JP2013164398A - Optical fiber measuring instrument and optical fiber measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber measuring instrument and an optical fiber measuring method capable of reliably detecting an axis deviation phenomenon and shortening a measuring time by improving measuring efficiency.SOLUTION: An optical fiber measuring instrument includes: a plurality of OTDR measurement devices 11 for measuring a transmission characteristic of a fiber F1 to be measured being a tape core wire having a plurality of coated optical fibers F1a; a dummy fiber F0 composed of the same number of coated optical fibers F0a as the number of the fibers F1 to be measured and being tape core wires, one end sides of which are connected to the plurality of OTDR measurement devices 11 in each tape core wire and the other end sides of which are integrated; an MAS 12 for confronting the dummy fiber F0 with the fiber F1 to be measured; and a control device 13 for acquiring measurement results of the OTDR measurement devices 11. The control device 13 has a function for determining that remeasurement is necessary in the case where the dummy fiber F0 is recognized to be inserted into a V groove 30 different from a prescribed one on the basis of the measurement results.

Description

  The present invention relates to an optical fiber measuring apparatus and an optical fiber measuring method for inspecting transmission characteristics in an optical cable.

  Conventionally, the transmission characteristic inspection of an optical fiber accommodated in an optical cable has been performed by an OTDR measuring instrument (Optical Time Domain Reflectmeter). When a multi-core optical fiber is a measurement target, a measurement auxiliary device (MAS) is used. : Multiple Alignment System).

  Specifically, in order to connect to the measurement dummy fiber, the ends of the plurality of tape cores that are the fibers to be measured are inserted into the plurality of V-grooves positioned and fixed in parallel on the MAS. To do. Next, the reverse end side of the dummy fiber connected to the OTDR measuring instrument is inserted into the movable head on the MAS. Next, the position of the movable head is controlled, and the dummy fibers are sequentially inserted into the appropriate V grooves in which the fibers to be measured are set. As a result, the end of the fiber to be measured and the end of the dummy fiber abut each other.

  Next, the operation of the OTDR measuring device is controlled by a computer in which inspection software is installed, and the quality of transmission characteristics in each of the plurality of tape cores is automatically determined (for example, see Patent Document 1). The inspection software performs pass / fail determination by controlling the operation of the OTDR measuring device and the MAS and analyzing the measurement data acquired from the OTDR measuring device.

JP 2006-90787 A

  However, in the optical fiber measurement method using the optical fiber measuring apparatus, when the dummy fiber set on the movable head is inserted into the V-groove, the dummy fiber is not inserted into an appropriate V-groove position, for example, adjacent to the V-groove. There is a case where it is erroneously inserted into the adjacent V groove. In this case, the V-groove connection with the regular fiber to be measured is not performed, resulting in an “axis misalignment” phenomenon that causes measurement leakage, and correct determination cannot be made.

Taking an example of 4-fiber ribbon measurement as an example, the pattern of occurrence of axial deviation will be described.
The generation pattern A is a case where a dummy fiber is erroneously inserted in the V groove position outside the both ends of the tape. In this case, since the conventional inspection software automatically determines that the connection loss is abnormal, there is a possibility that the occurrence of the axis deviation can be detected.
However, the original detection object of the connection loss abnormality is for the detection of the fiber end face abnormality (chip, inclination), contamination of foreign matter, or mixing of different types of fibers, and no axial displacement phenomenon is assumed. Therefore, even if it is automatically determined that the connection loss is abnormal in the conventional system, it cannot be determined whether the axis is misaligned or another factor.

  The generation pattern B is a case where the dummy fiber is erroneously inserted into the V groove position inside the both ends of the tape. In this case, the same center is continuously measured. Therefore, since the butt connection with the fiber to be measured has been established, the conventional inspection software does not cause a connection loss abnormality and cannot detect any axial deviation.

The following factors 1 to 3 are assumed as the main factors causing the above-mentioned shaft misalignment.
The generation factor 1 is insufficient movement accuracy of the movable head due to aging of the MAS. In other words, this is due to a deviation from the center of the valley of the V groove and a decrease in accuracy of the moving pitch.
The generation factor 2 is due to a large amount of shake at the tip due to bending of the dummy fiber.
The generation factor 3 is due to incomplete setting of the dummy fiber on the movable head.

