JP2007226440A - Optical fiber intrusion monitoring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To identify physical external force applied to a part of an optical fiber ring, and its position, and to detect cutting of the optical fiber ring and a cut position. <P>SOLUTION: This optical fiber intrusion monitoring device 1 is composed of an optical fiber vibration sensor detector 49 comprising two light sources 9, 25 different in wavelength and two kinds of light receiving parts 13, 29 for detecting the interference light of an optical fiber corresponding to the two light sources 9, 25; a first branch coupler 51 connected to the respective light sources 9, 25 and light receiving parts 9, 25 of the optical fiber vibration sensor detector 49; an optical cable 69 for a vibration sensor, which constitutes optical fiber ring interference type vibration sensors 23, 29 with one end side connected to the first branch coupler 51; and a second branch coupler 53 connected to the other end side of the optical cable 69 for the vibration sensor. A cable cutting detecting optical fiber 7 is stored in the optical cable 69 for the vibration sensor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical fiber intrusion monitoring apparatus, and in particular, when a physical external force is applied to a part of an optical fiber ring, the external force is detected and a position where the external force is applied is identified, and the optical fiber ring is cut or bent. The present invention relates to an optical fiber intrusion monitoring apparatus that detects the cutting or cutting position, or the bending change or bending position.

  In recent years, an interference type sensor using an optical fiber and a laser beam, which can be used as a means for crime prevention from intruders and as a falling rock detection means on roads and railways, has been proposed. For example, external force using the fact that the optical path length of the propagating light changes and the physical properties such as phase change because a part of the optical fiber cable is stressed by physical external force (mechanical stimulation) such as vibration. Stimulus detection devices are known.

  Referring to FIG. 5, for example, as shown in Non-Patent Document 1, an optical fiber ring interference type vibration sensor 101 is known. Advantages of the optical fiber ring interference type vibration sensor 101 include: (1) The vibration and impact transmitted to the optical fiber can be observed in real time. (2) A general optical fiber cable can be used for the sensor unit, and no special sensor unit is required. (3) Since all components other than the light source and the light receiving circuit are composed of passive optical elements, there is no need for power supply, lightning protection and explosion protection measures in the vicinity of the sensor section. At this time, it is necessary to know the position where the vibration is applied by the optical fiber ring interference type vibration sensor 101.

  Therefore, a conventional optical fiber ring interference type vibration sensor 101 includes a first interference type vibration sensor 103 and a second interference type vibration sensor 105, as shown in FIG. The vibration characteristics such as the vibration position and vibration level are identified by detecting and comparing the interference light intensities generated by the vibrations of the light beams having different wavelengths input to the two interference type vibration sensors 103 and 105.

  That is, the first interference type vibration sensor 103 is connected to a first port 109 connected to a first light source 107 that generates light having a wavelength band of 1.31 μm and a first light receiving unit 111 including a photodiode (PD). A first branch optical coupler 119 that branches from at least two ports (three ports in FIG. 5) to at least two third and fourth ports 115 and 117, and the first branched light. And a first optical fiber ring 121 optically connected to the coupler 119. The first optical fiber ring 121 has one end connected to the third port 115 and the other end connected to the fourth port 117.

  The second interference type vibration sensor 105 includes a fifth port 125 connected to a second light source 123 that generates light having a wavelength band of 1.55 μm different from that of the first light source 107, and a photodiode (PD). The second branch optical coupler 135 branches from at least two ports (three ports in FIG. 5) with the sixth port 129 connected to the second light receiving unit 127 to at least two seventh and eighth ports 131 and 133. And a second optical fiber ring 137 optically connected to the second branch optical coupler 135. The second optical fiber ring 137 has one end connected to the seventh port 131 and the other end connected to the eighth port 133.

  Further, in the first and second interference type vibration sensors 103 and 105, the midpoint X1 of the total length of the first optical fiber ring 121 and the midpoint X2 of the total length of the second optical fiber ring 137 are located on opposite sides. Preferably, the first and second optical fiber rings 121 and 137 are arranged symmetrically, and four portions of the optical fibers of the first and second optical fiber rings 121 and 137 excluding the respective midpoints X1 and X2 are arranged. Two optical fiber ring portions 141 that are branched by a third branching optical coupler 139 of two WDM couplers and are shared by both wavelength bands of 1.3 μm band and 1.55 μm band are formed.

