, the shaping discharge unit 14 may cause the discharge electrode 4d to perform shaping discharge in a state in which the pair of optical fibers F are spaced apart from each other more than during fusion splicing. In this case, the shaping discharge is performed with the distance Z between the pair of end faces F1 more appropriate, so that the pair of end faces F1 can be in a more appropriate state before fusion splicing. By performing shaping discharge in a state in which the pair of optical fibers F are spaced apart from each other, the rounding F3 of the end faces F1 can be appropriately suppressed.

[0078] The above describes embodiments of the fusion splicing apparatus and fusion splicing method according to the present disclosure. However, the present invention is not limited to the above-described embodiments. In other words, those skilled in the art will readily recognize that various modifications and variations are possible within the scope of the gist of the present invention as defined in the claims. In other words, the function, configuration, shape, size, number, material, and arrangement of each part of the fusion splicing apparatus, as well as the content and order of the steps of the fusion splicing method, can be modified as appropriate within the scope of the gist described above.

[0079] For example, the method of analyzing the end face F1 by the end face condition analysis unit 12 and the method of determining the end face F1 by the end face condition determination unit 13 may be further modified from the examples described above. For example, the end face condition analysis unit 12 may calculate the angle of a virtual line extending from the portion F2 of the end face F1 that protrudes most along the direction D3 to the portion of the end face F1 that is most recessed along the direction D3, relative to a first virtual line M1. The end face condition determination unit 13 may determine that the state of the end face F1 is in a specific state when the angle of the virtual line relative to the first virtual line M1 is equal to or greater than a certain angle, and may determine that the state of the end face F1 is not in a specific state when the angle of the virtual line relative to the first virtual line M1 is less than the certain angle.

[0080] In the above-described embodiment, the shaping discharge unit 14 and the discharge unit 15 have been described as separate functional components. However, the shaping discharge unit does not have to be a different physical component from the discharge unit, and the shaping discharge unit may be the same physical component as the discharge unit. As a physical component, the shaping discharge unit may be the same as the discharge unit or may be a different one. The function of the shaping discharge unit may be part of the function of the discharge unit. The shaping discharge unit may perform, as shaping discharge, an operation performed by the discharge unit under special conditions.

[0081] DESCRIPTION OF SYMBOLS 1...Fusion splicer 2...Windshield cover 3...Housing 4...Fusion splicing section 4b...Optical fiber holder 4c...Fiber positioning section 4d...Discharge electrode 5...Heater 6...Microscope 7...Monitor 8...Power switch 9...Connection start switch 10...Fusion splicer 11...Server 12...End face condition analysis section 13...End face condition determination section 14...Shaping discharge section 15...Discharge section 20...Information terminal A...Axis B...Block B1...First block B2...Second block B3...Third block F...Optical fiber F1...End face F2...Part F3...Roundness F4...Shape M...Image M1...First virtual line M2...Second virtual line M3...Third virtual line R1...First region R2...Second region T...Area T1...First area T2...Second area V1...First volume V2...second volume

Claims

1. A fusion splicing device that fusion-splices a pair of optical fibers together by electric discharge, comprising: a discharge electrode that generates electric discharge; a microscope that observes the optical fibers; an end face condition analysis unit that analyzes the condition of the end face of the optical fiber from an image of the optical fiber acquired by the microscope; an end face condition determination unit that determines whether the condition of the end face is a predetermined specific state; and a shaping discharge unit that causes the discharge electrode to generate a shaping discharge on the end face, which is a discharge for shaping the end face, when the end face condition determination unit determines that the condition of the end face is the specific state.

2. The fusion splicing device according to claim 1, wherein the end face condition analysis unit calculates a value indicating a defect state of the end face based on the image, and the end face condition determination unit determines whether the state of the end face is the specific state based on the magnitude relationship between the value indicating the defect state and a threshold value.

3. The fusion splicing apparatus according to claim 2, wherein the value indicating the defect state is a value based on the length of the defect portion of the end face determined based on the image.

4. The fusion splicing apparatus according to claim 2, wherein the value indicating the defect state is a value based on the area of ​​the defect portion of the end face determined based on the image.

5. The fusion splicing device according to claim 2, wherein the value indicating the defect state is a value based on the volume of the defect portion of the end face determined based on the image.

6. A fusion splicing device according to any one of claims 1 to 5, wherein the end face condition determination unit determines whether the state of the end face is the specific state based on a result of prior learning.

7. A fusion splicing device as claimed in any one of claims 1 to 6, wherein the end face condition analysis unit calculates a first defect amount, which is the defect amount of a portion located in a first direction, which is a direction intersecting the axis of the optical fiber in the image, as viewed from the axis of the optical fiber, and a second defect amount, which is the defect amount of a portion located in a second direction, which is the opposite direction to the first direction, as viewed from the axis of the optical fiber in the image; and the end face condition determination unit determines whether the state of the end face is the specific state from the first defect amount and the second defect amount.

