Fusion splicing device and core location method

Abstract

A fusion splicing device (1) according to an embodiment comprises: a discharge electrode (4) that generates a discharge; a microscope (13) that acquires brightness information from an optical fiber (F) heated by receiving the discharge; a distribution information acquisition unit (7) that acquires distribution information (B1) to (B5) indicating the relation between a position in the radial direction of the optical fiber and the brightness information; and a core position specification unit (8) that specifies the position of a core of the optical fiber from the distribution information. The microscope (13) acquires the brightness information multiple times with a time lag therebetween. The distribution information acquisition unit (7) acquires the distribution information from each of the multiple pieces of brightness information. The core position specification unit (8) specifies the position of the core (F1) of the optical fiber (F) by performing weighting such that the weight of the distribution information based on the brightness information acquired earlier among the multiple pieces of distribution information becomes greater than or equal to the weight of the distribution information based on the brightness information acquired later.

Description

Technical Field

[0001] The present disclosure relates to a fusion connection device and a core position identification method. This application claims priority based on Japanese Application No. 2021-061019 filed on March 31, 2021, and incorporates all the descriptions described in the above Japanese application.

Background Art

[0002] Patent Document 1 describes a method for identifying the type of optical fiber in a fusion connection device. The fusion connection device includes a pair of discharge electrodes for fusing and connecting a pair of optical fibers to each other, an imaging device for imaging the pair of optical fibers, and an image processing unit for performing image processing on the images of the pair of optical fibers imaged by the imaging device. The imaging device acquires images of the optical fiber in a state heated by discharge and images of the optical fiber in a non-heated state. The image processing unit identifies the type of optical fiber by performing image processing on the image of the optical fiber in the heated state and the image of the optical fiber in the non-heated state.

[0003] Patent Document 2 describes a method for identifying the eccentricity of the core of an optical fiber in a method of coupling optical waveguides. In this method, the core is excited by heating the optical waveguide and visible light is emitted from the core. The position of the core is identified from the intensity distribution of the emitted visible light. Then, the position of the cladding is identified by irradiating the optical waveguide with a lighting unit and measuring the intensity distribution of the light irradiated on the optical waveguide. The eccentricity of the core in the optical fiber is identified from the identified position of the core and the position of the cladding.

[0004] Patent Document 3 describes a fusion splicing apparatus that heats a pair of optical fibers by electrical discharge. In this fusion splicing apparatus, images of the thermal emission generated from the core and cladding of the optical fibers heated by electrical discharge are acquired. The dopant concentration in the core is higher than that in the cladding. Therefore, the acquired thermal emission brightness waveform has a peak in the core. This peak has a high correlation with the MFD (Mode Field Diameter) of the optical fiber. In the subsequent device, the MFD of the optical fiber is determined from the luminance waveform by utilizing the fact that the peak of the luminance waveform has a high correlation with the MFD. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2003 / 0164939 [Patent Document 2] Special Publication No. 2008-519970 [Patent Document 3] U.S. Patent Application Publication No. 2006 / 0051043 [Overview of the project]

[0006] The fusion splicing apparatus according to this disclosure is a fusion splicing apparatus that fusion splices a pair of optical fibers together by electrical discharge. The fusion splicing apparatus comprises a discharge electrode that generates an electrical discharge, a microscope that acquires brightness information from an optical fiber heated by the electrical discharge, a distribution information acquisition unit that acquires distribution information showing the relationship between the radial position of the optical fiber and the brightness information, and a core position identification unit that identifies the position of the optical fiber core from the distribution information. The microscope acquires brightness information multiple times with a time difference. The distribution information acquisition unit acquires distribution information from each of the multiple brightness information sets. The core position identification unit identifies the position of the optical fiber core by weighting the distribution information based on the brightness information acquired earlier among the multiple distribution information sets so that the weight of the distribution information based on the brightness information acquired later is greater than or equal to the weight of the distribution information based on the brightness information acquired later.

