Underwater double-point focusing acoustic beam former

Abstract

The underwater double-point focusing acoustic beam former comprises acoustic Luneberg lenses, the acoustic Luneberg lenses are arranged in front of an acoustic emitter at intervals, the acoustic Luneberg lenses comprise a first lens and a second lens, the second lens is arranged on the outer side of the first lens in a surrounding mode, and the second lens is arranged on the outer side of the second lens in a surrounding mode. The first lens is formed by a first lattice unit array, and the second lens is formed by a second lattice unit array. Therefore, by utilizing the interaction between the plane wave and the acoustic Luneberg lens, the acoustic wave signal generates two-point focusing, and a section of very long energy flow is formed between the two-point focusing, so that underwater acoustic beam forming is realized, directional transmission of the acoustic wave is further realized, the sensitivity and the resolution of the system are improved, and meanwhile, the acoustic wave beam forming effect is improved. And the signal-to-noise ratio and the anti-interference performance of the system can be improved.

Description

Technical Field

[0001] The invention relates to the field of acoustic technology, and in particular to an underwater dual-point focusing acoustic beam former. Background Art

[0002] Underwater acoustic beamforming technology is a technology that uses underwater acoustic waves for directional transmission and focusing. Underwater acoustic beamforming technology is widely used in medicine, sonar, underwater acoustic communication and other fields. In the medical field, acoustic beamforming technology is widely used in ultrasonic diagnosis and treatment. In the field of underwater communications, acoustic beamforming technology is widely used in acoustic wave communications. In the military field, acoustic beamforming technology is widely used in sonar detection and sonar imaging.

[0003] Traditional beamforming technology uses a large number of sensor arrays and controls the phase and amplitude of sound waves to form a beam in a specific direction in space, thereby achieving directional transmission and focusing of sound waves. The advantage is that it can achieve high-precision directional transmission and focusing, thereby improving the sensitivity and resolution of the system. At the same time, it can also reduce noise and interference, and improve the signal-to-noise ratio and anti-interference performance of the system.

[0004] However, in traditional acoustic beamforming technology, the use of sensor arrays makes the acoustic beamforming equipment expensive and bulky. In addition, the control of the phase and amplitude of the sound waves to form a beamforming requires a response algorithm and a large amount of calculation, which is not conducive to the use of acoustic beamforming technology in actual application scenarios. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes an underwater dual-point focusing acoustic beam former, which generates dual-point focusing of the acoustic wave signal by exciting a plane wave to interact with an acoustic Luneburg lens, thereby forming a long energy flow, i.e., an acoustic beam, between the dual-point focusing points. Underwater acoustic beam forming is achieved during directional transmission.

[0006] An underwater dual-point focusing acoustic beamformer according to an embodiment of the present invention includes:

[0007] an acoustic emitter, the acoustic emitter being used to generate a plane wave;

[0008] An acoustic Luneburg lens, wherein the acoustic Luneburg lens spacing is arranged in front of the acoustic emitter, and the acoustic Luneburg lens comprises: a first lens and a second lens, wherein the second lens ring is arranged outside the first lens, the first lens is formed by a first lattice unit array, and the second lens is formed by a second lattice unit array, wherein the refractive index between the first lens and the second lens satisfies the relationship:

[0009]

[0010] in: and r is the radial distance of the acoustic Luneburg lens, s=rn / R, n is the refractive index distribution, P a is the outer diameter of the first lens and is the inner diameter of the second lens, R is the outer diameter of the second lens, F1 is the focal length of the focus of the first lens, and F2 is the focal length of the focus of the second lens.

[0011] According to some embodiments of the present invention, the first lattice unit includes a first mass block and a first connecting plate, the ends of adjacent first connecting plates are connected in sequence and enclosed to form a prism, the first mass block is disposed in the prism and connected to the side edges of the prism; and / or

[0012] The second lattice unit includes a second mass block and a second connecting plate. Ends of adjacent second connecting plates are connected in sequence and enclosed to form a prism. The second mass block is disposed in the prism and connected to the side edges of the prism.

