CN111964772A - Underwater sound velocity measuring instrument based on acousto-optic effect - Google Patents
Underwater sound velocity measuring instrument based on acousto-optic effect Download PDFInfo
- Publication number
- CN111964772A CN111964772A CN202010849761.XA CN202010849761A CN111964772A CN 111964772 A CN111964772 A CN 111964772A CN 202010849761 A CN202010849761 A CN 202010849761A CN 111964772 A CN111964772 A CN 111964772A
- Authority
- CN
- China
- Prior art keywords
- beam splitter
- light
- laser
- sound wave
- path
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H5/00—Measuring propagation velocity of ultrasonic, sonic or infrasonic waves, e.g. of pressure waves
Abstract
The invention discloses an underwater sound velocity measuring instrument based on an acousto-optic effect, which comprises a light path consisting of a laser, five beam splitters, a reflector and a PD (photo diode), wherein the devices are arranged on two sides of a sound wave propagation area, and the PD is sequentially connected with a data acquisition module and an FPGA (field programmable gate array) data storage module; two calibrated glass windows for external calibration of the laser are also included. The reference light and the first measuring light in the light path form first interference light, and the reference light and the second measuring light form second interference light; after the sound wave is emitted, the obtained first interference light and the obtained second interference light are sent into the PD, a time domain signal generated when the sound wave signal passes through the light path comprises two distortion points, and the time interval between the two distortion points is the time of the sound wave from the first measuring light to the second measuring light. The invention utilizes the characteristics of acousto-optic effect and high precision and high accuracy of laser to express the acoustic information of the sound field in the form of acousto-optic effect, thereby obtaining high-precision sound velocity data.
Description
Technical Field
The invention relates to a sound velocity measurement system used in the ocean field, in particular to a high-precision underwater sound velocity measurement system applying an acousto-optic effect.
Background
The acoustic wave is a kind of mechanical wave, and the sound velocity is a basic physical quantity describing the propagation characteristic of the acoustic wave in the medium, and is related to the characteristic of the medium. By measuring the speed of sound in the medium, a lot of information can be known. Sonic measurements play an extremely important role in marine exploration. The sea water sound velocity is one of important parameters in the measurement processes of underwater sound wave distance measurement and positioning, flaw detection, marine environment detection and the like; the method has wide application and important functions on resource distribution, geological survey, hydrographic signal measurement, anti-diving, hydrogeology and national defense construction.
In conventional sound velocity measurement, there are generally divided into direct measurement and indirect measurement. The indirect method is to calculate the sound velocity indirectly through an empirical formula according to the functional relationship between the sound velocity and the temperature and the static pressure. Several representative empirical formulas are summarized internationally, and are: the Chen-Millero algorithm, the del Grosso algorithm, the Wilson algorithm. The algorithm formula has small error and high precision, but has poor adaptability. Different formulas are applied to different regions and different environments to obtain accurate results. Taking the Wilson sound velocity formula as an example, the accuracy can be optimized within the range of-4 ℃ < T <30 ℃, the pressure of 1kg/cm2< P <1000kg/cm2 and the salinity of 0< S < 37. However, for the measured area, the indexes are often unknown, which is contrary to the measurement principle and has more errors. In summary, indirect measurement has a major disadvantage. In the application of the direct measurement method, the transducer generates an ultrasonic signal through a piezoelectric effect, and the sound velocity is calculated by measuring the transceiving time delay of the signal. However, the mechanism for generating the ultrasonic wave is complex, so that the vibration starting point is unknown, the phase information can not be accurately captured, and the time delay signal can not be accurately measured.
Disclosure of Invention
Aiming at the prior art, the invention provides an underwater sound velocity measuring instrument based on an acousto-optic effect, which designs an optical path based on a Mach-Zehnder interferometer, and causes sudden change of optical signals on phases under continuous sound waves by utilizing the acousto-optic effect and laser interference so that the light carries special 'marking signals'. The phase-level mark signal measurement can obtain high-precision time information; under the condition that the distance between the first measuring light and the second measuring light is calibrated, the sound velocity can be accurately calculated. The method can measure the sound velocity with high precision and ensure the traceability of the sound velocity measurement.