[0007] The core location method relating to this disclosure is a core location method for determining the location of each core of a pair of optical fibers when a pair of optical fibers are fusion-spliced ​​together by electrical discharge. The core location method comprises the steps of generating an electrical discharge, acquiring brightness information from an optical fiber heated by the electrical discharge, acquiring distribution information showing the relationship between the radial position of the optical fiber and the brightness information, and determining the location of the optical fiber core from the distribution information. In the step of acquiring brightness information, brightness information is acquired multiple times with a time difference. In the step of acquiring distribution information, distribution information is acquired from each of the multiple brightness information sources. In the step of determining the core location, the location of the optical fiber core is determined by weighting the distribution information based on the brightness information acquired earlier among the multiple distribution information sources so that the weight of the distribution information based on the brightness information acquired later is greater than or equal to the weight of the distribution information based on the brightness information acquired later. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a diagram illustrating the overview of a fusion splicing apparatus according to one embodiment. [Figure 2] Figure 2 shows the optical system for observing the optical fiber in the fusion splicer shown in Figure 1. [Figure 3] Figure 3 schematically shows the positional relationship between the light source and microscope of the optical system in Figure 2 and the optical fiber. [Figure 4] Figure 4 shows the luminance waveform, which illustrates the relationship between the radial position of the optical fiber and its luminance, obtained from the luminance image. [Figure 5] Figure 5 is a schematic diagram showing the configuration for discharging into an optical fiber, observing the optical fiber, and acquiring distribution information. [Figure 6] Figure 6 is a schematic graph showing the relationship (distribution information) between the radial position of the optical fiber and the brightness of the optical fiber's brightness image due to light emission. [Figure 7] Figure 7 is a flowchart showing an example of the steps of a core location method according to one embodiment. [Modes for carrying out the invention]

[0009] Incidentally, in fusion splicing equipment, if the microscope resolution is insufficient, it may not be possible to accurately determine the position of the optical fiber core from the image. In this case, when a luminance waveform is acquired from the optical fiber image, the position of the peak in that luminance waveform cannot be obtained appropriately. As a result, it may not be possible to accurately determine the position of the optical fiber core. Therefore, it is necessary to determine the position of the optical fiber core with higher precision.

[0010] This disclosure aims to provide a fusion splicing apparatus and a core positioning method that can accurately determine the position of the core of an optical fiber.

[0011] [Description of Embodiments in this Disclosure] First, embodiments of this disclosure will be listed and described. One embodiment of a fusion splicing apparatus is a fusion splicing apparatus that fusion splices a pair of optical fibers together by electrical discharge. The fusion splicing apparatus comprises a discharge electrode that generates an electrical discharge, a microscope that acquires brightness information generated from an optical fiber heated by the electrical discharge, a distribution information acquisition unit that acquires distribution information showing the relationship between the radial position of the optical fiber and the brightness information, and a core position identification unit that identifies the position of the optical fiber core from the distribution information. The microscope acquires brightness information multiple times with a time difference. The distribution information acquisition unit acquires distribution information from each of the multiple brightness information. The core position identification unit identifies the position of the optical fiber core by weighting the distribution information based on the brightness information acquired earlier among the multiple distribution information so that the weight of the distribution information based on the brightness information acquired later is greater than or equal to the weight of the distribution information based on the brightness information acquired later. Here, the microscope comprises an observation lens group and an image sensor.

[0012] A core positioning method according to one embodiment is a core positioning method for determining the position of each core of a pair of optical fibers when a pair of optical fibers are fusion-spliced ​​together by electrical discharge. The core positioning method comprises the steps of generating an electrical discharge, acquiring brightness information of light generated from an optical fiber heated by the electrical discharge, acquiring distribution information showing the relationship between the radial position of the optical fiber and the brightness information, and determining the position of the optical fiber core from the distribution information. In the step of acquiring brightness information, brightness information is acquired multiple times with a time difference. In the step of acquiring distribution information, distribution information is acquired from each of the multiple brightness information sources. In the step of determining the core position, the position of the optical fiber core is determined by weighting the distribution information based on the brightness information acquired earlier among the multiple distribution information sources so that the weight of the distribution information based on the brightness information acquired later is greater than or equal to the weight of the distribution information based on the brightness information acquired later.

[0013] In this fusion splicing apparatus and core location method, a pair of optical fibers are heated by electrical discharge. When optical fibers are heated, the core emits light more strongly than the cladding. This fusion splicing apparatus and core location method uses the property that the core emits light more strongly to determine the position of the core. Multiple distribution information is obtained that shows the relationship between the radial position of the optical fiber and the luminance information of the emission, and the position of the core is determined from these multiple distribution information. Therefore, by using multiple distribution information, the variation in the position of the core to be determined can be suppressed, and the accuracy of the core's position can be improved. The distribution information based on the luminance information of the optical fiber due to emission changes over time. In the luminance distribution in the radial direction of the optical fiber obtained from the luminance information and position information, a high-luminance portion (peak) is created in the part of the luminance distribution corresponding to the core due to the strong emission of light from the core. However, this peak in the luminance distribution becomes broader over time, making it more difficult to determine the exact position of the core from the distribution information as time passes. In contrast, the peak in the distribution information that has not been long since the discharge has not become broader, so the exact position of the core can be determined from this distribution information. Therefore, the core location is identified by weighting multiple distribution information such that the weight of the distribution information based on the previously acquired luminance information is greater than or equal to the weight of the distribution information based on the later acquired luminance information. This allows the core location to be identified by giving greater weight to the distribution information that is not broad, thereby improving the accuracy of identifying the core location.

