Vector optical fiber sensing device with enhanced mechanical coupling structure

Abstract

The utility model discloses a vector optical fiber sensing device with an enhanced mechanical coupling structure, and belongs to the field of optical fiber sensing. The device comprises a mechanical coupling structure and an optical fiber sensor. Optical fibers are selected as vibration sensitive elements of the optical fiber sensor, at least two optical fibers are needed for forming vector sensing, a small hole is formed in the joint of the upper portions of the two vibrating diaphragms of the mechanical coupling structure, the optical fibers penetrate through the holes and are tightly fixed to the upper portions of the vibrating diaphragms, and therefore mechanical vibration energy of the vibrating diaphragms can be received. Through interaction of forces between the two vibrating diaphragms, two vibration modes of swinging and bending are formed, that is, the two vibration modes are generated by the mechanical coupling beam. The response phase difference of the two vibrating diaphragms is sensed and amplified through the two vibration modes, so that the detection capability of the optical fiber sensor on the incoming wave direction is enhanced. Under the condition that the size of the sensor is reduced, the phase response difference of two ends of the sensor to incoming wave signals is improved, and the angular resolution of the optical fiber sensor is improved.

Description

Technical Field

[0001] The utility model relates to a vector optical fiber sensing device with mechanical coupling structure enhancement, belonging to the field of optical fiber sensing. Background Art

[0002] In the marine environment, how to conduct high-sensitivity, high-resolution, and high-signal-to-noise ratio underwater acoustic signal detection has become the focus of researchers.

[0003] Sound waves are a kind of mechanical waves. The detection of sound signals mainly utilizes the characteristics of certain materials or structures that are sensitive to vibration. For example, piezoelectric materials, PVDF, etc., these materials can convert the mechanical energy of vibration into electrical signals, and the detection of sound signals can be realized through the readout circuit; or the micro-cantilever beam structure in MEMS will vibrate after being affected by mechanical waves. Through the reasonable design of MEMS structure, the vibration signal can be converted into an electrical signal to obtain sound information. Fiber optic sensing is also a detection method that can sense sound signals. Compared with traditional piezoelectric transducers, fiber optic sensors have the advantages of high sensitivity, small size, and strong anti-electromagnetic interference ability; compared with traditional MEMS structures, fiber optic sensors have the advantages of low transmission loss and low processing cost. Fiber optic sensors can be used in the field of underwater acoustic detection in a more complex environment, and have great potential in the future detection of underwater acoustic signals.

[0004] Take grating fiber sensing technology as an example. It uses photolithography technology to prepare a grating with periodic refractive index changes on a section of erbium-doped fiber. The laser can be generated by pumping this section of grating with a laser pump source, and the grating plays a role of filtering light. The grating is extremely sensitive to vibration changes. After sensing the sound pressure, the grating structure constant and effective refractive index will change slightly, thereby affecting the wavelength of the light emitted by the erbium-doped fiber. The change of the sound signal can be demodulated by detecting the wavelength using an interferometer or spectrometer.

[0005] By using two hydrophones with a certain distance between them, the direction of the sound signal can be determined through information differences such as the amplitude difference between ears and the time difference between ears, thus realizing vector sound signal detection. According to the acoustic diffraction limit formula:

[0006]

[0007] Where θ is the angle of the incoming wave, α is a coefficient with an order of magnitude of 1, λ is the wavelength of the signal, and d is the interaural distance. It can be seen that the minimum detection angle is inversely proportional to the interaural distance, that is, to obtain a higher angular resolution, the interaural distance must be large enough, which makes it difficult to design a small-sized vector hydrophone. When the size of the vector hydrophone is limited to a small value, the phase difference of the acoustic signals detected by the two optical fiber sensors will be very small, making it difficult to detect the direction of the incoming wave. Therefore, it is particularly important to amplify the phase difference of the acoustic signal detected by the optical fiber sensor. Utility Model Content

[0008] In order to solve the problem that the traditional optical fiber vector sensor has too large aperture requirements when performing vector signal detection, resulting in a large size. The purpose of the utility model is to provide a vector optical fiber sensing device enhanced by a mechanical coupling structure, which can enhance the optical fiber sensor's ability to detect the incoming wave direction by amplifying the incoming wave phase difference through a mechanical structure with coupling characteristics. The utility model can improve the phase response difference of the sensor at both ends to the incoming wave signal while reducing the size of the sensor, thereby improving the angular resolution of the optical fiber sensor.

[0009] The purpose of the utility model is achieved through the following solutions:

[0010] A vector optical fiber sensing device enhanced by a mechanical coupling structure, comprising a mechanical coupling structure and an optical fiber;

[0011] The mechanical coupling structure forms two vibration modes, rocking and bending, through the interaction of forces between the two diaphragms. That is, the two vibration modes are generated by the mechanical coupling beam. The response phase difference of the two diaphragms is sensed and amplified through the two vibration modes. The optical fiber senses and transmits the response phase difference, thereby realizing the detection of small-size vector signals.

[0012] The force interaction between the two diaphragms is achieved by connecting the two diaphragms through a beam; the optical fiber senses and transmits the response phase difference by connecting the optical fiber to the vibration sensitive part.

[0013] There are at least two optical fibers; the optical fibers are installed at small holes above the two diaphragms, and the optical fibers are passed through the holes and fixed tightly above the two diaphragms, so that they can receive the mechanical vibration energy of the diaphragms and determine the direction of the incoming waves by using the characteristics of the two diaphragms amplifying the phase difference of the vector sound signal.

