CN114578412A - Optical fiber micro-vibration detection measuring system - Google Patents

Abstract

The invention discloses an optical fiber micro-vibration detection measurement system, comprising at least one vibration transmission mechanism, a sensing optical fiber and a detection mechanism; the vibration transmission mechanism includes a base, a support column, a first pulley, a second pulley and a mass block; the sensing fiber It is wound around the first pulley and the second pulley, and one end of the sensing fiber is connected with the detection mechanism; the detection mechanism is used to inject a narrow linewidth laser pulse into the sensing fiber, and at the same time receive the backscattered light in the sensing fiber, And demodulate the phase change of the backscattered light. The beneficial effects of the invention are as follows: a distributed optical fiber sensing system based on phase demodulation uses the sensing optical fiber as a sensor to detect micro-vibration signals, and detects the phase change of the backscattered light in the sensing optical fiber along the path of the sensing optical fiber. For the vibration information of each point, the distributed optical fiber sensing system based on phase demodulation has the unique advantages of simple structure, easy layout, high cost performance, and can realize large-scale and high-precision measurement.

Description

An optical fiber micro-vibration detection measurement system

technical field

The invention relates to the technical field of micro-vibration detection, in particular to an optical fiber micro-vibration detection measurement system.

Background technique

As a very important micro-vibration wave, seismic wave has always been a major focus of micro-vibration research. The study of seismology originated from the need of human beings to resist earthquake disasters. Early seismology mainly studied and recorded the macroscopic phenomenon of earthquakes and the geographical distribution of earthquakes from the perspective of geology. At the beginning of the 20th century, due to the recording and analysis of seismic waves, seismology developed from a macroscopic description to a mathematical science, expanding the research field, and some branch disciplines appeared, with various applications.

Seismic wave detection is a key method to obtain surface hydrological information, understand the process and mechanism of major geological disasters, and prove the location and reserves of underground oil and gas reservoirs. By detecting and analyzing the transmission and evolution law of seismic waves in the geology, the near-surface geological structure status and time-lapse trend can be obtained by inversion, thereby providing important data support for geophysical related research.

In the field of building vibration testing, vibration testing mainly monitors the vibration response generated by a certain type of vibration signal, and analyzes the characteristics of vibration and its impact on the site or buildings around the vibration source. According to the different types of vibration signals, vibration testing can be roughly divided into micro-vibration testing, environmental vibration impact evaluation testing and engineering (construction) vibration impact evaluation testing.

Micro-vibration, also known as constant micro-motion or ground pulsation, is mainly caused by natural forces such as meteorological changes, tides, ocean waves, and man-made disturbances such as transportation and power machines. The multi-dimensional wave group of the test point is randomly combined, and its amplitude is a weak vibration of less than a few microns, which has the characteristics of a stable random process. The micro-vibration test mainly provides the excellent period of the site in the geotechnical investigation, and is used for the seismic isolation design of the construction project.

The environmental vibration impact assessment test is mainly aimed at precision workshops or equipment. This type of vibration mainly focuses on the intensity of vibration, usually in the nm~um level. Because this type of vibration can affect the measurement accuracy of precision instruments and meters, it also affects the precision of precision equipment. Precision. If there is a vibration source around the equipment, its influence should be measured. When the vibration influence exceeds the allowable value, vibration isolation or other effective measures must be taken for the designed precision instruments, meters, and equipment.

The construction vibration impact evaluation test is mainly aimed at evaluating the impact of the vibration generated by the construction machinery during the construction process on the surrounding existing buildings, people, equipment, etc., and even the possible damage. This type of vibration can be directly felt by humans, and its The strength is usually on the mm scale.