  Further, in the above optical fiber measuring apparatus, a single dummy fiber is held by a movable head and, for example, when measuring a 4-fiber ribbon, one dummy fiber is abutted and measured, and all measurements are performed. Takes a long time.

  An object of the present invention is to provide an optical fiber measuring apparatus and an optical fiber measuring method capable of reliably detecting an axial deviation phenomenon, improving measurement efficiency and shortening measurement time.

The optical fiber measuring device of the present invention capable of solving the above-mentioned problems is
A plurality of measuring devices for measuring transmission characteristics of a fiber to be measured, which is a tape core wire in which a plurality of optical fiber core wires are arranged in parallel and integrated;
Measurement is made of the same number of optical fiber cores as the number of fibers to be measured, and one end side is connected to each of the plurality of measuring devices, and the other end side is a tape core wire integrated by arranging a plurality of cores in parallel. Dummy fiber for
A measurement auxiliary device that abuts the other end of the measurement fiber on the V-groove block with the fiber to be measured;
A control device that acquires the measurement result of the measuring device and controls the operation of the measuring device and the measurement auxiliary device,
The control device has a function of determining that remeasurement is necessary when it is recognized that the measurement dummy fiber is inserted into a V groove different from a predetermined V groove based on the measurement result. Features.

  In the optical fiber measuring apparatus of the present invention, the measuring device is an OTDR measuring device, and if the connection loss measurement result measured from the waveform of the OTDR measuring device includes a value exceeding a predetermined value, re-measurement is required. Is preferably determined.

Further, the measuring method of the optical fiber of the present invention,
Insert a fiber to be measured, which is a tape core wire in which a plurality of optical fiber core wires are aligned in parallel, into the plurality of V grooves of the V groove block one by one,
A dummy fiber for measurement comprising optical fiber cores of the same number as the number of fibers to be measured, one end side being connected to a measuring device for each core and the other end side being a tape core wire integrated by arranging a plurality of cores in parallel The other end of the optical fiber is inserted into the V-groove, and is measured against the optical fiber to be measured to measure transmission characteristics,
Based on the measurement result of the measuring instrument, if it is recognized that the measurement dummy fiber is inserted into a V-groove different from a predetermined V-groove, it is determined that remeasurement is necessary.

  In the optical fiber measurement method of the present invention, when the OTDR measurement device is used as the measurement device and the connection loss measurement result measured from the waveform of the OTDR measurement device includes a measured value that exceeds a predetermined value, remeasurement is performed. It is preferable to determine that it is necessary.

According to the optical fiber measurement apparatus and the optical fiber measurement method of the present invention, the measurement dummy fiber having the same number of cores as the measurement fiber is used, and the measurement dummy fiber is abutted against the measurement fiber. To measure the transmission characteristics.
For example, in the case of measuring a plurality of fibers to be measured by sequentially moving one measurement fiber, a measurement dummy is provided inside either of the V grooves in which both ends of the fiber to be measured are inserted. When a fiber is mistakenly inserted, the same center can be measured continuously. Even in this case, the connection between the measurement dummy fiber and the fiber to be measured is established despite the erroneous measurement. That is, it may be determined that the axis is normal despite the occurrence of an axis shift.
On the other hand, in the present invention, transmission characteristics can be collectively measured with a measurement dummy fiber having the same number of cores as the number of fibers to be measured. The occurrence of defects (occurrence pattern B) can be eliminated.
In addition, when the measurement dummy fiber is misaligned (generation pattern A) with respect to the fiber to be measured, some of the measurement dummy fibers are not abutted against the fiber to be measured, resulting in extreme connection loss. A peculiar pattern with a high value is generated. Therefore, this peculiar pattern is easily detected, and the measurement fiber is inserted into a V-groove different from the predetermined V-groove, so that it can be determined that remeasurement is necessary.
In addition, by measuring the transmission characteristics in a lump with the same number of measurement fibers as the number of cores of the fiber to be measured, it is possible to measure all the cores of the fiber to be measured at the same time. The measurement time can be shortened.

It is a block diagram which shows the structure of the optical fiber measuring device which concerns on this invention. It is an enlarged view which shows the principal part of MAS of FIG. It is the schematic which shows the connection edge part of the optical fiber on the V-groove block of MAS of FIG. FIG. 4 is an explanatory diagram of occurrence of an axis deviation in FIG. 3. It is a flowchart which shows the measuring method of the optical fiber which concerns on this invention. It is a flowchart which shows the measuring method of the optical fiber which concerns on this invention.