  Therefore, in the first interference type vibration sensor 103, the propagation light having a wavelength band of 1.31 μm input from the first light source 107 is transmitted from the first port 109 to the third and fourth ports 115 of the first branch optical coupler 119. , 117 are branched into clockwise (Clock) light and counterclockwise (Counter Clock Wise: CCW) light, and the first optical fiber rings 121 are respectively connected as shown by the solid line in FIG. Go around. Each CW light and CCW light are combined again by the first branching optical coupler 119, and the first light receiving unit 111 detects the interference light.

  At this time, if vibration or impact is applied to the first optical fiber ring 121, that is, the optical fiber ring portion 141, a refractive index change occurs in the optical fiber. At this time, the first light receiving unit 111 detects this phenomenon as a change in the intensity of the interference light between the CW light and the CCW light that are phase-modulated by vibration.

  On the other hand, the second interference type vibration sensor 105 is substantially the same as the first interference type vibration sensor 103 described above, and the propagation light having a wavelength band of 1.55 μm input from the second light source 123 is the second branched light. The light is branched into CW light and CCW light by the coupler 135 and makes a round around the second optical fiber ring 137 as indicated by the dotted line in FIG. Each CW light and CCW light are combined again by the second branching optical coupler 135, and the interference light is detected by the second light receiving unit 127. A change in the intensity of the interference light between the CW light and the CCW light phase-modulated by vibration applied to the second optical fiber ring 137, that is, the optical fiber ring portion 141 is detected.

  Furthermore, by comparing the intensity changes of the interference light of the first and second interference type vibration sensors 103 and 105, the vibration characteristics such as the vibration position and vibration level of the excitation point are identified.

Therefore, the optical fiber ring portion 141 is accommodated in, for example, one vibration sensor optical cable so that the length L of the vibration sensor optical cable is increased, for example, several km to several tens km of a fence or the like. By extending the entire length, it is possible to detect the vibration position and vibration level of the excitation point generated when the intruder enters from the fence.
Fujikura Technical Review No. 103 (October 2002)

  By the way, in the conventional optical fiber ring interference type vibration sensor 101, it is possible to identify the vibration / impact and vibration position caused by an intruder or flying object, but the vibration sensor optical cable vibrates due to the intruder or flying object. There is a problem that when the shock is cut to such an extent that it cannot be detected, it may not be detected only by the first and second optical fiber rings 121 and 137 of the optical cable for vibration sensor.

  Further, even if the vibration sensor optical cable does not break, there is a possibility that an impact at a level at which the first and second optical fiber rings 121 and 137 increase in loss cannot be detected reliably. For example, there is a problem that the optical cable for vibration sensor may be bent and penetrated to such an extent that vibration and impact cannot be detected without being disconnected.

  The present invention has been made to solve the above-described problems.

In order to achieve the problem to be solved by the above invention, an optical fiber intrusion monitoring apparatus of the present invention includes an optical fiber vibration sensor detection device including a light source and a light receiving unit that detects interference light of the optical fiber, An optical cable for a vibration sensor constituting a first branch coupler connected to the light source and the light receiving portion of the optical fiber vibration sensor detection device, and an optical fiber ring interference type vibration sensor having one end connected to the first branch coupler. In an optical fiber intrusion monitoring device comprising:
The optical fiber for cable cutting | disconnection detection accommodated in the said optical cable for vibration sensors is provided, It is characterized by the above-mentioned.

An optical fiber intrusion monitoring device according to the present invention includes an optical fiber vibration sensor detection device including two light sources having different wavelengths and two types of light receiving units that detect interference light of an optical fiber corresponding to the two light sources. The optical fiber vibration sensor detection device includes a first branch coupler connected to each light source and each light receiving unit, and an optical fiber ring interference type vibration sensor having one end connected to the first branch coupler. In an optical fiber intrusion monitoring device comprising a vibration sensor optical cable and a second branch coupler connected to the other end of the vibration sensor optical cable,
The optical fiber for cable cutting | disconnection detection accommodated in the said optical cable for vibration sensors is provided, It is characterized by the above-mentioned.

  In the optical fiber intrusion monitoring apparatus according to the present invention, it is preferable that one end side of the optical fiber intrusion monitoring apparatus is connected to an OTDR that measures the cut and distance to the cut portion. .