In the field of seismic wave exploration and vibration testing, the existing mainstream seismic wave detection methods are point-type electrical detectors, which are limited by their inherent technical bottlenecks, hindering further development in related fields. On the one hand, the existing methods usually require long-term independent power supply and communication in the field, which is difficult to deploy and maintain; on the other hand, the detection array puts forward extremely high requirements on the clock synchronization accuracy of the detector network; Due to the ability of multiplexing technology, it is difficult to increase the network scale of detectors, which is not conducive to high-precision, wide-distance and large-scale seismic wave detection; finally, conventional seismic sensors, such as moving coil sensors (such as the Chinese utility model patent application number CN201720386233.9) ), piezoelectric sensors and MEMS sensors are made of electronic components, which are susceptible to electromagnetic interference and cannot meet the requirements in terms of accuracy and reliability. The development of a new generation of seismic wave and micro-vibration detection technology has become an important task faced by the rapid development of the field of geophysics.

To sum up, the existing micro-vibration detection methods (including building vibration detection methods and seismic wave detection methods) generally have technical problems that they are susceptible to electromagnetic interference and cannot meet the requirements in terms of accuracy and reliability.

SUMMARY OF THE INVENTION

In view of this, it is necessary to provide an optical fiber micro-vibration detection measurement system to solve the technical problem that the existing micro-vibration detection methods are susceptible to electromagnetic interference and cannot meet the requirements in terms of accuracy and reliability.

In order to achieve the above purpose, the present invention provides an optical fiber micro-vibration detection measurement system, including at least one vibration conduction mechanism, a sensing fiber and a detection mechanism;

The vibration transmission mechanism includes a base, a support column, a first pulley, a second pulley and a mass block, the base is placed on the ground of the measurement environment, and forms a force coupling with the ground, and the lower end of the support column is fixed on the a base, the first pulley is mounted on the upper end of the support column, the second pulley is located below the first pulley, and the mass block is suspended on the second pulley;

The sensing fiber is wound around the first pulley and the second pulley, and one end of the sensing fiber is connected to the detection mechanism;

The detection mechanism is used to inject a narrow linewidth laser pulse into the sensing fiber, receive backscattered light in the sensing fiber at the same time, and demodulate the phase change of the backscattered light.

In some embodiments, the vibration transmission mechanism further includes a top beam, the top beam is fixed on the upper end of the support column, and the first pulley is mounted on the top beam.

In some embodiments, the first pulley is rotatably disposed on the top beam.

In some embodiments, a helical first V-shaped groove is formed on the side wall of the first pulley, the sensing fiber is built in the first V-shaped groove, and the outer side wall of the sensing fiber is Fitted with the first V-shaped groove.

In some embodiments, the radius of the first pulley is greater than 20 mm.

In some embodiments, a helical second V-shaped groove is formed on the side wall of the second pulley, the sensing fiber is built in the second V-shaped groove, and the outer side wall of the sensing fiber is Fitted with the second V-shaped groove.

In some embodiments, the radius of the second pulley is greater than 20mm.

In some embodiments, the vibration transmission mechanism further includes a first tensioning wheel, the first tensioning wheel is rotatably disposed on the support column, the side wall of the first tensioning wheel and the detection mechanism and the sensing optical fiber between the first pulley and the first pulley.

In some embodiments, the vibration transmission mechanism further includes a second tensioning wheel, the second tensioning wheel is rotatably disposed on the support column, and the side wall of the second tensioning wheel is connected to the adjacent two The sensing optical fibers between the first pulleys of each of the vibration conduction mechanisms are arranged to fit together.

In some embodiments, the detection mechanism includes a narrow linewidth laser and a fiber phase demodulation terminal, the narrow linewidth laser is used to inject a narrow linewidth laser pulse into the sensing fiber, and the fiber phase demodulates The terminal is used for receiving the backscattered light in the sensing fiber, and demodulating the phase change of the backscattered light.

