JP4976143B2 - Impact vibration detector - Google Patents

Description

  The present invention relates to an impact vibration detection apparatus that can detect the intensity of impact or vibration caused by collision of an object using an optical fiber.

  Conventionally, when an optical fiber is attached to the wire of an existing fence and an intrusion act such as shifting the position of this wire occurs, external force such as shock or vibration is applied to the optical fiber attached to the wire, and this external force causes light to enter. There is an intrusion detection apparatus that generates polarization fluctuations in light propagating in a fiber, and makes an intrusion judgment by detecting the polarization fluctuations to issue an alarm (see Patent Document 1).

JP 2000-40187

  However, the conventional shock vibration detection device that makes an intrusion determination based on the polarization fluctuation generated in the optical fiber detects a large polarization fluctuation strength uniformly regardless of the magnitude of external force such as shock or vibration. In addition, it was only possible to detect the occurrence of shock and vibration.

  That is, the conventional shock vibration detection device cannot detect the magnitude of the polarization fluctuation corresponding to the magnitude of the external force such as shock or vibration, and therefore cannot detect the magnitude of the external force such as shock or vibration. .

  For this reason, for example, when detecting a falling rock, if a conventional impact vibration detection device is used, even if it is a large stone falling rock or a small stone falling rock, a warning is issued uniformly, and remotely. There was a problem that it was impossible to know what size and weight of rock fall occurred at the rock fall site.

  The present invention has been made in view of the above, and an object thereof is to provide an impact vibration detection device capable of detecting the magnitude of an external force such as an impact or vibration.

  In order to solve the above-mentioned problems and achieve the object, an impact vibration detection device according to the present invention is such that an optical fiber is wound around the surface of an elastic member having natural vibration, and the optical fiber is tightly bonded to the surface. A vibration sensor unit, a transmission transmission optical fiber connected to one end of the optical fiber, a reception transmission optical fiber connected to the other end of the optical fiber, and polarization via the transmission transmission optical fiber. A light source that outputs the transmitted light to the optical fiber, a light receiver that receives the light transmitted through the optical fiber for reception and transmission, and a light receiver that is provided between the light receiver and the optical fiber for reception transmission. A polarizer for polarizing the transmitted light, and a detecting means for detecting a polarization fluctuation intensity of the light received by the light receiver.

  Also, in the shock vibration detection device according to the present invention, in the above invention, the light source outputs non-polarized light, and transmits light between the light source and the transmission transmission optical fiber. A child is provided.

  The shock vibration detection device according to the present invention is the above-described invention, wherein a transmission optical fiber is provided in place of the transmission transmission optical fiber and the reception transmission optical fiber. Optical multiplexers / demultiplexers are provided and connected at both ends, one end of the optical fiber on the sensor unit side is connected to one optical multiplexer / demultiplexer, and the light on the light source side and the light receiver side is connected to the other optical multiplexer / demultiplexer. It is characterized by connecting fibers.

  In the shock vibration detection device according to the present invention, in the above invention, the elastic member is a plurality, and the optical fiber is wound around each elastic member and closely bonded to the surface of each elastic member. It is characterized by that.

  Also, in the impact vibration detection device according to the present invention, in the above invention, the elastic member has different natural vibrations, and the detection means is transmitted after a polarization fluctuation of light generated by the impact. The elastic member in which the impact is generated is specified based on the natural frequency of the polarization fluctuation.

  The shock vibration detection device according to the present invention is characterized in that, in the above-mentioned invention, a high-pass filter that transmits a frequency exceeding the natural frequency of the elastic member is provided downstream of the light receiver.

  The shock vibration detection device according to the present invention includes, in the above invention, four first to fourth light receivers, and an optical demultiplexer between each light receiver and the reception transmission optical fiber. And connecting the optical demultiplexer and the first light receiver, and connecting a second polarizer that transmits polarized light of 0 ° between the optical demultiplexer and the second light receiver. A 0 ° polarization component is output, a third polarizer that passes 45 ° polarization is connected between the optical demultiplexer and the third light receiver, and a 45 ° polarization component is output, A wave plate and a fourth polarizer are sequentially connected from the vibration sensor unit side between the optical demultiplexer and the third light receiver to output a clockwise polarized component, and the first to fourth components are output. Analyzing means for analyzing polarization fluctuations based on the light received by the light receiver is provided.

