Fusion splicing apparatus and fusion splicing method

Abstract

To provide a fusion connection device which can confirm a light conduction state of individual cores.SOLUTION: A fusion connection device includes a first holding part, a second holding part, a screen, a light source, a first measuring instrument, a discharge electrode, a first drive part, a second drive part, and a third drive part. The end face of a first optical fiber and the end face of a second optical fiber are opposite to each other. The light source makes test light incident on the first optical fiber. The screen is provided with a light guide part capable of passing only the test light emitted from one core among a plurality of cores of the first optical fiber, and the screen is arranged between the end face of the first optical fiber and the end face of the second optical fiber. The first measuring instrument measures intensity of leakage light leaked from the second optical fiber, among the test light which is emitted from the end face of the first optical fiber and is incident on the end face of the second optical fiber. The third drive part adjusts the position of the screen so that any one of the plurality of cores of the first optical fiber and the light guide part are arranged side by side in the axial direction of the first optical fiber.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a fusion connection device and a fusion connection method.

Background Art

[0002] Patent Documents 1 to 3 disclose a method for fusion-connecting two multi-core optical fibers. A multi-core optical fiber includes a plurality of cores and a cladding covering the plurality of cores.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 describes a method for fusion-connecting a first multi-core optical fiber and a second multi-core optical fiber, both of which have a plurality of cores and a cladding covering the plurality of cores. In this method, the connection end face of the first multi-core optical fiber and the connection end face of the second multi-core optical fiber are opposed so that the axis of the first multi-core optical fiber coincides with the axis of the second multi-core optical fiber. Next, test light is incident from the side of the first multi-core optical fiber and propagated through the cladding. Then, based on the test light detected from the second multi-core optical fiber, the angle around the axis of the first multi-core optical fiber and the angle around the axis of the second multi-core optical fiber are rotationally adjusted.

[0005] Patent Document 2 describes a method for fusion splicing a first optical fiber and a second optical fiber, both of which are multicore optical fibers. In this method, the central axes of the first optical fiber and the second optical fiber are made parallel, and the end faces of the first optical fiber and the end faces of the second optical fiber are brought facing each other. Next, a portion of the second optical fiber is bent. Next, light is incident on the core of the first optical fiber from one end or from the side of the first optical fiber, and the light emitted from the other end is incident on the second optical fiber. Next, the intensity of the light coming out of the bent portion of the second optical fiber is measured. Next, while maintaining the parallelism of the central axes of the first optical fiber and the second optical fiber, at least one of the first optical fiber and the second optical fiber is moved or rotated so that the light intensity is increased. Then, while maintaining the relative positions of the first optical fiber and the second optical fiber at which the light intensity is maximized, the distance between the first optical fiber and the second optical fiber is changed and their ends are connected.

[0006] Patent Document 3 describes a method for fusion splicing two multicore optical fibers, each having a plurality of cores, markers spaced apart from the plurality of cores, and a cladding covering the plurality of cores and markers. In this method, the two multicore optical fibers are positioned opposite each other, and light is shone from each side of the two multicore optical fibers. A monitor is placed between the two multicore optical fibers, and the monitor detects the profile of the light. Based on the position of the markers detected from the light profile, the two multicore optical fibers are aligned.

[0007] However, in the method of connecting two multicore optical fibers described in the above-mentioned Patent Documents 1 to 3, light propagates simultaneously through all cores, making it impossible to check the optical conductivity of individual cores.

[0008] This disclosure aims to provide a fusion splicing apparatus and a fusion splicing method that can confirm the optical conductivity state of individual cores. [Means for solving the problem]

[0009] This disclosure provides a fusion splicing apparatus for fusion splicing the end face of a first optical fiber having multiple cores to the end face of a second optical fiber having multiple cores. The fusion splicing apparatus comprises a first holding unit, a second holding unit, a screen, a light source, a first measuring instrument, a discharge electrode, a first driving unit, a second driving unit, and a third driving unit. The first holding unit holds the first optical fiber with its end face facing the end face of the second optical fiber. The second holding unit holds the second optical fiber with its end face facing the end face of the second optical fiber. The screen has a light guide portion through which only light emitted from one of the multiple cores of the first optical fiber can pass, and a light shielding portion that shields light that does not pass through the light guide portion, and is positioned between the end face of the first optical fiber and the end face of the second optical fiber. The light source incidents test light onto the first optical fiber. The first measuring instrument measures the intensity of leaked light that leaks from the second optical fiber out of the test light emitted from the end face of the first optical fiber and incident on the end face of the second optical fiber. The discharge electrode heats the end face of the first optical fiber and the end face of the second optical fiber. The first drive unit adjusts the position of the first holding unit and the first angle, which is the rotation angle around the axis of the first optical fiber. The second drive unit adjusts the position of the second holding unit and the second angle, which is the rotation angle around the axis of the second optical fiber. The third drive unit adjusts the position of the screen so that one of the multiple cores of the first optical fiber and the light guide are aligned in the axial direction of the first optical fiber, and retracts the screen from between the end face of the first optical fiber and the end face of the second optical fiber. [Effects of the Invention]

[0010] This disclosure makes it possible to provide a fusion splicing apparatus and a fusion splicing method that can confirm the optical conductivity state of individual cores. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a diagram illustrating the overview of a fusion splicing apparatus according to the first embodiment. [Figure 2]Figure 2 shows side views of the first and second optical fibers. [Figure 3] Figure 3 is a cross-sectional view of the first and second optical fibers in the III-III section shown in Figure 2. [Figure 4] Figure 4 is a front view of the screen. [Figure 5] Figure 5 shows that one of the multiple cores of the first optical fiber and the light guide are aligned in the axial direction of the first optical fiber. [Figure 6] Figure 6 shows that one of the multiple cores of the first optical fiber and the light guide are aligned in the axial direction of the first optical fiber. [Figure 7] Figure 7 shows that one of the multiple cores of the first optical fiber and the light guide are aligned in the axial direction of the first optical fiber. [Figure 8] Figure 8 shows that one of the multiple cores of the first optical fiber and the light guide are aligned in the axial direction of the first optical fiber. [Figure 9] Figure 9 shows that the marker and light guide of the first optical fiber are aligned in the axial direction of the first optical fiber. [Figure 10] Figure 10 schematically shows cross-sections of the first and second retaining parts along the YZ plane. [Figure 11] Figure 11 is a flowchart showing the operation of a fusion splicing device. [Figure 12] Figure 12 is a flowchart showing the operation of the fusion splicer when adjusting the relative rotation angles of the first and second optical fibers. [Figure 13] Figure 13 is a flowchart showing the operation of a fusion splicer when it measures the intensity of test light emitted from the core of the first optical fiber for each core, and when it measures the intensity of test light emitted from the marker of the first optical fiber. [Figure 14] Figure 14 is a flowchart showing the operation of a fusion splicer when it checks the fusion splice status between the end face of the first optical fiber and the end face of the second optical fiber. [Figure 15]FIG. 15 is a front view of a screen in which the light guide part is a condenser lens. [Figure 16] FIG. 16 is a flowchart showing the operation when the fusion connection device adjusts the rotation angle of the first optical fiber and the rotation angle of the second optical fiber using end face observation. [Figure 17] FIG. 17 is a diagram schematically showing a cross section along the YZ plane of the first holding part and the second holding part. [Figure 18] FIG. 18 is a diagram showing a part of the configuration of the fusion connection device according to the second embodiment. [Figure 19] FIG. 19 is a flowchart showing the operation when the fusion connection device measures the intensity of the test light emitted from each of the plurality of cores of the first optical fiber using the second measuring device.

Embodiments for Carrying out the Invention

[0012] [Description of Embodiments of the Present Disclosure] First, the contents of the embodiments of the present disclosure will be listed and described.