[0014] The core location identification unit may weight the distribution information based on luminance information acquired earlier than the distribution information based on luminance information acquired later. In this case, the weight of the distribution information based on earlier luminance information, where the peak is not broadened, is weighted more heavily than the weight of the distribution information based on later luminance information. Therefore, the accuracy of the core location can be further improved.

[0015] The microscope acquires luminance information n times with a time difference (n is a natural number of 3 or more), the distribution information acquisition unit acquires distribution information from each of the n luminance information, and the core position identification unit may perform weighting so that the weight of the distribution information based on the luminance information acquired at the (n - 1) - th time is heavier than the weight of the distribution information based on the luminance information acquired at the n - th time. In this case, the position of the core is identified by making the weight of the distribution information based on the luminance information acquired at the (n - 1) - th time, which is the one before the last, heavier than the weight of the distribution information based on the luminance information acquired at the n - th time, which is the last. Therefore, since the position of the core is identified by making the weight of the distribution information based on the luminance information acquired at the (n - 1) - th time heavier than the distribution information based on the luminance information acquired at the n - th time where the peak is broad, the accuracy of the position of the core to be identified can be further improved.

[0016] The core position identification unit determines the presence or absence of an abnormality for each of the plurality of distribution information, excludes the distribution information determined to be abnormal before identifying the position of the core, and may identify the position of the core using the plurality of distribution information after excluding the distribution information determined to be abnormal as the new plurality of distribution information. In this case, no weighting is performed on the abnormal distribution information, and the abnormal distribution information is excluded before weighting. Then, the position of the core is identified using the distribution information after the exclusion as the new plurality of distribution information. Therefore, by excluding the abnormal distribution information, the accuracy of the position of the core to be identified can be further improved.

[0017] [Details of Embodiments of the Present Disclosure] A specific example of the fusion connection device and the core position identification method according to an embodiment of the present disclosure will be described with reference to the drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant descriptions are omitted as appropriate. The drawings may be drawn with some parts simplified or exaggerated for ease of understanding, and the dimensional ratios and the like are not limited to those described in the drawings.

[0018] First, the configuration of an exemplary fusion splicing apparatus will be described while referring to FIG. 1. FIG. 1 is a diagram for explaining the outline of the fusion splicing apparatus. As shown in FIG. 1, the fusion splicing apparatus 1 is a fusion splicer that fuses and connects a pair of optical fibers F to each other. The fusion splicing apparatus 1 includes a V-groove clamp 2 having a V-groove 2b, a coating clamp 3, a pair of discharge electrodes 4, a V-groove drive unit 9 that drives the V-groove clamp 2, and a control unit 10. The control unit 10 has a distribution information acquisition unit 7 and a core position identification unit 8.

[0019] The V-groove clamp 2 and the coating clamp 3 are parts that support the optical fibers F to be fusion spliced. In the V-groove 2b of the V-groove clamp 2, the optical fibers F to be connected are positioned. The V-groove clamp 2 supports the part of the bare fiber where the coating is removed from the optical fiber F and the glass part is exposed. The coating clamp 3 holds the part of the optical fiber F with the coating. By the V-groove clamp 2 and the coating clamp 3, in the fusion splicing apparatus 1, the tips of the pair of optical fibers F are supported so as to face each other.

[0020] The pair of discharge electrodes 4 are arranged so as to face each other along a direction intersecting (for example, perpendicular) to the direction in which the optical fibers F extend. The optical fibers F are aligned in each of the plurality of V-grooves 2b.

[0021] In the fusion splicing apparatus 1, alignment of the pair of optical fibers F is performed by the V-groove drive unit 9 and the control unit 10. The V-groove drive unit 9 and the control unit 10 perform alignment of the pair of optical fibers F so that the pair of optical fibers F are aligned in a straight line. Then, discharge is performed between the discharge electrodes 4, and the tips of the pair of optical fibers F are heated and fusion spliced. For example, by the control unit 10 controlling the discharge current or discharge time of the discharge electrodes 4, fusion splicing is performed under fusion splicing conditions suitable for the type of the optical fiber F.

