JP6294858B2 - Optical fiber core inspection apparatus and method - Google Patents

Description

  The present invention relates to an optical fiber core inspection device and method for determining a connection state of optical fiber cores.

  Usually, a plurality of optical fiber cores are housed in an optical fiber cable laid between a station and a user's building for optical transmission. One terminal of the optical fiber cores is joined by an optical splitter and then connected to an OLT (Optical Line Terminal) provided on the station side, and the other terminal is an ONU (Optical Network) provided on the user side. Connected to the unit) or left unconnected.

  I want to know the connection status of multiple optical fiber cores housed in an optical fiber cable, that is, whether any device is connected to the end of the optical fiber core, or that some processing has been performed for the connection. In this case, it takes much time and cost to examine each of the terminals of the optical fiber core wires. Therefore, an apparatus capable of determining the connection state of the optical fiber cores has been developed in the middle of the optical fiber cable, that is, at a position away from the end of each optical fiber core wire.

  Patent Document 1 describes a technique for determining the passage state and the passage direction of an optical fiber core wire by detecting leakage light generated when test light passes through a curved optical fiber core wire. In the technique described in Patent Document 1, a part (determination point) of an optical fiber core wire is bent, and a photodetector such as a PD is provided on the station side (upstream side) and the user side (downstream side) of the determination point. Provided. In this state, when test light having a predetermined wavelength is emitted from the station side toward the user side, leakage light is generated mainly in the traveling direction side of the test light at the bending portion that is the determination point. Is detected.

  By the way, the ONU connected to the terminal on the user side of the optical fiber core wire includes a reflection part (termination) that reflects light having a wavelength used as test light. Therefore, when the ONU is connected to the user-side terminal of the optical fiber core wire, the test light is reflected by the reflecting unit, and the reflected light advances from the user side toward the station side. If it does so, since leak light will mainly generate | occur | produce in the advancing direction side of reflected light in the curved part which is a determination point, leak light is detected by station side PD. On the other hand, when the terminal on the user side of the optical fiber core is in an unconnected state, the test light is not reflected, so that the leakage light is hardly detected by the station side PD.

  Due to such a phenomenon, the technique described in Patent Literature 1 can determine that light is transmitted from the station side to the user side when the user side PD detects leakage light, and the station side PD leaks. When the light is detected, it can be determined that light is transmitted from the user side to the station side, that is, the test light is reflected by the reflection unit in the ONU.

JP 2008-148272 A

  In an actual optical fiber core laying environment, there may be a relatively large loss between the determination point and the reflection portion provided in the ONU due to an optical connector or a connection loss due to fusion. In particular, since the reflected light is doubly affected by the loss from the station side to the user side and from the user side to the station side, the reflected light can be greatly attenuated.

  In such a state, the signal intensity detected by the station-side PD as reflected light becomes small. Therefore, in the technique described in Patent Document 1, it is determined whether or not there is a reflecting portion in the terminal, that is, the optical fiber core wire is turned ONU. It may be difficult to determine whether it is connected. On the other hand, if the PD can detect light with high accuracy, it is easy to determine the presence or absence of a reflecting portion even if the loss is large. Therefore, it is required to further improve the measurement accuracy of the leaked light of the optical fiber core so that the connection state of the optical fiber core can be determined even in the presence of a large loss.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an optical fiber core inspection device capable of determining a connection state with high accuracy.

  According to a first aspect of the present invention, there is provided an optical fiber core inspection apparatus for determining a state of a terminal of the optical fiber core wire by detecting leakage light from the optical fiber core wire, A first portion that is provided so as to face the outside of the bending portion on one end side of the optical fiber core and measures the intensity of the leaked light; A detection unit; a second detection unit that is provided to face the outside of the bending unit on the other end side of the optical fiber core; and that measures the intensity of the leaked light; and the first detection unit; A light-shielding portion that is provided so as to be in contact with the outside of the bending portion between the second detection portion and attenuates the leakage light.