[0013] [1] A fusion splicing apparatus according to one aspect of this disclosure fusion splices the end face of a first optical fiber having multiple cores with the end face of a second optical fiber having multiple cores. This fusion splicing apparatus comprises a first holding unit, a second holding unit, a screen, a light source, a first measuring instrument, a discharge electrode, a first drive unit, a second drive unit, and a third drive unit. The first holding unit holds the first optical fiber with its end face facing the end face of the second optical fiber. The second holding unit holds the second optical fiber with its end face facing the end face of the second optical fiber. The screen is provided with a light guide that allows only light emitted from one of the multiple cores of the first optical fiber to pass through, and is positioned between the end face of the first optical fiber and the end face of the second optical fiber. The light source incidents test light onto the first optical fiber. The first measuring instrument measures the intensity of leaked light that leaks from the second optical fiber out of the test light emitted from the end face of the first optical fiber and incident on the end face of the second optical fiber. The discharge electrode heats the end face of the first optical fiber and the end face of the second optical fiber. The first drive unit adjusts the position of the first holding unit and the first angle, which is the rotation angle of the first optical fiber around its axis. The second drive unit adjusts the position of the second holding unit and the second angle, which is the rotation angle of the second optical fiber around its axis. The third drive unit adjusts the position of the screen so that one of the multiple cores of the first optical fiber and the light guide are aligned in the axial direction of the first optical fiber, and retracts the screen from between the end face of the first optical fiber and the end face of the second optical fiber.

[0014] In this fusion splicer, a light guide is provided on the screen, allowing only test light emitted from any core of the first optical fiber to pass through the screen. Therefore, the first measuring instrument can measure the intensity of the test light emitted from any core of the first optical fiber by measuring the intensity of the leaked light. Furthermore, the third drive unit adjusts the position of the screen so that one of the multiple cores of the first optical fiber and the light guide are aligned in the axial direction of the first optical fiber. Therefore, the first measuring instrument can measure the intensity of the test light emitted from each of the multiple cores of the first optical fiber for each core by measuring the intensity of the leaked light. This makes it possible to confirm the optical conductivity state of each of the multiple cores of the first optical fiber, the optical conductivity state of each of the multiple cores of the second optical fiber, and the positional relationship between the multiple cores of the first optical fiber and the multiple cores of the second optical fiber. Thus, the optical conductivity state of individual cores can be confirmed, and as a result, the first optical fiber and the second optical fiber can be fusion spliced ​​with low loss.

[0015] [2] In the fusion splicing apparatus described in [1] above, the third drive unit retracts the screen from between the end face of the first optical fiber and the end face of the second optical fiber, and the first drive unit and the second drive unit are adjusted to their respective first and second angles so that the leakage light measured by the first measuring instrument has the maximum intensity, and the first measuring instrument measures the first intensity, which is the intensity of the leakage light. The first measuring instrument also measures the core intensity, which is the intensity of the leakage light, for each of the multiple cores of the first optical fiber, when the third drive unit adjusts the position of the screen so that one of the multiple cores of the first optical fiber and the light guide are aligned in the axial direction of the first optical fiber. The end face of the first optical fiber and the end face of the second optical fiber may be fusion spliced ​​together if the ratio of the second intensity, which is the sum of the core intensities corresponding to each of the multiple cores of the first optical fiber, to the first intensity is within a predetermined first range. In this case, theoretically, the second intensity has a predetermined ratio to the first intensity. However, due to misalignment when each of the multiple cores of the first optical fiber and the light guide are aligned in the axial direction of the first optical fiber, the second intensity becomes smaller than the predetermined ratio to the first intensity. Therefore, by checking the ratio of the first intensity to the second intensity, it is possible to confirm whether the screen is positioned in the appropriate location.

[0016] [3] In the fusion splicing apparatus described in [1] or [2] above, the first measuring instrument may measure the core intensity, which is the intensity of leaked light, for each of the multiple cores of the first optical fiber when the third drive unit adjusts the position of the screen so that one of the multiple cores of the first optical fiber and the light guide are aligned in the axial direction of the first optical fiber. The end face of the first optical fiber and the end face of the second optical fiber may be fusion spliced ​​together when the ratio of the minimum core intensity to the maximum core intensity among the core intensities corresponding to each of the multiple cores of the first optical fiber is within a predetermined second range. If dust or scratches are present in any of the cores of the first optical fiber, the core intensity corresponding to that core will be smaller than the core intensity corresponding to a core without dust or scratches. With the above configuration, by confirming that the ratio of the maximum core intensity to the minimum core intensity is within a predetermined second range, it is possible to confirm that there is no dust or scratches in the core corresponding to the minimum core intensity. Therefore, the optical conductivity state of each of the multiple cores can be confirmed.

[0017] [4] In any of the fusion splicing devices described in [1] to [3] above, the first measuring instrument may measure the core intensity, which is the intensity of leaked light, for each of the multiple cores of the first optical fiber when the third driving unit adjusts the position of the screen so that one of the multiple cores of the first optical fiber and the light guide are aligned in the axial direction of the first optical fiber. The first measuring instrument may also measure the third intensity, which is the intensity of leaked light, when the end face of the first optical fiber and the end face of the second optical fiber are fusion spliced ​​together. The fusion splicing device may further include a determination unit for determining the state of the fusion splicing between the end face of the first optical fiber and the end face of the second optical fiber. The determination unit may determine that the state of the fusion splicing between the end face of the first optical fiber and the end face of the second optical fiber is abnormal if the ratio of the second intensity, which is the sum of the core intensities corresponding to each of the multiple cores of the first optical fiber, to the third intensity is outside a predetermined third range. In this case, theoretically, the third intensity has a predetermined ratio to the second intensity. However, due to the misalignment of the multiple cores of the first optical fiber and the multiple cores of the second optical fiber that occurs during fusion splicing, the ratio of the third intensity to the second intensity may be smaller than the predetermined ratio. In the above configuration, if the ratio of the third intensity to the second intensity is outside a predetermined third range, it is determined that the fusion splice state between the end face of the first optical fiber and the end face of the second optical fiber is abnormal. This makes it possible to detect the misalignment between the multiple cores of the first optical fiber and the multiple cores of the second optical fiber that occurs during fusion splicing.

[0018] [5] In any of the fusion splicers described in [1] to [4] above, the first optical fiber and the second optical fiber may further have markers. The third drive unit may further adjust the screen so that the light guide is aligned with the marker and the first optical fiber in the axial direction. By using the markers as positional references for the first and second angles, misconnection of the cores can be prevented even if the core arrangement has rotational symmetry.

[0019] [6] In any of the fusion splicing devices described in [1] to [5] above, the light guide may be a through hole. In this case, for example, compared to the case where the light guide is made of a transparent flat plate, the reflection of the test light by the light guide can be suppressed when the test light passes through the light guide. Therefore, it is possible to suppress the effect of the light source on the operation of the light source by the test light returning to the light source.

[0020] [7] In any of the fusion splicing devices described in [1] to [5] above, the light guide may be a focusing lens. In this case, the test light emitted from the end face of the first optical fiber is focused toward the end face of the second optical fiber by the focusing lens. Therefore, leakage of the test light can be suppressed between the time the test light is emitted from the end face of the first optical fiber and the time it is incident on the end face of the second optical fiber. Consequently, the amount of test light incident on the end face of the second optical fiber can be increased, and the amount of leaked light can be increased. As a result, the accuracy of the first measuring instrument when measuring the intensity of leaked light can be improved.

[0021] [8] In any of the fusion splicing devices described in [1] to [7] above, the light-shielding portion of the screen may be coated with an anti-reflective coating. In this case, the reflection of the test light by the screen can be suppressed. Therefore, it is possible to suppress the effect of the light source on the operation of the light source by the test light returning to the light source.