  Hereinafter, an embodiment of an optical fiber measuring device and an optical fiber measuring method of the present invention will be described. In the present embodiment, a case where the fiber to be measured is a four-core ribbon is described as an example.

  As shown in FIG. 1, the optical fiber measurement apparatus 10 of the present embodiment mainly includes an OTDR measuring instrument 11 to which one end side of a dummy fiber F0 is connected, and a dummy fiber F0 and a measured fiber F1 on a V-groove block 14. And a control device 13 that controls the operation of the OTDR measuring device 11 and the MAS 12. In this example, four OTDR measuring instruments 11 are installed.

  The fibers to be measured F1 are arranged in parallel with four optical fiber cores in contact with each other on one plane, and the outer periphery thereof is integrally covered with a tape core resin. One optical fiber core wire has a glass fiber composed of a core and a clad at its center, and its outer periphery is covered with a resin containing a colored layer.

  The OTDR measuring instrument 11 makes a light pulse incident on the fiber for measurement F1 and measures the return time and the amount of light of the backscattered light from each part, whereby the loss distribution and loss value (loss) on the fiber for measurement F1 are measured. Value), defect position, and the like. If there is a location where the loss is locally high in the fiber to be measured F1 itself, it appears as a change in inclination (step amount, section loss value) on the OTDR waveform, and such a change in inclination is regarded as a step abnormality or section loss abnormality. recognize.

  The control device 13 is installed with inspection software for transmission characteristic inspection. The control device 13 transmits a control signal 15 to the OTDR measuring instrument 11 to control the operation of the measuring instrument itself, receives the measurement data 16 acquired from the OTDR measuring instrument 11, and analyzes the measurement data 16 to pass or fail. Make a decision. At the same time, a control signal 17 is transmitted to the MAS 12 to control the operation of the movable head 20 to be described later, and the dummy fiber F0 is connected to each measured fiber F1 positioned at the connection portion P on the V-groove block 14. Butt the other end.

  As shown in FIG. 2, the MAS 12 has a movable head 20 that moves on the guide rail 22, a tape holder 23 that holds four fibers to be measured F <b> 1, and a fiber to be measured F <b> 1 for each tape holder 23. And a plurality of rows of stages 24. In front of each stage 24, a V-groove block 14 having a plurality of V-grooves 30 (see FIG. 3) is provided. The stage 24 is inclined by a predetermined angle toward the V-groove block 14.

  As shown in FIG. 3, the V-groove 30 of the V-groove block 14 has the first groove portion 30 a, the second groove portion 30 b, the third groove portion 30 c, and the fourth groove portion by alternately forming the valley portions 31 and the mountain portions 32. Eight or twelve groove portions including the groove portion 30d are formed. The pitch X of the V-groove 30 is adjacent to the glass fibers to be measured Gh1 to Gh4 exposed by peeling a predetermined length of resin including the colored layer of the optical fiber core wire F1a constituting the four fibers to be measured F1. The distance between the glass fibers coincides with, for example, the distance W between the central axes of the first glass fiber Gh1 and the second glass fiber Gh2. Therefore, the minimum moving distance of the movable head 20 in the direction of the arrow 25 is set to coincide with the pitch X of the V groove 30.

  As shown in FIG. 2, the movable head 20 is set so as to be movable in the direction of the arrow 25 by the guide rail 22. On the movable head 20, a dummy holder 21 for holding the dummy fiber F0 is provided. The dummy holder 21 is set so as to be movable by a predetermined distance in the direction of an arrow 26 perpendicular to the moving direction 25 of the movable head 20 along the guide rail 22. This dummy holder 21 holds the 4-fiber dummy fiber F0.

  The dummy fiber F0, which is a measurement dummy fiber, has four optical fiber cores F0a, the same number as the number of optical fiber cores F1a of the fiber F1 to be measured. Each is connected to a respective OTDR measuring device 11. The other end side of the optical fiber core wire F0a of the dummy fiber F0 is arranged in parallel with four adjacent to each other on one plane, and the outer periphery thereof is integrally covered with the tape core resin. It is in the state of the tape core. Similar to the fiber for measurement F1, the optical fiber core wire F0a of the dummy fiber F0 has a glass fiber composed of a core and a clad at the center, and the outer periphery thereof is covered with a fiber resin including a colored layer. In this dummy fiber F0, the pitch of the optical fiber core wire F0a is the same as that of the optical fiber core wire F1a of the fiber F1 to be measured.