In order to solve the technical problem, the underwater sound velocity measuring instrument based on the acousto-optic effect comprises a shell, wherein a light path is arranged in the shell, and optical devices included in the light path are a laser, five beam splitters, a reflector and a photoelectric detector which are respectively arranged on two sides of a sound wave propagation area; the five beam splitters are respectively marked as a first beam splitter, a second beam splitter, a third beam splitter, a fourth beam splitter and a fifth beam splitter; two opposite side walls of the shell are respectively provided with a calibration glass window for externally correcting laser to enable the laser to be equal in height, and the two calibration glass windows are respectively a first calibration glass window and a second calibration glass window; a data acquisition module and an FPGA data storage module are sequentially connected with the photoelectric detector;
the optical devices in the light path and the first calibration glass window and the second calibration glass window are arranged as follows:
the laser, the first beam splitter, the second beam splitter, the third beam splitter and the first calibration glass window are arranged on one side of the sound wave propagation area, and the reflector, the fourth beam splitter, the fifth beam splitter, the photoelectric detector and the second calibration glass window are arranged on the other side of the sound wave propagation area; the incident angles of all the beam splitters and the reflection angles of the reflectors are 45 degrees, so that the reflected light is perpendicular to the incident light; laser emitted by the laser is divided into two paths by the first beam splitter, one path passes through the sound wave to the fifth beam splitter to form reference light, and the other path is transmitted to the second beam splitter; the second beam splitter divides the received light into two paths, one path of the received light is transmitted to the third beam splitter through the second beam splitter and the other path of the received light is transmitted to the fourth beam splitter through the sound wave to form first measuring light; the third beam splitter divides the received laser into two paths, one path of the laser penetrates through the third beam splitter and is sent to the first calibration window, and the other path of the laser penetrates through the sound wave and is sent to the reflector to form second measuring light; after receiving the laser, the reflector reflects the laser to the fourth beam splitter; after receiving the laser of the second beam splitter, the fourth beam splitter reflects the laser to the fifth beam splitter; finally, the fifth beam splitter obtains first interference light formed by the reference light and the first measurement light from the fourth beam splitter and second interference light formed by the reference light and the second measurement light from the reflecting mirror;
after the sound wave is emitted, the fifth beam splitter drives the obtained first interference light and the second interference light into the photoelectric detector, a time domain signal generated when the sound wave signal passes through the light path comprises two distortion points, and the time interval between the two distortion points is the time for the sound wave to propagate from the first measurement light to the second measurement light.
Further, according to the underwater sound velocity measuring instrument, the laser emits laser with a wavelength of 632 nm. The photoelectric detector adopts an FDS100-CAL silicon photodiode.
Compared with the prior art, the invention has the beneficial effects that:
(1) the precision is high: because the time domain generates the phase-level mutation, the traceability is good, the precision is high, and the precision of the instrument can reach 10 proved by tests-4～10-5m/s, compared with the market, only 10 accurate tracks-3The sound velocity profiler for measuring the sound velocity by using the ringing method has higher precision.
(2) The traceability is high: because secondary conversion such as a piezoelectric device, a conversion circuit and the like is not needed, the traceability of the signal is ensured more reliably.
(3) The price is cheap: compared with tens of thousands of sound velocity profilers and up to hundreds of thousands of sound velocity profilers in the market, the product has low cost, so the cost has greater advantage.
Drawings
FIG. 1 is a schematic diagram of the optical path structure of an underwater sound velocity measuring instrument based on the acousto-optic effect;
FIG. 2 is a time domain signal generated when an acoustic wave signal passes through the optical path shown in FIG. 1;
FIG. 3 is a block diagram of the underwater sound velocity measurement process based on the acousto-optic effect.
Detailed Description
The invention will be further described with reference to the following figures and specific examples, which are not intended to limit the invention in any way.