[0022] The fusion splicer 1 includes an image observation mechanism 11 for observing the optical fiber F placed in the V-groove 2b of the V-groove clamp 2. Figure 2 shows the configuration of the image observation mechanism 11. The image observation mechanism 11 includes, for example, a light source 12 and a microscope 13. The light source 12 includes a first light source 12b and a second light source 12c. The microscope 13 includes a first microscope 13b and a second microscope 13c. The first light source 12b and the first microscope 13b are aligned along the X direction, sandwiching the optical fiber F. The second light source 12c and the second microscope 13c are aligned along the Y direction, intersecting the X direction, sandwiching the optical fiber F.

[0023] The angle between the X and Y directions is, for example, 60° or more and 120° or less. The first light source 12b emits light into the optical fiber F along the X direction. The second light source 12c emits light into the optical fiber F along the Y direction. The first microscope 13b observes the core F1 and cladding F2 of the optical fiber F by receiving light emitted from the first light source 12b along the X direction. The second microscope 13c observes the core F1 and cladding F2 of the optical fiber F by receiving light emitted from the second light source 12c along the Y direction.

[0024] The configurations and functions of the first light source 12b and the second light source 12c are, for example, identical. The configurations and functions of the first microscope 13b and the second microscope 13c are, for example, identical. Therefore, unless there is a particular need to distinguish them, the first light source 12b and the second light source 12c will be described collectively as light source 12. The first microscope 13b and the second microscope 13c will be described collectively as microscope 13.

[0025] Figure 3 is a schematic diagram showing the positional relationship between the light source 12, the optical fiber F, and the microscope 13. As shown in Figure 3, the light source 12, the optical fiber F, and the microscope 13 are arranged in a straight line. The light source 12 is, for example, a light-emitting element such as a light-emitting diode. As an example, the light source 12 emits light H, which is red light. The microscope 13 observes the optical fiber F by receiving the light H emitted from the light source 12 to the optical fiber F placed in the V-groove 2b.

[0026] The microscope 13 includes, for example, an observation lens and a camera. The camera is a CCD camera (Charge-Coupled Device Camera) or a CMOS camera (Complementary Metal Oxide Semiconductor Camera), etc. For example, the position of the microscope 13 is fixed in the fusion splicing device 1, and the position of the microscope 13 is kept constant. The observation results from the microscope 13 are acquired, for example, as an image. The image of the optical fiber F acquired by the microscope 13 is transmitted to the control unit 10 as image data.

[0027] The V-groove drive unit 9 is driven, for example, based on a control signal input from the control unit 10. The V-groove drive unit 9 moves the V-groove 2b. As the control unit 10, for example, a CPU (central processing unit) composed of one or more integrated circuits (ICs) is used. The control unit 10 acquires an image of the optical fiber F from the microscope 13, and for example, the image of the optical fiber F is stored in the control unit 10. The control unit 10 includes a core position identification unit 8 that acquires the center position of the core F1 of the optical fiber F from the acquired image data of the optical fiber F. The control unit 10 may use the acquired result to output a control signal to the V-groove drive unit 9 and control the V-groove drive unit 9.

[0028] The control unit 10 obtains the brightness waveform of the optical fiber F from the acquired image data of the optical fiber F. Figure 4 shows exemplary brightness waveforms D1 and D2 that illustrate the relationship between the radial position of the optical fiber F and the brightness of the image. As shown in Figures 3 and 4, in the image of the optical fiber F, for example, the core F1 portion is displayed as high brightness and the cladding F2 portion as low brightness. In this example of the image of the optical fiber F, the brightness decreases in the cladding F2 portion of the optical fiber F and becomes high when it reaches the core F1 of the optical fiber F. A peak D12 with high brightness appears in the brightness waveforms D1 and D2 near the center, sandwiched between a pair of low-brightness valleys D11.

[0029] The control unit 10 may acquire the outer diameter of the optical fiber F using the luminance waveforms D1 and D2. The control unit 10 may, for example, extract the bright area corresponding to the peak D12 as the part corresponding to the core and acquire the width of the bright area. When the luminance waveform D1 has a high resolution from the microscope 13, the waveform at the peak D12 can be acquired with high accuracy, so the position of the core F1 can be determined with high accuracy. However, when the luminance waveform D2 has a low resolution from the microscope 13, the accuracy of the waveform at the peak D12 may be low, so the position of the core F1 may not be able to be determined with high accuracy.