[0022] [9] Any of the fusion splicing devices described in [1] to [8] above may further include a second measuring instrument configured to move between a first position, where a screen is sandwiched between the end face of the first optical fiber and the device, and a second position, which is located away from the first position, and which measures the intensity of test light emitted from the end face of the first optical fiber through the light guide portion of the screen. With the second drive unit retracting the second optical fiber and the third drive unit adjusting the position of the screen so that the light guide portion and one of the multiple cores of the first optical fiber are aligned in the axial direction of the first optical fiber, the second measuring instrument may measure the intensity of test light emitted from each of the multiple cores of the first optical fiber through the light guide portion at the first position. After the measurement, the second measuring instrument may move to the second position, and the second drive unit may return the second optical fiber to a position facing the first optical fiber. In this case, the second measuring instrument directly measures the intensity of test light emitted from each of the cores of the first optical fiber for each core. Therefore, the optical conductivity of the multiple cores of the first optical fiber can be confirmed with even greater accuracy.

[0023]

[10] A fusion splicing method relating to one aspect of the present disclosure is a method for fusion splicing the end face of a first optical fiber having a plurality of cores to the end face of a second optical fiber having a plurality of cores. This fusion splicing method comprises the steps of: facing the end face of a first optical fiber and the end face of a second optical fiber; aligning the central axis of the first optical fiber and the central axis of the second optical fiber; adjusting the rotation angle of the first optical fiber about the axis and the rotation angle of the second optical fiber about the axis; injecting test light into the first optical fiber; measuring the intensity of leaked light leaking from the second optical fiber while shielding the test light emitted from the end face of the first optical fiber from all other test light except for the test light emitted from one of the plurality of cores of the first optical fiber; and determining whether or not to connect the end face of the first optical fiber and the end face of the second optical fiber based on the intensity of leaked light corresponding to each of the plurality of cores of the first optical fiber.

[0024] In this fusion splicing method, the intensity of leaked light from the second optical fiber is measured for each of the multiple cores of the first optical fiber, while other test light is shielded except for the test light emitted from one of the cores of the first optical fiber. Therefore, the intensity of leaked light corresponding to each of the multiple cores of the first optical fiber can be measured for each core. Based on the intensity of leaked light corresponding to each of the multiple cores of the first optical fiber, a decision is made as to whether or not to connect the end face of the first optical fiber and the end face of the second optical fiber. Thus, it is possible to prevent connecting the end face of the first optical fiber and the end face of the second optical fiber when the optical conductivity of the multiple cores is not good. [Details of the embodiments of this disclosure]

[0025] Specific examples of fusion splicing apparatus and fusion splicing method according to embodiments of this disclosure will be described below with reference to the drawings. This disclosure is not limited to these examples, but is intended to include all modifications within the meaning and scope of the claims, as indicated by the claims. In the following description, the same elements in the drawings are denoted by the same reference numerals, and redundant descriptions are omitted. (First Embodiment)

[0026] Figure 1 is a diagram illustrating the overview of a fusion splicing apparatus 1A according to the first embodiment. The XYZ Cartesian coordinate system is also shown in Figure 1. As shown in Figure 1, the fusion splicing apparatus 1A is a device for fusion splicing the end face F1a of a first optical fiber F1 and the end face F2a of a second optical fiber F2 together. Figure 2 is a side view of the first optical fiber F1 and the second optical fiber F2. Figure 3 is a cross-sectional view of the first optical fiber F1 and the second optical fiber F2 in the III-III section shown in Figure 2. As shown in Figure 3, the first optical fiber F1 and the second optical fiber F2 have a glass portion GL and a resin coating RS surrounding the outer periphery of the glass portion GL. The glass portion GL has one or more (four in the illustrated example) cores CR, one marker MK, and a common cladding CL surrounding these cores CR and marker MK. The marker MK is transparent. The marker MK may be opaque. The marker MK has a refractive index distribution capable of transmitting light.

[0027] As shown in Figure 2, in the first optical fiber F1, the tip portion GL1 of the glass portion GL, including the end face F1a, is exposed from the resin coating RS. In the second optical fiber F2, the tip portion GL2 of the glass portion GL, including the end face F2a, is exposed from the resin coating RS. These exposed portions are formed by removing the resin coating RS around the tip portions GL1 and GL2 before the fusion splicing operation.

[0028] Refer to Figure 1 again. The fusion splicer 1A comprises a first holding part 11 and a second holding part 12. The first holding part 11 holds the first optical fiber F1 with its end face F1a and end face F2a facing each other. While holding the first optical fiber F1, the first holding part 11 makes the position of the end face F1a of the first optical fiber F1 (position in the X, Y, and Z axes, respectively) and the rotation angle θ (first angle) around the central axis variable. The second holding part 12 holds the second optical fiber F2 with its end face F1a and end face F2a facing each other. While holding the second optical fiber F2, the second holding part 12 makes the position of the end face F2a of the second optical fiber F2 and the rotation angle θ (second angle) around the central axis variable. The first holding part 11 and the second holding part 12 are aligned along the Z axis direction, which is the central axis direction of the first optical fiber F1 and the second optical fiber F2. The first holding part 11 has a V groove 111 extending along the Z axis direction. The V-groove 111 accommodates the portion of the first optical fiber F1 excluding the tip portion GL1, i.e., the portion with the resin coating RS, and fixes the position of the first optical fiber F1 in the XY plane. The first holding portion 11 holds the first optical fiber F1 with the tip portion GL1 protruding. The second holding portion 12 has a V-groove 121 extending along the Z-axis direction. The V-groove 121 accommodates the portion of the second optical fiber F2 excluding the tip portion GL2, i.e., the portion with the resin coating RS, and fixes the position of the second optical fiber F2 in the XY plane. The second holding portion 12 holds the second optical fiber F2 with the tip portion GL2 protruding.

[0029] In one embodiment, the first holding part 11 and the second holding part 12 are made of resin. The first holding part 11 has, for example, a base 112 on which a first optical fiber F1 is placed and which has a V-groove 111 formed therein, and a lid 113 that is placed on the base 112. The base 112 and the lid 113 are arranged, for example, along the Y-axis direction intersecting the Z-axis direction. The second holding part 12 has, for example, a base 122 on which a second optical fiber F2 is placed and which has a V-groove 121 formed therein, and a lid 123 that is placed on the base 122. The base 122 and the lid 123 are arranged, for example, along the Y-axis direction.

[0030] The fusion splicing device 1A further comprises a first drive unit 21 and a second drive unit 22. The first drive unit 21 supports the first holding unit 11 and adjusts the position of the first holding unit 11 and the rotation angle θ of the first holding unit 11 about the Z axis. By adjusting the position and rotation angle θ of the first holding unit 11, the position and rotation angle θ of the end face F1a are adjusted. The second drive unit 22 supports the second holding unit 12 and adjusts the position of the second holding unit 12 and the rotation angle θ of the second holding unit 12 about the Z axis. By adjusting the position and rotation angle θ of the second holding unit 12, the position and rotation angle θ of the end face F2a are adjusted. The first drive unit 21 and the second drive unit 22 are configured to include, for example, motors.

[0031] The fusion splicer 1A further includes a screen 3. The screen 3 allows only the light emitted from one core CR of the light emitted from the end face F1a of the first optical fiber F1 to pass through, while blocking the light emitted from the other core CR. The screen 3 has a rectangular shape. The screen 3 is positioned between end faces F1a and F2a. The screen 3 can also be retracted to positions other than between end faces F1a and F2a. The thickness of the screen 3 is less than the distance between end faces F1a and F2a. The screen 3 extends along a plane perpendicular to the Z-axis direction. The position of the screen 3 is variable. Specifically, the position of the screen 3 is variable in the X and Y directions. The rotation angle of the screen 3 around the Z-axis may also be variable.

[0032] Figure 4 is a front view of screen 3. As shown in Figure 4, screen 3 has a light guide portion 3a and a light shielding portion 3b. The light guide portion 3a is a through-hole that penetrates screen 3 in the Z-axis direction. The light guide portion 3a has a circular shape when viewed from the Z-axis direction. The diameter of the light guide portion 3a is slightly larger than the diameter of each of the multiple cores CR of the first optical fiber F1. The diameter of the light guide portion 3a is larger than the diameter of the marker MK of the first optical fiber F1. Only light emitted from one core CR can pass through the light guide portion 3a. The light shielding portion 3b is made of a light-shielding material. Of the light emitted from the multiple cores CR of the first optical fiber F1, the light that does not pass through the light guide portion 3a is shielded by the light shielding portion 3b. The light shielding portion 3b is coated with an anti-reflective coating.

