阅读说明：本技术 一种基于激光多普勒测振的数字水听器及测振方法 (Digital hydrophone based on laser Doppler vibration measurement and vibration measurement method ) 是由 陆海丰 朱中华 吴雷 陈伟 于 2021-08-24 设计创作，主要内容包括：本发明公开了一种基于激光多普勒测振的数字水听器及测振方法,其技术方案要点是：包括外壳、隔音层、空气仓、振膜、镜头、光波导芯片、激光器、光电转换模块、处理芯片组成：所述外壳、所述空气仓和所述振膜组成声波探头；所述镜头起准直作用,从光波导将探测光引出并平行出射到所述振膜上；所述光波导芯片上集成了探测干涉仪,在厘米级大小的所述光波导芯片内实现多路分光/分波、合光/合波和相位控制功能；所述光电转换模块将干涉后光学信号转换为电信号供后续采集、处理、分析使用；所述处理芯片上集成有采集单元、处理单元、分析单元、控制单元和通讯单元；基于激光多普勒测振的数字水听器具有噪声小、灵敏度高的优点。(The invention discloses a digital hydrophone based on laser Doppler vibration measurement and a vibration measurement method, and the technical scheme is as follows: including shell, puigging, air storehouse, vibrating diaphragm, camera lens, optical waveguide chip, laser instrument, photoelectric conversion module, processing chip constitution: the shell, the air chamber and the diaphragm form a sound wave probe; the lens has a collimation effect, and the detection light is led out from the optical waveguide and parallelly emitted to the vibrating diaphragm; the optical waveguide chip is integrated with a detection interferometer, and the functions of multi-path light splitting/splitting, light combining/combining and phase control are realized in the centimeter-sized optical waveguide chip; the photoelectric conversion module converts the interfered optical signal into an electric signal for subsequent acquisition, processing and analysis; the processing chip is integrated with an acquisition unit, a processing unit, an analysis unit, a control unit and a communication unit; the digital hydrophone based on the laser Doppler vibration measurement has the advantages of low noise and high sensitivity.)

1. A digital hydrophone based on laser Doppler vibration measurement is characterized in that: including shell, puigging, air storehouse, vibrating diaphragm, camera lens, optical waveguide chip, laser instrument, photoelectric conversion module, processing chip constitution: the shell, the air chamber and the diaphragm form a sound wave probe; the lens has a collimation effect, and the detection light is led out from the optical waveguide and parallelly emitted to the vibrating diaphragm; the optical waveguide chip is integrated with a detection interferometer, and the functions of multi-path light splitting/splitting, light combining/combining and phase control are realized in the centimeter-sized optical waveguide chip; the photoelectric conversion module converts the interfered optical signal into an electric signal for subsequent acquisition, processing and analysis; the processing chip is integrated with a collecting unit, a processing unit, an analyzing unit, a control unit and a communication unit.

2. The digital hydrophone based on laser Doppler vibration measurement according to claim 1, wherein: the laser is a common linewidth laser.

3. The digital hydrophone based on laser Doppler vibration measurement according to claim 1, wherein: the protective housing is made of metal, and organic anticorrosive material is attached to the surface of the protective housing.

4. The digital hydrophone based on laser Doppler vibration measurement according to claim 1, wherein: the diaphragm is made of sound-sensitive materials.

5. The digital hydrophone based on laser Doppler vibration measurement according to claim 1, wherein: the whole shell is of a cylindrical capsule structure.

6. The digital hydrophone based on laser Doppler vibration measurement according to claim 1, wherein: the laser instrument sends and surveys light path and reference light path, survey the light path with the reference light path is connected to behind the photoelectric conversion module acquisition unit, acquisition unit is connected with processing unit, processing unit is connected with audio output, survey the light path and be connected with collimating lens, collimating lens is connected with vibration probe.