[0030] Therefore, in this embodiment, the position of the core F1 is determined using the light emitted from the optical fiber F during the discharge of the discharge electrode 4 to the optical fiber F. Figure 5 is a schematic diagram showing the configuration of the fusion splicing apparatus 1 for determining the position of the core F1. As shown in Figure 5, when the optical fiber F is heated by the discharge of the discharge electrode 4, the core F1 of the optical fiber F emits light more strongly than the cladding F2 due to the influence of the dopant. The microscope 13 acquires an image of the light emitted from the core F1 and an image of the light emitted from the optical fiber F.

[0031] As an example, the distribution information acquisition unit 7 acquires a waveform showing the distribution of light emission from an image of the light emission of the optical fiber F acquired by the microscope 13 as distribution information. In this embodiment, the "image of light emission (image of light emission)" corresponds to an example of "luminance information," and the "waveform (showing the distribution of light emission)" corresponds to an example of "distribution information." For example, the microscope 13 takes multiple images of the optical fiber F emitting light at different times, and the distribution information acquisition unit 7 acquires the waveform multiple times at different times. Figure 6 is a schematic graph showing the distribution information relating the radial position of the optical fiber F to the luminance information.

[0032] Figure 6 shows the distribution information B1 obtained at time t1, immediately after the discharge from the discharge electrode 4 to the optical fiber F; the distribution information B2 obtained at time t2, after time t1; the distribution information B3 obtained at time t3, after time t2; the distribution information B4 obtained at time t4, after time t3; and the distribution information B5 obtained at time t5, after time t4. However, the number of distribution information obtained does not have to be 5; it may be 2, 3, 4, or 6 or more. The time from time t1 to time t2, the time from time t2 to time t3, the time from time t3 to time t4, and the time from time t4 to time t5 are, for example, the same.

[0033] As shown in Figure 6, in all of the distribution information B1, B2, B3, B4, and B5, a peak K is observed near the center of the optical fiber F where core F1 is presumed to be present. However, peak K gradually broadens as time elapses since the discharge. Specifically, a clear peak K is obtained at time t1 immediately after the discharge, but as time progresses to t2 and t3, peak K gradually becomes smoother. After time t3, the waveform changes very little, and peak K becomes broad. As described above, in the distribution information obtained from brightness information due to light emission, peak K broadens over time, so it is desirable to place more emphasis on distribution information acquired at an earlier timing to pinpoint the location of core F1.

[0034] The core location identification unit 8 identifies the location of the core F1 of the optical fiber F from the distribution information B1 to B5 acquired by the distribution information acquisition unit 7, for example. The core location identification unit 8 identifies the location of the core F1 of the optical fiber F by weighting the distribution information B1, which was acquired first, so that the weight of the distribution information B1, which was acquired first, is greater than or equal to the weight of the distribution information B2, which was acquired later. In this embodiment, the core location identification unit 8 weights the distribution information so that the weight of distribution information B1 is greater than or equal to the weight of distribution information B2, the weight of distribution information B2 is greater than or equal to the weight of distribution information B3, the weight of distribution information B3 is greater than or equal to the weight of distribution information B4, and the weight of distribution information B4 is greater than or equal to the weight of distribution information B5.

[0035] An example of weighting of distribution information by the core location identification unit 8 will be explained. For example, let X1 be the position of optical fiber F at peak K of distribution information B1 (the position estimated to be the core), X2 be the position of optical fiber F at peak K of distribution information B2, X3 be the position of optical fiber F at peak K of distribution information B3, X4 be the position of optical fiber F at peak K of distribution information B4, and X5 be the position of optical fiber F at peak K of distribution information B5.

[0036] The core location identification unit 8 determines whether or not there are abnormalities in the distribution information B1 to B5. The core location identification unit 8 eliminates distribution information that has been determined to be abnormal before the weighting described later. As a specific example, the core location identification unit 8 compares each of the positions X1 to X5 of the distribution information B1 to B5 with a certain value. Then, the core location identification unit 8 eliminates the distribution information B1 to B5 when the difference between each of the positions X1 to X5 and the said certain value is greater than or equal to a threshold. The following example illustrates the case where none of the distribution information B1 to B5 have been eliminated.

