A high-precision fiber-optic vibration detector suitable for micro-signal detection in narrow space

Abstract

This invention discloses a high-precision fiber optic vibrometer suitable for detecting minute signals in confined spaces. It utilizes a lens-fiber optic probe and zero-difference interferometry to collect and process reflected signals, thus achieving a high-precision fiber optic vibrometer suitable for detecting minute vibrations in confined spaces. Based on a 100-micron-level lens-fiber optic probe, it penetrates deep into confined spaces to collect minute reflected light signals. Using a fiber optic circulator and zero-difference interferometry, the reflected light signals are extracted and processed. Based on the processed reflected signals, the amplitude of minute vibrations in the confined space is deduced. This invention has the advantages of resistance to environmental interference, high spatial resolution, and high detection sensitivity, with a displacement detection sensitivity of less than 5 pm·Hz. ‑1 / 2 It is applicable to vibration detection in various environments, especially for detecting minute vibrations in confined spaces.

Description

Technical Field

[0001] This invention relates to the field of vibration measurement, and in particular to a high-precision fiber optic vibration meter suitable for detecting minute signals in confined spaces. Background Technology

[0002] Vibration is ubiquitous in daily life. Over time, the vibration of mechanical structures can lead to aging and even damage of equipment, reducing operational efficiency and causing significant safety hazards. With the continuous development of industry and technology, the demand for high-precision vibration measurement in modern industry and scientific research is increasing, and mature methods have been widely applied in various fields such as non-destructive testing, metrology calibration, mechanical manufacturing and monitoring, and acoustic and optical communication.

[0003] Existing vibration measurement methods are generally divided into contact and non-contact types. Contact vibration measurement often utilizes the piezoelectric effect of quartz crystals and artificially polarized ceramics, offering low cost, but the contact between the sensor and the equipment alters the equipment's vibration state, leading to significant errors. Non-contact vibration measurement, on the other hand, can achieve measurement without contact with the equipment, avoiding interference. Non-contact vibration measurement is often combined with laser technology, such as laser triangulation, speckle measurement, and laser Doppler methods. Among these, the use of zero-difference interferometry to measure the laser Doppler displacement caused by object vibration has advantages such as resistance to environmental interference, high spatial resolution, and high detection sensitivity, and has been widely discussed.

[0004] Zero-difference interferometric laser vibrometers typically employ a traditional Michelson interferometer structure, splitting the laser beam into a measurement beam and a reference beam. The measurement beam, after reflection from the vibrating surface, generates a Doppler frequency shift, which beats with the reference beam at the detector's photosensitive surface. The detector converts the Doppler-shifted optical signal into an electrical signal of the corresponding frequency. The instrument's subsequent signal processing module extracts the instantaneous frequency of the signal from the electrical signal, thereby extracting the vibration information. When the vibrating object being measured is in a relatively confined space, the size of the probe is significantly limited. Furthermore, the measurement spot has a certain size and drifts relative to the detector due to vibrations in other directions. This increases the difficulty of receiving the measurement beam, especially in cases of weak vibration, such as cochlear basilar membrane vibration measurement, leading to a sharp drop in the signal-to-noise ratio. Therefore, improving the efficiency of reflected signal recovery in such situations is a key issue for laser Doppler vibrometers. Summary of the Invention

[0005] In view of the above problems, the purpose of this invention is to provide a fiber optic vibration meter suitable for detecting minute signals in confined spaces, which is resistant to environmental interference, has high spatial resolution, and high detection sensitivity. This invention employs a hundred-micron-level lens fiber optic probe to achieve high-efficiency recovery of reflected signals, and combines it with zero-difference interferometry technology to achieve rapid and accurate vibration detection.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A high-precision fiber optic vibrometer suitable for detecting minute signals in confined spaces, characterized by including the vibration plane of the sample under test, a detection light source, a reflected signal processing module, a lens fiber optic probe, a photodetector, a spectrum analyzer, and a data processing module, wherein:

[0008] The vibration plane of the sample to be tested is a vibrating entity whose vibration needs to be measured;

[0009] The detection light source is a narrow linewidth laser of arbitrary wavelength, which provides the optical signal required for measurement;

[0010] The reflection signal processing module is placed between the detection light source, the lens fiber probe, and the photodetector. Through optical path connection, the light generated by the detection light source enters the lens fiber probe. At the same time, it extracts the detection light reflected by the vibrating plane and the reference light reflected by the high-reflectivity lens. After combining the two beams, an interference light signal is generated and input into the photodetector.