[0013] According to some embodiments of the present invention, ends of adjacent first connecting plates are connected in sequence and enclosed to form a hexagonal prism, and ends of adjacent second connecting plates are connected in sequence and enclosed to form a hexagonal prism.

[0014] According to some embodiments of the present invention, the material of the first lattice unit is epoxy resin, and the material of the second lattice unit is epoxy resin.

[0015] According to some embodiments of the present invention, the first lens and the second lens are integrally connected.

[0016] According to some embodiments of the present invention, the acoustic Luneburg lens further includes: an upper cover plate and a lower cover plate, wherein the upper cover plate covers the upper ends of the first lens and the second lens, and the lower cover plate covers the lower ends of the first lens and the second lens.

[0017] According to some embodiments of the present invention, the device further comprises: a rotating member, one end of which is rotatably connected to the upper cover plate and / or the lower cover plate, and the other end of which is connected to the sound emitter.

[0018] Beneficial effects:

[0019] The present invention utilizes the interaction between plane waves and acoustic Luneburg lenses to produce double-point focusing of acoustic wave signals, and forms a very long energy flow between the double-point focusing points. The focusing length is about 15 times the wavelength, so that the acoustic beam is emitted in a directionally manner, thereby realizing underwater acoustic beamforming, and further realizing directional transmission of sound waves, so as to improve the sensitivity and resolution of the system. At the same time, it is also beneficial to improve the signal-to-noise ratio and anti-interference performance of the system.

[0020] In addition, the present invention realizes the beamforming effect through an acoustic Luneburg lens, which not only greatly reduces the number of sensors, but also is more lightweight than the existing beamforming equipment. It also does not need to control the phase and amplitude of the sound waves, which greatly reduces the computational workload.

[0021] The present invention can reduce the energy loss caused by shear waves and at the same time increase the focusing length of the sound waves through the structure of the concentric acoustic Luneburg lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0023] Figure 1 is a schematic diagram of the principle of an underwater dual-point focusing acoustic beamformer according to the present invention;

[0024] Figure 2 is a schematic structural diagram of an underwater dual-point focusing acoustic beamformer according to the present invention;

[0025] Figure 3 is a schematic structural diagram of an acoustic Luneburg lens according to the present invention;

[0026] Figure 4 Schematic diagram of the structure of the first lattice unit according to the present invention.

[0027] Reference numerals:

[0028] 100. Underwater dual-point focusing acoustic beamformer;

[0029] 1. Acoustic emitter; 2. Acoustic Luneburg lens; 21. First lens; 22. Second lens; 3. First lattice unit; 31. First mass block; 32. First connecting plate; 4. Upper cover plate; 5. Lower cover plate; 6. Rotating member. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present disclosure in conjunction with the drawings in the embodiments disclosed in this application. The description of the embodiments is actually only illustrative and exemplary, and does not serve as any limitation to the present disclosure and its application or use; based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without carrying out creative work should fall within the scope of protection of the present disclosure. In addition, the technologies, methods and equipment known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the technologies, methods and equipment should be regarded as part of the specification.

[0031] Combination Figures 1 to 4 As shown, an underwater dual-point focusing acoustic beam former 100 according to an embodiment of the present invention comprises at least: an acoustic transmitter 1 and an acoustic Luneburg lens 2, wherein the acoustic Luneburg lens 2 is arranged in front of the acoustic transmitter 1, and the acoustic Luneburg lens 2 comprises a first lens 21 and a second lens 22, wherein the second lens 22 is arranged in a ring outside the first lens 21, the first lens 21 is formed by an array of first lattice units 3, and the second lens 22 is formed by an array of second lattice units.

[0032] When in use, the acoustic transmitter 1 generates a plane wave, and then utilizes the interaction between the plane wave and the acoustic Luneburg lens 2 to make the acoustic wave signal produce double-point focusing, and form a strong energy flow between the double focal points. The focusing length reaches about 15 times the wavelength, so that the acoustic beam is emitted in a directionally manner, thereby realizing underwater acoustic beamforming, and then realizing directional transmission of sound waves, so as to improve the sensitivity and resolution of the system. At the same time, it is also beneficial to improve the signal-to-noise ratio and anti-interference performance of the system.