  A second aspect of the present invention is an optical fiber core inspection method for determining a state of an end of an optical fiber core, wherein a part of the optical fiber core is bent to form a bending portion; Measuring the intensity of leaked light from the bending portion by means of a first detector provided to face the outside of the bending portion on one end side of the optical fiber core; and Measuring the intensity of the leaked light by a second detector provided to face the outside of the curved portion on the other terminal side of the line; and the first detector and the second detection A light-shielding portion provided so as to be in contact with the outside of the curved portion with respect to a portion, attenuating the leakage light, an intensity of the leakage light measured by the first detection portion, and the second The intensity of the leaked light measured by the detector Based on, characterized in that it comprises and determining the status of the terminal of the optical fiber.

  In the present invention, a light shielding unit that attenuates leaked light is provided between the first detection unit and the second detection unit that are disposed along the optical fiber core wire. Since the light-shielding unit reduces leakage light that occurs in the opposite direction to the test light, the measurement accuracy of the leakage light can be improved, and the optical fiber core wire can be used even when a relatively large loss exists in the path of the test light. The connection state can be determined satisfactorily.

1 is a schematic diagram of an optical transmission system according to an embodiment of the present invention. It is a top view of the optical fiber core wire inspection device concerning one embodiment of the present invention. It is sectional drawing of the light shielding member which concerns on one Embodiment of this invention. It is a schematic diagram for demonstrating the leakage light which generate | occur | produces from an optical fiber core wire. It is a figure which shows the graph of the relationship between the distance between PD and PD sensitivity.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments. In the drawings described below, components having the same function are denoted by the same reference numerals, and repeated description thereof may be omitted.

(Embodiment)
FIG. 1 is a schematic cross-sectional view of an optical transmission system 10 according to the present embodiment. The optical transmission system 10 is a system that performs optical communication between the OLT 11 disposed in a station and the ONU 17 disposed in a user's building. In this embodiment, the station side (upstream side) refers to the OLT 11 side, and the user side (downstream side) refers to the ONU 17 side. Further, the downward direction indicates the direction from the OLT 11 toward the ONU 17, and the upward direction indicates the direction from the ONU 17 toward the OLT 11.

  The optical transmission system 10 includes an OLT 11 that transmits and receives an optical signal for performing optical communication, and a test light generator 12 that generates test light that is an optical signal for performing a transmission path test. The OLT 11 transmits an optical signal including information to the ONU 17 and receives an optical signal including information from the ONU 17.

  The test light generator 12 includes an arbitrary light emitting element such as a light emitting diode (LED) or a laser diode (LD), and emits test light having a predetermined wavelength used for the test. The wavelength of the test light may be any wavelength, and in this embodiment is 1650 nm. The wavelength of the test light emitted from the test light generator 12 is preferably different from the wavelength of the optical signal transmitted and received by the OLT 11.

  Although the OLT 11 and the test light generator 12 are provided as different devices in the present embodiment, the OLT 11 and the test light generator 12 may be provided as one device capable of emitting both the optical signal used for optical communication and the test light used for the test. Good.

  The optical signal from the OLT 11 and the test light from the test light generator 12 are multiplexed by the optical coupler 13 and further demultiplexed by the optical splitter 14. The light demultiplexed by the optical splitter 14 is emitted to a plurality of optical fiber cores 15 connected to the user side of the optical splitter 14. The optical coupler 13 is an arbitrary optical device that multiplexes the light input from the station side and outputs it to the user side, and the optical splitter 14 demultiplexes the light input from the station side into a predetermined number to the user side. Any optical device that outputs to For example, the optical coupler 13 is a Y-shaped branch, and the optical splitter 14 is a 1 × 8 optical splitter.

  At least a part of the plurality of optical fiber cores 15 along the longitudinal direction may be bundled and provided in one optical fiber cable, and another part may be divided one by one into a home as a user, It may be laid in a building such as a company or a store.

  The terminal 16 on the user side of the optical fiber 15 may be connected to the ONU 17 or may not be connected at all. Further, the terminal 16 may be left without being connected after the optical connector 19 is provided. When nothing is connected to the terminal 16 of the optical fiber core wire 15, the terminal 16 is not subjected to a treatment such as polishing, and hardly reflects the test light.