[0011] The lens fiber optic probe is placed in front of the vibration plane of the sample to be tested, so that it is focused on the vibration plane; the probe body is made of optical fiber, and its front end is fused into a microsphere lens coaxial with the fiber core by an optical fiber fusion splicer.

[0012] The photodetector is placed after the reflection signal processing module and is used to detect the interference light signal and convert it into an electrical signal;

[0013] The spectrum analyzer is connected to the photodetector circuit and obtains the frequency domain signal from the time domain interference signal through Fourier transform;

[0014] The data processing module, located after the spectrum analyzer, converts the frequency domain signal into actual vibration displacement.

[0015] Furthermore, the reflected signal processing module includes: an optical fiber splitter, an optical fiber combiner, a first optical fiber circulator, a second optical fiber circulator, an optical fiber coupler, a high-reflectivity mirror, a scanning PZT, a piezoelectric ceramic drive circuit, a proportional-integral controller, and a DC biasor or tee, connected via an optical path; wherein:

[0016] The fiber optic beam splitter, placed after the detection light source, splits the beam into a detection beam and a reference beam;

[0017] The fiber optic combiner, placed in front of the photodetector, combines the reflected probe light and reference light to generate an interference light signal.

[0018] The first fiber optic circulator is used to transmit the probe light to the lens fiber optic probe and extract the probe light reflected by the vibrating plane;

[0019] The second fiber optic circulator is used to transmit the reference light to the fiber optic coupler and extract the reference light reflected by the high-reflectivity lens;

[0020] The fiber optic coupler is placed after the second fiber optic circulator and is used for the mutual conversion between fiber optic light and spatial light.

[0021] The high-reflectivity lens is placed after the fiber optic coupler to reflect the reference light. Its distance from the fiber optic coupler is controlled by the excitation PZT, thereby changing the optical path of the reference light.

[0022] The scanning PZT, which is bonded to the back of the high-reflectivity lens, is an arbitrary-shaped piezoelectric ceramic sheet used to adjust the position of the high-reflectivity lens;

[0023] The piezoelectric ceramic drive, placed after the scanning PZT, is a piezoelectric ceramic controller that outputs a voltage from 0 to 200 V, causing the scanning PZT to move at the micrometer level.

[0024] The proportional-integral controller is placed between the piezoelectric ceramic driver and the DC bias or tee, and is used to receive the DC signal output by the DC bias, and after proportional-integral control, feed it back to the piezoelectric ceramic driver to lock the interference signal at the point of maximum slope.

[0025] The DC bias is connected to the output of the photodetector at its input, to the spectrum analyzer at its RF output, and to the proportional-integral controller at its DC output.

[0026] Furthermore, the lens fiber optic probe includes an optical fiber and a microsphere lens; wherein:

[0027] The fiber core is selected based on the required reflected light recovery efficiency, and its outer diameter is smaller than the space of the sample to be tested.

[0028] The microsphere lens is coaxial with the optical fiber, has a smooth and even surface, and has a radius of curvature greater than the outer diameter of the optical fiber but smaller than the space of the sample to be tested.

[0029] Furthermore, the data processing module is used to calculate the vibration displacement based on the frequency domain signal output by the spectrum analyzer. The calculation method is as follows: the wavelength of the detection light source is... The peak and valley values ​​of the interference signal After locking, the peak and valley values ​​of the interference signal are The vibration displacement is The proportional relationship is satisfied: Time-domain signal Able to generate frequency domain signals Represented as: ,in The impedance of the spectrum analyzer is given; the vibration displacement is obtained directly from the data on the spectrum analyzer, and the relationship is as follows:

[0030] .

[0031] This invention is applicable to high-precision vibration measurement in multiple industrial and scientific research fields. Except for the lens and optical fiber, the instruments used are all common laboratory instruments, which are simple to assemble and easy to operate.

[0032] Compared with the prior art, the advantages of this invention include:

[0033] 1) A hundred-micron-level lens fiber optic probe is used to improve the recovery efficiency of reflected light signals in narrow space environments. On the other hand, the probe length can be customized at will, the size is small, it can go deep into the detection area, avoid some external interference, and can be applied to more complex vibration measurement situations.