[0037] The core position identification unit 8 identifies the position Z of core F1 using the following equation (1), with W1 being the weight (weighting coefficient) for distribution information B1, W2 being less than or equal to W1 for distribution information B2, W3 being less than or equal to W2 for distribution information B3, W4 being less than or equal to W3 for distribution information B4, and W5 being less than or equal to W4 for distribution information B5. The sum of W1 to W5 is 1. Z = (X1) × W1 + (X2) × W2 + (X3) × W3 + (X4)×W4+(X5)×W5···(1) The above describes an example of weighting distribution information and determining the location of core F1 by the core location identification unit 8. However, the method of weighting distribution information and determining the location of core F1 is not limited to the above example and can be changed as appropriate.

[0038] For example, in the above example, when determining the position Z of core F1 after finding the positions X1 to X5 from each of the distribution information B1 to B5, the weighting coefficient Wi for the distribution information Bi (where i is a natural number) that has been determined to be abnormal may be set to 0. Also, the distribution information Bi that has been determined to be abnormal may be excluded (it may not be included in the calculation) before determining the positions X1 to X5 from each of the distribution information B1 to B5. In the example above, positions X1 to X5 were used to determine whether or not it was abnormal. However, if the determination of whether or not it was abnormal was made using other criteria and the result of that determination was used, the abnormal distribution information could be excluded before determining the positions X1 to X5.

[0039] For weighting, the luminance information X(t,m,n) at a certain time t and specific position (m,n) (where m,n are relative coordinates indicating position information) may be weighted first, and the weighted average value XS may be calculated as shown in equation (2). XS(m,n)=X(1,m,n)×W1+X(2,m,n)×W2+ X(3,m,n)×W3+X(4,m,n)×W4+ X(5,m,n)×W5 ···(2) The position Z of core F1 may be determined using XS(m,n) obtained in this way.

[0040] Next, the core positioning method according to the embodiment will be described with reference to Figure 7. Figure 7 shows an example of the steps of the core positioning method according to the embodiment. First, a pair of optical fibers F are placed in the V-groove 2b of the V-groove clamp 2 (step S1). At this time, the optical fibers F are supported by the V-groove clamp 2 and the covering clamp 3. The optical fibers F are positioned in the V-groove 2b so that the tips of the pair of optical fibers F face each other.

[0041] Next, the light source 12 stops emitting light H (step S2). That is, the light source 12 is stopped to eliminate the influence of light H from the light source 12. After that, the discharge electrode 4 discharges light onto the optical fiber F (step S3). The optical fiber F is heated by the discharge and emits light, and the microscope 13 acquires a brightness image (brightness information) of the emitted light. Then, the distribution information acquisition unit 7 acquires the aforementioned distribution information from the brightness information (step S4).

[0042] For example, it is determined whether the distribution information acquisition unit 7 has acquired X pieces of distribution information (where X is a natural number greater than or equal to 2) (step S5). If it is determined that X pieces of distribution information have been acquired, the process proceeds to step S6. On the other hand, if it is determined that X pieces of distribution information have not been acquired, the process returns to step S4, and the acquisition of brightness information by the microscope 13 and the acquisition of distribution information by the distribution information acquisition unit 7 are performed again.

[0043] The following describes an example where the value of X is 5 and the distribution information acquisition unit 7 acquires distribution information B1 to B5. In step S6, the core location identification unit 8 identifies the provisional location of core F1 from each of the distribution information B1 to B5. As a specific example, the core location identification unit 8 acquires the positions X1 to X5 of peak K shown in Figure 6 as the provisional location of core F1.

[0044] The core location identification unit 8 determines whether each of the distribution information B1 to B5 acquired by the distribution information acquisition unit 7 is abnormal, and excludes the distribution information that is determined to be abnormal (step S7). Then, the core location identification unit 8 assigns weights to each of the distribution information B1 to B5 that is not determined to be abnormal (step S8). As a specific example, the core location identification unit 8 determines the weight W1 for distribution information B1, the weight W2 for distribution information B2, the weight W3 for distribution information B3, the weight W4 for distribution information B4, and the weight W5 for distribution information B5. At this time, the weights are determined such that weight W1 is greater than or equal to weight W2, weight W2 is greater than or equal to weight W3, weight W3 is greater than or equal to weight W4, and weight W4 is greater than or equal to weight W5.

[0045] Then, the core location unit 8 uses the weights W1 to W5 described above to determine the position of the core F1 of the optical fiber F (step S9). Specifically, the core location unit 8 determines the position Z of the core F1 using the equation (1) described above. After these steps, the series of steps of the core location method is completed.

[0046] The effects and advantages obtained from the fusion splicing apparatus 1 and core location method according to this embodiment will be explained. In the fusion splicing apparatus 1 and core location method according to this embodiment, a pair of optical fibers F are heated by electrical discharge. When the optical fibers F are heated, the core F1 emits light more strongly than the cladding F2.

