JP2007225397A - Method and structure for laying optical cable for vibration sensor use in optical fiber invasion monitoring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To identify an external physical force applied to part of an optical fiber ring and its position and to repair a break in the optical fiber ring easily. <P>SOLUTION: The optical fiber invasion monitoring system 1 comprises two light sources having different wavelengths, an optical fiber vibration sensor detection system 43 provide with two kinds of light receiving sections for detecting interference light corresponding to the two light sources, a first branching/coupling device 45 connected to the light sources and light receiving sections of the optical fiber vibration sensor detection system 43, an optical cable for vibration sensor use 63 of which one end is connected to the first branching/coupling device 45 and which constitutes an optical fiber ring interference vibration sensor, and a second branching/coupling device 47 connected to the other end of the optical cable for vibration sensor use 63. The optical cable for vibration sensor use 63 is provided with extra length parts 69 at appropriate intervals in its longitudinal direction and is laid on a monitoring structural member 65. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for laying an optical cable for a vibration sensor and a structure thereof, and in particular, when a physical external force is applied to a part of the optical fiber ring, the detection of the external force and the position where the external force is applied are identified. The present invention relates to a method for laying an optical cable for a vibration sensor in an optical fiber intrusion monitoring apparatus constituting an interference type vibration sensor and its structure.

  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. 4, 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 the following. (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, no power source, lightning protection or explosion proof measures are required 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 1.3 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. One end of the second optical fiber ring 137 is connected to the seventh port 131 and the other end is 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.

  Accordingly, in the first interference type vibration sensor 103, the propagation light having a wavelength band of 1.3 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 Wise: CW) 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 coupler 135 splits the light into CW light and CCW light, 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.

The optical fiber ring interference type vibration sensor 101 includes a vibration sensor optical cable 143 in which an optical fiber ring portion 141 is accommodated, and the length L of the vibration sensor optical cable 143 is increased so that FIG. As shown in FIG. 4, for example, an appropriate portion of the vibration sensor optical cable 143 is fixed to a monitoring structural member such as a fence 145 stretched around a monitoring section with a fixing tool 147, for example, several kilometers to several tens of kilometers. The optical fiber intrusion monitoring apparatus is configured by extending the entire length and laying the apparatus. It is possible to detect the vibration position and vibration level of the excitation point generated when an intruder enters from the fence 145.
Fujikura Technical Review No. 103 (October 2002)

  By the way, in the conventional optical fiber ring interference type vibration sensor 101, when the vibration sensor optical cable 143 is cut by an intruder or a flying object as shown in FIG. It is necessary to connect and repair the portion 149 again, but it is necessary to connect two portions at both ends thereof to the cutting portion 149 of the vibration sensor optical cable 143 with another repair optical cable. There was a problem that it took a lot of time to connect the optical cable.

  In addition, when the connection is repaired by using another optical cable for repair as described above, the entire length of the first and second optical fiber rings 121 and 137 including the optical fiber ring portion 141 is changed. Since it is necessary to reset the system of the fiber ring interference type vibration sensor 101, there is a problem that the resetting operation takes a lot of time.

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

In order to achieve the object to be solved by the invention, a method for laying an optical cable for a vibration sensor in an optical fiber intrusion monitoring apparatus according to the invention includes a light source and a light receiving unit that detects interference light of the optical fiber. A fiber vibration sensor detection device, 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 having one end connected to the first branch coupler An optical cable for a vibration sensor in an optical fiber intrusion monitoring device composed of an optical cable for a vibration sensor constituting a sensor,
The vibration sensor optical cable is laid with an extra length provided at appropriate intervals in the longitudinal direction.