[0034] 2) By combining zero-difference interferometry with piezoelectric ceramic driving circuits, the interference signal is locked at the point of maximum slope, allowing observation of the changes in interference signal caused by minute vibration displacements. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the present invention;

[0036] Figure 2 This is a schematic diagram of the basement membrane vibration signal measured in the absence of microwaves in an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the basement membrane vibration signal measured in a microwave environment according to an embodiment of the present invention. Detailed Implementation

[0038] This invention provides a fiber optic vibration meter suitable for detecting minute signals in confined spaces, resistant to environmental interference, with high spatial resolution and high detection sensitivity. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0039] See Figure 1 The present invention provides a high-precision fiber optic vibrometer suitable for detecting minute signals in confined spaces, comprising: a vibration plane 1 of the sample to be tested, a detection light source 2, a reflection signal processing module 3, a lens fiber optic probe 4, a photodetector 5, a spectrum analyzer 6, and a data processing module 7, wherein:

[0040] The vibration plane 1 of the sample to be tested is a vibration entity whose vibration needs to be measured;

[0041] The detection light source 2 is a narrow linewidth laser of arbitrary wavelength, which provides the optical signal required for measurement;

[0042] The reflected signal processing module 3, based on fiber optic circulator and zero-difference interferometry, adopts a traditional Michelson interferometer structure and is placed between the detection light source 2, the lens fiber optic probe 4, and the photodetector 5. Through optical path connection, the light generated by the detection light source 2 enters the lens fiber optic probe 4. At the same time, the detection light reflected by the vibration plane 1 and the reference light reflected by the high-reflectivity lens 34 are extracted. The two beams are combined to generate an interference light signal, which is then input into the photodetector 5.

[0043] The lens fiber optic probe 4 is placed in front of the vibration plane 1 of the sample to be tested, so that it is focused on the vibration plane 1; the probe body is made of optical fiber 41, and its front end is sintered into a microsphere lens 42 coaxial with the fiber core by an optical fiber fusion splicer.

[0044] The photodetector 5 is placed after the reflection signal processing module 3 and is used to detect the interference light signal and convert it into an electrical signal.

[0045] The spectrum analyzer 6 is connected to the photodetector 5 circuit, and obtains the frequency domain signal from the time domain interference signal through Fourier transform;

[0046] The data processing module 7, located after the spectrum analyzer 6, converts the spectrum signal into actual vibration displacement.

[0047] See Figure 1 The reflection signal processing module 3 described in this invention includes: an optical fiber splitter 311, an optical fiber combiner 312, a first optical fiber circulator 321, a second optical fiber circulator 322, an optical fiber coupler 33, a high-reflectivity mirror 34, a scanning PZT 35, a piezoelectric ceramic driving circuit 36, a proportional-integral controller 37, and a DC bias or tee 38, wherein:

[0048] The fiber optic beam splitter 311 is placed after the detection light source 2 to split the beam into a detection beam and a reference beam;

[0049] The fiber optic combiner 312 is placed in front of the photodetector 5 to combine the reflected probe light and reference light to generate an interference light signal.

[0050] The first fiber optic circulator 321 is used to transmit the probe light to the lens fiber optic probe 4 and extract the probe light reflected by the vibrating plane 1;

[0051] The second fiber optic circulator 322 is used to transmit the reference light to the fiber optic coupler 33 and extract the reference light reflected by the high-reflectivity lens 34;

[0052] The fiber optic coupler 33 is placed after the second fiber optic circulator 322 and is used for the mutual conversion between fiber optic light and spatial light.

[0053] The high-reflectivity lens 34 is placed after the fiber optic coupler 33 to reflect the reference light. Its distance from the fiber optic coupler 33 can be controlled by the excitation PZT 35, thereby changing the optical path of the reference light.

[0054] The scanning PZT 35, which is attached to the back of the high-reflectivity lens 34, is an arbitrary-shaped piezoelectric ceramic sheet used to adjust the position of the high-reflectivity lens 34.

[0055] The piezoelectric ceramic drive 36, placed after the scanning PZT 35, is a piezoelectric ceramic controller that outputs a voltage from 0 to 200V, causing the scanning PZT 35 to move at the micrometer level.