  When the terminal 16 of the optical fiber core wire 15 is connected to the ONU 17, the terminal 16 is connected to a reflection unit 18 (termination) provided in the ONU 17. The reflection unit 18 reflects the test light used for the test and returns it to the station side, and allows the optical signal used for optical communication to pass through and input it to the ONU 17. The reflection unit 18 is an optical filter configured to reflect, for example, light having a wavelength of test light (1650 nm in the present embodiment) and to pass light having other wavelengths.

  Thus, since the terminal 16 of the optical fiber core 15 can have a plurality of states, each of the plurality of optical fiber cores 15 is connected (live) or not connected in the optical transmission system 10. It is required that the connection state can be determined. Furthermore, since the optical fiber core wire 15 provided with the optical connector 19 at the terminal 16 can be used immediately, it is desirable that the presence or absence of the optical connector 19 can be detected.

  The optical fiber core inspection device 100 according to the present embodiment can determine the connection state in the middle of the optical fiber core 15, that is, at a position away from the terminal 16 of the optical fiber core 15. The optical fiber core inspection device 100 determines the connection state by sandwiching the optical fiber core 15 without cutting the optical fiber core 15.

  FIG. 2 is a top view of the optical fiber core inspection apparatus 100 according to the present embodiment. FIG. 2 shows the periphery of a portion where the optical fiber core 15 is held in the optical fiber core inspection apparatus 100, and other portions are omitted. Further, the portion hidden by the front member is indicated by a broken line.

  The optical fiber core inspection device 100 includes a fixing unit including a convex fixing unit 101 and a concave fixing unit 102. The convex fixing portion 101 has a convex surface 101 a that is curved in a mountain shape along the extending direction of the optical fiber core wire 15. The concave fixed portion 102 has a concave surface 102a that is curved in a valley shape so as to be substantially parallel to the convex surface 101a of the convex fixed portion 101.

  The convex fixing part 101 is configured to be movable in a direction approaching and moving away from the concave fixing part 102 (direction B in FIG. 2). As long as the convex fixing part 101 and the concave fixing part 102 can be relatively approached and separated from each other, either the convex fixing part 101 or the concave fixing part 102 may be movable, or both may be movable. Good.

  The concave fixed part 102 includes a station side PD 103 provided on the local side (OLT 11 side) of the concave surface 102a as a first detection part, and a user side PD 104 provided on the user side (ONU 17 side) as a second detection part. Is provided. The station-side PD 103 and the user-side PD 104 are photodiodes (PD) that detect the intensity of incident light, respectively. The station-side PD 103 and the user-side PD 104 are connected to a control unit (not shown) and transmit information including the detected intensity of the optical signal as an electric signal to the control unit. The control unit may be an arbitrary computer or an electric circuit that can acquire the intensity of the optical signal based on the electric signal from the PD and perform an operation for determining the connection state. As long as the intensity of leaked light can be detected, not only PD but also any optical sensor such as photomultiplier may be used.

  The station-side PD 103 and the user-side PD 104 are provided so as to face the optical fiber core wire 15 in the concave fixed portion 102, respectively. On the concave surface 102a of the concave fixing portion 102 between the station side PD 103 and the user side PD 104 and the optical fiber core wire 15, a window that transmits at least light having the wavelength of the test light is provided. Therefore, leakage light generated when the test light passes through the optical fiber core 15 enters the station-side PD 103 and the user-side PD 104 through the window.

  The station side PD 103 and the user side PD 104 are arranged at a distance X along the extending direction of the optical fiber core wire 15. The distance X is a distance between the centers of the station side PD 103 and the user side PD 104.

  A light shielding member 105 is provided at the central portion of the concave surface 102 a of the concave fixed portion 102, that is, the central portion between the station side PD 103 and the user side PD 104. The light shielding member 105 is a member for attenuating or blocking the leaked light from the optical fiber core wire 15. The light shielding member 105 attenuates at least the light having the wavelength of the test light. The light shielding member 105 desirably has a light shielding property for attenuating the intensity of light having the wavelength of the test light to 50% or less, and more desirably has a light shielding property for attenuating to 1% or less. The light shielding member 105 may be made of any material having the light shielding properties described above, but in the present embodiment, the light shielding member 105 is made of an elastic body such as rubber or resin.