In addition, the method for laying the optical cable for the vibration sensor in the optical fiber intrusion monitoring apparatus according to the present invention includes two light sources having different wavelengths and two types of light receiving units that detect interference light corresponding to the two light sources. A fiber vibration sensor detection device, a first branch coupler connected to each light source and each light receiving portion of the optical fiber vibration sensor detection device, and an optical fiber ring interference type in which one end side is connected to the first branch coupler This is a method for laying an optical cable for a vibration sensor in an optical fiber intrusion monitoring apparatus comprising: an optical cable for a vibration sensor that constitutes the vibration sensor of the first sensor; and a second branch coupler connected to the other end of the optical cable for vibration sensor. And
In the longitudinal direction of the optical cable for vibration sensor, extra length portions are provided at appropriate intervals and installed.

The laying structure of the optical cable for the vibration sensor in the optical fiber intrusion monitoring apparatus according to 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, and the optical fiber vibration sensor detection device. A first branch coupler connected to the light source and the light receiving section, and a vibration sensor optical cable constituting an optical fiber ring interference type vibration sensor having one end connected to the first branch coupler. An installation structure of an optical cable for a vibration sensor in an optical fiber intrusion monitoring device,
The vibration sensor optical cable is attached to a monitoring structure, and the vibration sensor optical cable is provided with an extra length portion at an appropriate interval in the longitudinal direction.

Moreover, the laying structure of the vibration sensor optical cable in the optical fiber intrusion monitoring apparatus according to the present invention includes two light sources having different wavelengths and two types of light receiving units that detect interference light corresponding to the two light sources. A fiber vibration sensor detection device, a first branch coupler connected to each light source and each light receiving portion of the optical fiber vibration sensor detection device, and an optical fiber ring interference type in which one end side is connected to the first branch coupler The vibration sensor optical cable in the optical fiber intrusion monitoring apparatus is composed of a vibration sensor optical cable constituting the vibration sensor and a second branch coupler connected to the other end of the vibration sensor optical cable. And
The vibration sensor optical cable is attached to a monitoring structure, and the vibration sensor optical cable is provided with an extra length portion at an appropriate interval in the longitudinal direction.

  As can be understood from the means for solving the above problems, according to the method for laying the vibration sensor optical cable in the optical fiber intrusion monitoring apparatus of the present invention, the vibration sensor optical cable is cut by an intruder or a flying object. Even if there is a surplus part at every appropriate interval in the longitudinal direction of the optical cable for vibration sensor, there is no need for another repairing optical cable as in the past, and the nearest surplus part can be easily pulled The cut portion can be reconnected and repaired. Therefore, since the vibration sensor optical cable for repair is connected at one place, the time required for repair work can be shortened. In addition, since the entire length of the vibration sensor optical cable does not change in order to connect the extra length parts by hand, it is not necessary to reset the system of the optical fiber ring interference type vibration sensor as in the prior art. The time required for repair work can be shortened.

  Further, according to the method of laying the optical cable for the vibration sensor in the optical fiber intrusion monitoring apparatus of the present invention, the intensity change of the two interference lights in which the light having different wavelengths is phase-modulated by the vibration at the excitation point is detected and compared. Thus, the present invention can be applied to an optical cable for a vibration sensor that can identify vibration characteristics such as the vibration position and vibration level of the excitation point, and the same effect as the above-described method for laying the optical cable for vibration sensor can be obtained.

  Further, according to the laying structure of the vibration sensor optical cable in the optical fiber intrusion monitoring apparatus of the present invention, the vibration sensor is the same as the above laying method, and even if the vibration sensor optical cable is cut by an intruder or a flying object, the vibration sensor Since the optical cable has extra length portions at appropriate intervals in the longitudinal direction, it is not necessary to use another optical cable for repair as in the prior art, and the cutting portion is easily pulled by handing the nearest extra length portion. Can be connected again and repaired. Therefore, since the vibration sensor optical cable for repair is connected at one place, the time required for repair work can be shortened. Moreover, since the entire length of the vibration sensor optical cable does not change in order to connect the extra length parts by hand, it is not necessary to reset the system of the optical fiber ring interference type vibration sensor as in the prior art. The time required for repair work can be shortened.