7. A vibration measurement method of a digital hydrophone based on laser Doppler vibration measurement is characterized by comprising the following steps: the method comprises the following steps:

s1, emitting laser by the laser, and splitting the laser into a detection light path and a reference light path;

s2, the detection light beam is emitted to the elastic diaphragm in parallel through the collimating lens, and the detection light beam returns to the optical waveguide chip through the scattering primary path of the elastic diaphragm;

s3, conducting external sound waves to the elastic diaphragm, carrying vibration information by scattered light beams, interfering on the optical waveguide chip, and then, emitting the interference to the photoelectric conversion module to convert the interference into an electric signal;

and S4, acquiring, processing and analyzing through an acquisition unit of the special chip, analyzing the sound wave signals through a series of algorithms, and finally converting the sound wave signals into digital signals and transmitting the digital signals through a signal line.

Technical Field

The invention relates to the field of water depth detection, in particular to a digital hydrophone based on laser Doppler vibration measurement and a vibration measurement method.

Background

The sonar equipment is a 'leeward ear' in the field of offshore military and can intercept the sound emitted by submarines, ships and warships and the like at a long distance. However, with the development of underwater acoustic countermeasure and anti-countermeasure technology, especially the appearance of quiet submarines, the noise frequency is reduced to about hundred hertz, and the noise level is even lower than the ocean background noise, so that the traditional piezoelectric hydrophone is rather inattentive.

In recent years, with the development of optical fiber sensing technology, the optical fiber hydrophone is used as a novel underwater sound detection device, the sensitivity of the optical fiber hydrophone can reach-140 dBrad/μ Pa (2021 literature 'Distributed optical fiber based on phi-OTDR and bits field test' phase shift sensitivity-146 dB rad/μ Pa and 2009 'characteristic research' phase shift sensitivity-153 dB rad/μ Pa with an air cavity core type optical fiber hydrophone characteristic is not large), long-distance signal transmission of hundreds of kilometers can be realized, and the optical fiber hydrophone is rapidly developed due to the technical advantages. However, the fiber optic hydrophone has large noise due to polarization fading and the like (Polarized light that high coherence laser exported is through long-distance single mode fiber transmission, influence such as low birefringence light path and fiber optic interferometer because optic fibre microbend, distortion, environmental change make polarization state random variation, this makes the interference of light unstable in the fiber optic hydrophone, when two bundles of interference light polarization state orthogonalizations very much, output signal's visibility is zero, sensing signal disappears completely at this moment), its sensitivity hardly further promotes simultaneously, need new technological means urgently to further promote detectivity and SNR.

In summary, the optical fiber hydrophone has a significant advantage over the piezoelectric type hydrophone at present, but has a large noise and a bottleneck for improving sensitivity, and has the following main defects: the noise is large, and the noise is amplified gradually in the transmission process due to polarization fading; the sensitivity is slowly improved; although the optical fiber hydrophone has various sensitivity enhancing structures, the finally detected variation of the optical fiber is limited by the properties of the optical fiber material, and the sensitivity is close to the limit (the smaller the Young modulus is, the more sensitive the vibration is), so other methods, structures and materials are required to be searched for to improve the sensitivity.

Disclosure of Invention

Aiming at the problems mentioned in the background technology, the invention aims to provide a digital hydrophone and a vibration measurement method based on laser Doppler vibration measurement so as to solve the problems mentioned in the background technology.

The technical purpose of the invention is realized by the following technical scheme:

the utility model provides a digital hydrophone based on laser Doppler vibration measurement, includes shell, puigging, air storehouse, vibrating diaphragm, camera lens, optical waveguide chip, laser instrument, photoelectric conversion module, handles the chip and constitutes: the shell, the air chamber and the diaphragm form a sound wave probe; the lens has a collimation effect, and the detection light is led out from the optical waveguide and parallelly emitted to the vibrating diaphragm; the optical waveguide chip is integrated with a detection interferometer, and the functions of multi-path light splitting/splitting, light combining/combining and phase control are realized in the centimeter-sized optical waveguide chip; the photoelectric conversion module converts the interfered optical signal into an electric signal for subsequent acquisition, processing and analysis; the processing chip is integrated with a collecting unit, a processing unit, an analyzing unit, a control unit and a communication unit.