Compared with the prior art, the beneficial effect of the technical solution proposed by the present invention is: in use, when a micro-vibration source excites micro-vibration and is coupled to the vibration transmission mechanism through the ground, the micro-vibration will be transmitted to the first pulley through the base, thereby The micro-vibration of the first pulley and the second pulley is caused, and the sensing fiber is wound back and forth between the first pulley and the second pulley, which increases the corresponding sensing length of the sensing fiber, thereby increasing the micro-vibration detection of the fiber. The sensitivity of the system, the micro-vibration generated by the first pulley and the second pulley will cause the stress change of the sensing fiber to change the characteristics of the transmitted light and the backscattered light in the sensing fiber. The detection mechanism is used to calculate the phase change of the backscattered light generated by the sensing fiber, and the micro-vibration information of the test environment can be obtained by calibrating different mass blocks;

The distributed optical fiber sensing system based on phase demodulation uses the sensing fiber as a sensor to detect micro-vibration signals, and detects the vibration information of each point along the sensing fiber by detecting the phase change of the backscattered light in the sensing fiber. Compared with other types of micro-vibration detectors, the distributed optical fiber sensing system based on phase demodulation has the advantages of simple structure, easy layout, high cost performance, and low sensitivity. Electromagnetic interference can achieve unique advantages such as large-scale and high-precision measurement, and can well solve the bottleneck in the current micro-vibration detection scheme.

Description of drawings

1 is a schematic three-dimensional structural diagram of an embodiment (including only one vibration conduction mechanism) of an optical fiber micro-vibration detection measurement system provided by the present invention;

2 is a schematic three-dimensional structural diagram of another embodiment (including two vibration conduction mechanisms) of the optical fiber micro-vibration detection measurement system provided by the present invention;

3 is a schematic diagram of the noise floor obtained by the optical fiber micro-vibration measurement system provided by the present invention in a natural environment;

4 is a schematic diagram of the time-domain vibration information detected by the optical fiber micro-vibration measurement system provided by the present invention in a large building;

5 is a schematic diagram of frequency domain information detected by the optical fiber micro-vibration measurement system provided by the present invention in a large building;

In the figure: 1-vibration transmission mechanism, 11-base, 12-support column, 13-first pulley, 131-first V-shaped groove, 14-second pulley, 141-second V-shaped groove, 15-mass block , 16-top beam, 17-first tensioning wheel, 18-second tensioning wheel, 2-sensing fiber, 3-detection mechanism.

Detailed ways

The preferred embodiments of the present invention are specifically described below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present application, and together with the embodiments of the present invention, are used to explain the principles of the present invention, but are not used to limit the scope of the present invention.

Referring to FIG. 1 , the present invention provides an optical fiber micro-vibration detection measurement system, including at least one vibration transmission mechanism 1 , a sensing fiber 2 and a detection mechanism 3 .

The vibration transmission mechanism 1 includes a base 11, a support column 12, a first pulley 13, a second pulley 14 and a mass block 15. The base 11 is placed on the ground of the detection environment and forms a force coupling with the ground. The lower end of the column 12 is fixed to the base 11 , the support column 12 can also be integrally formed with the base 7 , the support column 12 is used for the transmission of strain and stress, and the first pulley 13 is installed on the upper end of the support column 12 , the second pulley 14 is located below the first pulley 13 , and the mass block 15 is suspended on the second pulley 14 . It should be noted that other numbers of pulley structures can also be used. The specific number of pulley structures is not strictly limited, and can be adjusted according to needs. The pulley structure should be used to tension the sensing fiber 2 and make each section of the sensing fiber 2 receive tension. The force is consistent, so that the multi-segment sensing fibers 2 are subjected to the action of micro-vibration at the same time.