  Further, according to the laying structure of the vibration sensor optical cable in the optical fiber intrusion monitoring apparatus of the present invention, the intensity change of the two interference lights in which the light having different wavelengths is phase-modulated by the vibration at the excitation point is detected and compared. Thus, the present invention can also be applied to an optical cable for a vibration sensor that can identify vibration characteristics such as a vibration position and a vibration level of the excitation point, and the same effect as the above-described laying structure of the optical cable for a vibration sensor can be obtained.

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

  Referring to FIGS. 1A to 1C and FIG. 2, as shown in FIG. 2, 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. Thus, vibration characteristics such as the vibration position and vibration level of the excitation point are identified.

  The first interference type vibration sensor 3 is connected to a first port 9 connected to a first light source 7 that generates light having a wavelength band of 1.3 μm, and a first light receiving unit 11 including a photodiode (PD). A first branched optical coupler 19 that branches from at least two ports (three ports in FIG. 2) to at least two third and fourth ports 15 and 17 and the first branched light. And a first optical fiber ring 21 optically connected to the coupler 19. One end of the first optical fiber ring 21 is connected to the third port 15 and the other end is connected to the fourth port 17.

  The second interference type vibration sensor 5 includes a fifth port 25 connected to a second light source 23 that generates light having a wavelength band of 1.55 μm different from that of the first light source 7, and a photodiode (PD). A second branch optical coupler 35 that branches from at least two ports (three ports in FIG. 2) to the sixth port 29 connected to the second light receiving unit 27 to at least two seventh and eighth ports 31 and 33. And a second optical fiber ring 37 optically connected to the second branch optical coupler 35. One end of the second optical fiber ring 37 is connected to the seventh port 31 and the other end is connected to the eighth port 33.

  In this embodiment, 3 × 3 couplers are used for the first and second branch optical couplers 19 and 35, 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 21 and the midpoint X2 of the total length of the second optical fiber ring 37 are located on opposite sides. Preferably, the first and second optical fiber rings 21 and 37 are arranged symmetrically, and four portions of the optical fibers of the first and second optical fiber rings 21 and 37 excluding the midpoints X1 and X2 are provided. It is constituted by two optical fiber ring portions 41 that are branched by a third branching optical coupler 39 of one WDM coupler and shared in both wavelength bands of 1.3 μm band and 1.55 μm band.

  Therefore, in the first interference type vibration sensor 3, propagating light having a wavelength band of 1.3 μm input from the first light source 7 is transmitted from the first port 9 to the third and fourth ports 15 of the first branch optical coupler 19. , 17 and branched into clockwise (Clock) light and counterclockwise (Counter Clock Wise: CCW) light, and the first optical fiber rings 21 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 19, and the first light receiving unit 11 detects the interference light. At this time, in the static state where no vibration / impact is applied, the optical path length in the first optical fiber ring 21 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 11 is constant.

  However, when a physical external force (mechanical stimulus) such as vibration is applied to the first optical fiber ring 21, that is, the optical fiber ring portion 41, a refractive index change occurs in the optical fiber. At this time, the first light receiving unit 11 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.

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 11 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 11 is reached, the intensity of the interference light detected by the first light receiving unit 11 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 23 is the second branched light. The coupler 35 branches the light into CW light and CCW light, and each makes a round of the second optical fiber ring 37 as indicated by a dotted line in FIG. Each CW light and CCW light are combined again by the second branch optical coupler 35, and the interference light is detected by the second light receiving unit 27. 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 37, that is, the optical fiber ring portion 41 is detected.

At this time, when the phase change due to vibration changes sufficiently slowly with respect to the time of the light from the excitation point to the first and second light receiving portions 11 and 27, the 1.3 μm band and the 1.55 μm band, respectively. 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. The ratio can be calculated.

  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 7 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 light in the 1.55 μm band input from the second light source 23 is phase-modulated by vibration, a part of the optical fiber ring portion 41 may be subjected to a physical phenomenon such as vibration. Vibration characteristics such as the vibration position and vibration level of the excitation point to which the external force is applied can be identified.