  In the above-described invention, the shock vibration detection device according to the present invention includes the transmission-side polarizer provided on the vibration sensor unit side of the transmission transmission optical fiber, and the vibration sensor unit side of the reception transmission optical fiber. A polarizer is provided, and a depolarizer is provided between the light source and the transmission transmission optical fiber to output the input light in a non-polarized state.

  In the impact vibration detection device according to the present invention as set forth in the invention described above, the elastic member is any one of a flat plate, a square member, a pillar member, or a combination of one or more.

  In the impact vibration detection device according to the present invention as set forth in the invention described above, the elastic member is an iron material.

  The shock vibration detection device according to the present invention is a light that propagates through the optical fiber of a vibration sensor unit in which an optical fiber is wound around the surface of an elastic member having natural vibration and the optical fiber is closely bonded to the surface. Is output in accordance with the magnitude of the impact / vibration generated in the elastic member, so that the magnitude of the external force of the impact / vibration applied to the elastic member can be detected.

  Hereinafter, an impact vibration detection apparatus which is the best mode for carrying out the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of an impact vibration detection apparatus according to Embodiment 1 of the present invention. In FIG. 1, the shock vibration detection device is realized by an LED, a semiconductor laser, or the like, and includes a light source 1 that emits light, a polarizer 3A that polarizes and outputs light emitted from the light source 1, and a polarizer 3A. It is realized by the optical fiber 2A for transmitting the output light and an elastic member having natural vibration such as an iron plate, and is wound around the surface of the panel 4A and the panel 4A that receives external shock and vibration, and on this surface. An optical fiber 2B that transmits light output from the optical fiber 4B and an optical fiber 4B that is closely bonded and that imparts polarization fluctuations to light transmitted by shock and vibration received by the panel 4A. And a polarizer 3B that polarizes and outputs the light output from the optical fiber 2B and a photodiode or the like, and receives the light output from the polarizer 3B. That includes a light receiver 5, and an oscilloscope 6 for outputting a time change of polarization fluctuations intensity is the intensity of the light received by the light receiver 5.

  Here, when a semiconductor laser is used as the light source 1, since the output light from the semiconductor laser is already polarized, a configuration in which the polarizer 3A is omitted can be employed. Further, a high pass filter 5A is provided in the light receiver 5, and the high pass filter 5A has a characteristic of passing a frequency exceeding the natural frequency of the elastic member 4A. Further, the close bonding between the panel 4A and the optical fiber 4B in the sensor unit 4 is performed using a resin or an adhesive.

  The light output from the light source 1 becomes light polarized by the polarizer 3A, and this polarized light is transmitted through the optical fiber 2A and passes through the optical fiber 4B in the sensor unit 4. At this time, the panel 4A When an external force such as shock or vibration is applied, the light propagating through the optical fiber 4B undergoes polarization fluctuation, and this polarization-fluctuated light is transmitted through the optical fiber 2B and input to the light receiver 5 via the polarizer 3B. The FIG. 2 is a diagram showing a temporal change in the received light intensity P detected by the light receiver 5, and as shown in FIG. 2, the received light intensity P is deviated between T1 and the time point when the impact / vibration is applied. Amplitude fluctuations of the wave fluctuation intensity ΔP occur, and then the extra vibration due to the natural vibration of the panel 4A occurs during T2.

  3 and 4 are schematic diagrams showing temporal fluctuations of the received light intensity P from which the natural vibration has been removed by the high-pass filter 5A. FIG. 3 shows a case where a small impact / vibration is applied, and FIG. This shows the case where a large impact or vibration is applied. 3 and 4, when a small shock / vibration is applied to the panel 4A, a small polarization fluctuation intensity ΔP is generated, and when a large shock / vibration is applied to the panel 4A, a large polarization fluctuation intensity. It can be seen that ΔP is generated.