[0056] The proportional-integral controller 37 is placed between the piezoelectric ceramic driver 36 and the DC bias or tee 38. It is used to receive the DC signal output by the DC bias 38, and after proportional-integral control, it is fed back to the piezoelectric ceramic driver 36 to lock the interference signal at the point of maximum slope.

[0057] The DC bias or three-way 38 has its input terminal connected to the output terminal of the photodetector 5, its RF output terminal connected to the spectrum analyzer 6, and its DC output terminal connected to the proportional-integral controller 37.

[0058] See Figure 1 The lens fiber optic probe 4 in this invention includes an optical fiber 41 and a microsphere lens 42: wherein:

[0059] The fiber 41 has a core selected based on the required reflected light recovery efficiency, and its outer diameter is smaller than the space of the sample to be tested.

[0060] The microsphere lens 42 is coaxial with the optical fiber 41, has a smooth and neat surface, and has a radius of curvature greater than the outer diameter of the optical fiber 41 but smaller than the space of the sample to be tested.

[0061] The data processing module 7 is used to calculate the vibration displacement based on the frequency domain signal output by the spectrum analyzer 6. The calculation method is as follows: the wavelength of the detection light source is... The peak and valley values ​​of the interference signal After locking, the peak and valley values ​​of the interference signal are The vibration displacement is The proportional relationship is satisfied: Time-domain signal Able to generate frequency domain signals Represented as: ,in The impedance of the spectrum analyzer is given; the vibration displacement is directly obtained from the data on spectrum analyzer 6, and the relationship is as follows:

[0062] .

[0063] In the specific implementation of this invention, the specifications of the fiber optic bundle splitter 311, fiber optic bundle combiner 312, first fiber optic circulator 321, second fiber optic circulator 322, fiber optic coupler 33, high-reflectivity mirror 34, lens fiber optic probe 4, and photodetector 5 need to correspond to the laser wavelength of the detection light source 2.

[0064] Example

[0065] This embodiment applies the fiber optic vibrometer described in this invention to the study of microwave auditory effects in the biomedical field.

[0066] The microwave auditory effect refers to the auditory sensation produced when a person is irradiated by microwave pulses. The mechanism of hearing is as follows: sound stimuli are collected by the auricle, travel through the external auditory canal to the tympanic membrane, causing mechanical movement of the ossicular chain. The vibration of the stapes footplate causes movement of the oval window. Energy is transmitted to the endolymph and perilymph in the cochlea, causing fluid vibration. The movement of hair cells on the basilar membrane generates bioelectrical activity. Nerve impulses travel along the ascending neural pathway of the auditory nerve to the auditory cortex, producing hearing. Mechanical studies have shown that after microwave pulses are absorbed by head tissues, they emit a pressure wave that propagates through bone conduction to the inner ear. In the inner ear, the cochlear receptors are activated through the same process as normal hearing. Depending on the power of the impacting microwave pulse, the induced sound pressure level may greatly exceed the threshold of auditory perception, leading to tissue damage. Therefore, the microwave auditory effect can be used in fields such as encrypted communication and electronic interference.

[0067] This embodiment uses guinea pigs as a carrier for in vivo experiments, mainly to study whether the auditory perception of guinea pigs is affected by microwave pulse irradiation. Earphones are placed at the opening of the guinea pig's ear canal to provide sound stimulation. According to the mechanism of hearing, this will cause vibration of the basilar membrane of the cochlea. The vibration of the basilar membrane can be measured by drilling a hole in the cochlea to expose the basilar membrane. Since the size of the hole is related to the strength of the response signal (affected by the internal pressure of the cochlea, the larger the hole, the smaller the response signal amplitude), generally, a small hole with a diameter of about 300 μm is drilled at a suitable location in the cochlea. Common vibration meter probes are difficult to insert into this hole, requiring a specially designed vibration measurement probe.

[0068] To achieve the above objectives, this invention includes a 100-micron-level fiber optic vibration probe, employing a large-core multimode fiber with a central high-refractive-index glass core diameter of 62.5 μm, a low-refractive-index silicon glass cladding diameter of 125 μm, and a 280 μm diameter microsphere lens fired at the fiber's front end. Its advantages are:

[0069] 1. The overall diameter of the probe is less than 300μm, allowing it to penetrate deep into the cochlear opening;

[0070] 2. Using large-core optical fiber combined with a microsphere lens structure, the efficiency of recovering reflected light reaches about 10%.