8. A fusion splicing device as claimed in any one of claims 1 to 6, wherein the end face condition analysis unit calculates a degree of symmetry indicating the symmetry between a portion located in a first direction, which is a direction intersecting the axis of the optical fiber in the image, as viewed from the axis of the optical fiber, and a portion located in a second direction, which is the opposite direction to the first direction, as viewed from the axis of the optical fiber in the image; and the end face condition determination unit determines from the degree of symmetry whether the state of the end face is in the specific state.

9. A fusion splicing device according to any one of claims 1 to 8, wherein the end face condition analysis unit calculates a first length, which is the maximum length of the defect on the end face located in a first direction, which is a direction intersecting the axis as viewed from the axis of the optical fiber in the image, and a second length, which is the maximum length of the defect on the end face located in a second direction, which is the opposite direction to the first direction as viewed from the axis of the optical fiber in the image; the end face condition analysis unit calculates at least one of the sum of the first length and the second length, and the ratio of the first length to the second length or the ratio of the second length to the first length; and the end face condition determination unit determines the condition of the end face using at least one of the calculated sum and the ratio as a value indicating the defect condition.

10. A fusion splicing device as claimed in any one of claims 1 to 8, wherein the end face condition analysis unit calculates a first area of ​​a defective portion of the end face located in a first direction that intersects with the axis of the optical fiber in the image as viewed from the axis of the optical fiber, and a second area of ​​a defective portion of the end face located in a second direction that is opposite to the first direction as viewed from the axis of the optical fiber in the image; the end face condition analysis unit calculates at least one of the sum of the first area and the second area, and the ratio of the first area to the second area or the ratio of the second area to the first area; and the end face condition determination unit determines the condition of the end face using at least one of the calculated sum and the ratio as a value indicating the defect condition.

11. A fusion splicing device according to any one of claims 1 to 8, wherein the end face condition analysis unit calculates a first volume of a defective portion of the end face located in a first direction that intersects with the axis of the optical fiber in the image as viewed from the axis of the optical fiber, and a second volume of a defective portion of the end face located in a second direction that is opposite to the first direction as viewed from the axis of the optical fiber in the image; the end face condition analysis unit calculates at least one of the sum of the first volume and the second volume, and the ratio of the first volume to the second volume or the ratio of the second volume to the first volume; and the end face condition determination unit determines the condition of the end face using at least one of the calculated sum and the ratio as a value indicating the defect condition.

12. A fusion splicing device according to any one of claims 1 to 11, wherein the shaping discharge section causes the discharge electrode to perform the shaping discharge in a state in which the pair of optical fibers are spaced apart from each other more than during fusion splicing.

13. A fusion splicing device according to any one of claims 1 to 11, wherein the shaping discharge section causes the discharge electrode to perform the shaping discharge in a state in which the pair of optical fibers are closer to each other than during fusion splicing.

14. A fusion splicing device according to any one of claims 1 to 13, wherein the heat quantity of the shaped discharge is smaller than the heat quantity of the discharge during fusion splicing and is greater than the heat quantity of a preliminary discharge carried out prior to the fusion splicing.

15. A fusion splicing apparatus according to any one of claims 1 to 14, wherein the heat quantity of the shaped discharge is at least 10 times the heat quantity of a preliminary discharge carried out prior to the fusion splicing.

16. A fusion splicing apparatus according to any one of claims 1 to 15, wherein the duration of the shaping discharge is longer than the duration of the preliminary discharge carried out prior to the fusion splicing.

17. A fusion splicing apparatus according to any one of claims 1 to 16, wherein the duration of the shaped discharge is 1.0 second or more and 2.0 seconds or less.

18. A fusion splicing device according to any one of claims 1 to 17, wherein the shaping discharge section performs the shaping discharge while changing the positions of the pair of optical fibers.

19. A fusion splicing device according to any one of claims 1 to 18, wherein the shaping discharge unit moves the pair of optical fibers to a position where the radius of curvature of the rounded end faces is equal to or greater than a pre-stored lower limit value.

20. A fusion splicing method in which a pair of optical fibers are fusion-spliced ​​to each other using a discharge electrode, comprising: a step of observing the optical fibers with a microscope; a step of analyzing the state of the end face of the optical fiber from an image of the optical fiber acquired by the microscope; a step of determining whether the state of the end face is a predetermined specific state; and a step of causing the discharge electrode to perform a shaping discharge on the end face, which is a discharge for shaping the end face, when it is determined that the state of the end face is the specific state.

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