  By placing the optical fiber core wire 15 between the convex fixing portion 101 and the concave fixing portion 102 and bringing the convex fixing portion 101 and the concave fixing portion 102 close to each other, the optical fiber core wire 15 is connected to the convex fixing portion 101. Pressed. As a result, a curved portion 15 a that is curved along the convex surface 101 a of the convex fixing portion 101 is formed in the optical fiber core wire 15. In this state, the optical fiber core wire 15 is pressed and fixed to the light shielding member 105 by the convex fixing portion 101. That is, in a state where the optical fiber core wire 15 is fixed, the light shielding member 105 contacts the outside of the curved portion 15 a of the optical fiber core wire 15. Here, when the inscribed circle inscribed in the curve of the curved portion 15a is considered, the outside of the curved portion 15a is located outside the curved portion 15a (optical fiber core wire 15) along the radial direction of the inscribed circle. Point to. The station-side PD 103 and the user-side PD 104 are located at approximately the same distance from the bending portion 15a so as to face the outside of the bending portion 15a. The bending portion 15a is a determination point for the connection state of the optical fiber core wire 15 in the present embodiment.

  FIG. 3 is a cross-sectional view of the light shielding member 105 taken along line AA in FIG. FIG. 3 shows a state where the optical fiber core wire 15 is fixed so as to contact the light shielding member 105. In this embodiment, since the light shielding member 105 is configured using an elastic body, when the optical fiber core wire 15 is pushed by the convex fixing portion 101, at least a part of the optical fiber core wire 15 is placed on the light shielding member 105. Sink. Then, the optical fiber core wire 15 and the light shielding member 105 come into contact with each other instead of a line. That is, the light shielding member 105 contacts the optical fiber core wire 15 with a spread in the circumferential direction in the cross section of the optical fiber core wire 15.

  Leaked light from the optical fiber core 15 is generated from the side surface of the optical fiber core 15 with an area. Therefore, when the light shielding member 105 is in contact with the optical fiber core wire 15, some leaked light passes through the gap between the light shielding member 105 and the optical fiber core wire 15 and may not be sufficiently shielded. On the other hand, in this embodiment, since the light shielding member 105, which is an elastic body, is in contact with the optical fiber core wire 15 on the surface, the path of the leaked light can be blocked over a wide range and the leaked light can be effectively attenuated. Further, since the light shielding member 105, which is an elastic body, relieves stress applied to the optical fiber core 15, the optical fiber core 15 may be damaged or microbends may be generated in the optical fiber core 15. Can be suppressed.

  FIGS. 4A to 4C are schematic diagrams for explaining the leakage light generated from the optical fiber core wire. 4A shows a state in which nothing is connected to the terminal 16 of the optical fiber core wire 15, and FIG. 4B shows a state in which the ONU 17 is connected to the terminal 16 of the optical fiber core wire 15. In order to improve sensitivity to leakage light and reduce the size of the apparatus, the station side PD 103 and the user side PD 104 are provided close to the curved portion 15 a of the optical fiber core wire 15.

  The light detected by the user side PD 104 when the light passes through the bending portion 15a is referred to as user side leakage light D, and the light detected by the station side PD 103 is referred to as station side leakage light E. The attenuation amount β used for determining the connection state of the optical fiber core wire 15 in the present embodiment is defined by the following equation (1).

Here, β is the attenuation (dB), α ₁ is the light intensity (dBm) detected by the station-side PD 103, and α ₂ is the light intensity (dBm) detected by the user-side PD 104. .

  4A and 4B, the test light C travels from the station side toward the user side. When the test light C passes through the bending portion 15a, a large user-side leakage light D is detected in the user-side PD 104 mainly in the light traveling direction.

  In the state of FIG. 4A, since the reflection hardly occurs at the terminal 16 where no processing is performed, it can be considered that no reflected light is generated. However, a small local station side PD 103 on the side opposite to the traveling direction of the test light C is also caused by light due to irregular reflection caused by the coating of the optical fiber core 15 or light passing through a gap between the optical fiber core 15 and the PD. Leaked light E is detected.

  In the state shown in FIG. 4B, the test light C is reflected by the reflection unit 18 of the ONU 17, and the reflected light F travels from the user side toward the station side. The intensity of the reflected light F is a value close to the intensity of the test light C, although it is somewhat attenuated due to the influence of a loss that may exist between the curved portion 15a (determination point) and the ONU 17. Therefore, when the reflected light F passes through the curved portion 15a, the local side leakage light E having an intensity close to that of the user side leakage light D is detected mainly in the local side PD 103 in the light traveling direction.

