CN215297708U - High-directivity laser induced sound underwater target detection system - Google Patents
High-directivity laser induced sound underwater target detection system Download PDFInfo
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- CN215297708U CN215297708U CN202121328282.XU CN202121328282U CN215297708U CN 215297708 U CN215297708 U CN 215297708U CN 202121328282 U CN202121328282 U CN 202121328282U CN 215297708 U CN215297708 U CN 215297708U
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Abstract
The utility model relates to a high directive property laser sends sound target detection system under water belongs to target detection technical field under water, and it includes: a laser for generating a laser signal; the hydrophone is used for receiving the acoustic wave signal reflected by the underwater target object; the master control upper computer is in communication connection with the laser and the hydrophone respectively; the beam splitter is used for dividing the laser signal generated by the laser into a plurality of beam splitting laser signals and is connected with the laser; the detector comprises a hemispherical bowl-shaped reflection shell and a beam expanding and focusing device, wherein the beam expanding and focusing device is used for expanding and focusing split laser signals, the beam expanding and focusing device and the split laser signals are in consistent quantity and are arranged in a one-to-one correspondence mode, laser outlets of the beam expanding and focusing device face the position of the spherical center of the reflection shell, and the inner surface of the reflection shell is arranged to be an acoustic reflection surface. The high-directivity laser induced sound underwater target detection system can generate a plane wave laser induced sound signal with high directivity.
Description
Technical Field
The utility model belongs to the technical field of target detection under water, especially, relate to a high directive property laser sends sound target detection system under water.
Background
With the continuous development and progress of military modern technology, the environment of naval underwater operation becomes more and more complex, the underwater advanced underwater navigation noise reduction technology and a plurality of novel unmanned underwater vehicle technologies are rapidly developed, the traditional underwater guidance system cannot meet the trend of current informationized operation and large environment, and especially the technical application problems of detection distance, precision, complex background interference resistance and the like of underwater detection guidance equipment are increasingly prominent.
At present, the underwater target detection mainly comprises two means of optical detection and acoustic detection. Among them, optical detection mainly uses an imaging method to detect underwater targets, however, propagation attenuation of underwater light waves is very large, and the distance of propagation and measurement is limited. The acoustic detection is a mainstream technology for detecting underwater targets, and mainly uses sonar to detect underwater targets, however, the defects of the sonar technology in the aspects of detection precision, anti-interference capability, maneuverability and the like become problems to be solved urgently for accurately detecting underwater guided weapon targets. In recent years, laser-induced acoustic underwater target detection technology has been gradually developed due to the characteristics of non-contact type, narrow pulse, wide frequency spectrum, flexibility and the like of laser-induced acoustic, such as an underwater target detection system and method based on a laser-induced acoustic scanning mode disclosed in patent CN 110389345A. However, in the current laser sounding technology, strong pulse laser generated by a laser is mainly directly focused in an aqueous medium to generate a light breakdown effect, and a generated sound wave signal is a spherical wave signal, so that the defects of poor directivity, low resolution and large detection distance error are caused when an underwater target is detected, and the requirements of high directivity, high precision and high resolution detection cannot be met.
SUMMERY OF THE UTILITY MODEL
The weak point that exists among the target detection technique under water to current laser sound that causes, the utility model provides a high directive property laser sound target detection system under water can produce the plane wave laser sound signal that causes that has high directive property to solve the poor technical problem of directive property that current laser sound causes and exists among the target detection technique under water.
The utility model provides a high directive property laser sends sound target detection system under water, include:
a laser for generating a laser signal;
the hydrophone is used for receiving the acoustic wave signal reflected by the underwater target object;
the master control upper computer is in communication connection with the laser and the hydrophone respectively;
further comprising:
the beam splitter is used for dividing the laser signal generated by the laser into a plurality of beam splitting laser signals and is connected with the laser;
the detector comprises a hemispherical bowl-shaped reflection shell and a beam expanding and focusing device, wherein the beam expanding and focusing device is used for expanding and focusing divided laser signals, the beam expanding and focusing device and the divided laser signals are consistent in quantity and are arranged in a one-to-one correspondence mode, laser outlets of the beam expanding and focusing device face the spherical center position of the reflection shell to converge all the divided laser signals to the spherical center position of the reflection shell, and the inner surface of the reflection shell is arranged to be an acoustic reflection surface to restrict the propagation direction of sound wave signals generated when water is subjected to an optical breakdown effect at the spherical center position.
The technical scheme can generate plane wave laser sound-induced signals with high directivity, and solves the technical problem of poor directivity in the existing laser sound-induced underwater target detection technology.
In some of these embodiments, the laser is a fiber laser.
In some of these embodiments, the beam splitter is a fiber optic beam splitter.
In some embodiments, the beam expanding and focusing devices are mounted on the reflecting shell and are arranged close to the edge of the open side of the reflecting shell, and the beam expanding and focusing devices are uniformly distributed along the circumferential direction of the open side of the reflecting shell, so that the breakdown effect is more favorably generated.
In some embodiments, the probe further includes an extension cylinder abutting against the open side of the reflective housing, so as to restrict the propagation direction of the acoustic signal reflected by the non-reflective housing and improve the directivity.