The design idea of the invention is to reflect the target sound velocity by using the strictly designed light path signal of the acousto-optic effect side quantity and the information carried by the characteristic signal.
As shown in fig. 1, the underwater sound velocity measuring instrument based on the acousto-optic effect provided by the present invention includes a housing, a light path is arranged in the housing, and optical devices included in the light path are a laser 7, five beam splitters, a reflector 4 and a Photodetector (PD)8 which are respectively arranged at two sides of a sound wave propagation region; the five beam splitters are respectively marked as a first beam splitter 1, a second beam splitter 2, a third beam splitter 3, a fourth beam splitter 5 and a fifth beam splitter 6; two opposite side walls of the shell are respectively provided with a calibration glass window for externally correcting laser to enable the laser to be equal in height, the two calibration glass windows are respectively a first calibration glass window 9 and a second calibration glass window 10, and the two calibration glass windows are convenient for adjusting the angle and the height of the laser and ensure that the laser is equal in height and orthogonal; and the PD8 is sequentially connected with a data acquisition module and an FPGA data storage module.
The data acquisition module and the FPGA data storage module are arranged on the back of the shell, and the adjustable constant current source is further distributed on the back of the shell to supply power for the laser 7, the PD8 and the data acquisition module and the FPGA data storage module for the PD.
The arrangement of the optical devices in the optical path is as follows:
the laser 7, the first beam splitter 1, the second beam splitter 2, the third beam splitter 3 and the first calibration glass window 9 are arranged on one side of the sound wave propagation area, and the reflecting mirror 4, the fourth beam splitter 5, the fifth beam splitter 6, the PD8 and the second calibration glass window 10 are arranged on the other side of the sound wave propagation area; the incident angle of all the beam splitters and the reflection angle of the mirror 4 are 45 deg., so that the reflected light is orthogonal to the incident light.
The laser 7 in the present invention is a laser capable of generating stable coherent light, and its specific type is not limited. The constant current source provides stable current for a light source of the laser 7, so that the laser 7 can generate stable laser with the wavelength of 632nm, the laser 7 emits the laser with the wavelength of 632nm, the laser emitted by the laser 7 is divided into two paths through the first beam splitter 1, one path passes through the sound wave to the fifth beam splitter 6 to form reference light, and the other path passes through the second beam splitter 2;
the second beam splitter 2 splits the received light into two paths, one path of the received light is transmitted to the third beam splitter 3 through the second beam splitter 2, and the other path of the received light is transmitted to the fourth beam splitter 5 through the acoustic wave to form first measuring light;
the third beam splitter 3 divides the received laser into two paths, one path is transmitted to the first calibration window through the third beam splitter 3, and the other path passes through the acoustic wave to the reflector 4 to form second measuring light;
after receiving the laser, the reflector 4 reflects the laser to the fourth beam splitter 5; after receiving the laser light of the second beam splitter 2, the fourth beam splitter 5 reflects the laser light to the fifth beam splitter 6; finally, the fifth beam splitter 6 obtains first interference light formed by the reference light and the first measurement light from the fourth beam splitter 5 and second interference light formed by the reference light and the second measurement light from the reflecting mirror 4;
after the sound wave is emitted, the fifth beam splitter 6 emits the obtained first interference light and second interference light into the PD8, and a time domain signal generated when the sound wave signal passes through the above optical path includes two distortion points x1 and x2 in fig. 2, and a time interval between the two distortion points is a time when the sound wave propagates from the first measurement light to the second measurement light.
As shown in FIG. 2, at the laser interference position, there are two distinct frequency changes as the mark point x carrying the acoustic information1、x2Thereby analyzing the distance x between the marked places of the sound waves1-x2. The obtained acoustic signals are processed by a communication circuit through PD8, and are accessed to a data acquisition module and an FPGA data storage module on the back of the shell under the acquisition of high-speed sampling frequency, and the obtained signals are stored for later analysis and processing. The subsequent processing can easily calculate the time difference t at the marked part by identifying the marked part.