  Therefore, the amount of attenuation β when the reflecting portion 18 is present (the state of FIG. 4B) is smaller than the amount of attenuation β when the reflecting portion 18 is not present (the state of FIG. 4A). Therefore, the presence / absence of the reflection portion 18 can be determined by comparing the attenuation amount β to be measured with the attenuation amount β when the reflection portion 18 is not present.

  In the state of FIG. 4A, the station side leakage light E detected in the direction opposite to the traveling direction of the test light C is indistinguishable from that generated by the reflected light. It becomes a factor which reduces the precision which determines the presence or absence.

  Specifically, when there is no reflecting portion, the PD measurement limit is set to −80 dBm, and the intensity of the user side leakage light D generated in the traveling direction of the test light C is set to −30 dBm. Assuming an ideal condition where the station side leakage light E is not generated in the direction opposite to the traveling direction of the test light C, the amount of attenuation β = −30 − (− 80) = 50 dB. On the other hand, if the intensity of the station side leakage light E generated in the direction opposite to the traveling direction of the test light C is −40 dBm as a realistic condition, the attenuation amount β = −30 − (− 40) = 10 dB. As described above, the attenuation amount β decreases from 50 dB under the ideal condition to 10 dB under the realistic condition, so that the accuracy of determining the presence or absence of the reflecting portion 18 decreases.

  That is, since the attenuation amount β is reduced by the station side leakage light E in the direction opposite to the traveling direction of the test light C, the change in the attenuation amount β due to the presence or absence of the reflection portion 18 is buried in the loss on the path, and the reflection portion The presence or absence of 18 may not be correctly determined. Therefore, it is desirable to reduce the station side leakage light E generated in the direction opposite to the traveling direction of the test light C.

  As shown in FIG. 2, the optical fiber core wire inspection device 100 according to the present embodiment includes a light shielding member 105 between the station side PD 103 and the user side PD 104. The light shielding member 105 shields light caused by irregular reflection caused by the coating of the optical fiber core 15 and closes the gap between the optical fiber core 15 and the concave fixed portion 102, so that the station is generated in the direction opposite to the traveling direction of the test light C. The side leakage light E can be reduced. Therefore, the optical fiber core wire inspection device 100 according to the present embodiment can improve the accuracy of determining the presence or absence of the reflection unit 18 in the terminal 16.

  FIG. 4C shows a state where the optical connector 19 is provided at the terminal 16 of the optical fiber core wire 15. When the optical connector 19 is provided at the terminal 16 of the optical fiber core wire 15, the terminal 16 is usually polished, so that a part (about 1/25) of the test light C is reflected. For this reason, when the optical connector 19 is provided, the reflected light F that is smaller than when the reflecting portion 18 is provided travels from the user side toward the station side.

  Therefore, in the case where the optical connector 19 is provided, the amount of attenuation β is smaller than the case where there is no reflecting portion 18 (the state in FIG. 4A) and the reflecting portion 18 is present (the state in FIG. 4B). Attenuation amount β larger than the attenuation amount β of () is measured. According to the optical fiber core wire inspection device 100 according to the present embodiment, since the accuracy of the reflection determination at the terminal 16 can be improved, the presence / absence of the optical connector 19 may be determined.

(Example)
Using the optical fiber core wire inspection apparatus 100 according to the above-described embodiment, an attenuation measurement experiment was performed. In the measurement experiment, the distance X between the station-side PD 103 and the user-side PD 104 is changed, the presence / absence of the light shielding member 105, the presence / absence of the reflection unit 18 (or the optical connector 19), and the distance between the determination point and the terminal 16 are measured. The attenuation value β was measured by changing the loss value.

  The distance X between the station-side PD 103 and the user-side PD 104 is a distance between the center of the station-side PD 103 and the center of the user-side PD 104 as shown in FIG. As the value of the distance X, 9.9 mm, 10.5 mm, and 11.1 mm were used.