  Before the dummy fiber F0 is attached to the dummy holder 21, the fiber glass at the tip of the optical fiber core wire F0a is peeled to expose the dummy glass fibers Gd1 to Gd4 having a predetermined length. The dummy fiber F0 is attached to a predetermined position of the dummy holder 21 on the movable head 20. Therefore, the moving distance of the dummy holder 21 in the direction of the arrow 26 is the distance between the tip of the dummy glass fibers Gd1 to Gd4 and the tip of the glass fibers Gh1 to Gh4 to be measured arranged on the V-groove block 14. Set to match Y.

  The cause of shaft misalignment will be described. The relationship between the glass diameter D0 (for example, 125 μm) of the dummy glass fibers Gd1 to Gd4 and the pitch X (for example, 250 μm) of the V groove 30 of the V groove block 14 that matches the minimum moving distance of the movable head 20 is A case where X = 2D0 is described as an example.

  As shown in FIG. 4, in the optical fiber measurement device 10 according to the present embodiment, the four-core dummy glass fibers Gd <b> 1 to Gd <b> 4 are arranged by the movable head 20 and the V-groove block 14 in which the glass fibers to be measured Gh <b> 1 to Gh <b> 4 are arranged. The position is controlled at the center of the valley 31 in the V groove 30.

  The allowable range for controlling the position in each groove 30 is ± 125 μm before and after the center position of the valley 31. When this allowable range (± 125 μm) is exceeded, each of the dummy glass fibers Gd1 to Gd4 enters the adjacent groove portion 30 and "axial misalignment" occurs. For example, when the dummy glass fibers Gd1 to Gd4 are shifted to the right in FIG. 3 by 125 μm or more, the dummy glass fibers Gd1 are erroneously inserted into the groove portions 30 in which none of the glass fibers to be measured Gh1 to Gh4 are arranged. Further, the dummy glass fiber Gd2 is erroneously inserted into the first groove 30a, the dummy glass fiber Gd3 is erroneously inserted into the second groove 30b, and the dummy glass fiber Gd4 is erroneously inserted into the third groove 30c.

Next, an optical fiber measurement method according to this embodiment will be described.
Automatic detection is possible by grasping the peculiar pattern at the time of occurrence of axis misalignment and incorporating judgment logic into the inspection software. Hereinafter, the determination logic to be incorporated will be described. In the present embodiment, a case where the fiber to be measured is a four-core ribbon is described as an example.

  For example, the generation pattern A is assumed when the dummy glass fibers Gd1 to Gd4 are shifted to the right side in FIG. 3 by 125 μm or more. Specifically, as described above, the dummy glass fiber Gd1 is erroneously inserted into the groove portion 30 in which none of the glass fibers to be measured Gh1 to Gh4 is arranged. Further, the dummy glass fiber Gd2 is erroneously inserted into the first groove 30a, the dummy glass fiber Gd3 is erroneously inserted into the second groove 30b, and the dummy glass fiber Gd4 is erroneously inserted into the third groove 30c. In this case, there is a dummy glass fiber Gd1 in which the glass fiber of the connection partner is not connected at all, and the measurement data in this dummy glass fiber Gd1 is extremely connection loss compared to the other dummy glass fibers Gd2 to Gd4. A peculiar pattern has a higher value.

  Based on the actual value of the connection loss abnormality due to foreign matter adhering to the fiber end face or the cutting state and the connection loss value in the unconnected state (about 31 dB), the determination reference value of “complete axis deviation” is set to 30 dB or more. Therefore, by newly adding this judgment reference value (30 dB or more) dedicated to detecting the axis deviation, the axis deviation can be reliably detected. Here, the complete axis deviation means that the possibility of axis deviation is approximately 100%. Further, depending on the OTDR measuring instrument 11 used, the determination reference value may be 20 dB or more.

  As shown in FIG. 5, as a measurement procedure, first, a connection loss is measured in a temporary matching state, and a preliminary measurement process (step S <b> 1) for temporarily holding a connection loss value is performed.

  Next, the first connection loss determination (step S2) is performed based on the determination reference value (30 dB or more). If there is a connection loss value of 30 dB or more, “complete axis deviation” is displayed as the axis deviation handling process (step S3).