[0071] 3. Simple operation, no need to adjust the light path;

[0072] 4. Suitable for strong magnetic environments and will not be affected by strong magnetic environments that generate microwaves;

[0073] This embodiment uses a detection light source with a wavelength of 1064 nm, according to Figure 1 The optical path is constructed and connected, and the following components are selected for a wavelength of 1064 nm: fiber optic bundle splitter 311, fiber optic bundle combiner 312, first fiber optic circulator 321, second fiber optic circulator 322, fiber optic coupler 33, high-reflectivity mirror 34, lens fiber optic probe 4, and photodetector 5. (See also...) Figure 1 The high-reflectivity mirror 34 is a LAYERTEC Laser mirror 111524 with a diameter of 12.7 mm. The scanning PZT 35 is a NAC2124. The piezoelectric ceramic driver 36 is a PI E662. The proportional-integral controller 37 is an LB1005. The high-reflectivity mirror 34 and the scanning PZT 35 are bonded together with epoxy resin adhesive with a low coefficient of thermal expansion to ensure that the coaxial position between the components is not damaged during the connection process.

[0074] After the optical circuit is connected, the position of the high-reflectivity mirror 34 is first adjusted using the scanning PZT 35, piezoelectric ceramic drive 36, and proportional-integral controller 37 to lock the interference signal at the point of maximum slope. This is to facilitate the detection of minute vibration displacements and improve the signal-to-noise ratio. The optical signal is converted into an electrical signal by the photodetector 5, and after being shunted by the DC biaser 38, the DC signal is input to the proportional-integral controller 37. The scanning range of the proportional-integral controller 37 is adjusted to continuously reduce the position movement of the high-reflectivity mirror 34. The PID parameters of the proportional-integral controller 37 are adjusted so that the interference signal is finally locked at the point of maximum slope.

[0075] Once the interference signal is locked, the experiment can begin. The earphone is placed on the guinea pig's ear, and sound stimulation of any frequency is provided via a signal generator. The lens fiber optic probe 4 is inserted into the cochlear opening and positioned in front of the vibration plane 1. The position of the lens fiber optic probe 4 is adjusted, and the spectral data near the corresponding frequency is observed on the spectrum analyzer 6. Through the data processing module 7, the spectral data can be converted into actual vibration displacement data. A schematic diagram of the vibration signal of the cochlear basilar membrane under 6 kHz sound stimulation is shown below. Figure 2 As shown.

[0076] In this embodiment, the vibration of the cochlear basilar membrane was measured under both microwave-free and microwave-free environments. Without microwaves, the displacement amplitude of the basilar membrane vibration was measured under sound stimuli of different frequencies and volumes. With microwaves added, the displacement data of the basilar membrane vibration was measured at different microwave distances. The schematic diagram of the cochlear basilar membrane vibration signals under 6 kHz sound stimulation and microwave stimulation at different distances is shown below. Figure 3 As shown.

[0077] In summary, this invention is applicable to high-precision vibration measurement in multiple fields such as industry and scientific research; it adopts a hundred-micron-level lens fiber optic probe, which can achieve efficient optical signal transmission in confined spaces, and the probe length can be customized according to actual needs, with a compact size that facilitates deep insertion into the area to be measured; by combining zero-difference interferometry technology with piezoelectric ceramic driving circuit, the interference signal can be locked at the point of maximum slope, enabling precise measurement of minute vibration displacements; the instruments used, except for the lens fiber optic, are all common laboratory equipment, which are easy to assemble and operate.