  1A to 1C, 2 and 3 together, the first light source 7, the first light receiving unit 11, the second light source 23, and the second light receiving unit 27 are optical fiber vibration sensor detection devices. For example, it is accommodated in the vibration detector main body 43. The first branch optical coupler 19 is accommodated in the first branch coupler 45. The second branch optical coupler 35 is accommodated in the second branch coupler 47.

  The first light source 7 and the first light receiving unit 11 to the first branching optical coupler 19 are connected by a first optical fiber 49 (three cores in FIG. 2), respectively, and the second light source 23 and the second light receiving unit are connected. The section 27 and the second branch optical coupler 35 are connected by a second optical fiber 51 (three cores in FIG. 2).

  Therefore, between the vibration detector main body 43 and the first branch coupler 45, the first and second optical fibers 49 and 51 have a total of 6 cores, for example, 1 as shown in FIG. The tension member 53 is vertically attached and connected by an approach optical cable 57 configured by sheathing the entire outer periphery with a jacket 55.

  Further, between the first branch coupler 45 and the second branch coupler 47, the optical fiber ring portion 41 of the shared portion of the second optical fiber 51 (three cores) and the first and second optical fiber rings 21 and 37 is provided. As shown in FIG. 1 (C), a total of 5 cores (2 cores), for example, are vertically attached to one tension member 59 and the entire outer periphery thereof is sheathed with a jacket 61. They are connected by a vibration sensor optical cable 63.

  Further, in the optical fiber intrusion monitoring apparatus 1 according to this embodiment, the vibration sensor optical cable 63 is shown in FIGS. 1 (A) and 3 (A) with the length L arbitrarily increased. As shown, for example, an appropriate portion of the vibration sensor optical cable 63 is fixed to a monitoring structural member such as a fence 65 stretched around the monitoring section with a fixing device 67 and the like, and extended over a total length of several kilometers to several tens of kilometers. To be laid.

  At this time, the extra length portion 69 of about 500 mm is provided and wired to the fence 65 at appropriate intervals of, for example, several meters to several tens of meters in the longitudinal direction of the vibration sensor optical cable 63. Is the main feature of the form.

  With the above configuration, the vibration position (distance to the excitation point) and vibration level of the vibration sensor optical cable 63 generated when an intruder enters from the fence 65 are the first and second optical fiber rings 21, 21. It can be detected by 37 optical fiber ring portions 41. Moreover, as shown in FIG. 3B, when the vibration sensor optical cable 63 is cut by an intruder or a flying object, it is necessary to reconnect the cut portion 71 and repair it. Since there is an extra length portion 69 at every appropriate interval in the longitudinal direction of the vibration sensor optical cable 63, a separate repair optical cable is not required as in the prior art, as shown by the arrow in FIG. The nearest surplus length portion 69 can be easily pulled around and the cutting portion 71 can be connected again to be repaired.

  Accordingly, since the vibration sensor optical cable 63 for repair is connected at one place, the time required for repair work can be reduced. In addition, since the overall length of the vibration sensor optical cable 63 hardly changes because the extra length portion 69 is connected by hand, the so-called optical fiber ring interference type of the optical fiber intrusion monitoring apparatus 1 as in the prior art is used. Since it is not necessary to reset the vibration sensor system, it is possible to significantly reduce the time required for repair work.

  In the optical fiber intrusion monitoring apparatus 1 of the above-described embodiment, the case where the first and second interference type vibration sensors 3 and 5 are provided has been described. However, the case where only the first interference type vibration sensor 3 is provided. It is also applicable to.

  In other words, in the optical fiber intrusion monitoring apparatus in this case, the first interference type vibration sensor 3 includes the first light source 7, the first light receiving unit 11, the first branch optical coupler 19, and the first optical fiber ring 21, and this An optical cable for a vibration sensor that houses the first optical fiber ring 21 is configured.