If the connection loss value is less than 30 dB, the second connection loss determination (step S4) is performed. If the connection loss value exceeds the upper limit of the reference value and is less than 30 dB, reconnection is performed as many times as the number of registered reconnections as the reconnection process (step S5). Is displayed. In addition, when reconnection is performed and the reference value is satisfied, the following normal measurement is performed.
When the connection loss values satisfy the reference values for all the dummy glass fibers Gd1 to Gd4, the total length loss, connection loss, section loss, and abnormal point information for all the measured glass fibers Gh1 to Gh4 in the normal measurement (step S6). Then, DB registration (step S7) for acquiring the terminal reflection amount and storing it in the database is performed.

(Remeasurement confirmation process)
Next, as shown in FIG. 6, remeasurement confirmation processing (step S32) is performed based on the determination result of each tape holder on the stage. In this basic processing step, the first step and the second step are sequentially performed step by step.

<First step>
In the first step, the complete axis deviation is re-measured to make it good or abnormal in connection loss. As shown in FIG. 6, this is a case where a complete axis deviation exists, and complete axis deviation confirmation and remeasurement processing (step S33) is performed. First, it is confirmed whether or not the dummy fiber F0 is broken. Here, the decentering refers to a state in which the glass portion of the dummy fiber F0 is completely broken under the influence of pressure measurement or bending.

  If the dummy fiber F0 is not decentered, it is determined that the complete axis is misaligned, and by pressing the complete axis misalignment button, the measurement center that has been automatically operated and the connection loss abnormality are changed to the complete axis misalignment. Thereafter, the whole heart is remeasured.

  If the dummy fiber F0 is broken, it is determined that there is no complete axis misalignment, and the dummy breaker is displayed by pressing the dummy breaker button. Re-measure all hearts in automatic mode.

<Second step>
The second step re-measures connection loss anomalies and makes them all good.

  This is a case where there is no complete axis misalignment but there is a connection loss abnormality, and the connection loss abnormality remeasurement process (step S34) is performed.

The process proceeds according to the following procedure.
1) Perform re-measurement in the manual mode or automatic mode for the whole heart of the connection loss abnormality.
2) Make the whole heart a good heart by re-measurement.

  Finally, after completion of the measurement of the final remeasurement center, a remeasurement center confirmation process (step S36) is performed, and the inspection operation is completed. If an axis misalignment or connection loss abnormality is confirmed by this confirmation processing, feedback to the complete axis misalignment confirmation and remeasurement processing (step S33) or connection loss abnormality remeasurement processing (step S34) is performed again. I do.

  As described above, in the optical fiber measurement device and the optical fiber measurement method of this embodiment, the dummy fibers F0 having the same number of cores as the fibers F1 to be measured are used, and the dummy glass fibers Gd1 of the dummy fibers F0 are used. ˜Gd4 is butted against each glass fiber to be measured Gh1 to Gh4 of the fiber to be measured F1, and the transmission characteristic is measured by the OTDR measuring instrument 11.

  For example, when measuring a plurality of fibers to be measured by sequentially moving a single-fiber dummy fiber, the dummy fiber dummy is placed inside either of the V grooves into which both ends of the fiber to be measured are inserted. When a glass fiber is inserted incorrectly, the same center may be measured continuously, and the connection between the dummy glass fiber and the measured glass fiber of the measured fiber is established despite the erroneous measurement. . That is, it may be determined that the axis is normal despite the occurrence of an axis shift.

  On the other hand, in the present invention, transmission characteristics can be collectively measured with the dummy fibers F0 having the same number of cores as the fibers F1 to be measured, and therefore measurement by continuous measurement of the same core due to axial misalignment. The occurrence of defects (occurrence pattern B) can be eliminated.

  Further, when the dummy fiber F0 is misaligned (generation pattern A) with respect to the fiber for measurement F1, the dummy glass fiber that does not face the glass fibers for measurement Gh1 to Gh4 of the fiber for measurement F1. Exists, and a peculiar pattern in which the connection loss value becomes extremely high is generated. Therefore, this peculiar pattern is easily detected, and since the dummy fiber F0 is inserted into the V groove 30 different from the predetermined V groove 30, it can be determined that remeasurement is necessary.