[0047] In the fusion splicing apparatus 1 and core positioning method, the position of core F1 is determined by utilizing the property that core F1 emits light more strongly. Distribution information B1 to B5, which shows the relationship between the radial position of the optical fiber F and brightness information (e.g., brightness of the image of the emitted light), is acquired, and the position of core F1 is determined from the distribution information B1 to B5. Therefore, by using multiple distribution information B1 to B5, the variation in the core F1 to be identified can be suppressed, thereby improving the accuracy of the position of the core F1 to be identified.

[0048] The distribution information based on the luminance information of the optical fiber F due to light emission changes over time. In distribution information B1 to B5, a peak K is generated in the core F1 region due to the strong light emission from core F1. As time passes, the peak K in distribution information B1 to B5 becomes broader, making it more difficult to pinpoint the exact location of core F1. In contrast, the peak K in distribution information B1, which has not been long since discharge, is not broadened, so the exact location of core F1 can be pinpointed from distribution information B1. Therefore, for distribution information B1 to B5, for example, the weight W1 of distribution information B1 based on the luminance information acquired earlier is weighted so that it is greater than or equal to the weight W2 of distribution information B2 based on the luminance information acquired later, thereby pinpointing the location of core F1.

[0049] The microscope 13 may acquire brightness information n times with a time difference (where n is a natural number greater than or equal to 3), and the distribution information acquisition unit 7 may acquire distribution information from each of the n brightness information. The core position identification unit 8 may weight the distribution information based on the (n-1)th brightness information acquisition so that it is heavier than the weight of the distribution information based on the nth brightness information acquisition. As a specific example, the microscope 13 may acquire brightness information from the optical fiber F five times with a time difference (for example, by taking five images), and the distribution information acquisition unit 7 may acquire distribution information B1 to B5 based on each of the five brightness information. The core position identification unit 8 may then weight the distribution information B4 based on the fourth brightness information acquisition so that it is heavier than the weight W5 of the fifth brightness information acquisition.

[0050] In this case, the position of core F1 is determined by making the weight of the distribution information based on the luminance information acquired in the (n-1)th instance (the second to last instance) heavier than the weight of the distribution information based on the luminance information acquired in the nth instance (the last instance). Therefore, the position of core F1 is determined by making the weight of the distribution information based on the luminance information acquired in the (n-1)th instance heavier than the distribution information based on the luminance information acquired in the nth instance (where peak K is broad), thus improving the accuracy of determining the position of core F1. The core position determination unit 8 may also weight the distribution information such that the weight W1 of the distribution information B1 based on the luminance information acquired in the first instance is heavier than the weight W2 of the distribution information B2 based on the luminance information acquired in the second instance. In this case as well, the same effect as above can be obtained.

[0051] The core position identification unit 8 may weight the distribution information B1 to B5 such that the weight of the distribution information based on the luminance information acquired earlier is heavier than the weight of the distribution information based on the luminance information acquired later. For example, weight W1 may be greater than weight W2, weight W2 may be greater than weight W3, weight W3 may be greater than weight W4, and weight W4 may be greater than weight W5. In this case, by weighting the distribution information based on the earlier luminance information, where the peak K is not broadened, heavier than the distribution information based on the later luminance information, the positional accuracy of the core F1 to be identified can be further improved.

[0052] The core location identification unit 8 may determine whether each of the distribution information B1 to B5 is abnormal, exclude any distribution information determined to be abnormal before weighting, and then use the remaining distribution information B1 to B5 as new multiple distribution information B1 to B5 to identify the location of core F1. In this case, abnormal distribution information is not weighted and is excluded before weighting. Then, the distribution information B1 to B5 after the exclusion is used as new multiple distribution information B1 to B5 to identify the location of core F1. Therefore, by excluding abnormal distribution information, the accuracy of identifying the location of core F1 can be further improved.

[0053] In this embodiment, the fusion splicing device 1 has the microscope 13 fixed in position, and the position of the microscope 13 is immutable. Even when the microscope 13 is fixed in this way, the microscope 13 acquires brightness information multiple times with a time difference, and the core position identification unit 8 weights the distribution information B1 based on the brightness information acquired earlier so that the weight W1 of the distribution information B1 based on the brightness information acquired later is equal to or greater than the weight W2 of the distribution information B2 based on the brightness information acquired later. Therefore, the position of the core F1 can be identified with high accuracy. In other words, the position of the core F1 can be identified with high accuracy even when the microscope 13 is fixed or when the resolution of the microscope 13 is low.