[0033] The configuration of screen 3 can be any configuration that can block light other than the light emitted from one of the multiple core CRs of the first optical fiber F1.

[0034] The fusion splicer 1A further comprises a third drive unit 23. The third drive unit 23 supports the screen 3 and adjusts the position of the screen 3. By adjusting the position of the screen 3, the relative position of the light guide unit 3a with respect to the first optical fiber F1 and the second optical fiber F2 is adjusted.

[0035] Figures 5-8 show that one of the multiple cores CR of the first optical fiber F1 and the light guide portion 3a are aligned in the axial direction of the first optical fiber F1. Figure 9 shows that the marker MK of the first optical fiber F1 and the light guide portion 3a are aligned in the axial direction of the first optical fiber F1. As shown in Figures 5-8, the third drive unit 23 adjusts the position of the screen 3 so that one of the multiple cores CR of the first optical fiber F1 and the light guide portion 3a are aligned in the axial direction of the first optical fiber F1. As shown in Figure 9, the third drive unit 23 adjusts the position of the screen 3 so that the marker MK of the first optical fiber F1 and the light guide portion 3a are aligned in the axial direction of the first optical fiber F1. The third drive unit 23 also moves the screen 3 to position it between end faces F1a and F2a, and to retract the screen 3 from between end faces F1a and F2a. The third drive unit 23 is configured, for example, to include a motor.

[0036] The fusion splicing device 1A further comprises a pair of discharge electrodes 2. The pair of discharge electrodes 2 are positioned so that their end faces F1a and F2a face each other. The pair of discharge electrodes 2 are positioned so as to face each other along the X-axis direction, which intersects both the Z-axis direction and the Y-axis direction. The pair of discharge electrodes 2 are heating units that heat the end faces F1a and F2a by discharge in order to melt them in close proximity to each other. The end faces F1a and F2a are heated and melted in close proximity to each other, and the first optical fiber F1 and the second optical fiber F2 are fusion spliced ​​together.

[0037] The fusion splicing device 1A further comprises a control unit 4A. The control unit 4A may be composed of a computer including, for example, a CPU and memory. The control unit 4A is electrically connected to a power source (not shown) that supplies power to the discharge electrode 2 and controls the discharge current and discharge time of the discharge electrode 2. This ensures that fusion splicing is performed under conditions suitable for the types of first optical fiber F1 and second optical fiber F2. The control unit 4A also controls the operation of the first drive unit 21, the second drive unit 22 and the third drive unit 23. The operation of the first drive unit 21 and the second drive unit 22 includes bringing end faces F1a and F2a closer together, adjusting the relative position of end faces F1a and F2a in the XY plane (i.e., axial alignment), and adjusting the relative rotation angle θ between end faces F1a and F2a. The operation of the third drive unit 23 includes adjusting the position of the screen 3, positioning the screen 3 between end faces F1a and F2a, and retracting the screen 3 from between end faces F1a and F2a.

[0038] The control unit 4A aligns the axes of the first optical fiber F1 and the second optical fiber F2 as follows: First, cameras (not shown) positioned to the sides of the end faces F1a and F2a (in two directions that intersect with the Z-axis direction and are mutually orthogonal) are used to image the area around the end faces F1a and F2a. Then, the control unit 4A controls the first drive unit 21 and the second drive unit 22 so that the central axes of the first optical fiber F1 and the second optical fiber F2 included in the observed image coincide with each other.

[0039] Figure 10 is a schematic diagram showing cross-sections of the first holding part 11 and the second holding part 12 along the YZ plane. As shown in Figure 10, the fusion splicer 1A further comprises a light source 30 and a first measuring instrument 40. The light source 30 incidents test light L1 onto the first optical fiber F1. Specifically, the light source 30 irradiates the resin coating RS of the first optical fiber F1 with test light L1. In one example, the light source 30 is provided inside the first holding part 11 so as to be in contact with the first optical fiber F1. The light source 30 may also be provided so as to press the resin coating RS of the first optical fiber F1. The arrangement of the light source 30 is not limited to this, and the light source 30 may be provided outside the first holding part 11. Also, the light source 30 may be provided away from the first optical fiber F1. In that case, the first optical fiber F1 may be bent to form a curved portion, and the test light L1 may be incident on the curved portion. The position from which the light source 30 emits the test light L1 toward the first optical fiber F1 is such that the propagation of the test light L1 in the common cladding CL is sufficiently attenuated at the end face F1a, in the Z-axis direction. The test light L1 emitted from the end face F1a of the first optical fiber F1 is incident on the end face F2a of the second optical fiber F2.

[0040] The first measuring instrument 40 measures the intensity of leaked light L2 leaking from the second optical fiber F2. The first measuring instrument 40 is a power meter that measures the intensity of leaked light L2 leaking through the resin coating RS of the second optical fiber F2 when its end faces F1a and F2a are in close proximity to each other. In one example, the first measuring instrument 40 is installed inside the second holding part 12 so as to be in contact with the second optical fiber F2. The arrangement of the first measuring instrument 40 is not limited to this, and the first measuring instrument 40 may be installed outside the second holding part 12. Alternatively, the first measuring instrument 40 may be installed away from the second optical fiber F2. In that case, the second optical fiber F2 may be bent to form a curved section, and the leaked light L2 leaking from that curved section may be detected.

[0041] The light source 30 and the first measuring instrument 40 are electrically connected to the control unit 4A shown in Figure 1. The control unit 4A controls the output operation of the test light L1 in the light source 30 and receives a signal regarding the light intensity of the leaked light L2 detected by the first measuring instrument 40 as input from the first measuring instrument 40. The test light L1 irradiated onto the resin coating RS of the first optical fiber F1 passes through the resin coating RS of the first optical fiber F1 and enters the glass portion GL, where it collects at each core CR and marker MK. When the screen 3 is retracted from between the end faces F1a and F2a, the test light L1 propagates through each core CR and marker MK of the first optical fiber F1, then propagates through each core CR and marker MK of the second optical fiber F2, and the leaked light L2 leaks through the resin coating RS of the second optical fiber F2. This leaked leaked light L2 is detected by the first measuring instrument 40. Note that in Figure 10, one core CR is shown as a representative of the multiple cores CR and marker MKs.

[0042] If the positions of the core CR of the first optical fiber F1 and the core CR of the second optical fiber F2 are misaligned, the greater the misalignment, the more difficult it becomes for the test light L1 to propagate from the core CR of the first optical fiber F1 to the core CR of the second optical fiber F2, and the lower the intensity of the leaked light L2 detected by the first measuring instrument 40. Similarly, if the positions of the marker MK of the first optical fiber F1 and the marker MK of the second optical fiber F2 are misaligned, the greater the misalignment, the more difficult it becomes for the test light L1 to propagate from the marker MK of the first optical fiber F1 to the marker MK of the second optical fiber F2, and the lower the intensity of the leaked light L2 detected by the first measuring instrument 40. Therefore, the control unit 4A controls one or both of the first drive unit 21 and the second drive unit 22 to adjust the relative rotation angle θ between the end faces F1a and F2a so that the intensity of the leaked light L2 detected by the first measuring instrument 40 approaches its maximum value. This allows the position of the core CR of the first optical fiber F1 and the position of the core CR of the second optical fiber F2 to be aligned with each other.

[0043] When screen 3 is positioned between end faces F1a and F2a, the test light L1 propagating through the core CR of the first optical fiber F1 that faces the light guide 3a passes through the light guide 3a. The test light L1 propagating through the core CR of the first optical fiber F1 that faces the light shielding 3b is shielded by the light shielding 3b. The test light L1 that has passed through the light guide 3a propagates through the core CR of the second optical fiber F2 that faces the light guide 3a, and the leaked light L2 leaks through the resin coating RS of the second optical fiber F2.