The sensing fiber 2 is wound around the first pulley 13 and the second pulley 14 , and one end of the sensing fiber 2 is connected to the detection mechanism 3 . Specifically, the sensing fiber 2 is wound back and forth between the first pulley 13 and the second pulley 14, and a certain prestress is applied to the sensing fiber 2 by a mass 15, so that each section of the sensing fiber 2 is subjected to The force is consistent to ensure the consistency of its detection, and the micro-vibration signal can be transmitted to the sensing fiber 2, so that the sensing fiber 2 is strained, and then the backscattered light in the sensing fiber 2 (such as Rayleigh The phase of the backscattered light) changes, so as to realize the measurement of micro-vibration. At the same time, the sensing fiber 2 is prestressed by the mass block 15 to make it in a tensioned state, so that the sensing fiber 2 and the first pulley are in a state of tension. There is no relative displacement between 13 and the second pulley 14, which ensures that the initial prestress of the sensing fiber 2 remains unchanged when it is arranged, so that it can sense the external micro-vibration signal. The sensing fiber 2 adopts a microstructure point high scattering rate fiber, and the microstructure point high scattering rate fiber increases the backscattered light, so as to improve the scattered light intensity, increase the sensing sensitivity, and achieve the purpose of improving the signal-to-noise ratio. Multiple high-scattering microstructure points can be introduced between the first pulley 13 and the second pulley 14, and the micro-vibration signals between multiple groups of different high-scattering microstructure points can be obtained during measurement, and comprehensive analysis can be performed in subsequent processing. Improve the accuracy and reliability of the signal.

The detection mechanism 3 is used to inject a narrow linewidth laser pulse into the sensing fiber 2, receive the backscattered light in the sensing fiber 2 at the same time, and demodulate the phase change of the backscattered light. , in order to obtain the relevant characteristic parameters of the micro-vibration received by the sensing fiber 2, so as to achieve the purpose of real-time online survey of the micro-vibration.

In use, when a micro-vibration source excites micro-vibration and is coupled to the vibration transmission mechanism 1 through the ground, the micro-vibration will be transmitted to the first pulley 13 through the base 11, thereby causing the micro-vibration of the first pulley 13 and the second pulley 14 to transmit The sensing fiber 2 is wound back and forth between the first pulley 13 and the second pulley 14 to increase the corresponding sensing length of the sensing fiber 2, thereby increasing the sensitivity of the fiber micro-vibration detection system. The first pulley The micro-vibration generated by 13 and the second pulley 14 will cause the stress of the sensing fiber 2 to change, so that the characteristics of the transmitted light and the backscattered light in the sensing fiber 2 will change. The detection mechanism 3 is used for The phase change of the backscattered light generated by the sensing fiber 2 is calculated, and the micro-vibration information of the test environment can be obtained by calibrating different mass blocks 15 .

Because the optical fiber sensor has the characteristics of large dynamic range, high sensitivity, high feasibility of multiplexing, and strong anti-electromagnetic interference ability. The distributed optical fiber sensing system based on phase demodulation uses the sensing fiber 2 as a sensor to detect micro-vibration signals, and detects the vibration of each point along the path of the sensing fiber 2 by detecting the phase change of the backscattered light in the sensing fiber 2 Information, the sensing fiber 2 is not only used as a signal transmission medium, but also can be used as a sensor medium. In the present invention, a high-scattering microstructure point fiber is also used as the sensing fiber 2 to improve the sensitivity of the system. Compared with other types of micro-vibration detectors, the distributed optical fiber sensing system based on phase demodulation has the unique advantages of simple structure, easy layout, high cost performance, less susceptible to electromagnetic interference, and can achieve large-scale and high-precision measurement. It is a good solution to the bottleneck in the current micro-vibration detection scheme.