  In the optical fiber intrusion monitoring apparatus according to the present invention, in the optical fiber intrusion monitoring apparatus, the bending loss level of the cable break detection optical fiber is made larger than the bending loss level of the optical fiber ring interference type vibration sensor. It is preferable.

  In the optical fiber intrusion monitoring device according to the present invention, in the optical fiber intrusion monitoring device, the optical fiber for cable disconnection detection is disposed on the outer peripheral side of the vibration sensor optical cable from the optical fiber ring interference type vibration sensor. It is preferable.

  In the optical fiber intrusion monitoring apparatus according to the present invention, it is preferable that the optical fiber intrusion monitoring apparatus includes a plurality of the cable cut detection optical fibers.

  As can be understood from the means for solving the above problems, according to the present invention, the optical cable for the vibration sensor is laid and wired on a monitoring structural member such as a fence, and an intruder enters the fence. The vibration characteristics at the excitation point generated when the optical fiber ring interferometric vibration sensor in the optical cable for the vibration sensor can be detected by detecting the intensity change of the interference light whose phase is modulated by the vibration. In addition, when the vibration sensor optical cable is cut by an intruder or a flying object, the cut and the cutting position can be reliably detected by the cable cutting detection optical fiber.

  Further, according to the present invention, the vibration sensor optical cable is laid and wired on a monitoring structural member such as a fence, and vibrations at an excitation point generated when an intruder enters the fence are detected by the vibration sensor optical cable. In the optical fiber ring interference type vibration sensor, the vibration position and vibration level of the excitation point are detected by detecting and comparing the intensity changes of the two interference lights in which lights having different wavelengths are phase-modulated by the vibration. In addition, when the vibration sensor optical cable is cut by an intruder or a flying object, the cutting and cutting position can be reliably detected by the cable cutting detection optical fiber.

  Embodiments of the present invention will be described below with reference to the drawings.

  Referring to FIG. 1 and FIGS. 2A to 2C, as shown in FIG. 1, the optical fiber intrusion monitoring apparatus 1 according to this embodiment includes a first interference type vibration sensor 3 and Using the second interference type vibration sensor 5 to detect and compare the intensity of each interference light generated by the vibration of different wavelengths of light input to the first and second interference type vibration sensors 3 and 5. In addition to identifying vibration characteristics such as the vibration position and vibration level of the excitation point, the cable cutting detection optical fiber 7 was cut or bent by an intruder or a flying object using the cable cutting detection optical fiber 7. In this case, the cutting and the cutting position are detected.

  The first interference type vibration sensor 3 is connected to a first port 11 connected to a first light source 9 that generates light having a wavelength band of 1.31 μm and a first light receiving unit 13 including a photodiode (PD). A first branched optical coupler 21 that branches from at least two ports (three ports in FIG. 1) to at least two third and fourth ports 17 and 19 and the first branched light. And a first optical fiber ring 23 optically connected to the coupler 21. The first optical fiber ring 23 has one end connected to the third port 17 and the other end connected to the fourth port 19.

  The second interference type vibration sensor 5 includes a fifth port 27 connected to a second light source 25 that generates light having a wavelength band of 1.55 μm different from that of the first light source 9, and a photodiode (PD). A second branch optical coupler 37 that branches from at least two ports (four ports in FIG. 1) to the sixth port 31 connected to the second light receiving unit 29 to at least two seventh and eighth ports 33 and 35. And a second optical fiber ring 39 optically connected to the second branch optical coupler 37. The second optical fiber ring 39 has one end connected to the seventh port 33 and the other end connected to the eighth port 35.

  In this embodiment, 3 × 3 couplers are used for the first and second branch optical couplers 21 and 37, respectively.

  Further, in the first and second interference type vibration sensors 3 and 5, the midpoint X1 of the total length of the first optical fiber ring 23 and the midpoint X2 of the total length of the second optical fiber ring 39 are positioned on opposite sides. Preferably, the first and second optical fiber rings 23 and 39 are symmetrically arranged, and four portions of the optical fibers excluding the middle points X1 and X2 of the first and second optical fiber rings 23 and 39 are arranged. It is configured by two optical fiber ring portions 43 that are branched by the third branching optical coupler 41 of two WDM couplers and shared in both the 1.3 μm band and the 1.55 μm band.