Example (b): except that the sound wave is transmitted in the water area, other devices work in a closed environment, for convenience of explanation, the device is represented in a simplified form, as shown in fig. 1, except for a shell of a shell instrument, a laser 7, five beam splitters, a reflector 4 and a PD8 are distributed on the front surface in the shell, and are respectively arranged on two sides of a sound wave transmission area. The laser 7 emits laser with 632nm wavelength, the PD8 adopts FDS100-CAL silicon photodiode, and the back of the shell is provided with an adjustable constant current source for supplying power to the laser, an FPGA data storage module and a data acquisition module for connecting the PD 8. The laser 7 in this embodiment is a model L520P50 laser.
The flow of the measurement by using the underwater sound velocity measuring instrument based on the acousto-optic effect provided by the invention is shown in fig. 3, and comprises the following steps:
firstly, a constant current source is switched on to supply power to a coherent light source of the L520P50 laser to calibrate an optical path. The light path is as shown in fig. 1, the first beam splitter 1, the second beam splitter 2, the third beam splitter 3, the fourth beam splitter 5, the fifth beam splitter 6 and the reflector 4 are adjusted, and the laser is externally calibrated through the first calibration glass window 9 and the second calibration glass window 10. The accuracy of the height and the angle of the light path is ensured by utilizing the space advantage of the external environment, so that the incident angle of each beam splitter and the reflection angle of the reflector are both 90 degrees.
After the light path is calibrated, laser is ensured to be injected into the FDS100-CAL silicon photodiode, and signals can be acquired.
The energy converter and the underwater sound velocity measuring instrument with the structure are placed under water.
The signal generator is used for inputting a sinusoidal signal with the natural frequency to the transducer, so that the transducer resonates, and the utilization rate of the signal is maximized.
And keeping the underwater sound velocity measuring instrument powered off for a period of time, and stopping inputting signals to the transducer.
The instrument retrieves and reads the data, which in the form of an analog signal, clearly indicates and contains a modulated laser signal under a continuous acoustic wave. The signal comprises two parts: firstly, acousto-optic modulation signals: under the action of sound waves, laser is modulated into three continuous laser signals with corresponding frequencies; secondly, distortion signal: at the critical position of three sections of acousto-optic signals, obvious distortion signals are provided to distinguish the three sections of acousto-optic modulation signals, and the distortion signals are used for measuring the flight time of the acoustic waves.
While the present invention has been described with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, which are illustrative only and not restrictive, and various modifications which do not depart from the spirit of the present invention and which are intended to be covered by the claims of the present invention may be made by those skilled in the art.
Claims (3)
1. An underwater sound velocity measuring instrument based on acousto-optic effect comprises a shell, a light path is arranged in the shell, and the underwater sound velocity measuring instrument is characterized in that,
the optical devices included in the optical path are a laser (7), five beam splitters, a reflector (4) and a photoelectric detector (8) which are respectively arranged at two sides of the sound wave propagation area; the five beam splitters are respectively marked as a first beam splitter (1), a second beam splitter (2), a third beam splitter (3), a fourth beam splitter (5) and a fifth beam splitter (6);
two opposite side walls of the shell are respectively provided with a calibration glass window for externally correcting laser to enable the laser to be equal in height, and the two calibration glass windows are respectively a first calibration glass window (9) and a second calibration glass window (10);
a data acquisition module and an FPGA data storage module are sequentially connected with the photoelectric detector (8);
the arrangement of the optical components and the first (9) and second (10) calibration glass windows in the light path is as follows:
the laser (7), the first beam splitter (1), the second beam splitter (2), the third beam splitter (3) and the first calibration glass window (9) are arranged on one side of a sound wave propagation area, and the reflector (4), the fourth beam splitter (5), the fifth beam splitter (6), the photoelectric detector (8) and the second calibration glass window (10) are arranged on the other side of the sound wave propagation area; the incident angles of all the beam splitters and the reflection angle of the reflector (4) are 45 degrees, so that the reflected light is perpendicular to the incident light;
laser emitted by the laser (7) is divided into two paths by the first beam splitter (1), one path passes through the sound wave to the fifth beam splitter (6) to form reference light, and the other path is transmitted to the second beam splitter (2);
the second beam splitter (2) splits the received light into two paths, one path of the received light is transmitted to the third beam splitter (3) through the second beam splitter (2), and the other path of the received light is transmitted to the fourth beam splitter (5) through the sound wave to form first measuring light;
the third beam splitter (3) divides the received laser into two paths, one path of the laser penetrates through the third beam splitter (3) and is sent to the first calibration window, and the other path of the laser penetrates through the sound wave and is sent to the reflector (4) to form second measuring light;
after receiving the laser, the reflector (4) reflects the laser to the fourth beam splitter (5); after receiving the laser of the second beam splitter (2), the fourth beam splitter (5) reflects the laser to the fifth beam splitter (6); finally, the fifth beam splitter (6) obtains first interference light formed by the reference light and the first measurement light from the fourth beam splitter (5) and second interference light formed by the reference light and the second measurement light from the reflector (4);
after the sound wave is emitted, the fifth beam splitter (6) enables the obtained first interference light and the second interference light to enter the photoelectric detector (8), a time domain signal generated when the sound wave signal passes through the light path comprises two distortion points, and the time interval between the two distortion points is the time for the sound wave to propagate from the first measurement light to the second measurement light.
2. The underwater sound speed measuring instrument according to claim 1, wherein the laser (7) emits laser light having a wavelength of 632 nm.
3. The underwater sound speed measuring instrument according to claim 1, wherein the photodetector (8) employs an FDS100-CAL silicon photodiode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010849761.XA CN111964772A (en) | 2020-08-21 | 2020-08-21 | Underwater sound velocity measuring instrument based on acousto-optic effect |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010849761.XA CN111964772A (en) | 2020-08-21 | 2020-08-21 | Underwater sound velocity measuring instrument based on acousto-optic effect |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111964772A true CN111964772A (en) | 2020-11-20 |
Family
ID=73391472
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010849761.XA Pending CN111964772A (en) | 2020-08-21 | 2020-08-21 | Underwater sound velocity measuring instrument based on acousto-optic effect |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111964772A (en) |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4429994A (en) * | 1980-12-22 | 1984-02-07 | The United States Of America As Represented By The Secretary Of The Navy | System for remotely determining velocity of sound in water |
| US4926395A (en) * | 1987-10-15 | 1990-05-15 | The Regents Of The University Of California | Method and system for measuring sound velocity |
| US5379270A (en) * | 1994-03-25 | 1995-01-03 | The United States Of America As Represented By The Secretary Of The Navy | Acoustic-optic sound velocity profiler |
| US6067861A (en) * | 1998-06-18 | 2000-05-30 | Battelle Memorial Institute | Method and apparatus for ultrasonic doppler velocimetry using speed of sound and reflection mode pulsed wideband doppler |
| CN204115856U (en) * | 2014-10-21 | 2015-01-21 | 四川大学 | A kind of heterodyne interference type vialog based on laser doppler |
| CN107764388A (en) * | 2017-09-28 | 2018-03-06 | 天津大学 | A kind of high-precision sound velocity in seawater measuring method based on acoustooptical effect |
| CN108896221A (en) * | 2018-06-30 | 2018-11-27 | 天津大学 | A kind of shockwave signal detection device and method interfered based on Mach-increasing Dare |