[0014] The utility model discloses a working method of a vector optical fiber sensing device enhanced by a mechanical coupling structure as follows: the base of the mechanical coupling structure is fixed at a position where vector signal detection is required, and after receiving a vibration signal, two diaphragms will generate corresponding vibration modes according to the direction of the incoming wave, and the two diaphragms are used to amplify the phase difference of the vector acoustic signal, and the phase difference of the two optical fiber vector acoustic signals is read to determine the incoming wave direction of the vector signal.

[0015] Beneficial effects:

[0016] 1. The utility model discloses a vector optical fiber sensing device enhanced by a mechanical coupling structure. The mechanical coupling structure forms two vibration modes, rocking and bending, through the interaction of forces between two diaphragms. The response phase difference of the two diaphragms is sensed and amplified by the two vibration modes, thereby realizing the detection of small-size vector signals. The utility model can cooperate with optical fiber for sensing. Compared with traditional vibration sensors, it has the advantages of high sensitivity, small size, light weight and no charge on the wet end, and can be applied to the detection of acoustic signals underwater and in the air.

[0017] 2. The utility model discloses a vector optical fiber sensing device with a mechanical coupling structure enhancement, which enhances the optical fiber sensor's ability to detect the direction of incoming waves by amplifying the phase difference of incoming waves through a mechanical structure with coupling characteristics. It can achieve low-frequency and high-angle resolution detection in a small volume, and solves the problem that the prior art vector acoustic detector must increase the aperture to obtain high-angle resolution.

[0018] 3. The utility model discloses a vector optical fiber sensing device with a mechanical coupling structure enhancement. The mechanical coupling structure has low complexity and can be prepared using a variety of materials and preparation technologies, thereby reducing the production and application costs of optical fiber sensors and achieving large-scale deployment, making optical fiber sensors more suitable for use in the fields of marine fisheries, marine resource exploration, etc.

[0019] 4. The utility model discloses a vector optical fiber sensing device with a mechanical coupling structure enhancement, which can be matched with the optical fiber in a variety of ways, and different installation methods can be selected according to actual conditions.

[0020] 5. The utility model discloses a vector optical fiber sensing device with a mechanical coupling structure enhancement. The sensor can be matched with a variety of common optical fiber sensors by designing through holes on the diaphragm. It is convenient and flexible and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the mechanical coupling structure in Example 1.

[0022] Figure 2 This is the structure after optical integration in Example 1.

[0023] Figure 3 This is the mechanical coupling structure in Example 2.

[0024] Figure 4 This is the structure after optical integration in Example 2.

[0025] Figure 5 This is the mechanical coupling structure in Example 3. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described below with reference to the accompanying drawings.

[0027] Example 1

[0028] Based on the basic topological structure described in the invention content, the mechanical coupling structure is designed as follows Figure 1 As shown. The device is 27.5mm long and 10.5mm wide. A small hole with a radius of 0.4mm is designed at the connection between the diaphragm and the cross bridge. This structure can be mass-produced by 3D printing. The optical fiber is immersed in the prepared PDMS solution to coat the surface of the optical fiber with a layer of PDMS polymer. The optical fiber is inserted into the small hole and then solidified statically to complete the connection and integration of the optical fiber and the mechanically coupled optical fiber detection enhancement structure. The effect is as follows Figure 2 shown.

[0029] Example 2

[0030] Based on the basic topological structure described in the invention content, the mechanical coupling structure is designed as follows Figure 3 As shown. The device is 27.5mm long and 10.5mm wide. A small hole with a radius of 0.4mm is designed 1.5mm above the connection between the diaphragm and the cross bridge. This position is verified by simulation to be the vibration maximum point. This structure can be mass-produced by 3D printing. The optical fiber is immersed in the prepared PDMS solution to coat the surface of the optical fiber with a layer of PDMS polymer, and then inserted into the small hole. After static curing, the connection and integration of the optical fiber and the mechanical coupling optical fiber detection enhancement structure are completed. The effect is as follows Figure 4 shown.

[0031] Example 3

[0032] Based on the basic topological structure described in the invention content, the mechanical coupling structure is designed as follows Figure 5 As shown. The device is 27.5mm long, 10.5mm wide and 29mm high. A long hole is opened in the square structure below the diaphragm. The length of the long hole is 29mm. This structure can be prepared in batches by 3D printing. The optical fiber is immersed in the prepared PDMS solution to coat the surface of the optical fiber with a layer of PDMS polymer, and then inserted into the small hole. After static curing, the connection and integration of the optical fiber and the mechanical coupling optical fiber detection enhancement structure can be completed.

Claims

1. A vector optical fiber sensing device enhanced by a mechanical coupling structure, characterized in that: including a mechanical coupling structure and an optical fiber; The mechanical coupling structure connects the two diaphragms through a beam. At this time, the two diaphragms interact with each other, thus forming two vibration modes: rocking and bending. The optical fiber is connected to the vibration-sensitive part, and the optical fiber senses and transmits the response phase difference, thereby realizing the detection of small-size vector signals. The number of optical fibers is at least two; the optical fibers are installed at small holes above the two diaphragms, and the optical fibers are passed through the holes and fixed closely above the two diaphragms.

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