Preferably, the laser is a common linewidth laser.

Preferably, the protective housing is made of metal, and an organic anticorrosive material is attached to the outer surface of the protective housing.

Preferably, the diaphragm is made of sound-sensitive material.

Preferably, the shell is of a cylindrical capsule structure as a whole.

Preferably, the laser device emits a detection light path and a reference light path, the detection light path and the reference light path are connected to the acquisition unit after passing through the photoelectric conversion module, the acquisition unit is connected with the processing unit, the processing unit is connected with the audio output, the detection light path is connected with the collimating lens, and the collimating lens is connected with the vibration probe.

The invention also provides a vibration measuring method of the digital hydrophone based on laser Doppler vibration measurement, which comprises the following steps:

s1, emitting laser by the laser, and splitting the laser into a detection light path and a reference light path;

s2, the detection light beam is emitted to the elastic diaphragm in parallel through the collimating lens, and the detection light beam returns to the optical waveguide chip through the scattering primary path of the elastic diaphragm;

s3, conducting external sound waves to the elastic diaphragm, carrying vibration information by scattered light beams, interfering on the optical waveguide chip, and then, emitting the interference to the photoelectric conversion module to convert the interference into an electric signal;

and S4, acquiring, processing and analyzing through an acquisition unit of the special chip, analyzing the sound wave signals through a series of algorithms, and finally converting the sound wave signals into digital signals and transmitting the digital signals through a signal line.

In summary, the invention mainly has the following beneficial effects:

1. the invention adopts frequency modulation continuous wave coherent demodulation, has extremely high sensitivity, adopts a common communication laser, does not need a narrow line width light source and greatly reduces the cost;

2. the invention designs the optimized optical waveguide chip by using the unique optical technology to realize the integration and miniaturization of the process of processing, transmitting and receiving the sensing signal, because the polarization-preserving effect of the optical waveguide is very good (more than 60 dB), and the system noise is as low as

3. The acquisition processing part of the invention adopts a special chip, so that the volume and the power consumption can be greatly reduced, and the power consumption can be as low as 10 mW;

4. the invention directly detects the vibration at the vibrating diaphragm, the Young modulus of the vibrating diaphragm is small, the vibration amplitude is large with the same sound intensity, and the system sensitivity can reach-80 dB rad/mu Pa to the maximum.

Drawings

FIG. 1 is a system schematic of the present invention;

fig. 2 is a schematic diagram of the structure of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Referring to fig. 1 and 2, a digital hydrophone based on laser doppler vibration measurement includes a housing, a sound insulation layer, an air chamber, a diaphragm, a lens, an optical waveguide chip, a laser, a photoelectric conversion module, and a processing chip: the shell, the air chamber and the diaphragm form a sound wave probe; the lens has a collimation effect, and the detection light is led out from the optical waveguide and parallelly emitted to the vibrating diaphragm; the optical waveguide chip is integrated with a detection interferometer, and the functions of multi-path light splitting/splitting, light combining/combining and phase control are realized in the centimeter-sized optical waveguide chip; the photoelectric conversion module converts the interfered optical signal into an electric signal for subsequent acquisition, processing and analysis; the processing chip is integrated with a collecting unit, a processing unit, an analyzing unit, a control unit and a communication unit.