  As a result, as shown in FIG. 5, it is possible to obtain an intensity detectable range E in which the polarization fluctuation intensity ΔP changes in accordance with the magnitude of the impact / vibration, that is, the vibration / impact strength. In the intensity detectable range E, by obtaining the polarization fluctuation intensity ΔP, it is possible to obtain the impact / vibration intensity corresponding to the polarization fluctuation intensity ΔP on a one-to-one basis. In addition, in the conventional impact vibration detection apparatus, this intensity | strength detectable range E cannot be obtained, but only the presence or absence of an impact and a vibration was detected.

  6-8 is a figure which shows the time change of the polarization fluctuation intensity actually measured. In this measurement, an iron plate of 1800 mm × 900 mm × 4 mm is used as the panel 4A, a single mode fiber is used as the optical fiber 4B, FIG. 6 shows a case where a weight of 1 kg collides with the panel 4A, and FIG. FIG. 8 shows a case where a weight of 3 kg collides with the panel 4A, and FIG. 8 shows a case where a weight of 5 kg collides with the panel 4A. 6 to 8, when the impact / vibration strength is increased to 1 kg, 3 kg, and 5 kg, the polarization fluctuation strength ΔP increases substantially linearly to 0.06, 0.12, and 0.24. I understand. That is, it can be seen that the optical fiber 4B converts the impact / vibration intensity into the polarization fluctuation intensity.

  In addition, the intensity | strength detectable range E can be changed by changing the shape of the elastic member which is the panel 4A, for example, thickness and width. For example, the impact / vibration strength can be detected by changing the polarization fluctuation strength in the “t” order or the “g” order instead of the “kg” order in the weight. Furthermore, the intensity detectable range E can be changed also by changing the material of the elastic member which is the panel 4A.

  Also, the assumption that the elastic member which is the panel 4A has natural vibration is that even this elastic member is close to a rigid body, and the natural vibration is generated even by an impact and the shape of the elastic member itself is substantially maintained. This is because it is considered that the polarization fluctuation strength corresponding to the shock / vibration strength is generated.

  In addition, in addition to using the above-described resin or adhesive, the panel 4A and the optical fiber 4B may be provided with a projection, for example, so that the panel 4A is wound, and the optical fiber 4B is wound around the projection. The optical fiber 4B may be wound between the protrusions. Further, a tube such as a metal tube or fiber reinforced plastic may be provided on the panel 4A, and the optical fiber 4B may be wound around the tube.

  Further, the panel 4A has a flat plate shape, but is not limited thereto, and may be an elastic member having natural vibration, and may be a prism, a cylinder, or a cylinder. In this case, the optical fiber 4B is wound around a prism or cylinder. Further, the surface of the panel 4A or the like does not have to be a flat surface, and may be an uneven curved surface.

  In the first embodiment, an optical fiber is tightly bonded to the panel 4A which is an elastic member having natural vibration, and the optical fiber optically converts the impact / vibration intensity received by the panel 4A into a polarization fluctuation intensity. Therefore, the magnitude of the external force of impact / vibration applied to the panel 4A can be detected. In particular, when the first embodiment is applied to rock fall detection, the distance between the optical fibers 2A and 2B is increased, and the sensor unit 4 is provided at the rock fall site to determine how large the fall rock is. You can know remotely.

(Embodiment 2)
Next, a second embodiment of the present invention will be described. In the first embodiment described above, the two optical fibers 2A and 2B are used up to the sensor unit 4, but in this second embodiment, the distance between the sensor unit 4, the light source 1 and the light receiver 5 is 1. They are connected with a single optical fiber.

  That is, as shown in FIG. 9, the optical fibers 2A and 2B shown in FIG. 1 are replaced with a single optical fiber 2 for optical transmission, and the optical fiber 2 is realized by an optical coupler or an optical circulator at both ends. Two optical multiplexers / demultiplexers 7 are provided. The optical multiplexer / demultiplexer 7 on the sensor unit 4 side has one end connected to the optical fiber 2 and the other end connected to both ends of the optical fiber 4B of the sensor unit 4 so that the semiconductor laser 11 and the light receiver 5 corresponding to the light source 1 are connected. The optical multiplexer / demultiplexer 7 on the photodiode 15 side corresponding to is connected to the optical fiber 2 at one end and to the polarizer 3A on the semiconductor laser 11 side and the polarizer 3B on the photodiode 15 side.