[0044] Similarly, when screen 3 is positioned between end faces F1a and F2a, and the marker MK of the first optical fiber F1 faces the light guide 3a, the test light L1 emitted from marker MK passes through the light guide 3a. At this time, all test light L1 except for the test light L1 emitted from marker MK is blocked by the light shielding 3b. The test light L1 that has passed through the light guide 3a propagates through the marker MK of the second optical fiber F2, and the leaked light L2 leaks through the resin coating RS of the second optical fiber F2.

[0045] Figure 11 is a flowchart showing the operation of the fusion splicing device 1A. Referring to Figure 11, the operation of the fusion splicing device 1A and the fusion splicing method according to this embodiment will be described. When the screen 3 is positioned between end faces F1a and F2a, the fusion splicing device 1A retracts the screen 3 from between end faces F1a and F2a. First, in step ST11, the control unit 4A controls the first drive unit 21 and the second drive unit 22 so that end faces F1a and F2a move closer to each other. As a result, end faces F1a and F2a face each other. However, a small gap exists between end faces F1a and F2a. For example, there is a gap between end faces F1a and F2a with a length of 50 μm or less. Next, in step ST12, a camera positioned to the side of end faces F1a and F2a is used to image the area around end faces F1a and F2a. Then, the control unit 4A controls the first drive unit 21 and the second drive unit 22 so that the central axes of the first optical fiber F1 and the second optical fiber F2 included in the observed image coincide with each other.

[0046] In step ST13, the relative rotation angle θ of the first optical fiber F1 and the second optical fiber F2 is adjusted. Step ST13 will be explained in detail with reference to Figure 12. Figure 12 is a flowchart showing the operation of the fusion splicer 1A when adjusting the relative rotation angle θ of the first optical fiber F1 and the second optical fiber F2. In step ST131, the light source 30 irradiates the resin coating RS of the first optical fiber F1 with test light L1. Then, in step ST132, the first measuring instrument 40 measures the intensity of the leaked light L2 leaking through the resin coating RS of the second optical fiber F2. Then, in step ST133, the control unit 4A adjusts the relative rotation angle θ of the first optical fiber F1 and the second optical fiber F2 based on the intensity of the leaked light L2 measured in step ST132. At this time, the control unit 4A controls one or both of the first drive unit 21 and the second drive unit 22 to adjust the relative rotation angle θ between the end face F1a and the end face F2a so that the intensity of the leaked light L2 measured by the first measuring instrument 40 approaches its maximum value. The control unit 4A records the first intensity, which is the maximum value of the intensity of the leaked light L2 measured by the first measuring instrument 40.

[0047] Returning to Figure 10, in step ST14, the intensity of the test light L1 emitted from each of the multiple cores CR of the first optical fiber F1 is measured, as well as the intensity of the test light L1 emitted from the marker MK of the first optical fiber F1. The details of step ST14 will be explained with reference to Figure 13. Figure 13 is a flowchart showing the operation of the fusion splicer 1A when it measures the intensity of the test light L1 emitted from each of the cores CR of the first optical fiber F1, as well as the intensity of the test light L1 emitted from the marker MK of the first optical fiber F1. In step ST141, the third drive unit 23 positions the screen 3 between the end faces F1a and F2a. In step ST142, the third drive unit 23 adjusts the position of the screen 3. Specifically, the third drive unit 23 adjusts the position of the screen 3 so that the light guide 3a is aligned with one of the multiple cores CR and marker MK of the first optical fiber F1 in the axial direction of the first optical fiber F1.

[0048] The third drive unit 23 may adjust the position of the screen 3 based on the coordinates of each core CR of the first optical fiber F1 and the coordinates of the marker MK, which are captured by a camera (not shown) located on the side between end faces F1a and F2a. The third drive unit 23 may also adjust the position of the screen 3 based on the position of the marker MK of the first optical fiber F1 captured by the camera, and data relating to the coordinates of each core of the first optical fiber F1 and the coordinates of the marker MK.

[0049] Then, in step ST143, the light source 30 irradiates the resin coating RS of the first optical fiber F1 with test light L1. Then, in step ST144, the first measuring instrument 40 measures the intensity of the leaked light L2 that leaks through the resin coating RS of the second optical fiber F2. The control unit 4A records the intensity of the leaked light L2 corresponding to each core CR of the first optical fiber F1 from the leaked light L2 measured by the first measuring instrument 40 as the core intensity. The control unit 4A also records the intensity of the leaked light L2 corresponding to the marker MK of the first optical fiber F1 from the leaked light L2 measured by the first measuring instrument 40 as the marker intensity. By measuring the intensity of the leaked light L2, the control unit 4A essentially measures the intensity of the test light L1. The control unit 4A records the core intensity in association with each of the multiple cores CR of the first optical fiber F1. Specifically, it records the core intensity in association with the coordinates of each of the multiple cores CR of the first optical fiber F1. Then, in step ST145, the control unit 4A determines whether or not it has measured the intensity of the test light L1 emitted from each of the cores CR and markers MK of the first optical fiber F1. If there are any unmeasured cores CR or markers MK among the multiple cores CR and markers MK of the first optical fiber F1, the control unit 4A adjusts the position of the screen 3 so that either the unmeasured core CR or marker MK and the light guide 3a are aligned in the axial direction of the first optical fiber F1. Then, steps ST142 to ST144 are performed again.

[0050] If the control unit 4A determines in step ST145 that it has measured the intensity of the test light L1 emitted from each of the cores CR and markers MK of the first optical fiber F1, then in step ST146, the control unit 4A calculates a second intensity, which is the sum of the core intensities corresponding to each of the multiple cores CR of the first optical fiber F1. The second intensity may further include the marker intensities. The control unit 4A then calculates the ratio of the first intensity to the second intensity. The control unit 4A determines whether the ratio of the first intensity to the second intensity is within a predetermined first range. The predetermined first range is, for example, defined as the range of values ​​obtained by dividing the second intensity by the first intensity.

[0051] If the control unit 4A determines in step ST146 that the ratio of the first intensity to the second intensity is within a predetermined first range, then step ST147 is performed. If the control unit 4A determines in step ST146 that the ratio of the first intensity to the second intensity is not within a predetermined first range, then the process returns to step ST13, and each step is performed in the order of the flowchart shown in Figure 11.

[0052] In step ST147, the control unit 4A calculates the ratio of the maximum core strength to the minimum core strength. The maximum core strength is the highest core strength among the core strengths corresponding to each of the multiple cores CR of the first optical fiber F1. The maximum core strength may also be the maximum value among the core strength and marker strength corresponding to each of the multiple cores CR of the first optical fiber F1. The minimum core strength is the lowest core strength among the core strengths corresponding to each of the multiple cores CR of the first optical fiber F1. The minimum core strength may also be the minimum value among the core strength and marker strength corresponding to each of the multiple cores CR of the first optical fiber F1. The control unit 4A determines whether the ratio of the maximum core strength to the minimum core strength is within a predetermined second range. The predetermined second range is defined, for example, as the range of values ​​obtained by dividing the maximum core strength by the minimum core strength.

[0053] If the control unit 4A determines in step ST147 that the ratio of the maximum core strength to the minimum core strength is within a predetermined second range, then step ST148 is performed. If the control unit 4A determines in step ST147 that the ratio of the maximum core strength to the minimum core strength is not within the predetermined second range, then the process returns to step ST13, and each step is performed in the order of the flowchart shown in Figure 11.

[0054] In step ST148, the control unit 4A retracts the screen 3 from between the end face F1a and the end face F2a.

[0055] Returning to Figure 11, in step ST15, a discharge is performed between the pair of discharge electrodes 2, heating and melting the respective end faces F1a and F2a of the first optical fiber F1 and the second optical fiber F2, and connecting them to each other. Then, in step ST16, the fusion splice state between end face F1a and end face F2a is confirmed. The details of step ST16 will be explained with reference to Figure 14. Figure 14 is a flowchart showing the operation of the fusion splice device 1A when it confirms the fusion splice state between end face F1a and end face F2a.