In this embodiment, the sensing fiber 2 adopts a micro-structured scattering-enhanced optical fiber, and the prepared micro-structured scattering-enhancing optical fiber introduces a series of discretely distributed micro-structure scattering points into the optical fiber, and divides the optical fiber into several independent blocks . Introduce a plurality of equally spaced and discretely distributed scattering enhancement points in the microstructure scattering enhancement fiber; when an event changes at any point on the microstructure scattering enhancement fiber, two adjacent points containing the event can be found. For microstructure scattering points, events on the fiber block can be obtained by demodulation by calculating the optical phase difference between the two microstructure scattering points. If the optical phase difference between the i-th and j-th microstructure points can be expressed as:

Among them, ne is the effective refractive index of the optical fiber, and _{d ij} is the distance between the two microstructure points . When a micro-vibration or force is applied to this fiber, the refractive index and length of the fiber will change due to the elastic-optic effect of the fiber. changes, the phase change can be expressed as:

Further, the relationship between the phase and the change of the strain rate Δɛ on the fiber can be obtained:

Among them, Ke is the index of refraction index of fiber strain which can be _regarded as a constant . Therefore, the change of the phase difference between the two strong scatter points has a linear relationship with the strain rate of the optical fiber. By calculating the phase, the stress distribution on the optical fiber can be obtained. And every two microstructure points and the sensing fiber between them can be regarded as a sensing unit, so as to realize all-fiber distributed sensing. In the present invention, multiple pulley structures are adopted to increase the length of the sensing optical fiber 2, that is, d _ij , and increase Δφ _ij to achieve the purpose of improving the sensitivity of the system.

In order to specifically realize the installation of the first pulley 13, please refer to FIG. 1, in a preferred embodiment, the vibration transmission mechanism 1 further includes a top beam 16, and the top beam 16 is fixed on the upper end of the support column 12, The first pulley 13 is mounted on the top beam 16 . In another embodiment, the support column 12 can also adopt a triangular structure, and the first pulley 13 can follow the intersection point. In this case, the top beam 16 does not need to be provided.

Further, the base 11, the support column 12, the first pulley 13 and the second pulley 14 are all made of materials that can be well coupled with the micro-vibration, so that the micro-vibration signal can be better sensed to the sensing fiber, Get high-precision measurement results.

In order to facilitate the winding of the sensing fiber 2 on the first pulley 13 and the second pulley 14, please refer to FIG. 1, in a preferred embodiment, the first pulley 13 is rotatably arranged on the top beam 16, Therefore, during installation, the first pulley 13 can be rotated, so that the sensing fiber 2 can be wound around the first pulley 13 and the second pulley 14, thereby improving the installation efficiency.

In order to prevent the relative sliding between the sensing fiber 2 and the first pulley 13 from affecting the detection result, please refer to FIG. 1 , in a preferred embodiment, the side wall of the first pulley 13 is provided with a helical The first V-shaped groove 131, the sensing optical fiber 2 is built in the first V-shaped groove 131, the outer side wall of the sensing optical fiber 2 and the first V-shaped groove are arranged to fit 131, and the first V-shaped groove 131 is arranged. The groove diameter of a V-shaped groove 131 is the same as the outer diameter of the sensing fiber 2, so as to make the force coupling between the first V-shaped groove 131 and the sensing fiber 2, while preventing the sensing fiber 2 There is relative sliding with the first pulley 13, so that the detection accuracy can be improved.

In order to ensure that the sensing fiber 2 is in a low-loss transmission state, please refer to FIG. 1 . In a preferred embodiment, the radius of the first pulley 14 is greater than 20 mm, so as to avoid transmission loss of the sensing fiber 2 due to excessive curvature. increase.

In order to prevent the relative sliding between the sensing fiber 2 and the second pulley 14 from affecting the detection result, please refer to FIG. 1 , in a preferred embodiment, the side wall of the second pulley 14 is provided with a spiral The second V-shaped groove 141, the sensing optical fiber 2 is built in the second V-shaped groove 141, and the outer side wall of the sensing optical fiber 2 is attached to the second V-shaped groove 141, so that all the The force coupling between the second V-shaped groove 141 and the sensing fiber 2 prevents relative sliding between the sensing fiber 2 and the second pulley 14 , thereby improving the detection accuracy.