  The light output from the semiconductor laser 11 is polarized by the polarizer 3A, and this polarized light is input to the optical fiber 4B of the sensor unit 4 via the optical multiplexer / demultiplexer 7, the optical fiber 2, and the optical multiplexer / demultiplexer 7. The light output from the optical fiber 4B is input to the polarizer 3B via the optical multiplexer / demultiplexer 7, the optical fiber 2, and the optical multiplexer / demultiplexer 7, and is output to the photodiode 15.

  In the second embodiment, a simple device is required because only one transmission optical fiber is required between the sensor unit 4 and the semiconductor laser 11 and the photodiode 15 as in the case of falling rock detection. Can be realized. In particular, the effect is large in an apparatus in which the optical fiber for transmission to be disposed is a long distance, such as rock fall detection.

(Embodiment 3)
Next, a third embodiment of the present invention will be described. In the first embodiment described above, the number of the panels 4A provided in the sensor unit 4 is one, but in the third embodiment, the plurality of panels 4A receive the impact / vibration.

  That is, as shown in FIG. 10, three panels 4A are provided in the sensor unit 4, and the optical fiber 4B is wound around each panel 4A and is closely bonded. Other configurations are the same as those of the first embodiment.

  In the third embodiment, for example, even if the impact / vibration applied to one panel 4A is large and damaged, only the damaged panel 4A needs to be replaced, and the maintainability is improved.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described. In the third embodiment described above, it is assumed that the three panels 4A are all the same, but in this fourth embodiment, the panels 4A-1 to 4A-3 are arranged with different natural vibrations. ing.

  That is, as shown in FIG. 11, the natural frequencies of the panels 4A-1 to 4A-3 are f1 to f3, respectively. Other configurations are the same as those of the third embodiment. However, the high pass filter 6 shown in FIG. 1 is not provided. Here, if the natural frequencies of the panels 4A-1 to 4A-3 are different, the natural vibrations generated in the period T2 shown in FIG. 2 are different. Therefore, the polarization fluctuation intensity in the period T1 generated before the natural vibrations. , That is, a panel to which impact / vibration is applied can be identified, and the occurrence position of the impact / vibration can be identified.

  For example, when an impact / vibration is applied to the panel 4A-2 as shown in FIG. 11, the waveform of the natural frequency f2 of the panel 4A-2 is obtained in the period T2, as shown in FIG. The position where the shock / vibration occurs can be specified. Of course, in this case, the impact / vibration strength can be known from the polarization fluctuation strength generated in the period T1.

  In the fourth embodiment, since the natural frequencies of the panels 4A-1 to 4A-3 are made different, it is possible to obtain the impact / vibration strength and to specify the location where the impact / vibration occurs. it can.

(Embodiment 5)
Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, the polarization state can be further analyzed.

  FIG. 13: is a block diagram which shows the structure of the impact vibration detection apparatus concerning Embodiment 5 of this invention. In FIG. 13, an optical demultiplexer 9 is provided at the subsequent stage of the optical fiber 2B so as to demultiplex light input from the sensor unit 4 side. The front stage of the oscilloscope 6 is provided with four photodiodes 15A to 15D, the optical demultiplexer 9 and the photodiode 15A are directly connected, and 0 ° between the optical demultiplexer 9 and the photodiode 15B. A polarizer 3B that outputs a polarization state is provided, a 0 ° polarization component is output from the polarizer 3B, and a 45 ° polarization state is output between the optical demultiplexer 9 and the photodiode 15C. 3C is provided to output a polarization component of 45 ° from the polarizer 3C, and between the optical demultiplexer 9 and the photodiode 15D, a wave plate 8 that is a quarter-wave plate from the optical demultiplexer 9 side. And a polarizer 3D are provided, and a clockwise polarized component is output from the polarizer 3D.

  The light output from the photodiode 15A can detect the polarization fluctuation intensity using the oscilloscope 6 as in the first to fourth embodiments.