[0033] Specifically, the first lens 21 and the second lens 22 may be designed as a split nested structure, which is conducive to mass production. Of course, more preferably, the first lens 21 and the second lens 22 are designed as an integrated structure, which has better structural consistency.

[0034] In order to make the interaction between the plane wave and the acoustic Luneburg lens produce double-point focusing, the refractive index between the first lens and the second lens satisfies the relationship:

[0035]

[0036] in: and r is the radial distance of the acoustic Luneburg lens, s = rn / R, P a is the outer diameter of the first lens and is the inner diameter of the second lens, R is the outer diameter of the second lens, F1 is the focal length of the focus of the first lens, and F2 is the focal length of the focus of the second lens.

[0037] Therefore, the refractive index distribution of the acoustic Luneburg lens 2 is related to the size of the lens and the position of the lens focal length. Therefore, through the pre-designed parameter values ​​of the focal length of the first lens 21 and the focal length of the second lens 22, combined with the radial dimensions of the first lens 21 and the second lens 22, the distribution of the refractive index of the first lens 21 and the refractive index of the second lens 22 can be determined.

[0038] Once the refractive index distribution law is determined, the lattice units are designed to meet the refractive index distribution, including changing the size and structure of the lattice units, and then placing the corresponding lattice units at the corresponding positions of the lens.

[0039] Further, based on the above embodiment, Figure 4 As shown, the first lattice unit 3 includes a first mass block 31 and a first connecting plate 32, wherein the ends of adjacent first connecting plates 32 are connected in sequence and enclosed to form a prism, and the first mass block 31 is arranged in the prism and connected to the side edges of the prism, so that a lower shear modulus can be achieved, thereby achieving a better beam forming effect.

[0040] When in use, the filling rate of the first lattice unit 3 can be changed by changing the length and width of the mass block, thereby affecting the effective density and effective refractive index of the unit structure.

[0041] Similarly, the second lattice unit includes a second mass block and a second connecting plate, the ends of adjacent second connecting plates are sequentially connected and enclosed to form a prism, and the second mass block is disposed in the prism and connected to the side edges of the prism.

[0042] Specifically, in actual use, in order to achieve the refractive index distribution required by the acoustic Luneburg lens 2, the following steps are performed;

[0043] S1: Design a hexagonal lattice unit structure;

[0044] S2: adjusting the length or width of the mass block to form a hexagonal lattice unit structure under different mass block shapes, and then calculating the dispersion curves of the hexagonal lattice unit structure under these different mass block shapes by COMSOL software;

[0045] S3: The velocity of the bending sound wave is then calculated from the dispersion curve;

[0046] S4: Calculate the refractive index of the unit structure by the formula n=c / v, where n is the refractive index distribution, c is the speed of the sound wave in water, and v is the speed of the pressure wave in the unit structure;

[0047] S5: Finally, the refractive index distribution of the acoustic Luneburg lens 2 is corrected by changing the length or width of the mass block until the refractive index of the hexagonal lattice unit meets the refractive index requirement of the acoustic black hole.

[0048] Preferably, the cross-section of the first lattice unit 3 is a regular hexagon, and the cross-section of the second lattice unit is also a regular hexagon, that is, the ends of adjacent first connecting plates 32 are connected in sequence and enclosed to form a regular hexagonal prism. Similarly, the ends of adjacent second connecting plates are connected in sequence and enclosed to form a regular hexagonal prism.

[0049] Since sound waves propagate in water, water can only carry compression waves. If the compression waves in the water come into contact with the traditional acoustic Luneburg lens 2, part of the energy will be converted into shear waves. This part of the energy will be consumed at the traditional acoustic Luneburg lens 2 and can no longer be transmitted into the water from the traditional acoustic Luneburg lens 2. Water cannot carry shear waves, thereby causing energy loss.

[0050] Therefore, the present invention not only suppresses the generation of shear waves and reduces the energy loss caused by shear waves by using a regular hexagonal structure as the unit cell of the acoustic Luneburg lens 2, but also satisfies the distribution of the lens refractive index and impedance matching. In addition, the concentric circular acoustic Luneburg lens 2 design increases the focusing length of the acoustic waves.