[0054] Embodiments of the fusion splicing apparatus and core location method described herein have been explained above. However, the present invention is not limited to the embodiments described above. That is, it will be readily apparent to those skilled in the art that the present invention can be modified and altered in various ways within the scope of the gist described in the claims. The configuration of each part of the fusion splicing apparatus, as well as the content and sequence of steps of the core location method, are not limited to the embodiments described above and can be changed as appropriate.

[0055] For example, in the embodiment described above, a core position identification unit 8 was described that weights distribution information B1 acquired the first time such that its weight W1 is greater than or equal to the weight W2 of distribution information B2, the weight W2 of distribution information B2 is greater than or equal to the weight W3 of distribution information B3, the weight W3 of distribution information B3 is greater than or equal to the weight W4 of distribution information B4, and the weight W4 of distribution information B4 is greater than or equal to the weight W5 of distribution information B5. However, the core position identification unit may use different weighting coefficients depending on the time elapsed since the discharge. Specifically, the core position identification unit may assign weight r1 to the distribution information obtained between the discharge start time v0 and time v1, weight r2 to the distribution information obtained between time v1 and time v2, and weight r3 to the distribution information obtained after time v2, with weight r1 being greater than or equal to weight r2 and weight r2 being greater than or equal to weight r3. In this case as well, the position of the core can be identified by prioritizing the distribution information based on brightness information that has not been elapsed for a long time since the discharge, so the same effects as in the embodiment described above can be obtained. [Explanation of Symbols]

[0056] 1…Fusion splicing device 2…V-groove clamp 2b…V groove 3…Covered Clamp 4…Discharge electrode 7…Distribution information acquisition unit 8... Core location identification unit 9…V-groove drive unit 10…Control Unit 11…Image observation mechanism 12...Light source 12b…1st light source 12c…Second light source 13…Microscope 13b...First Microscope 13c...Second Microscope B1~B5…Distribution information D1, D2... Brightness waveform D11…Tanibe D12... Yamabe F... Optical fiber F1... Core F2...Clad H...light K...Peak

Claims

1. A fusion splicing device that fuses a pair of optical fibers together by electrical discharge, A discharge electrode that generates a discharge, A microscope that acquires brightness information from an optical fiber heated by the aforementioned discharge, A distribution information acquisition unit that acquires distribution information showing the relationship between the radial position of the optical fiber and the brightness information, A core position identification unit that identifies the position of the optical fiber core from the distribution information, Equipped with, The microscope acquires the brightness information multiple times with a time difference, The distribution information acquisition unit acquires the distribution information from each of the plurality of luminance information, The core position identification unit identifies the position of the optical fiber core by weighting the distribution information based on the brightness information acquired earlier among the plurality of distribution information, such that the weight of the distribution information based on the brightness information acquired later is heavier. Fusion splicing device.

2. The microscope acquires the brightness information n times with a time difference (where n is a natural number of 3 or more), The distribution information acquisition unit acquires the distribution information from each of the n luminance information items, The core position identification unit weights the distribution information based on the brightness information acquired on the (n-1)th occasion so that the weight of the distribution information based on the brightness information acquired on the nth occasion is heavier. The fusion splicing apparatus according to claim 1.

3. The core position identification unit determines whether each of the plurality of distribution information is abnormal, removes the distribution information determined to be abnormal before identifying the core's position, and uses the plurality of distribution information remaining after removing the distribution information determined to be abnormal as new plurality of distribution information to identify the core's position. A fusion splicing apparatus according to claim 1 or claim 2.

4. A core positioning method for determining the position of each core of a pair of optical fibers when a pair of optical fibers are fusion-spliced ​​together by electrical discharge, The process of generating an electrical discharge, A step of acquiring brightness information from an optical fiber that has been heated by the aforementioned discharge, A step of acquiring distribution information showing the relationship between the position in the radial direction of the optical fiber and the brightness information, A step of determining the position of the optical fiber core from the distribution information, Equipped with, In the process of acquiring the brightness information, the brightness information is acquired multiple times with a time difference between each acquisition. In the step of acquiring the distribution information, the distribution information is acquired from each of the multiple luminance information sources. In the step of determining the position of the core, the position of the optical fiber core is determined by weighting the distribution information based on the brightness information acquired earlier among the multiple distribution pieces of information so that the weight of the distribution information based on the brightness information acquired later is heavier. Core location locating method.

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