In order to ensure that the sensing fiber 2 is in a low-loss transmission state, please refer to FIG. 1 , in a preferred embodiment, the radius of the second pulley 14 is greater than 20 mm, so as to avoid transmission loss of the sensing fiber 2 due to excessive curvature increase.

In order to prevent the sensing fiber 2 between the detection mechanism 3 and the first pulley 13 from loosening and affecting the detection result, please refer to FIG. 1 , in a preferred embodiment, the vibration transmission mechanism 1 further includes a first A tensioning wheel 17, the first tensioning wheel 17 is rotatably arranged on the support column 12, between the side wall of the first tensioning wheel 17 and the detection mechanism 3 and the first pulley 13 The sensing optical fibers 2 of the two parts are arranged in close contact, so that the sensing optical fibers 2 between the detection mechanism 3 and the first pulley 13 can be kept in a tensioned state.

In order to realize multi-component distributed micro-vibration measurement, please refer to FIG. 1 and FIG. 2 , a plurality of the vibration transmission mechanisms 1 are connected in series through the sensing fiber 2 , so that only one sensing fiber 2 can be used to realize the measurement. The multi-component distributed micro-vibration measurement can also locate the seismic source through the vibration signals detected by each sensing unit.

In order to prevent the sensing fiber 2 between the first pulleys 13 of the two adjacent vibration conduction mechanisms 1 from loosening and affecting the detection result, please refer to FIG. 1 and FIG. 2 . In a preferred embodiment, the The vibration transmission mechanism 1 further includes a second tensioning wheel 18, the second tensioning wheel 18 is rotatably arranged on the support column 12, and the side wall of the second tensioning wheel 18 is connected to the adjacent two The sensing optical fibers 2 between the first pulleys 13 of the vibration conducting mechanism 1 are arranged in close contact, so that the sensing fibers 2 between the first pulleys 13 of the two adjacent vibration conducting mechanisms 1 can be kept in a tensioned state .

In order to specifically realize the function of the detection mechanism 3, please refer to FIG. 1. In a preferred embodiment, the detection mechanism 3 includes a narrow linewidth laser and an optical fiber phase demodulation terminal. A narrow linewidth laser pulse is incident in the sensing fiber 2, and the fiber phase demodulation terminal is used to receive the backscattered light in the sensing fiber 2, and demodulate the phase change of the backscattered light to obtain Obtain the relevant characteristic parameters of the micro-vibration received by the sensing fiber 2, so as to achieve the purpose of real-time online survey of the micro-vibration. The optical fiber phase demodulation terminal adopts a coherent detection scheme, and the intensity of the received optical signal depends on the local oscillator light intensity and the signal light intensity, and the stronger local oscillator light can significantly improve the intensity of the optical signal at the detector end. Therefore, the microstructure scattering-enhanced optical fiber sensing system based on coherent detection can realize the enhancement of the optical signal-to-noise ratio at both the sensing fiber and the receiving end, so that the detection is sufficient to reach the level required in the field of ground strain.

It should be pointed out that the mass block 15 is used to ensure the natural hanging state of the pulley block structure, and its quality will affect the sensitivity of the optical fiber micro-vibration measurement system, and the mass blocks 15 with different masses are in the sensing fiber 2. The generated prestress is different, which will lead to different detection sensitivities. By calibrating the sensitivity corresponding to the mass blocks 15 with different masses, the sensitivity of the corresponding optical fiber micro-vibration detection system under different mass blocks can be obtained, so that the most suitable one can be selected. Mass mass 15. Therefore, the optical fiber micro-vibration measurement system needs to perform sensitivity calibration on the mass blocks 15 of different masses.