  The loss between the bending portion 15a (determination point) and the terminal 16 was set by providing an optical attenuator (optical attenuator). The transmission loss of the optical fiber itself is neglected because it is a very small value in the installation environment (up to several hundred meters) of the optical transmission system 10 according to the present invention.

  First, Table 1 shows the results of measuring the attenuation β for each combination of the distance X and the presence / absence of the light shielding member 105 when there is no reflecting portion 18 (in the case of FIG. 4A). The value of the attenuation β in Table 1 is a criterion for determining whether the reflection unit 18 or the optical connector 19 is present. That is, in each condition of Tables 2 to 5 to be described later, when a value smaller than the attenuation amount β of Table 1 is measured, it can be determined that the reflecting portion 18 (or the optical connector 19) is present. On the other hand, when the same value as the attenuation amount β in Table 1 is measured, the presence or absence of the reflecting portion 18 (or the optical connector 19) cannot be determined.

  Next, in the case where there is the reflection portion 18 (in the case of FIG. 4B) and there is no loss (the loss is 0 dB), the attenuation amount β for each combination of the distance X and the presence or absence of the light shielding member 105. The results of measuring are shown in Table 2.

  As shown in Table 2, when there is no loss, the attenuation amount β is lower than that in Table 1 under any condition, and therefore it can be determined that the reflecting portion 18 is present.

  Next, the result of measuring the attenuation β for each combination of the distance X and the presence / absence of the light shielding member 105 in the case where there is the reflection portion 18 (in the case of FIG. 4B) and the loss is 5 dB. Table 3 shows.

  As shown in Table 3, when there is a loss of 5 dB, it is determined that the reflection part 18 is present because the attenuation β is lower than that in Table 1 under the conditions where the distance X is 10.5 mm and 11.1 mm. can do. When the distance X is 9.9 mm, it can be determined that the reflection part 18 is present because the attenuation amount β is lower than that in Table 1 when the light shielding member 105 is present, but the light shielding member 105 is not present. The presence or absence of the reflection portion 18 cannot be determined.

  Next, the result of measuring the attenuation β for each combination of the distance X and the presence or absence of the light shielding member 105 in the case where there is the reflecting portion 18 (in the case of FIG. 4B) and the loss is 9 dB. Table 4 shows.

  As shown in Table 4, when there is a loss of 9 dB, the presence or absence of the reflecting portion 18 cannot be determined under the conditions where the distance X is 9.9 mm and 10.5 mm. When the distance X is 11.1 mm, it can be determined that the reflection portion 18 is present because the attenuation β is lower than that in Table 1 when the light shielding member 105 is present, but the light shielding member 105 is not present. The presence or absence of the reflection portion 18 cannot be determined.

  As can be seen from Tables 1 to 4, it is easier to determine the presence or absence of the reflecting portion 18 when the light shielding member 105 is present than when the light shielding member 105 is absent. Also, the greater the distance X between the station-side PD 103 and the user-side PD 104 is, the easier it is to determine the presence or absence of the reflection unit 18.

  Conventionally, if there is a loss of 5 dB or more between the determination point and the terminal 16, it is difficult to determine the presence or absence of the reflecting portion 18. On the other hand, since the optical fiber core wire inspection device 100 includes the light shielding member 105, the detection accuracy of the attenuation amount β is improved, and the presence or absence of the reflecting portion 18 can be determined even when there is a loss of 5 dB or more. In particular, when the distance X is 11 mm or more and the light shielding member 105 is present, the presence or absence of the reflecting portion 18 can be determined even when the loss between the determination point and the terminal 16 is as large as 9 dB. .

  Furthermore, Table 5 shows the results of measuring the attenuation β for each combination of the distance X and the presence or absence of the light shielding member 105 when the optical connector 19 is provided instead of the reflecting portion 18 (in the case of FIG. 4C). The loss between the determination point and the terminal 16 was set to 0 dB.

  As shown in Table 5, when the optical connector 19 is provided, the presence / absence of the reflecting portion 18 cannot be determined under the condition that the distance X is 9.9 mm, but the attenuation amount under the condition that the distance X is 11.1 mm. Since β is lower than that in Table 1, it can be determined that the reflecting portion 18 is present. Under the condition that the distance X is 10.5 mm, when the light shielding member 105 is present, it can be determined that the reflection portion 18 is present because the attenuation amount β is lower than that in Table 1, but there is no light shielding member 105. In this case, the presence or absence of the reflecting portion 18 cannot be determined.