[0051] In some embodiments of the present invention, the first lattice unit 3 may be made of epoxy resin, and the second lattice unit may also be made of epoxy resin. The epoxy resin material can effectively isolate noise and reduce propagation and reflection, which is more conducive to reducing acoustic impedance mismatch.

[0052] In some embodiments of the present invention, Figure 1 As shown, the acoustic Luneburg lens 2 further includes an upper cover plate 4 and a lower cover plate 5, wherein the upper cover plate 4 tightly covers the upper ends of the first lens 21 and the second lens 22, and the lower cover plate 5 tightly covers the lower ends of the first lens 21 and the second lens 22, so that a closed whole is formed between the upper cover plate 4, the lower cover plate 5, the first lens 21 and the second lens 22, so that the acoustic Luneburg lens 2 is fixed between the upper cover plate 4 and the lower cover plate 5.

[0053] Further, based on the above embodiment, Figure 1 As shown, the underwater dual-point focusing acoustic beam former 100 further includes a rotating member 6, which is a rotating connecting rod. Of course, the rotating member 6 can also be a rotating bracket, wherein one end of the rotating member 6 is rotatably connected to the axis of the lower cover plate 5, and the other end is connected to the acoustic emitter 1. When in use, the acoustic emitter 1 can follow the rotating member 6 to rotate along the axis of the acoustic Luneburg lens 2, thereby changing the incident angle of the sound source, realizing wide-angle beam forming, and further more conveniently realizing a wide range of directional sound wave transmission effects.

[0054] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0055] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0056] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. An underwater dual-point focusing acoustic beamformer, characterized in that: include: an acoustic emitter, the acoustic emitter being used to generate a plane wave; An acoustic Luneburg lens, wherein the acoustic Luneburg lens spacing is arranged in front of the acoustic emitter, and the acoustic Luneburg lens comprises: a first lens and a second lens, wherein the second lens ring is arranged outside the first lens, the first lens is formed by a first lattice unit array, and the second lens is formed by a second lattice unit array, wherein the refractive index between the first lens and the second lens satisfies the relationship: in: and r is the radial distance of the acoustic Luneburg lens, s=rn / R, n is the refractive index distribution, P a is the outer diameter of the first lens and is the inner diameter of the second lens, R is the outer diameter of the second lens, F1 is the focal length of the focus of the first lens, and F2 is the focal length of the focus of the second lens.

2. The underwater dual-point focusing acoustic beamformer according to claim 1, characterized in that: The first lattice unit comprises a first mass block and a first connecting plate, the ends of adjacent first connecting plates are connected in sequence and enclosed to form a prism, the first mass block is disposed in the prism and connected to the side edges of the prism; and / or The second lattice unit includes a second mass block and a second connecting plate. Ends of adjacent second connecting plates are connected in sequence and enclosed to form a prism. The second mass block is disposed in the prism and connected to the side edges of the prism.

3. The underwater dual-point focusing acoustic beamformer according to claim 2, characterized in that: The ends of the adjacent first connecting plates are connected in sequence and enclosed to form a hexagonal prism, and the ends of the adjacent second connecting plates are connected in sequence and enclosed to form a hexagonal prism.

4. An underwater dual-point focusing acoustic beamformer according to any one of claims 1 to 3, characterized in that: The first lattice unit is made of epoxy resin, and the second lattice unit is made of epoxy resin.

5. The underwater dual-point focusing acoustic beamformer according to claim 1, characterized in that: The first lens and the second lens are integrally connected.

6. The underwater dual-point focusing acoustic beamformer according to claim 1, characterized in that: The acoustic Luneburg lens further includes an upper cover plate and a lower cover plate, wherein the upper cover plate is arranged to cover the upper ends of the first lens and the second lens, and the lower cover plate is arranged to cover the lower ends of the first lens and the second lens.

7. The underwater dual-point focusing acoustic beamformer according to claim 6, characterized in that: Also includes: A rotating member, one end of which is rotatably connected to the upper cover plate and / or the lower cover plate, and the other end of which is connected to the sound emitter.

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