[0056] In step S161, the light source 30 irradiates the resin coating RS of the first optical fiber F1 with test light L1. Then, in step ST162, the first measuring instrument 40 measures the intensity of the leaked light L2 that leaks through the resin coating RS of the second optical fiber F2. The control unit 4A records the third intensity, which is the intensity of the leaked light L2 measured by the first measuring instrument 40. Then, in step ST163, the control unit 4A determines whether the ratio of the second intensity to the third intensity is within a predetermined third range. The predetermined third range is defined, for example, as the range of values ​​obtained by dividing the third intensity by the second intensity. If the ratio of the second intensity to the third intensity is within the predetermined third range, the control unit 4A determines that the fusion splice state between end faces F1a and F2a is normal. If the ratio of the second intensity to the third intensity is outside the predetermined third range, the control unit 4A determines that the fusion splice state between end faces F1a and F2a is abnormal. The control unit 4A is an example of a determination unit in this embodiment.

[0057] In step ST163, if the control unit 4A determines that the fusion splice state between end face F1a and end face F2a is abnormal, the fusion splice device 1A may inform the user that the fusion splice state between end face F1a and end face F2a is abnormal. In this case, the fusion splice device 1A may further include a configuration that outputs a signal that the user can perceive through sight or hearing that the fusion splice state between end face F1a and end face F2a is abnormal. If the control unit 4A determines in step ST163 that the fusion splice state between end face F1a and end face F2a is abnormal, the process returns to step ST11 and each step is performed in the order of the flowchart shown in Figure 11.

[0058] The effects obtained by the fusion splicing apparatus 1A and fusion splicing method of this embodiment, which have the above configuration, will now be described. In the fusion splicing apparatus 1A of this embodiment, the test light L1 emitted from any of the cores CR of the first optical fiber F1 passes through the screen 3 by the light guide 3a. Similarly, in the fusion splicing method of this embodiment, all test light L1 except for the test light L1 emitted from any of the cores CR of the first optical fiber F1 is blocked. Therefore, the first measuring instrument 40 can measure the intensity of the test light L1 emitted from any of the cores CR of the first optical fiber F1 by measuring the intensity of the leaked light L2 leaking from the second optical fiber F2. Furthermore, in the fusion splicing apparatus 1A of this embodiment, the third drive unit 23 adjusts the position of the screen 3 so that one of the multiple cores CR of the first optical fiber F1 and the light guide 3a are aligned in the axial direction of the first optical fiber F1. Therefore, the first measuring instrument 40 can measure the intensity of the test light L1 emitted from each of the multiple core CRs of the first optical fiber F1 for each core CR by measuring the intensity of the leaked light L2 leaking from the second optical fiber F2. In the fusion splicing method of this embodiment, the process of measuring the intensity of the leaked light L2 leaking from the second optical fiber F2 is performed for each of the multiple core CRs of the first optical fiber F1, while shielding the other test light L1s emitted from the end face F1a of the first optical fiber F1, except for the test light L1 emitted from any of the core CRs of the first optical fiber F1. This makes it possible to confirm the optical conductivity state of each of the multiple core CRs of the first optical fiber F1, the optical conductivity state of each of the multiple core CRs of the second optical fiber F2, and the positional relationship between the multiple core CRs of the first optical fiber F1 and the multiple core CRs of the second optical fiber F2. Thus, the optical conductivity state of each individual core CR can be confirmed.

[0059] As described above, the first measuring instrument 40 may measure the first intensity, which is the intensity of the leaked light L2, when the third driving unit 23 retracts the screen 3 from between the end faces F1a and F2a, and the first driving unit 21 and the second driving unit 22 are each adjusted to have their rotation angles θ such that the leaked light L2 measured by the first measuring instrument 40 is at its maximum intensity. The first measuring instrument 40 may also measure the core intensity, which is the intensity of the leaked light L2, for each of the multiple cores CR of the first optical fiber F1, when the third driving unit 23 adjusts the position of the screen 3 so that one of the multiple cores CR of the first optical fiber F1 and the light guide 3a are aligned in the axial direction of the first optical fiber F1. The end faces F1a and F2a may be fusion spliced ​​together when the ratio of the second intensity, which is the sum of the core intensities corresponding to each of the multiple cores CR of the first optical fiber F1, to the first intensity is within a predetermined first range. In this case, theoretically, the second intensity has a predetermined ratio to the first intensity. However, when each of the multiple cores CR of the first optical fiber F1 and the light guide portion 3a are aligned in the axial direction of the first optical fiber F1, a misalignment occurs, causing the second intensity to become smaller than the predetermined ratio to the first intensity. Therefore, by checking the ratio of the first intensity to the second intensity, it is possible to confirm whether the screen 3 is positioned appropriately.

[0060] As described above, end faces F1a and F2a may be fusion spliced ​​together if the ratio of the minimum core strength to the maximum core strength among the core strengths corresponding to each of the multiple cores CR of the first optical fiber F1 is within a predetermined second range. If dust or scratches are present in any of the multiple cores CR of the first optical fiber F1, the core strength corresponding to that core CR will be smaller than the core strength corresponding to a core CR that does not have dust or scratches. With the above configuration, by confirming that the ratio of the maximum core strength to the minimum core strength is within a predetermined second range, it is possible to confirm that there is no dust or scratches in the core CR corresponding to the minimum core strength. Therefore, the optical conductivity state of each of the multiple cores CR can be confirmed.

[0061] As described above, when end faces F1a and F2a are fusion-spliced, the first measuring instrument 40 may measure the third intensity, which is the intensity of the leaked light L2. The fusion splicing device 1A may further include a control unit 4A (determination unit) that determines the state of the fusion splicing between end faces F1a and F2a. The control unit 4A may determine that the state of the fusion splicing between end faces F1a and F2a is abnormal if the ratio of the second intensity, which is the sum of the core intensities corresponding to each of the multiple cores CR of the first optical fiber F1, to the third intensity is outside a predetermined third range. In this case, theoretically, the third intensity has a predetermined ratio to the second intensity. However, due to the misalignment of the multiple cores CR of the first optical fiber F1 and the multiple cores CR of the second optical fiber F2 that occurs during fusion splicing, the ratio of the third intensity to the second intensity may become smaller than the predetermined ratio. In the above configuration, if the ratio of the third intensity to the second intensity is outside a predetermined third range, it is determined that the fusion splice state between end face F1a and end face F2a is abnormal. This makes it possible to detect the misalignment between the multiple cores CR of the first optical fiber F1 and the multiple cores CR of the second optical fiber F2 that occurs during fusion splicing.

[0062] As mentioned above, the first optical fiber F1 and the second optical fiber F2 may further have markers MK. The third drive unit 23 may further adjust the screen 3 so that the light guide 3a is aligned with the marker MK in the axial direction of the first optical fiber F1. By using the marker MK as a position reference for the rotation angle θ around the axis of the first optical fiber F1 and the rotation angle θ around the axis of the second optical fiber F2, misconnection of the core CR can be prevented even if the core CR arrangement has rotational symmetry.

[0063] As mentioned above, the light guide 3a may be a through hole. In this case, for example, compared to the case where the light guide 3a is made of a transparent flat plate, the reflection of the test light L1 by the light guide 3a can be suppressed when the test light L1 passes through the light guide 3a. Therefore, it is possible to suppress the effect of the test light L1 returning to the light source 30 on the operation of the light source 30.

[0064] As mentioned above, the light-shielding portion 3b of the screen 3 may be coated with an anti-reflective coating. In this case, the reflection of the test light L1 by the screen 3 can be suppressed. Therefore, it is possible to suppress the effect of the light source 30 on the operation of the light source 30 by the test light L1 returning to the light source 30.