In this embodiment, the base 11 , the support column 12 , the first pulley 13 and the second pulley 14 all need to be made of materials with a small thermal expansion coefficient. It should be noted that the optical fiber micro-vibration measurement system needs to be installed in a relatively stable and quiet environment to reduce the interference caused by the external environment (temperature convection, animal activity, etc.) to the sensing fiber 2 . When the micro-vibration is transmitted to the support column 12 , a force will be generated on the sensing fiber 2 through the first pulley 13 and the second pulley 14 . Therefore, the strain value received by the sensing fiber 2 can be obtained by demodulating the phase change of the sensing fiber 2, and the real-time monitoring of the micro-vibration can be completed through the continuous demodulation of the fiber phase demodulation system.

In the embodiment of the present invention, the optical fiber phase demodulation system is based on injecting a light source into the sensing fiber 2 through a narrow linewidth laser, receiving the backscattered light generated by the light source, and performing high-resolution on the received backscattered light. Accurate phase demodulation is used to obtain the phase information of the optical path. Since the phase change and strain are in a one-to-one correspondence, the strain information on the fiber can be obtained. The basic principle is that the sensing fiber 2 is subjected to micro-vibration, and the phase change caused by the strain of the sensing fiber 2 can be obtained by demodulating the phase change of the sensing fiber 2. Here, in order to increase the intensity of the backscattered light generated, the sensing fiber 2 adopts a microstructure point high scattering rate fiber, which can increase the intensity of the backscattered light, improve the signal-to-noise ratio, and suppress the coherent fading phenomenon, Guarantee the reliability of the signal.

Please refer to FIG. 3-FIG. 5. FIG. 3-FIG. 5 are schematic diagrams of experimental test results of the optical fiber micro-vibration measurement system provided by the present invention.

As shown in FIG. 3 , FIG. 3 is a schematic diagram of the noise floor obtained by the optical fiber micro-vibration measurement system provided by the present invention in a natural environment.

As shown in Figure 3, the noise floor obtained by the optical fiber micro-vibration measurement system in the natural environment is basically maintained below 100mrad/√Hz in the low-frequency signal. According to the theoretical calculation of sensitivity, the optical fiber micro-vibration measurement system can measure The obtained minimum strain value should be at the level of 10 ^-9 ɛ , which meets the minimum strain measurement requirements for micro-vibration.

As shown in FIG. 4 and FIG. 5 , FIG. 4 and FIG. 5 are the vibration information detected by the optical fiber micro-vibration measurement system provided by the present invention in a large building.

As shown in FIG. 4 , the time domain vibration information detected by the optical fiber micro-vibration measurement system provided in the present invention in a large building can clearly observe the natural vibration of the building with a specific law. FIG. 5 is a schematic diagram of the frequency domain information of the vibration, and three characteristic frequency points can be clearly observed, which proves the feasibility of the present invention.

To sum up, the beneficial effects of the technical solutions provided by the present invention are as follows:

(1) The optical fiber micro-vibration detection measurement system proposed by the present invention is placed on the ground of the test environment, and the micro-vibration information is sensed on the sensing fiber 2 through the vibration transmission mechanism 1, and the sensing fiber 2 receives the micro-vibration signal. The influence produces a phase change, and the micro-vibration information can be obtained by demodulating the phase change, which realizes the high-precision measurement of the micro-vibration. The whole system has a simple structure and is easy to deploy;

(2) In the optical fiber micro-vibration detection measurement system proposed by the present invention, the sensing fiber 2 adopts the micro-structured scattering-enhanced optical fiber as the sensitive unit, combined with a certain sensitivity-enhancing installation method, and realizes high-precision micro-vibration detection through the phase demodulation system;

(3) In the optical fiber micro-vibration detection measurement system proposed by the present invention, a plurality of high-scattering rate micro-structure points can be introduced between the pulley groups of the sensing fiber 2, and the distance between multiple groups of different high-scattering micro-structure points can be obtained during measurement. The micro-vibration signal is processed and analyzed comprehensively, which can improve the accuracy and reliability of the signal;