  Moreover, by measuring the transmission characteristics collectively with the dummy fibers F0 having the same number of cores as the fibers F1 to be measured, it is possible to measure all the cores of the fiber F1 to be measured at the same time. Can be improved and the measurement time can be shortened.

  In addition, when the OTDR measuring instrument 11 is used and the measurement result of the connection loss measured from the waveform of the OTDR measuring instrument 11 includes a predetermined reference value that is a predetermined value or more, it is determined that remeasurement is necessary. Thus, the axial deviation of the dummy fiber F0 with respect to the fiber F1 to be measured can be reliably detected.

  In the above embodiment, the four dummy fibers F0 are used for the four measured fibers F1, but the number of the measured fibers F1 and the dummy fibers F0 is not limited to four. For example, if the measured fiber F1 has two cores, the dummy fiber F0 also has two cores, and if the measured fiber F1 has eight cores, the dummy fiber F0 also has eight cores.

In the above embodiment, one OTDR measuring device 11 is provided for each of the four dummy fibers F0. Therefore, in the case of 8 cores, 8 OTDR measuring instruments 11 are required.
As the OTDR measuring instrument 11, one having a plurality of input / output ports is preferably used. For example, in the case of OTDR measuring instrument 11 having two input / output ports, the number of units required for eight cores is four, and in the case of OTDR measuring instrument 11 having four input / output ports, it is required for eight cores. The number will be two.

  In addition to using the OTDR measuring instrument 11 having a plurality of input / output ports, a new optical channel selector (number of switching channels) is provided between the measurement dummy fiber and the OTDR measuring instrument (only one input / output port). : 2 × 4 and 2 × 8), it is possible to measure four or eight cores with only two OTDR measuring instruments.

  Note that the optical fiber measurement device and the optical fiber measurement method of the present invention are not limited to the above-described embodiments, and can be appropriately modified and improved. In addition, the material, shape, dimension, numerical value, form, number, location, and the like of each component in the above-described embodiment are arbitrary and are not limited as long as the present invention can be achieved.

  10: Optical fiber measuring device, 11: OTDR measuring device, 12: MAS (measuring auxiliary device), 13: Control device, 14: V groove block, 30: V groove, F0: Dummy fiber (measuring fiber), F1: Fibers to be measured, F0a, F1a: optical fiber core wire

Claims (4)

A plurality of measuring devices for measuring transmission characteristics of a fiber to be measured, which is a tape core wire in which a plurality of optical fiber core wires are arranged in parallel and integrated;
Measurement is made of the same number of optical fiber cores as the number of fibers to be measured, and one end side is connected to each of the plurality of measuring devices, and the other end side is a tape core wire integrated by arranging a plurality of cores in parallel. Dummy fiber for
A measurement auxiliary device that abuts the other end of the measurement fiber on the V-groove block with the fiber to be measured;
A controller for obtaining the measurement result of the measuring device and controlling the operation of the measuring device and the measurement auxiliary device;
The control device has a function of determining that remeasurement is necessary when it is recognized that the measurement dummy fiber is inserted into a V-groove different from a predetermined V-groove based on the measurement result. Optical fiber measuring device. The optical fiber measuring device according to claim 1,
The measuring device is an OTDR measuring device, and when the connection loss measurement result measured from the waveform of the OTDR measuring device includes a value exceeding a predetermined value, it is determined that re-measurement is necessary. Fiber measuring device. Insert a fiber to be measured, which is a tape core wire in which a plurality of optical fiber core wires are aligned in parallel, into the plurality of V grooves of the V groove block one by one,
A dummy fiber for measurement comprising optical fiber cores of the same number as the number of fibers to be measured, one end side being connected to a measuring device for each core and the other end side being a tape core wire integrated by arranging a plurality of cores in parallel The other end of the optical fiber is inserted into the V-groove, and is measured against the optical fiber to be measured to measure transmission characteristics,
An optical fiber measuring method characterized in that, if it is recognized that the measurement dummy fiber is inserted into a V-groove different from a predetermined V-groove based on the measurement result of the measuring device, it is determined that remeasurement is necessary. . A method for measuring an optical fiber according to claim 3,
An optical fiber characterized in that an OTDR measuring instrument is used as the measuring instrument, and it is determined that re-measurement is required when a connection loss measurement result measured from the waveform of the OTDR measuring instrument includes a predetermined value or more. Measuring method.

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