[0065] In this embodiment, the light guide 3a may be a focusing lens 3c. Figure 15 is a front view of a screen 3 in which the light guide 3a is a focusing lens 3c. The focusing lens 3c focuses the test light L1 emitted from any of the cores CR of the first optical fiber F1 toward the focusing lens 3c toward the core CR of the second optical fiber F2 corresponding to the core CR from which the test light L1 was emitted. The focusing lens 3c focuses the test light L1 emitted from the marker MK of the first optical fiber F1 toward the marker MK of the second optical fiber F2. In this case, the test light L1 emitted from the end face F1a is focused toward the end face F2a by the focusing lens. Therefore, leakage of the test light L1 can be suppressed between the time the test light L1 is emitted from the end face F1a and the time it is incident on the end face F2a. Consequently, the amount of light incident on the end face F2a can be increased, and the amount of leaked light L2 can be increased. As a result, the accuracy of the first measuring instrument 40 when measuring the intensity of leaked light L2 can be improved.

[0066] In the fusion splicing method of this embodiment, the decision of whether or not to connect end faces F1a and F2a may be made based on the intensity of leaked light L2 measured for each of the multiple cores CR of the first optical fiber F1. Alternatively, in the fusion splicing method of this embodiment, the decision of whether or not to connect end faces F1a and F2a may be made based on the intensity of leaked light L2 measured for each of the multiple cores CR and markers MK of the first optical fiber F1. In this case, it is possible to prevent connecting end faces F1a and F2a when the optical conductivity of the multiple cores CR is poor.

[0067] In step ST146, if the control unit 4A determines that the ratio of the first intensity to the second intensity is not within a predetermined first range, the control unit 4A checks each core intensity and marker intensity to determine the optimal coordinates of each core CR of the first optical fiber F1 where the core intensity is maximum, and the optimal coordinates of the marker MK where the marker intensity is maximum. Then, based on the average value of these coordinates, the relative rotation angle θ between the first optical fiber F1 and the second optical fiber F2 may be adjusted. Alternatively, the relative rotation angle θ between the first optical fiber F1 and the second optical fiber F2 may be adjusted based on the optimal coordinate of either each core CR of the first optical fiber F1 or the marker MK. The same applies if, in step ST147, the control unit 4A determines that the ratio of the maximum core intensity to the minimum core intensity is not within a predetermined second range.

[0068] Instead of performing step ST13, the fusion splicer 1A may perform step ST13A as shown in Figure 16. In step ST13A, the rotation angle θ of the first optical fiber F1 and the rotation angle θ of the second optical fiber F2 are adjusted using end-face observation. Step ST13A will be described in detail with reference to Figures 16 and 17. Figure 16 is a flowchart showing the operation of the fusion splicer 1A when adjusting the rotation angle θ of the first optical fiber F1 and the rotation angle θ of the second optical fiber F2 using end-face observation. Figure 17 is a schematic diagram showing cross-sections of the first holding part 11 and the second holding part 12 along the YZ plane.

[0069] As shown in Figure 17, the fusion splicer 1A further includes a light source 31, an imaging unit 60, and a mirror 61. The light source 31 incidents test light L1 onto the second optical fiber F2. Specifically, the light source 31 irradiates the resin coating RS of the second optical fiber F2 with test light L1. In one example, the light source 31 is positioned inside the second holding unit 12 so as to be in contact with the second optical fiber F2.

[0070] The imaging unit 60 is a camera that acquires observation images of the end faces F1a and F2a of the first optical fiber F1 and the second optical fiber F2, respectively. In the illustrated example, the imaging unit 60 is positioned to the side of the end faces F1a and F2a (along the XY plane in Figure 1). The mirror 61 is positioned between the end face F1a of the first optical fiber F1 and the end face F2a of the second optical fiber F2. The angle of the mirror 61 is adjusted along the rotation direction A1 depending on whether the imaging unit 60 is imaging the end face F1a of the first optical fiber F1 or observing the end face F2a of the second optical fiber F2. When the mirror 61 is positioned to reflect the observation light from the end face F1a of the first optical fiber F1 towards the imaging unit 60, the imaging unit 60 outputs an observation image of the end face F1a of the first optical fiber F1. When the mirror 61 is positioned to reflect the observation light from the end face F2a of the second optical fiber F2 toward the imaging unit 60, the imaging unit 60 outputs an observation image of the end face F2a of the second optical fiber F2. The mirror 61 is retracted to a position away from the space between the end faces F1a and F2a by a drive unit (not shown) of the fusion splicing device 1A.

[0071] In step ST131A, a mirror 61 is placed between the end face F1a of the first optical fiber F1 and the end face F2a of the second optical fiber F2. In step ST132A, test light L1 is shone onto the resin coating RS of the first optical fiber F1. The image of the first optical fiber F1 is reflected by the mirror 61, and the imaging unit 60 acquires an observation image of the end face F1a of the first optical fiber F1. Then, in step 133A, the mirror 61 is rotated along the rotation direction A1. Then, in step 134A, test light L1 is shone onto the resin coating RS of the second optical fiber F2. The image of the second optical fiber F2 is reflected by the mirror 61, and the imaging unit 60 acquires an observation image of the end face F2a of the second optical fiber F2. In the subsequent step ST135A, the relative rotation angle θ between the first optical fiber F1 and the second optical fiber F2 is adjusted based on the observation images of the end face F1a of the first optical fiber F1 and the end face F2a of the second optical fiber F2. In step ST136A, the mirror 61 is retracted. (Second Embodiment)

[0072] Figure 18 shows a part of the configuration of the fusion splicing device 1B according to the second embodiment. The fusion splicing device 1B mainly differs from the fusion splicing device 1A according to the first embodiment in that it further includes a second measuring instrument 50. Instead of the control unit 4A that is included in the fusion splicing device 1A, the fusion splicing device 1B is equipped with a control unit 4B.

[0073] The second measuring instrument 50 measures the intensity of the test light L1 emitted after passing through the light guide section 3a. The second measuring instrument 50 is a power meter that measures the intensity of the test light L1 when it is in close proximity to the screen 3. When the second optical fiber F2 is retracted from the axis of the first optical fiber F1, the second measuring instrument 50 is positioned in a first position with the screen 3 between it and the end face F1a. The second measuring instrument 50 is configured to be movable between its first position and a second position located away from the first position.

[0074] The control unit 4B differs from the control unit 4A mainly in that it is further electrically connected to the second measuring instrument 50 and receives a signal from the second measuring instrument 50 regarding the light intensity of the test light L1 measured by the second measuring instrument 50.

[0075] The operation of fusion splicer 1B differs from that of fusion splicer 1A in that it performs step ST10, shown in Figure 19, before step ST11, shown in Figure 11. In step ST10, the intensity of the test light L1 emitted from each of the multiple cores CR of the first optical fiber F1 is measured for each core CR using the second measuring instrument 50. Step ST10 will be explained in detail with reference to Figure 19. Figure 19 is a flowchart showing the operation of fusion splicer 1B when it measures the intensity of the test light L1 emitted from each of the multiple cores CR of the first optical fiber F1 using the second measuring instrument 50.

[0076] First, in step ST101, the fusion splicer 1B arranges the first optical fiber F1, the screen 3, and the second measuring instrument 50 in that order in the Z-axis direction. In step ST102, the third drive unit 23 adjusts the position of the screen 3. Specifically, the third drive unit 23 adjusts the position of the screen 3 so that the light guide 3a is aligned with one of the multiple cores CR and markers MK of the first optical fiber F1 in the axial direction of the first optical fiber F1. Then, in step ST103, the light source 30 irradiates the resin coating RS of the first optical fiber F1 with test light L1. Then, in step ST104, the second measuring instrument 50 measures the intensity of the test light L1 emitted from one core CR and passing through the light guide 3a. The control unit 4B records the intensity of the test light L1 measured by the second measuring instrument 50.

[0077] Then, in step ST105, the control unit 4B determines whether or not it has measured the intensity of the test light L1 emitted from each of the cores CR and markers MK of the first optical fiber F1. If there are any unmeasured cores CR or markers MK among the multiple cores CR and markers MK of the first optical fiber F1, the control unit 4B adjusts the position of the screen 3 so that either the unmeasured core CR or marker MK and the light guide 3a are aligned in the axial direction of the first optical fiber F1. Then, steps ST102 to ST104 are performed again.