  Accordingly, in the first interference type vibration sensor 3, propagating light having a wavelength band of 1.3 μm input from the first light source 9 is transmitted from the first port 11 to the third and fourth ports 17 of the first branch optical coupler 21. , 19 and branched into clockwise (Clock Wise: CW) light and counterclockwise (Counter Clock Wise: CCW) light, and as shown by the solid line in FIG. Go around. Each CW light and CCW light are combined again by the first branching optical coupler 21, and the first light receiving unit 13 detects the interference light. At this time, in a static state where no vibration or impact is applied, the optical path length in the first optical fiber ring 23 of the CW light and the CCW light is the same, so the phase difference between the two becomes constant, The signal detected by the first light receiving unit 13 is constant.

  However, when a physical external force (mechanical stimulus) such as vibration is applied to the first optical fiber ring 23, that is, the optical fiber ring portion 43, a refractive index change occurs in the optical fiber. At this time, in the first light receiving unit 13, this phenomenon is detected as a change in the intensity of the interference light between the CW light and the CCW light phase-modulated by vibration.

For example, when phase modulation occurs at the excitation point at time t, the time T _CW until the CW light reaches the first light receiving unit 13 from the excitation point and the CCW light from the excitation point to the first light receiving unit. _Assuming that the time T _CCW until reaching 13 is reached, the intensity of the interference light detected by the first light-receiving unit 13 is a function of the added phase modulation and two variables between the time T _CW and the time T _CCW. Will be given. Since this detail is shown in Non-Patent Document 1, the description thereof is omitted.

  On the other hand, the second interference type vibration sensor 5 is substantially the same as the first interference type vibration sensor 3 described above, and the propagation light having a wavelength band of 1.55 μm input from the second light source 25 is the second branched light. The coupler 37 splits the light into CW light and CCW light and makes a round around the second optical fiber ring 39 as indicated by the dotted line in FIG. Each CW light and CCW light are combined again by the second branch optical coupler 37, and the interference light is detected by the second light receiving unit 29. A change in the intensity of the interference light between the CW light and the CCW light that are phase-modulated by vibration applied to the second optical fiber ring 39, that is, the optical fiber ring portion 43, is detected.

At this time, when the phase change due to vibration changes sufficiently slowly with respect to the time of light from the excitation point to the first and second light-receiving portions 13 and 29, respectively in the 1.3 μm band and the 1.55 μm band. The resulting phase differences Δφ _1.3 and Δφ _1.55 can be calculated, and the distances to the excitation points are the phase differences Δφ _1.3 and Δφ _{1.55 that} occur in the 1.3 μm band and 1.55 μm band, respectively. It can be calculated by the ratio.

  As described above, the intensity change of the interference light obtained by phase-modulating the 1.3 μm band light input from the first light source 9 by the first interference type vibration sensor 3 and the second interference type vibration sensor 5. By detecting and comparing the intensity change of the interference light in which the 1.55 μm band light input from the second light source 25 is phase-modulated by vibration, a part of the optical fiber ring portion 43 may be subjected to physical or the like. Vibration characteristics such as the vibration position and vibration level of the excitation point to which the external force is applied can be identified.

  Next, the cable cutting detection optical fiber 7 constituting the main part of the embodiment of the present invention will be described in detail.

  The cable-cutting detection optical fiber 7 is combined vertically with the first and second optical fiber rings 23 and 39. That is, for example, an OTDR (Optical Time Domain Reflectometer) is used as an optical measuring instrument in which the left end of the cable cutting detection optical fiber 7 in FIG. 47 is connected, and the other end on the right side of the optical fiber 7 for detecting cable breakage in FIG. 1 is opened.

  In this embodiment, as described above, the OTDR 47 is used as an optical measuring instrument, but an optical power meter generally used as an optical measuring instrument may be used. However, since the optical power meter requires a device on the opposite side and a power source, the above-described OTDR 47 is preferable.

  1 and 2A to 2C together, the first light source 9, the first light receiving unit 13, the second light source 25, and the second light receiving unit 29 are used as an optical fiber vibration sensor detection device, for example. It is accommodated in the vibration detector main body 49. The first branch optical coupler 21 is accommodated in the first branch coupler 51. The second branch optical coupler 37 is accommodated in the second branch coupler 53.

  The first light source 9 and the first light receiving unit 13 to the first branching optical coupler 21 are connected by a first optical fiber 55 (three cores in FIG. 1), respectively, and the second light source 25 and the second light receiving unit are connected. The section 29 to the second branch optical coupler 37 are connected by a second optical fiber 57 (three cores in FIG. 1).