  Since the reflectance at the terminal 16 provided with the optical connector 19 is small (about 1/25), it has been difficult to determine the presence or absence of the optical connector 19 in the past. On the other hand, since the optical fiber core inspection device 100 includes the light shielding member 105, the detection accuracy of the attenuation amount is improved, and the presence or absence of the optical connector 19 (more precisely, the polishing of the terminal 16 provided with the optical connector 19 is polished. The presence or absence of processing) can be determined.

  Next, an experiment for examining a preferable range of the distance X between the station-side PD 103 and the user-side PD 104 was performed. FIG. 5 is a graph showing a relationship between the distance X between the PDs and the sensitivity of the PD. The horizontal axis in FIG. 5 is the distance X (mm) between the PDs, and the vertical axis is the PD sensitivity (relative value, no unit). The sensitivity of the PD is a ratio of the intensity of leaked light detected by the user side PD 104 to the intensity of the test light C passing through the optical fiber core wire 15. That is, the detection accuracy improves as the PD sensitivity increases. In FIG. 5, the relative value of the sensitivity is used on the basis of the value when the distance X between the PDs having the maximum sensitivity X = 4.45 mm.

  As shown in FIG. 5, when the distance X between the PDs exceeds 15 mm, the sensitivity of the PD becomes about 1/10 of the maximum value. For this reason, if the distance X is too large, the light receiving characteristics of the leaked light of the station side PD 103 and the user side PD 104 are deteriorated, and the measurement accuracy of the attenuation is lowered. Therefore, it is desirable that the distance X between the PDs is 11 mm or more and 15 mm or less in order to improve the measurement accuracy of the attenuation, in combination with the result of the above-described attenuation measurement experiment.

  As described above, according to the optical fiber core inspection device 100 according to one embodiment of the present invention, some processing is performed on the terminal 16 of the optical fiber core 15 in order to improve the detection accuracy of the attenuation amount. That is, it can be determined that the reflecting portion 18 is connected and that polishing is performed when the optical connector 19 is installed.

  The present invention is not limited to the above-described embodiments and examples, and can be modified without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 15 Optical fiber core wire 15a Bending part 101 Convex fixed part 102 Concave fixed part 103 Station side PD
104 User side PD
105 Shading member

Claims (6)

An optical fiber core inspection device for determining a state of a terminal of the optical fiber core wire by detecting leakage light from the optical fiber core wire,
A fixing portion that forms a bending portion by bending a part of the optical fiber core;
A first detector that is provided on one end side of the optical fiber core so as to face the outside of the curved portion, and measures the intensity of the leaked light;
A second detector for measuring the intensity of the leaked light, provided to face the outside of the curved portion on the other end side of the optical fiber core;
A light-shielding part that is provided between the first detection part and the second detection part so as to be in contact with the outside of the bending part, and attenuates the leakage light;
A device comprising:   The apparatus according to claim 1, wherein a distance between the first detection unit and the second detection unit is 11 mm or more.   The apparatus according to claim 2, wherein a distance between the first detection unit and the second detection unit is 15 mm or less.   The apparatus according to any one of claims 1 to 3, wherein the light shielding unit is configured using an elastic body.   The apparatus according to claim 1, wherein each of the first detection unit and the second detection unit is a photodiode. An optical fiber core inspection method for determining a state of a terminal of an optical fiber core,
Bending a portion of the optical fiber core to form a curved portion;
Measuring the intensity of leakage light from the bending portion by a first detection unit provided to face the outside of the bending portion on one end side of the optical fiber core;
Measuring the intensity of the leaked light by a second detector provided so as to face the outside of the curved portion on the other end side of the optical fiber core;
Attenuating the leaked light by a light-shielding portion provided so as to be in contact with the outside of the bending portion between the first detection portion and the second detection portion;
Determining the state of the terminal of the optical fiber core based on the intensity of the leaked light measured by the first detector and the intensity of the leaked light measured by the second detector When,
A method comprising the steps of:

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