[0078] If the control unit 4B determines that it has measured the intensity of the test light L1 emitted from all the cores CR of the first optical fiber F1, in step ST106, the screen 3 and the second measuring instrument 50 are moved to a retracted position. Specifically, the second measuring instrument 50 is moved to the second position described above. Then, in step ST107, the second optical fiber F2 is returned to its original position. Specifically, the second optical fiber F2 is positioned so that its end face F1a and its end face F2a face each other.

[0079] The effects obtained by the fusion splicing apparatus 1B of the second embodiment having the above configuration will now be described. In the fusion splicing apparatus 1B according to the second embodiment, the second measuring instrument 50 directly measures the intensity of the test light L1 emitted from each of the cores CR of the first optical fiber F1 for each core CR. Therefore, the optical conductivity state of the multiple cores CR of the first optical fiber F1 can be confirmed with even greater accuracy.

[0080] If the light emission efficiency when light exits from the core CR of the second optical fiber F2 through the resin coating RS is known, the sum of the intensities of the test light L1 measured by the second measuring instrument 50, corresponding to each of the multiple cores CR of the first optical fiber F1, may be compared with the intensity of the leaked light L2. This allows the amount of loss at the boundary between the first optical fiber F1 and the second optical fiber F2 to be derived. [Explanation of symbols]

[0081] 1A, 1B... Fusion splicing equipment 11...First holding part 12...Second holding part 2...Discharge electrode 21...First drive unit 22...Second drive unit 23...Third drive unit 3…Screen 3a...Light guiding part 3b…shading part 30…Light source 40…First measuring device 50…Second measuring device CR... Core F1... First Optical Fiber F1a...end face F2...Second optical fiber F2a...end face L1…Test light L2... Leaked light MK... Marker θ... Rotation angle (first angle, second angle)

Claims

1. A fusion splicing apparatus for fusion splicing the end face of a first optical fiber having multiple cores and the end face of a second optical fiber having multiple cores, A first holding portion holds the first optical fiber with the end face of the first optical fiber and the end face of the second optical fiber facing each other, A second holding portion holds the second optical fiber in a state where the end face of the first optical fiber and the end face of the second optical fiber are facing each other, A screen is disposed between the end face of the first optical fiber and the end face of the second optical fiber, having a light guide portion through which only light emitted from one of the multiple cores of the first optical fiber can pass, and a light shielding portion that shields light that does not pass through the light guide portion. A light source that simultaneously emits test light into the multiple cores of the first optical fiber, A first measuring instrument for measuring the intensity of leaked light that leaks from the second optical fiber, out of the test light emitted from the end face of the first optical fiber and incident on the end face of the second optical fiber, A discharge electrode that heats the end face of the first optical fiber and the end face of the second optical fiber, A first drive unit that adjusts the position of the first holding portion and the first angle, which is the rotation angle of the first optical fiber around its axis, A second drive unit adjusts the position of the second holding portion and the second angle, which is the rotation angle of the second optical fiber around its axis. A third drive unit that adjusts the position of the screen so that one of the plurality of cores of the first optical fiber and the light guide portion are aligned in the axial direction of the first optical fiber, and retracts the screen from between the end face of the first optical fiber and the end face of the second optical fiber, A fusion splicing device equipped with the following features.

2. The third drive unit retracts the screen from between the end face of the first optical fiber and the end face of the second optical fiber, and the first drive unit and the second drive unit each adjust the first angle and the second angle, respectively, so that the leaked light measured by the first measuring instrument has the maximum intensity. With this adjustment, the first measuring instrument measures the first intensity, which is the intensity of the leaked light. The first measuring instrument measures the core intensity, which is the intensity of the leaked light, for each of the multiple cores of the first optical fiber, when the third drive unit adjusts the position of the screen so that one of the multiple cores of the first optical fiber and the light guide portion are aligned in the axial direction of the first optical fiber. The fusion splicing apparatus according to claim 1, wherein the end face of the first optical fiber and the end face of the second optical fiber are fusion spliced ​​together when the ratio of the second strength, which is the sum of the core strengths corresponding to each of the plurality of cores of the first optical fiber, to the first strength is within a predetermined first range.

3. The first measuring instrument measures the core intensity, which is the intensity of the leaked light, for each of the multiple cores of the first optical fiber, when the third drive unit adjusts the position of the screen so that one of the multiple cores of the first optical fiber and the light guide portion are aligned in the axial direction of the first optical fiber. The fusion splicing apparatus according to claim 1, wherein the end face of the first optical fiber and the end face of the second optical fiber are fusion spliced ​​together when the ratio of the minimum core strength to the maximum core strength among the core strengths corresponding to each of the plurality of cores of the first optical fiber is within a predetermined second range.

4. The first measuring instrument measures the core intensity, which is the intensity of the leaked light, for each of the multiple cores of the first optical fiber, when the third drive unit adjusts the position of the screen so that one of the multiple cores of the first optical fiber and the light guide portion are aligned in the axial direction of the first optical fiber. With the end face of the first optical fiber and the end face of the second optical fiber fused together, the first measuring instrument measures the third intensity, which is the intensity of the leaked light. The fusion splicing apparatus further includes a determination unit for determining the state of fusion splicing between the end face of the first optical fiber and the end face of the second optical fiber. The fusion splicing apparatus according to claim 1, wherein the determination unit determines that the state of the fusion splicing between the end face of the first optical fiber and the end face of the second optical fiber is abnormal when the ratio of the second strength, which is the sum of the core strengths corresponding to each of the plurality of cores of the first optical fiber, to the third strength is outside a predetermined third range.

5. The first optical fiber and the second optical fiber further have markers, The fusion splicing apparatus according to any one of claims 1 to 4, wherein the third drive unit further adjusts the screen so that the light guide is aligned with the marker and the first optical fiber in the axial direction.

6. The fusion splicing apparatus according to any one of claims 1 to 4, wherein the light guide portion is a through hole.

7. The fusion splicing apparatus according to any one of claims 1 to 4, wherein the light guide portion is a focusing lens.

8. The fusion splicing apparatus according to any one of claims 1 to 4, wherein the light-shielding portion of the screen is coated with an anti-reflective coating.

9. The device further comprises a second measuring instrument configured to be movable between a first position, which sandwiches the screen between itself and the end face of the first optical fiber, and a second position, which is located away from the first position, and which measures the intensity of the test light emitted from the end face of the first optical fiber through the light guide portion of the screen, The fusion splicing apparatus according to any one of claims 1 to 4, wherein the second drive unit retracts the second optical fiber, and the third drive unit adjusts the position of the screen so that the light guide and one of the plurality of cores of the first optical fiber are aligned in the axial direction of the first optical fiber, the second measuring instrument measures the intensity of the test light emitted from each of the plurality of cores of the first optical fiber through the light guide at the first position, and after the measurement, the second measuring instrument moves to the second position, and the second drive unit returns the second optical fiber to a position facing the first optical fiber.

10. A fusion splicing method for fusion splicing the end face of a first optical fiber having multiple cores and the end face of a second optical fiber having multiple cores, A step of bringing the end face of the first optical fiber and the end face of the second optical fiber facing each other, A step of aligning the central axis of the first optical fiber and the central axis of the second optical fiber, A step of adjusting the rotation angle of the first optical fiber around its axis and the rotation angle of the second optical fiber around its axis, A step of simultaneously irradiating the multiple cores of the first optical fiber with test light, A step of measuring the intensity of leaked light leaking from the second optical fiber, while shielding the test light emitted from the end face of the first optical fiber, except for the test light emitted from one of the multiple cores of the first optical fiber, is performed for each of the multiple cores of the first optical fiber. A step of determining whether or not to connect the end face of the first optical fiber and the end face of the second optical fiber based on the intensity of the leaked light corresponding to each of the plurality of cores of the first optical fiber, A fusion splicing method comprising the above.

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