  Therefore, even in this case, a physical external force such as vibration generated when an intruder enters the fence 65 can be detected by the first optical fiber ring 21, and the above-described vibration sensor optical cable can be detected by an intruder or a flying object. When cut, the cutting portion 71 can be easily connected and repaired as in the above-described embodiment. That is, when only the first optical fiber ring 21 is used, the vibration characteristics detected when the first and second interference-type vibration sensors 3 and 5 are used are different from those of the extra length portion 69 of the optical cable for the vibration sensor. The effect is the same as that of the above-described embodiment.

(A) is a perspective view which shows roughly the optical fiber penetration | invasion monitoring apparatus of embodiment of this invention, (B) is sectional drawing of the arrow IB-IB line of (A), (C) is ( It is sectional drawing of the arrow IC-IC line of A). 1 is a circuit diagram schematically showing an optical fiber intrusion monitoring apparatus according to an embodiment of the present invention. (A) is a front view which shows roughly the installation structure of the optical cable for vibration sensors in the optical fiber penetration | invasion monitoring apparatus of embodiment of this invention, (B) is the optical cable for vibration sensors of (A) cut | disconnected. It is a schematic explanatory drawing which shows a state, (C) is a schematic explanatory drawing when repairing a cutting part. It is a circuit diagram which shows schematically the conventional optical fiber ring interference type vibration sensor. (A) is a front view schematically showing a conventional construction structure of a vibration sensor optical cable, and (B) is a schematic explanatory view showing a state in which the vibration sensor optical cable of (A) is cut.

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 9 1st port 11 1st light-receiving part 13 2nd port 15 3rd port 17 1st 4 port 19 1st branch optical coupler 21 1st optical fiber ring 23 2nd light source 25 5th port 27 2nd light-receiving part 29 6th port 31 7th port 33 8th port 35 2nd branch optical coupler 37 2nd optical fiber Ring 39 Third branch optical coupler 41 Optical fiber ring portion 43 Vibration detector main body (optical fiber vibration sensor detection device)
45 First branch coupler 47 Second branch coupler 57 Optical cable for approach 63 Optical cable for vibration sensor 65 Fence (structural member for monitoring)
67 Fixing tool 69 Extra length portion X1 Midpoint X2 of first optical fiber ring Midpoint of second optical fiber ring

Claims (4)

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, An optical cable for a vibration sensor in an optical fiber intrusion monitoring apparatus, comprising: an optical cable for a vibration sensor that constitutes an optical fiber ring interference type vibration sensor having one end connected to a first branch coupler;
A method for laying an optical cable for vibration sensor in an optical fiber intrusion monitoring apparatus, wherein an extra length portion is provided at appropriate intervals in the longitudinal direction of the optical cable for vibration sensor. 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 An optical cable for a vibration sensor in an optical fiber intrusion monitoring device comprising: a second branch coupler connected to the side;
A method for laying an optical cable for vibration sensor in an optical fiber intrusion monitoring apparatus, wherein an extra length portion is provided at appropriate intervals in the longitudinal direction of the optical cable for vibration sensor. 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, An optical cable for a vibration sensor in an optical fiber intrusion monitoring device comprising an optical cable for a vibration sensor that constitutes an optical fiber ring interference type vibration sensor having one end connected to the first branch coupler,
The installation of the optical cable for a vibration sensor in an optical fiber intrusion monitoring apparatus, wherein the optical cable for a vibration sensor is attached to a monitoring structure, and an extra length is provided at an appropriate interval in the longitudinal direction of the optical cable for the vibration sensor. Construction. 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 An optical cable for a vibration sensor in an optical fiber intrusion monitoring device constituted by a second branch coupler connected to the side,
The installation of the optical cable for a vibration sensor in an optical fiber intrusion monitoring apparatus, wherein the optical cable for a vibration sensor is attached to a monitoring structure, and an extra length is provided at an appropriate interval in the longitudinal direction of the optical cable for the vibration sensor. Construction.

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