A fiber optic hydrophone array element and fiber optic hydrophone array

Abstract

This invention discloses a fiber optic hydrophone element and a fiber optic hydrophone array, relating to the field of underwater acoustic sensing technology. The fiber optic hydrophone element comprises: a frame assembly with spherical ends and a cylindrical center; a spherical steering assembly installed in each of the spherical cavities to enable the fiber optic hydrophone element to swing and bend; an acoustic-sensitive layer assembly including an elastic layer and an optical fiber ring; the elastic layer being tightly fitted to the outer surface of the frame assembly; the optical fiber ring being continuously and tightly wound around the outer surface of the elastic layer, in single or multiple layers in an odd number of layers; and a cladding layer surrounding the optical fiber ring; a damping buffer assembly connected to the spherical steering assembly, installed in the cylindrical cavity in the middle of the frame assembly and abutting against the inner wall of the cylindrical cavity, to achieve damping and vibration reduction of the fiber optic hydrophone element; and a connecting rod with one end connected to the spherical steering assembly and the other end used to connect to other fiber optic hydrophone elements.

Description

Technical Field

[0001] This invention relates to the field of underwater acoustic sensing technology, and in particular to a fiber optic hydrophone element and a fiber optic hydrophone array. Background Technology

[0002] Fiber optic hydrophones extract acoustic signals by demodulating changes in optical signals within the fiber, such as phase, intensity, or wavelength. They are primarily used to study sound propagation characteristics, noise, reverberation, and target acoustic properties in marine acoustic environments. While narrow-diameter hydrophone arrays are core equipment for modern underwater acoustic monitoring and offer advantages such as high sensitivity and resistance to electromagnetic interference, they still face numerous technical bottlenecks and limitations. For example, traditional arrays use Kevlar ropes for connection and load-bearing between elements. The narrow diameter of these ropes limits their tensile strength, making them prone to breakage and unsuitable for deep-sea environments. Furthermore, the limited size of the arrays restricts effective vibration reduction measures, leading to significant crosstalk between different elements and hindering the detection of low-frequency sounds.

[0003] To meet the demand for highly sensitive, narrow-diameter fiber optic hydrophones in deep-sea applications, it is necessary to design the hydrophone array elements with tensile strength enhancement and vibration reduction to effectively isolate various high and low frequency vibrations encountered during array application, and to meet the practical application requirements of flexible bending and swaying of the array. Summary of the Invention

[0004] The purpose of this application is to provide a fiber optic hydrophone element and a fiber optic hydrophone array, which aims to solve the problems of weak tensile strength, lack of damping and vibration reduction capabilities, and inflexible array bending and swinging of existing fiber optic hydrophones.

[0005] To solve the above problems, the technical solution proposed by this invention is as follows:

[0006] A frame assembly, wherein the frame assembly has a cavity with spherical ends and a cylindrical middle, and a spherical steering assembly is installed in the spherical cavity at each end of the frame assembly;

[0007] A spherical steering assembly is installed in a spherical cavity at one end of the frame assembly to enable the oscillation and bending of the fiber optic hydrophone array element.

[0008] The acoustic layer assembly includes an elastic layer and an optical fiber ring. The elastic layer is tightly attached to the outer surface of the frame assembly. The optical fiber ring is continuously and tightly wound on the outer surface of the elastic layer, and is wound in single or multiple layers in an odd number of layers. The outer side of the optical fiber ring is covered with a cladding layer.

[0009] A damping buffer assembly is connected to the spherical steering assembly, installed in the cylindrical cavity in the middle of the frame assembly and abutting against the inner wall of the cylindrical cavity, for realizing the damping and vibration reduction effect of the fiber optic hydrophone array element.

[0010] A connecting rod, one end of which is connected to the sphere steering assembly, and the other end of which is used to connect to other fiber optic hydrophone array elements.

[0011] Furthermore, the frame assembly is assembled from two concave spherical rings and a cylinder. The two concave spherical rings are symmetrically distributed at both ends of the cylinder. The concave spherical rings have spherical cavities inside, and the cylinder has cylindrical cavities inside. One end of the concave spherical rings has a conical opening.

[0012] Furthermore, a rounded transition is adopted between the conical opening and the spherical cavity, and the swing of the spherical steering assembly is limited by the angle of the conical opening.

[0013] Furthermore, the ball steering assembly includes a flexible ball head and a first support frame, the first support frame passing through the flexible ball head, having an annular bayonet at one end and being assembled and connected to the connecting rod, and a gourd-shaped opening structure at the other end for connecting the damping buffer assembly.