(4) In the optical fiber micro-vibration detection measurement system proposed by the present invention, a plurality of vibration transmission mechanisms 1 are connected in series, and a multi-component distributed micro-vibration detection can be realized by using a sensing optical fiber 2 and the same data processing system, which solves the problem of The existing micro-measuring vibration system is difficult to network and reuse, and it is difficult to realize distributed detection and other problems;

(5) The optical fiber micro-vibration detection measurement system proposed by the present invention arranges the sensing optical fiber on the pulley structure of the adjacent vibration conducting mechanism 1 in a way of winding back and forth, so that the length of the sensing optical fiber 2 is increased and the performance of the sensing optical fiber 2 is improved. Sensitivity; at the same time, the V-shaped grooves are carved on the pulley structure to ensure the consistent force of each section of the sensing fiber, and to ensure the high accuracy of the measurement results;

(6) The optical fiber micro-vibration detection measurement system proposed by the present invention can change the prestress of the sensing fiber 2 by changing the mass size of the mass block 15, and can further adjust the response sensitivity of the sensing fiber 2, which plays a role of calibration. . After multiple calibrations, the most suitable mass can be selected.

The above is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited to this. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention. , all should be covered within the protection scope of the present invention.

Claims (10)

1. An optical fiber micro-vibration detection measuring system is characterized by comprising at least one vibration conduction mechanism, a sensing optical fiber and a detection mechanism;

the vibration transmission mechanism comprises a substrate, a support column, a first pulley, a second pulley and a mass block, wherein the substrate is placed on the ground of a detection environment and forms stress coupling with the ground, the lower end of the support column is fixed on the substrate, the first pulley is installed at the upper end of the support column, the second pulley is positioned below the first pulley, and the mass block is suspended on the second pulley;

the sensing optical fiber is wound on the first pulley and the second pulley, and one end of the sensing optical fiber is connected with the detection mechanism;

the detection mechanism is used for injecting narrow linewidth laser pulses into the sensing optical fiber, receiving back scattering light in the sensing optical fiber and demodulating phase change of the back scattering light.

2. The fiber micro-vibration detection measurement system of claim 1, wherein the vibration conduction mechanism further comprises a top beam fixed to an upper end of the support column, and the first pulley is mounted on the top beam.

3. The fiber optic micro-vibration detection measurement system of claim 2, wherein the first pulley is rotatably disposed on the top beam.

4. The system according to claim 1, wherein a first spiral V-groove is formed on a side wall of the first pulley, the sensing fiber is disposed in the first V-groove, and an outer side wall of the sensing fiber is attached to the first V-groove.

5. The fiber optic micro-vibration detection measurement system of claim 1, wherein the radius of the first pulley is greater than 20 mm.

6. The system according to claim 1, wherein a second spiral V-groove is formed in a side wall of the second pulley, the sensing fiber is disposed in the second V-groove, and an outer side wall of the sensing fiber is attached to the second V-groove.

7. The fiber optic micro-vibration detection measurement system of claim 1, wherein the radius of the second pulley is greater than 20 mm.

8. The fiber micro-vibration detection measurement system of claim 1, wherein the vibration conduction mechanism further comprises a first tension wheel rotatably disposed on the support column, and a side wall of the first tension wheel is disposed in contact with the sensing fiber between the detection mechanism and the first pulley.

9. The fiber micro-vibration detection measurement system according to claim 1, wherein the vibration transmission mechanism further comprises a second tension wheel, the second tension wheel is rotatably disposed on the support column, and a side wall of the second tension wheel is disposed in contact with the sensing fiber between the first pulleys of two adjacent vibration transmission mechanisms.

10. The fiber micro-vibration detection measurement system of claim 1, wherein the detection mechanism comprises a narrow linewidth laser for injecting narrow linewidth laser pulses into the sensing fiber and a fiber phase demodulation terminal for receiving the backscattered light from the sensing fiber and demodulating the phase change of the backscattered light.

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