  On the other hand, the light outputs detected by the photodiodes 15B to 15D are input to the analysis device 10, and the analysis device 10 uses the three light outputs and a predetermined general formula to calculate the Stokes parameter S1, which represents the polarization state. S2 and S3 are calculated. Further, the analysis device 10 detects a change in the polarization state of the light propagated through the optical fiber 4B based on the Stokes parameters S1, S2, and S3. For example, out of the amount of change in the Stokes parameters S1, S2 and S3, the maximum value or the time integral value thereof, the polarization movement angle obtained from the Stokes parameters S1, S2 and S3 or the time integral value thereof are used. Detect wave conditions. Here, the polarization movement angle is an angle when the Stokes parameters S1, S2, and S3 are represented by three orthogonal coordinate systems representing three coordinate components on the Poincare sphere.

  In the fifth embodiment, the analysis device 10 further obtains the Stokes parameter and analyzes the change in the polarization state using the Stokes parameter, so that the detailed polarization fluctuation state can be grasped.

(Embodiment 6)
Next, a sixth embodiment of the present invention will be described. In the sixth embodiment, only the impact / vibration generated in the panel 4A can be detected.

  FIG. 14 is a block diagram showing a configuration of an impact vibration detection device according to Embodiment 6 of the present invention. As shown in FIG. 14, a depolarizer 20 that converts light output from the semiconductor laser 11 into a non-polarized state is connected to the semiconductor laser 11 side of the optical fiber 2A, and is connected to the sensor unit 4 side of the optical fiber 2A. The polarizer 13A is connected through the optical fiber 2C. Further, the polarizer 13B is connected to the sensor unit 4 side of the optical fiber 2B via the connection optical fiber 2D, and the polarizer 15 is not provided on the photodiode 15 side of the optical fiber 2B, and is connected to the photodiode 15 as it is. .

  In this case, since the light transmitted through the optical fiber 2A is non-polarized light, the light polarized by the polarizer 13A is input to the sensor unit 4 without being affected by the polarization fluctuation that occurs in the optical fiber 2A. The light subjected to the polarization fluctuation at 4 is immediately converted into light polarized by the polarizer 13B, and this polarized light is generated in the optical fiber 2B because the photodiode 15 receives the intensity regardless of the polarization direction. The light is input to the photodiode 15 without being affected by the polarization fluctuation. In other words, it is possible to output only the polarization fluctuation generated in the sensor unit 4, particularly the optical fiber 4 B, to the photodiode 15 without being affected by the polarization fluctuation generated in the optical fibers 2 A and 2 B. Wave fluctuation intensity can be measured.

  In the sixth embodiment, it is possible to detect only the polarization fluctuation that occurs only in the part to be measured, that is, the sensor unit 4, and to obtain a highly accurate polarization fluctuation intensity.

  In the first to sixth embodiments described above, detection or analysis is performed by the oscilloscope 6 or the analysis device 10. However, a configuration in which a warning or the like is notified to the outside based on these detection results or analysis results. It is good.

  Furthermore, in Embodiment 1-6 mentioned above, although the sensor part 4 was one place, not only this but the some sensor part 4 is provided, and each sensor part 4 is connected with the optical fiber for transmission. You may do it. By setting it as such a structure, the falling rock detection with respect to the falling rock location discretely arrange | positioned, for example is realizable with a simple structure.

It is a block diagram which shows the structure of the impact vibration detection apparatus concerning Embodiment 1 of this invention. It is a figure which shows the time change of the received light intensity detected with a light receiver. It is the figure which showed the time change of the polarization fluctuation intensity when it is a case where a small impact and vibration are given, and a high-pass filter passes. It is the figure which showed the time change of the polarization | polarized-light fluctuation intensity when a big impact and a vibration are given and a high-pass filter passes. It is a figure which shows the change of the polarization fluctuation intensity with respect to impact and vibration intensity. It is a figure which shows the measurement result of the time change of polarization | polarized-light fluctuation intensity when the impact of 1 kg of weight is applied. It is a figure which shows the measurement result of the time change of polarization | polarized-light fluctuation intensity when the impact of 3 kg of weight is applied. It is a figure which shows the measurement result of the time change of polarization | polarized-light fluctuation intensity when the impact of 5 kg of weight is applied. It is a block diagram which shows the structure of the impact vibration detection apparatus concerning Embodiment 2 of this invention. It is a block diagram which shows the structure of the impact vibration detection apparatus concerning Embodiment 3 of this invention. It is a block diagram which shows the structure of the impact vibration detection apparatus concerning Embodiment 4 of this invention. It is a figure which shows the time change of received light intensity when an impact and a vibration are applied to the specific panel of FIG. It is a block diagram which shows the structure of the impact vibration detection apparatus concerning Embodiment 5 of this invention. It is a block diagram which shows the structure of the impact vibration detection apparatus concerning Embodiment 6 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2, 2A, 2B, 2C, 2D, 4B Optical fiber 3A, 3B, 3C, 3D, 13A, 13B Polarizer 4 Sensor part 4A, 4A-1-4A-3 Panel 5 Light receiver 5A High pass filter 6 Oscilloscope 7 Optical multiplexer / demultiplexer 8 Wavelength plate 9 Optical demultiplexer 10 Analyzing device 11 Semiconductor laser 15, 15A-15D Photodiode 20 Depolarizer