[0014] Furthermore, the center of the gourd-shaped opening structure coincides with the center of the flexible ball head.

[0015] Furthermore, one end of the connecting rod is an open annular structure. By passing the open annular structure through the annular bayonet and then closing and fixing it, the assembly of the connecting rod and the first support frame is achieved.

[0016] Furthermore, the damping buffer assembly includes a second support frame, a third support frame, a spring, and a bellows, wherein the bellows includes an axial bellows and a radial bellows;

[0017] The radial bellows is coaxially mounted in the cylindrical cavity of the frame assembly, and its outer circumferential surface abuts against the inner wall of the cylindrical cavity.

[0018] The axial corrugated tube is installed inside the cylindrical cavity, with a cylindrical opening in the middle. The cylindrical opening is used to install the second support frame. The inner wall of the axial corrugated tube is provided with a corrugated folding structure that connects to the cylindrical opening.

[0019] The third support frame is cylindrical and is movably installed inside the radial bellows and is coaxial with the radial bellows.

[0020] One end of the second support frame is a convex spherical surface, which forms a contact pair with the concave spherical groove at one end of the spherical steering assembly, and the other end is installed at the cylindrical opening of the axial bellows;

[0021] The spring is installed inside the third support frame to provide axial restoring force to the second support frame.

[0022] Furthermore, the cylindrical opening is interference-fitted with the second support frame.

[0023] Furthermore, each of the two ball steering assemblies is connected to a damping buffer assembly, and the two damping buffer assemblies are symmetrically and independently arranged in the cylindrical cavity of the frame assembly.

[0024] The present invention also proposes an optical fiber hydrophone array, which is formed by sequentially connecting several of the above-mentioned optical fiber hydrophone array elements.

[0025] The technical solutions provided by the embodiments of this application may include the following beneficial effects:

[0026] As can be seen from the above embodiments, the fiber optic hydrophone array element of this application has a compact structure and damping vibration reduction function, which can effectively isolate various high and low frequency vibrations encountered by the array and improve the detection performance of the array; the fiber optic hydrophone array elements have strong tensile strength after being assembled into a fine array and are not easy to break; the array can be flexibly bent and swung to meet the needs of more application scenarios.

[0027] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0028] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0029] Figure 1 This is a schematic diagram of a fiber optic hydrophone array element according to an exemplary embodiment.

[0030] Figure 2 This is a cross-sectional view of an optical fiber hydrophone array element according to an exemplary embodiment.

[0031] Figure 3 This is a schematic diagram of components of a fiber optic hydrophone array element according to an exemplary embodiment.

[0032] Figure 4 This is a schematic diagram of a gourd-shaped opening structure of a first support frame according to an exemplary embodiment.

[0033] Reference numerals: 110, connecting rod; 120, ball steering assembly; 1201, flexible ball head; 1202, first support frame; 1203, bayonet; 130, frame assembly; 1301, concave ball ring; 1302, cylinder; 1303, snap ring; 140, damping buffer assembly; 1401, second support frame; 1402, third support frame; 1403, spring; 1404, radial bellows; 1405, axial bellows; 150, acoustic layer assembly; 1501, elastic layer; 1502, fiber optic ring; 160, cladding layer. Detailed Implementation

[0034] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0035] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0036] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0037] This application provides an optical fiber hydrophone array element, such as Figure 1-3As shown, it can achieve array element miniaturization while possessing strong load-bearing capacity, flexible swinging ability, and good vibration isolation effect. It includes a spherical steering assembly 120, a frame assembly 130, a damping buffer assembly 140, an acoustic sensitive layer assembly 150, a connecting rod 110, and a covering layer 160. The frame assembly 130 has a cavity with spherical ends and a cylindrical middle section. A spherical steering assembly 120 is installed in each of the spherical cavities at both ends of the frame assembly 130. The spherical steering assembly 120 is installed in the spherical cavity at one end of the frame assembly 130 to realize the swinging and bending of the fiber optic hydrophone array element. The acoustic sensitive layer assembly 150 includes an elastic layer 1... 501 and fiber optic ring 1502, the elastic layer 1501 is tightly attached to the outer surface of the frame assembly 130, the fiber optic ring 1502 is continuously and tightly wound on the outer surface of the elastic layer 1501, and is wound in single or multiple layers in odd number of layers, the outer side of the fiber optic ring 1502 is wrapped with a cladding layer 160; the damping buffer assembly 140 is connected to the spherical steering assembly 120, installed in the cylindrical cavity in the middle of the frame assembly 130 and abutting against the inner wall of the cylindrical cavity, for realizing the damping and vibration reduction effect of the fiber optic hydrophone array element; one end of the connecting rod 110 is connected to the spherical steering assembly 120, and the other end is used to connect with other fiber optic hydrophone array elements.