  Therefore, between the vibration detector main body 49 and the first branch coupler 51, the first and second optical fibers 55 and 57 (6 cores) and the cable cutting detection optical fiber 7 (1 core) have a total of 7 cores. As shown in FIG. 2 (B), for example, it is vertically attached to one tension member 59 and is connected by an optical cable for approach 63 constituted by sheathing the entire outer periphery with a jacket 61. .

  Further, between the first branch coupler 51 and the second branch coupler 53, the optical fiber ring portion 43 of the shared portion of the second optical fiber 57 (three cores) and the first and second optical fiber rings 23 and 39 is provided. As shown in FIG. 2 (C), a total of 6 cores (2 cores) and the cable cut detection optical fiber 7 (1 core) are vertically attached to, for example, one tension member 65 and all of them. The outer periphery is connected by a vibration sensor optical cable 69 configured with a sheath 67 as a sheath.

  With the configuration described above, in the optical fiber intrusion monitoring apparatus 1 according to this embodiment, the above-described vibration sensor optical cable 69 has an arbitrarily long length L, for example, for monitoring the fence 71 and the like stretched around the monitoring section. By extending the structural member over the entire length of several kilometers to several tens of kilometers, the vibration position of the vibration sensor optical cable 69 generated when the intruder enters from the fence 71 (distance to the excitation point). ) And the vibration level can be detected by the optical fiber ring portion 43 of the first and second optical fiber rings 23 and 39, and when the vibration sensor optical cable 69 is cut by an intruder or a flying object, the cutting and cutting are performed. The position can be reliably detected by the optical fiber 7 for detecting cable breakage.

  Note that the above-described optical fiber 7 for detecting cable breakage desirably has a bending loss level higher than the bending loss level of the first and second optical fiber rings 23 and 39, particularly the optical fiber ring portion 43. In this case, for example, when the vibration sensor optical cable 69 is not cut, the first and second optical fiber rings 23 and 39 are bent and penetrated to such an extent that vibration and impact at an increased loss level cannot be detected. However, as shown in FIG. 3, the bending loss level of the optical fiber 7 for detecting cable breakage changes more greatly than the bending loss level of the first and second optical fiber rings 23 and 39. The bending and the bending position can be reliably detected by the optical fiber 7 for use.

  Further, as shown in FIG. 4A, the above-described optical fiber 7 for detecting cable breakage is the optical fiber ring portion of the first and second optical fiber rings 23 and 39 in the vibration sensor optical cable 69. It is desirable to be arranged on the outer peripheral side than 43. As a result, the vibration sensor optical cable 69 is more easily damaged than the optical fiber ring portion 43. In other words, when the vibration sensor optical cable 69 is damaged by flying objects or the like, if only the optical fiber ring portion 43 is damaged and the cable cut detection optical fiber 7 is not damaged, the vibration sensor optical cable 69 is cut or bent. Can be prevented from being reliably detected.

  Further, as shown in FIG. 4B, the vibration sensor optical cable 69 includes a plurality (four in the figure) of the cable cutting detection optical fibers 7 that are arranged on the outer periphery of the optical fiber ring portion 43. It is desirable to be arranged on the side. Thereby, the cutting | disconnection or bending by the optical cable 69 for vibration sensors can be detected still more reliably. If there are a plurality of cable cutting detection optical fibers 7, even if they are not necessarily arranged on the outer peripheral side of the optical fiber ring portion 43, the cutting or bending can be detected more reliably as the number increases.

  In the optical fiber intrusion monitoring apparatus 1 according to the above-described embodiment, the case where the first and second interference type vibration sensors 3 and 5 and the cable cut detection optical fiber 7 are provided has been described. The present invention can also be applied to the case where only the mold vibration sensor 3 and the cable cutting detection optical fiber 7 are provided.

  That is, in the optical fiber intrusion monitoring apparatus 1 in this case, in the optical fiber ring interference type vibration sensor, the first interference type vibration sensor 3 includes the first light source 9, the first light receiving unit 13, the first branch optical coupler 21, and the first light. The optical fiber for vibration sensor is composed of the first optical fiber ring 23 and the optical fiber 7 for detecting the cable cut vertically and combined with the first optical fiber ring 23, and one end of the optical fiber 7 for detecting the cable cut is formed. The first optical fiber ring 23 is optically connected to the midpoint X1 side of the entire length via a branch optical coupler. This branching optical coupler may be the same as the second branching optical coupler 37 described above, or even if only the seventh port 33 and the ninth port 45 in the second branching optical coupler 37 are provided, Other configurations may be used.