Claims (10)

A vibration sensor portion wound creep optical fiber, and is the optical fiber to the respective surfaces are closely attached to each surface of the plurality of elastic members having different natural frequencies from each other,
An optical fiber for transmission transmission connected to one end of the optical fiber;
An optical fiber for receiving transmission connected to the other end of the optical fiber;
A light source that outputs polarized light to the optical fiber via the transmission transmission optical fiber;
A light receiver that receives the light transmitted through the optical fiber via the optical fiber for receiving transmission;
A polarizer for polarizing light transmitted between the optical receiver and the optical fiber for reception transmission;
Detecting means for detecting the polarization fluctuation intensity of the light received by the light receiver;
And the detecting means identifies the elastic member in which the impact has occurred based on the natural frequency of the polarization variation of the elastic member transmitted after the polarization variation of light generated by the impact. Impact vibration detector. The light source outputs unpolarized light,
The impact vibration detection apparatus according to claim 1, wherein a transmission-side polarizer that polarizes light is provided between the light source and the transmission transmission optical fiber. In addition to providing one transmission optical fiber instead of the transmission transmission optical fiber and the reception transmission optical fiber, connecting by providing an optical multiplexer / demultiplexer at both ends of the transmission optical fiber,
Connect each end of the optical fiber on the sensor unit side to one optical multiplexer / demultiplexer,
The impact vibration detection device according to claim 1, wherein the optical fiber on the light source side and the light receiver side is connected to the other optical multiplexer / demultiplexer. The impact vibration detection apparatus according to claim 1, wherein the detection unit detects the magnitude of the impact or vibration from the intensity of the polarization fluctuation. The impact vibration detection apparatus according to claim 4, wherein an impact caused by falling rocks is detected. Shock vibration sensing device according to any one of claims 1-5, characterized in that a high-pass filter for transmitting frequencies above the natural frequency of the elastic member in a subsequent stage of the receiver. While providing four first to fourth light receivers, an optical demultiplexer is provided between each light receiver and the optical fiber for reception transmission,
Connecting the optical demultiplexer and the first light receiver;
Connecting a second polarizer that transmits 0 ° polarized light between the optical demultiplexer and the second light receiver to output a 0 ° polarized component;
Connecting a third polarizer that passes 45 ° polarized light between the optical demultiplexer and the third light receiver to output a 45 ° polarized component;
Between the optical demultiplexer and the third light receiver, a wavelength plate and a fourth polarizer are sequentially connected from the vibration sensor unit side to output a clockwise polarized component,
7. The shock vibration detection apparatus according to claim 1, further comprising an analyzing unit that analyzes polarization fluctuations based on light received by the first to fourth light receivers. . The transmission side polarizer is provided on the vibration sensor unit side of the transmission optical fiber,
The polarizer is provided on the vibration sensor unit side of the optical fiber for reception transmission,
8. The depolarizer that outputs the input light in a non-polarized state is provided between the light source and the transmission transmission optical fiber, according to claim 2. Impact vibration detector.   The impact vibration detection device according to claim 1, wherein the elastic member is one of a flat plate, a square member, and a pillar member, or a combination of one or more.   The impact vibration detection device according to claim 1, wherein the elastic member is an iron material.

Images