[0038] Specifically, the frame assembly 130 is composed of two concave spherical rings 1301 and a cylinder 1302. One end of the concave spherical ring 1301 has a conical opening and a spherical cavity inside. The angle of the conical opening can be determined by the bending radius after arraying. The spherical cavity matches the spherical surface of the flexible ball head of the ball steering assembly. The conical opening and the spherical cavity are transitioned by a rounded corner. The angle of the conical opening can generally be in the range of 60° to 120°. The conical surface can limit the swing of the ball steering assembly 120. The concave spherical rings 1301 are symmetrically distributed at both ends of the cylinder 1302 and are connected by threads. After assembly, they form an internal cavity. The two spherical cavities are used to install the ball steering assembly 120, and the cylindrical cavity in the middle is used to install the damping buffer assembly 140. The outer circumference of the frame assembly 130 is used to install the acoustic layer assembly 150 and the covering layer 160.

[0039] Specifically, the spherical steering assembly 120 includes: a first support frame 1202 and a flexible ball head 1201. The flexible ball head 1201 is adapted to and contacts the spherical cavities at both ends of the frame assembly 130 and is axially and radially limited. The first support frame passes through the flexible ball head. One end of the first support frame 1202 has a snap-fit ​​1203. By passing one end of the connecting rod 110 (which is initially an open annular structure) through the annular snap-fit ​​1203, and then pressing the open annular structure of the connecting rod 110 together, and welding the closed part to shape it, the assembly of the connecting rod 110 and the annular snap-fit ​​1203 is achieved. The other end is designed as a gourd-shaped open structure, such as... Figure 4 As shown, the gourd-shaped opening structure with a larger radius spherical inner cavity near the outer end forms a contact pair with the convex spherical support rod of the damping buffer assembly 140, which can transmit compressive force to the damping buffer assembly 140 along the axial direction.

[0040] It should be noted that each of the two spherical steering components 120 is connected to a damping buffer component 140. The two damping buffer components 140 are symmetrically arranged in the cylindrical cavity of the frame component 130. The two damping buffer components are independent and will not affect each other.

[0041] In one embodiment, the flexible ball head 1201 is wrapped around the outside of the first support frame 1202 by vulcanization. The center of the gourd-shaped opening structure of the first support frame 1202 coincides with the center of the flexible ball head 1201. The annular opening of the first support frame 1202 can swing freely along the center of the flexible ball head 1201. The swing range is a conical range, which is limited by the conical opening angle of the concave ball ring 1301.

[0042] Specifically, the damping buffer assembly 140 includes: a second support frame 1401, a third support frame 1402, a spring 1403, and a bellows. The bellows can be made of rubber and include an axial bellows 1405 and a radial bellows 1404. The damping spring 1403 and the bellows constitute a multi-damping system, enabling the array element to achieve damping and vibration reduction effects in both the radial and axial directions, while also having the freedom to swing.

[0043] The radial bellows 1404 is coaxially installed in the cylindrical cavity of the frame assembly 130, and its outer circumferential surface abuts against the inner wall of the cylindrical cavity to achieve radial limiting. The two sides of the radial bellows are axially limited by snap rings 1303.

[0044] The axial bellows 1405 is installed in the mounting groove of the cylindrical cavity through a transition fit to achieve radial and axial limiting. Its inner wall has a corrugated fold structure between it and the second support frame 1401. A cylindrical opening is opened in the middle of the axial bellows. The cylindrical opening is used to install the round rod at the end of the second support frame 1401, thereby buffering and supporting the end of the second support frame 1401. The diameter of the cylindrical opening is slightly smaller than the outer diameter of the round rod at the end of the second support frame 1401, that is, the two are interference fit.

[0045] The third support frame 1402 is cylindrical with an inner cavity and is coaxially installed inside the radial bellows 1404. It can swing along the axial and radial directions of the radial bellows 1404.

[0046] The second support frame 1401 is coaxially installed inside the third support frame 1402. One end of the second support frame 1401 is a convex spherical surface that is adapted to the concave spherical groove at one end of the first support frame 1202 to form a contact pair. The other end is installed at the axial opening of the axial bellows 1404.

[0047] The spring 1403 is installed in the inner cavity of the third support frame 1402 to provide axial restoring force for the second support frame 1401 and to undertake a certain damping and vibration reduction function.