  Accordingly, even in this case, a physical external force such as vibration generated when an intruder enters from the fence 71 can be detected by the first optical fiber ring 23, and the vibration sensor optical cable 69 is cut by the intruder or flying objects. Alternatively, when bent, the cutting and cutting position, or the bending and bending position can be reliably detected. That is, when only the first optical fiber ring 23 is used, the vibration characteristics detected by the first and second interference type vibration sensors 3 and 5 are different from those described above. This is the same as the description of the embodiment described above.

1 is a circuit diagram schematically showing an optical fiber intrusion monitoring apparatus according to an embodiment of the present invention. (A) is a perspective view which shows schematically the vibration sensor of the optical fiber penetration | invasion monitoring apparatus which concerns on embodiment of this invention, (B) is sectional drawing of the arrow IIB-IIB line | wire of (A), C) is a sectional view taken along line IIC-IIC in (A). It is a graph which shows the change of the loss loss level of the optical fiber for cable cutting | disconnection detection in other embodiment of this invention. (A) is sectional drawing which shows other embodiment changed to FIG.2 (C), (B) is sectional drawing which shows other embodiment changed to FIG.2 (C). It is a circuit diagram which shows schematically the conventional optical fiber ring interference type vibration sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical fiber penetration | invasion monitoring apparatus 3 1st interference type vibration sensor 5 2nd interference type vibration sensor 7 Optical fiber 9 for cable cutting | disconnection detection 1st light source 11 1st port 13 1st light-receiving part 15 2nd port 17 3rd port 19 1st 4 port 21 1st branch optical coupler 23 1st optical fiber ring 25 2nd light source 27 5th port 29 2nd light-receiving part 31 6th port 33 7th port 35 8th port 37 2nd branch optical coupler 39 2nd optical fiber Ring 41 Third branch optical coupler 43 Optical fiber ring part 47 OTDR (optical measuring device)
49 Vibration detector body (optical fiber vibration sensor detector)
51 First branch coupler 53 Second branch coupler 63 Optical cable for approach 69 Optical cable for vibration sensor 71 Fence X1 Midpoint X1 of the first optical fiber ring Midpoint of the second optical fiber ring

Claims (6)

An optical fiber vibration sensor detection device comprising a light source and a light receiving unit for detecting interference light of the optical fiber, a first branch coupler connected to the light source and the light receiving unit of the optical fiber vibration sensor detection device, In an optical fiber intrusion monitoring device comprising a vibration sensor optical cable constituting an optical fiber ring interference type vibration sensor having one end connected to the first branch coupler,
An optical fiber intrusion monitoring apparatus comprising a cable cut detection optical fiber housed in the vibration sensor optical cable. An optical fiber vibration sensor detection device including two light sources having different wavelengths and two types of light receiving units that detect interference light corresponding to the two light sources, and each light source and each of the optical fiber vibration sensor detection devices A first branch coupler connected to the light receiving unit, an optical cable for a vibration sensor constituting an optical fiber ring interference type vibration sensor having one end connected to the first branch coupler, and the other end of the optical cable for the vibration sensor In an optical fiber intrusion monitoring device comprising a second branch coupler connected to the side,
An optical fiber intrusion monitoring apparatus comprising a cable cut detection optical fiber housed in the vibration sensor optical cable.   The optical fiber intrusion monitoring apparatus according to claim 1 or 2, wherein one end side of the cable cutting detection optical fiber is connected to an OTDR for measuring the cutting and distance to the cutting portion.   4. The optical fiber intrusion monitoring apparatus according to claim 1, wherein a bending loss level of the cable cutting detection optical fiber is made larger than a bending loss level of the optical fiber ring interference type vibration sensor.   5. The optical fiber according to claim 1, wherein the optical fiber for cable disconnection detection is arranged on an outer peripheral side of the optical fiber for vibration sensor than the optical fiber ring interference type vibration sensor. Intrusion monitoring device. The optical fiber intrusion monitoring apparatus according to any one of claims 1 to 5, wherein there are a plurality of cable disconnection detection optical fibers.

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