Referring to fig. 1 and 2, a digital hydrophone based on laser doppler vibration measurement, the laser emits laser, which is split into a detection optical path and a reference optical path (including delay line, compensating the inconsistency between the reference arm and the detection arm), the detection beam is emitted in parallel to an elastic diaphragm through a collimating lens, the beam returns to an optical waveguide chip through a diaphragm scattering original path, external sound waves are transmitted to the diaphragm, vibration information is carried by the scattered light beams, interference is finally carried out on the optical waveguide chip, the interference is incident on a photoelectric conversion module, the signals are converted into electric signals, the electric signals are collected and processed and analyzed through a collection unit of a special chip, sound wave signals are analyzed through a series of algorithms, and finally the electric signals are converted into digital signals and transmitted through signal lines. At present, the optical fiber hydrophone has higher performance, detects sound waves through optical fibers, and essentially conducts the sound waves to detection optical fibers to cause the optical fibers to generate strain so as to change the measurement to be detected. The scheme detects sound waves by measuring the vibration of the elastic diaphragm, and the Young modulus of the film is far smaller than that of the optical fiber, so that the change amplitude is larger under the same sound pressure. The Young modulus of the optical fiber is 73GPa, the difference between the Young modulus of the optical fiber and the Young modulus of the polyethylene is more than 20 GPa, meanwhile, the film thickness is thinner than the optical fiber, the contact surface with a sound field is larger, and the actual phase sensitivity is far higher than that of an optical fiber sensor. Actually measuring the vibration amplitude of the polyethylene film to be 200nm under 1000Hz and 60dB, and converting the vibration amplitude of the polyethylene film to be 46dB of phase sensitivity difference when the glass plate is only 1nm (the two have the same size); meanwhile, the noise of the system is about 10pm, because the output of the hydrophone is a digital signal, the noise cannot be increased due to the extension of the transmission distance, and therefore high-sensitivity and low-noise output is achieved.

Wherein the laser is a common linewidth laser; the common line width laser basically can meet the requirements that the line width is less than 1nm, the wavelength is an infrared band, and the wavelength is 1310nm/1550 nm; has better adaptability.

The protective shell is made of metal, and an organic anticorrosive material is attached to the outer surface of the protective shell; the organic anticorrosive material may be rubber, PVC, etc.

Wherein the diaphragm is made of sound-sensitive material; the sound sensitive material has the advantages of low Young modulus and sensitivity to sound vibration.

Wherein the shell is of a cylindrical capsule structure as a whole; the structure has strong water pressure resistance.

The sound insulation layer can shield the influence of sound waves on the reference light path, and meanwhile, reverse sound waves can be prevented from being transmitted to the vibrating diaphragm, so that the sensitivity is reduced due to vibration cancellation.

The laser device sends a detection light path and a reference light path, the detection light path and the reference light path are connected to the acquisition unit after passing through the photoelectric conversion module, the acquisition unit is connected with the processing unit, the processing unit is connected with audio output, the detection light path is connected with the collimating lens, and the collimating lens is connected with the vibration probe.

The embodiment adopts frequency modulation continuous wave coherent demodulation, has extremely high sensitivity, adopts a common communication laser, does not need a narrow line width light source, and greatly reduces the cost; the optical waveguide chip optimized by using unique optical technology design realizes the sensing signal positionThe integration and miniaturization of the physical transmitting and receiving process are realized, because the polarization maintaining effect of the optical waveguide is good (more than 60 dB), and the noise of the system is as low asThe acquisition processing part of the invention adopts a special chip, so that the volume and the power consumption can be greatly reduced, and the power consumption can be as low as 10 mW; the invention directly detects the vibration at the vibrating diaphragm, the Young modulus of the vibrating diaphragm is small, the vibration amplitude is large with the same sound intensity, and the system sensitivity can reach-80 dBrad/mu Pa to the maximum.

Example 2

A vibration measurement method of a digital hydrophone based on laser Doppler vibration measurement comprises the following steps:

s1, emitting laser by the laser, and splitting the laser into a detection light path and a reference light path;

s2, the detection light beam is emitted to the elastic diaphragm in parallel through the collimating lens, and the detection light beam returns to the optical waveguide chip through the scattering primary path of the elastic diaphragm;

s3, conducting external sound waves to the elastic diaphragm, carrying vibration information by scattered light beams, interfering on the optical waveguide chip, and then, emitting the interference to the photoelectric conversion module to convert the interference into an electric signal;

and S4, acquiring, processing and analyzing through an acquisition unit of the special chip, analyzing the sound wave signals through a series of algorithms, and finally converting the sound wave signals into digital signals and transmitting the digital signals through a signal line.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.