[0048] In a specific implementation, the outer circle of the third support frame 1402 can swing freely with damping inside the radial bellows 1404, and one end of the second support frame 1401 can swing freely with damping inside the axial bellows 1405.

[0049] Specifically, the radial bellows 1404 and axial bellows 1405 provide assembly space for the second support frame 1401 and the third support frame 1402, and together with the spring 1403, achieve multiple damping and vibration reduction. The outer diameter of the radial bellows 1404 is equal to the inner diameter of the main cylinder 1302, while the outer diameter of the axial bellows 1405 is larger than the inner diameter of the main cylinder 1302.

[0050] Specifically, the connecting rod 110 is made of high-strength alloy material, which has strong tensile strength, thus greatly improving the tensile strength of the arrayed fine-diameter array; the axial bellows 1405 and radial bellows 1404 are made of NBR (nitrile rubber), which improves bending fatigue performance; the flexible ball head 1201 can be made of high-elastic rubber material, which has the function of buffering and damping, and has good wear resistance; one end of the connecting rod 110 is connected to the bayonet 1203 of the first support frame 1202, and the gap of the bayonet 1203 after connection is sufficient to allow the connecting rod 110 to swing arbitrarily.

[0051] Specifically, the flexible ball head 1201 of the ball steering assembly 120 and the spherical cavity of the frame assembly 130 form a ball hinge rotation pair; the concave ball groove of the first support frame 1202 of the ball steering assembly 120 and the convex spherical surface of the third support frame 1402 also form a ball hinge rotation pair, which greatly increases the swing flexibility of the array elements after array formation and makes the bending radius of the array smaller.

[0052] In practice, the maximum radial profile dimensions of both the connecting rod 110 and the ball steering assembly 120 should not exceed the outer diameter of the covering layer 160.

[0053] Specifically, both the ball steering assembly 120 and the damping buffer assembly 140 have damping and vibration reduction functions. The flexible ball head 1201 first plays a vibration isolation role on the vibration of the connecting rod 110. The radial bellows 1404, axial bellows 1405 and spring 1403 in the damping buffer assembly 140 further isolate vibration, so as to effectively reduce the impact of the connecting rod 110 on the overall vibration of the array.

[0054] Specifically, the flexible ball head 1201, radial bellows, and axial bellows can control the vibration isolation frequency range by setting the rubber hardness, and are suitable for high-frequency vibration isolation (above 200Hz); the spring 1403 can control the vibration isolation frequency range by setting the spring stiffness, and is suitable for low-frequency vibration isolation (below 200Hz), and also has a certain attenuation effect on high-frequency vibration.

[0055] Specifically, the acoustic layer assembly 150 includes an elastic layer 1501 and an optical fiber ring 1502. The elastic layer 1501 is tightly fitted onto the outer circular surface of the frame assembly 130, and the optical fiber ring 1502 is continuously and tightly wound around the outer circular surface of the elastic layer 1501. The winding is performed in single or multiple layers in an odd number of layers, and the optical fiber is a bend-resistant optical fiber. The cladding layer 160 is made of acoustically transparent rubber and is wrapped around the outside of the optical fiber ring 1502 to isolate the optical fiber from the external medium, which can ensure the effective fit between the optical fiber and the elastic layer 1501 and play a sealing role.

[0056] In specific implementation, the outer diameter of the acoustic layer 150 is D1, and its length is L. The outer diameter of the fiber in the fiber ring 1502 is d1, and the total fiber length is L1. To ensure sufficient sensitivity of the array elements during demodulation, L1 ≥ 10m, and the length L of the acoustic layer 150 ≥ 10000d1 / πD1 (unit: mm). After assembly, the inner diameter of the acoustic layer 150 is equal to the outer diameter of the frame assembly 130, and the winding diameter of the fiber ring 1502 is equal to the outer diameter of the elastic layer 1501. Furthermore, the length of the cladding layer 160 should be greater than the length of the acoustic layer 150, less than the total length of the frame assembly 130, and uniformly and symmetrically arranged outside the frame assembly 130.

[0057] In a fiber optic hydrophone array element, a fiber optic loop 1502 of length L1 is continuously and tightly wound around the outer circular surface of an elastic layer 1501. When the array element is in an acoustic field environment, the outer circular surface of the elastic layer 1501 undergoes micro-deformation under the action of sound pressure P. This micro-deformation causes deformation of the fiber optic loop tightly attached to its surface, and the fiber optic loop also produces a deformation of... The total length of the fiber optic loop changes, meaning the optical path length of the light within the fiber changes. Using a demodulation instrument, the change in the phase of the Rayleigh scattered light caused by this change in optical path length can be detected. The change in the phase of the Rayleigh scattered light can be observed. It is positively correlated with the sound pressure intensity P, thus realizing the sensing function of the array element for external sound pressure. Define the sound pressure sensitivity M of the sensing array element, then: ,in and Proportional.