| CN111238337A (en) * | 2020-01-21 | 2020-06-05 | 中国计量科学研究院 | Step gauge calibration method and system capable of eliminating Abbe errors based on laser interference |
-
2020
- 2020-08-21 CN CN202010849761.XA patent/CN111964772A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4429994A (en) * | 1980-12-22 | 1984-02-07 | The United States Of America As Represented By The Secretary Of The Navy | System for remotely determining velocity of sound in water |
| US4926395A (en) * | 1987-10-15 | 1990-05-15 | The Regents Of The University Of California | Method and system for measuring sound velocity |
| US5379270A (en) * | 1994-03-25 | 1995-01-03 | The United States Of America As Represented By The Secretary Of The Navy | Acoustic-optic sound velocity profiler |
| US6067861A (en) * | 1998-06-18 | 2000-05-30 | Battelle Memorial Institute | Method and apparatus for ultrasonic doppler velocimetry using speed of sound and reflection mode pulsed wideband doppler |
| CN204115856U (en) * | 2014-10-21 | 2015-01-21 | 四川大学 | A kind of heterodyne interference type vialog based on laser doppler |
| CN107764388A (en) * | 2017-09-28 | 2018-03-06 | 天津大学 | A kind of high-precision sound velocity in seawater measuring method based on acoustooptical effect |
| CN108896221A (en) * | 2018-06-30 | 2018-11-27 | 天津大学 | A kind of shockwave signal detection device and method interfered based on Mach-increasing Dare |
| CN111238337A (en) * | 2020-01-21 | 2020-06-05 | 中国计量科学研究院 | Step gauge calibration method and system capable of eliminating Abbe errors based on laser interference |
Non-Patent Citations (1)
| Title |
|---|
| 薛彬: "基于声光效应的海水声速测量", 《中国激光》 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102175376B (en) | Multi-laser-beam heterodyne micro-impulse-measuring device and method | |
| CN108844613B (en) | High-precision seawater sound velocity measurement method based on optical frequency comb interference | |
| CN107764388B (en) | High-precision seawater sound velocity measurement method based on acousto-optic effect | |
| CN110411335A (en) | Differential type sinusoidal phase modulation laser interference surface nanometer-displacement device and method | |
| CN103528511A (en) | Sinusoidal phase modulation type laser self-mixing interferometer and measuring method thereof | |
| CN103364371B (en) | The absorption coefficient of atmospheric aerosol Novel differential measurement method of coaxial-type photothermal interference | |
| CN108037311B (en) | High-precision seawater flow velocity measurement method based on acousto-optic effect | |
| CN114858264B (en) | Sound velocity measurement device and method for submarine surveying and sonar surveying | |
| CN105446051A (en) | Laser acousto-optical scanning method and device thereof | |
| CN115407351A (en) | Interferometric time light detection and ranging system and method and device for determining object distance | |
| CN110631511B (en) | Right-angle prism type angle sensing measurement device and method based on multi-longitudinal-mode self-mixing effect | |
| CN105547197A (en) | Method and device for simultaneously measuring angle and vibration based on laser self mixing interference | |
| CN102998284A (en) | Measurement device and measurement method for transparent medium refractive index | |
| Zhang et al. | Influence of water on underwater distance measurement by a laser range finder | |
| CN115290175B (en) | Sea water sound velocity measuring device and method and ocean distance measuring system | |
| CN111964772A (en) | Underwater sound velocity measuring instrument based on acousto-optic effect | |
| CN102103011B (en) | High-precision laser interference hydrophone | |
| CN103954392A (en) | Device for measuring torsional pendulum micro impulse through linear frequency modulation multi-beam laser heterodyning and torsional pendulum micro impulse measuring method based on device | |
| CN111189528B (en) | High-precision underwater sound velocity measurement method based on femtosecond laser frequency comb | |
| CN109633672A (en) | Pulse type laser range-measurement system and its distance measuring method | |
| CN115420367A (en) | Calibration device and method for concave surface reflection focusing type laser vibration meter | |
| CN113970367A (en) | Free field laser absolute calibration method of interference type optical fiber hydrophone | |
| CN201892568U (en) | High-precision laser interference type hydrophone | |
| USH1370H (en) | Interferometric vibration and thermal expansion compensator | |
| CN108693247B (en) | Laser surface acoustic wave detection system based on double measuring beams and use method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20201120 |