[0078] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-precision fiber optic vibration meter suitable for detecting minute signals in confined spaces, characterized in that, The system includes a vibration plane of the sample under test (1), a detection light source (2), a reflection signal processing module (3), a lens fiber optic probe (4), a photodetector (5), a spectrum analyzer (6), and a data processing module (7), wherein: The vibration plane (1) of the sample to be tested is a vibration entity whose vibration needs to be measured; The detection light source (2) is a narrow linewidth laser of arbitrary wavelength, which provides the optical signal required for measurement; The reflection signal processing module (3) is placed between the detection light source (2) and the lens fiber probe (4) and photodetector (5). Through optical path connection, the light generated by the detection light source (2) enters the lens fiber probe (4). At the same time, the detection light reflected by the vibration plane (1) and the reference light reflected by the high reflectivity lens (34) are extracted. The two beams are combined to generate an interference light signal, which is then input into the photodetector (5). The lens fiber optic probe (4) is placed in front of the vibration plane (1) of the sample to be tested, so that it is focused on the vibration plane (1); the probe body is made of optical fiber (41), and its front end is made into a microsphere lens (42) coaxial with the fiber core by an optical fiber fusion splicer. The photodetector (5) is placed after the reflection signal processing module (3) and is used to detect the interference light signal and convert it into an electrical signal; The spectrum analyzer (6) is connected to the photodetector (5) circuit and obtains the frequency domain signal by Fourier transform of the time domain interference signal; The data processing module (7) is placed after the spectrum analyzer (6) to convert the frequency domain signal into a real vibration displacement.

2. The high-precision fiber optic vibration meter according to claim 1, characterized in that, The reflected signal processing module (3) includes: an optical fiber splitter (311), an optical fiber combiner (312), a first optical fiber circulator (321), a second optical fiber circulator (322), an optical fiber coupler (33), a high-reflectivity mirror (34), a scanning PZT (35), a piezoelectric ceramic driving circuit (36), a proportional-integral controller (37), and a DC bias or tee (38), connected via an optical path; wherein: The fiber beam splitter (311) is placed after the detection light source (2) to split the beam into a detection beam and a reference beam; The fiber optic combiner (312) is placed in front of the photodetector (5) to combine the reflected probe light and the reference light to generate an interference light signal; The first fiber optic circulator (321) is used to transmit the probe light to the lens fiber optic probe (4) and extract the probe light reflected by the vibrating plane (1); The second fiber optic circulator (322) is used to transmit the reference light to the fiber optic coupler (33) and extract the reference light reflected by the high-reflectivity mirror (34); The fiber optic coupler (33) is placed after the second fiber optic circulator (322) and is used for the mutual conversion between fiber optic light and spatial light. The high-reflectivity lens (34) is placed after the fiber optic coupler (33) to reflect the reference light. Its distance from the fiber optic coupler (33) is controlled by the excitation PZT (35), thereby changing the optical path of the reference light. The scanning PZT (35) is bonded to the back of the high-reflectivity lens (34) and is an arbitrary-shaped piezoelectric ceramic sheet used to adjust the position of the high-reflectivity lens (34); The piezoelectric ceramic drive (36), placed after the scanning PZT (35), is a piezoelectric ceramic controller that outputs a voltage of 0 to 200V to cause the scanning PZT (35) to move at the micrometer level. The proportional-integral controller (37) is placed between the piezoelectric ceramic drive (36) and the DC bias or tee (38) to receive the DC signal output by the DC bias (38), and feed it back to the piezoelectric ceramic drive (36) after proportional-integral control, so as to lock the interference signal at the point of maximum slope. The DC bias (38) has its input terminal connected to the output terminal of the photodetector (5), its radio frequency output terminal connected to the spectrum analyzer (6), and its DC output terminal connected to the proportional-integral controller (37).

3. The high-precision fiber optic vibration meter according to claim 1, characterized in that, The lens fiber optic probe (4) includes an optical fiber (41) and a microsphere lens (42); wherein: The fiber (41) has a core selected based on the required reflected light recovery efficiency, and its outer diameter is smaller than the space of the sample to be tested. The microsphere lens (42) is coaxial with the optical fiber (41), has a smooth and neat surface, and has a radius of curvature greater than the outer diameter of the optical fiber (41) and smaller than the space of the sample to be tested.

4. The high-precision fiber optic vibration meter according to claim 1, characterized in that, The data processing module (7) is used to calculate the vibration displacement based on the frequency domain signal output by the spectrum analyzer (6). The calculation method is as follows: the wavelength of the detection light source is... The peak and valley values ​​of the interference signal After locking, the peak and valley values ​​of the interference signal are The vibration displacement is The proportional relationship is satisfied: Time-domain signal Able to generate frequency domain signals Represented as: ,in The impedance of the spectrum analyzer is given; the vibration displacement is obtained directly from the data on the spectrum analyzer (6), and the relationship is as follows: 。

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