[0058] The system employs a combination structure of a spherical steering component 120 and a connecting rod 110. Since the connecting rod 110 is a rigid structure made of alloy material, it solves the problem of weak tensile strength in thin-diameter cables. Furthermore, after arraying, it can flexibly bend and swing in all directions of space via the spherical steering component 120. The damping buffer component 140 effectively reduces the vibration or impact generated by the connecting rod 110, preventing abnormal vibration or impact from being transmitted to the elastic layer 1501 through the connecting rod 110, thus improving the application reliability of the sensing array elements. The flexible ball head 1201 contains a first support frame 1202, one end of which is connected to the connecting rod 110, and the other end to the damping buffer. The support rod of component 140 is in contact; the damping buffer component 140 is installed in the cylindrical cavity inside the frame component 130, and one damping buffer component 140 is installed for each ball steering component 120; the damping buffer component 140 contains a second support frame 1401, and a vibration damping spring 1403 is installed inside the second support frame 1401, which is connected to the bellows to form a multi-damping vibration reduction system; the elastic layer 1501 and the fiber ring 1502 are provided with a covering layer 160, which is made of sound-permeable rubber to isolate the optical fiber from the external medium, which can ensure the effective fit between the fiber ring 1502 and the elastic layer 1501 and play a sealing role.

[0059] Furthermore, the fiber optic hydrophone array elements can be interconnected via connecting rods 110 to form an array. Therefore, this application also provides a fiber optic hydrophone array formed by sequentially connecting the aforementioned fiber optic hydrophone array elements.

[0060] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.

[0061] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A fiber optic hydrophone array element, characterized in that, The application relates to a frame assembly, a ball turning assembly, a sound-sensitive layer assembly, a damping buffer assembly and a connecting rod. The frame assembly is internally provided with two spherical cavities and a cylindrical cavity, and a ball turning assembly is arranged in each of the two spherical cavities. The ball turning assembly is arranged in the spherical cavity at one end of the frame assembly and is used for swinging and bending of a fiber hydrophone array element. The sound-sensitive layer assembly comprises an elastic layer and a fiber ring, the elastic layer is tightly attached to the outer surface of the frame assembly, the fiber ring is continuously and tightly wound on the outer surface of the elastic layer, the fiber ring is wound in odd layers, and the outer side of the fiber ring is wrapped with a cladding layer. The damping buffer assembly is connected with the ball turning assembly, is arranged in the cylindrical cavity of the frame assembly and is in abutment with the inner wall of the cylindrical cavity, and is used for damping and vibration reduction of the fiber hydrophone array element. One end of the connecting rod is connected with the ball turning assembly, and the other end is used for connecting other fiber hydrophone array elements. Further, the damping buffer assembly comprises a second support framework, a third support framework, a spring and a bellows. The radial bellows is coaxially arranged in the cylindrical cavity of the frame assembly, and the outer peripheral surface of the radial bellows is in abutment with the inner wall of the cylindrical cavity. The axial bellows is arranged in the cylindrical cavity, and a cylindrical opening is formed in the middle of the axial bellows. The second support framework is movably arranged in the radial bellows coaxially with the radial bellows. One end of the second support framework is a convex spherical surface, and the other end is arranged at the cylindrical opening of the axial bellows. The spring is arranged in the third support framework, and provides axial restoring force for the second support framework.

2. The fiber hydrophone of claim 1, wherein, The frame assembly is assembled by two concave spherical rings and a cylinder.

3. The fiber hydrophone of claim 2, wherein, The conical opening and the spherical cavity are connected through a round corner transition.

4. The fiber hydrophone of claim 1, wherein, The ball turning assembly comprises a flexible ball head and a first support framework.

5. The fiber hydrophone of claim 4, wherein, One end of the connecting rod is an open ring structure.

6. The fiber hydrophone of claim 4, wherein, The cylindrical opening and the second support framework are in interference fit.

7. The fiber hydrophone of claim 1, wherein, ​ 8. The fiber hydrophone of claim 1, wherein, Two said ball steering assemblies are respectively connected with a damping buffer assembly, and two said damping buffer assemblies are symmetrically and independently arranged in the cylindrical cavity of the frame assembly.

9. An optical fiber hydrophone array, characterized by, A plurality of the fiber hydrophone elements according to any one of claims 1-8 are sequentially connected.

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