In some embodiments, the beam expanding and focusing devices are mounted on the extension cylinder and are arranged close to the edge of the open side of the reflection shell, and the beam expanding and focusing devices are uniformly distributed along the circumferential direction of the extension cylinder, so that the breakdown effect is more favorably generated.
In some of these embodiments, the expanded beam focusing apparatus includes an expanding member for expanding the beam and a focusing member for focusing.
In some embodiments, the hydrophone is fixedly arranged on the outer wall of the extension cylinder body, so that the hydrophone is more convenient to recover.
In some embodiments, the number of the hydrophones is multiple, and the multiple hydrophones are uniformly distributed on the outer wall of the extension cylinder body around the circumference of the extension cylinder body, so that the receiving effect of the sound wave signals is improved.
Based on the technical scheme, the embodiment of the utility model provides a high directive property laser sound-induced underwater target detection system can produce the plane wave laser sound-induced signal that has high directive property, has improved the detection precision and the sensitivity of target under water, but has strengthened directive property and mobility of target detection under water.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without undue limitation to the invention. In the drawings:
fig. 1 is a schematic structural diagram of a high directivity laser induced acoustic underwater target detection system provided in an embodiment of the present invention;
fig. 2 is the embodiment of the utility model provides a structure schematic diagram of the detector of hydrophone is installed to the high directive laser induced acoustic underwater target detection system.
In the figure:
1. a laser; 2. a beam splitter; 3. a detector; 31. a reflective housing; 32. a beam expanding and focusing device; 33. an extension cylinder; 4. a hydrophone; 5. a master control upper computer; 6. an underwater target; 7. a fixture.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only some, not all embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.
In the description of the present invention, it should be understood that the terms "center", "inside", "outside", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in fig. 2 only for convenience of description and simplification of description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore should not be construed as limiting the present invention.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.
As shown in the attached drawing 1, the embodiment of the utility model relates to a high directive laser sends sound underwater target detection system, including laser instrument 1, beam splitter 2, detector 3, hydrophone 4 and master control host computer 5.
The laser 1 is used for generating laser signals, preferably is an optical fiber laser to emit strong pulse laser, and has the advantages of simple structure, small volume and easy realization of mobility measurement; the laser wavelength is preferably 1064nm, the output energy is preferably 600mJ, and the pulse width is preferably 6-8 ns.
The beam splitter 2 is used for splitting the laser signal generated by the laser 1 into a plurality of split laser signals, and is connected to the laser 1. When a fiber laser is selected as the laser 1, the beam splitter 2 is selected corresponding to the fiber beam splitter. This embodiment specifically employs a 1X6 fiber beam splitter to differentiate the laser signal generated by laser 1 into 6 split laser signals of equal energy.
As shown in fig. 2, the detector 3 includes a hemispherical bowl-shaped reflection housing 31 and a beam expanding and focusing device 32 for expanding and focusing the split laser signals, the beam expanding and focusing device 32 is in one-to-one correspondence with the split laser signals, laser outlets of the beam expanding and focusing device 32 face the spherical center of the reflection housing 31, and an inner surface of the reflection housing 31 is an acoustic reflection surface. When adopting this detector 3, through the beam expanding focusing device 32 that sets up, can assemble whole minute laser signal in reflection casing 31's centre of sphere position department, when detector 3 arranged in under water, water produced the light breakdown effect in centre of sphere position department to produce the sound wave signal, the sound wave signal produces the back, and partial sound wave signal directly propagates away, and partial sound wave signal passes through the internal surface reflection restraint propagation direction of reflection casing 31, thereby converts the plane wave signal of high directive property into. This detector 3 can remove under water, has strengthened the mobility of sound source signal, and the design of hemisphere bowl form reflection casing 31 does benefit to and converts the spherical sound signal into the plane wave signal of high directive property, and simultaneously, the centre of sphere position department that multi-beam divides laser signal coaction in reflection casing 31 of detector 3 more is favorable to producing the puncture effect, and the sound source quality that produces in centre of sphere position department is better, has the characteristics that the sound pressure level is high, the frequency spectrum is wide.
As shown in fig. 2, in this embodiment, the probe 3 further includes an extension cylinder 33 abutting against the open side of the reflection housing 31, and an inner wall of the extension cylinder 33 is a sound wave vibration surface, so that the propagation direction of the sound wave signal that is not reflected by the reflection housing 31 can be restricted, and the directivity can be improved.
As shown in fig. 2, the beam expanding and focusing devices 32 are mounted on the extension cylinder 33 and are preferably disposed near the open side edge of the reflection housing 31, and the beam expanding and focusing devices 32 are uniformly distributed along the circumference of the extension cylinder 33, which is more favorable for generating the breakdown effect. It is understood that the expanded beam focusing devices 32 can be directly mounted on the reflective shell 31 by those skilled in the art, and the expanded beam focusing devices 32 are preferably disposed near the edge of the open side of the reflective shell 31, and the expanded beam focusing devices 32 are uniformly distributed along the circumference of the open side of the reflective shell 31.
For the expanded beam focusing device 32, it should be noted that the expanded beam focusing device 32 includes a beam expanding part for expanding beams and a focusing part for focusing, where the beam expanding part may adopt a beam expanding lens, etc., and the focusing part may adopt a focusing lens, etc.
The hydrophone 4 is used for receiving the acoustic wave signal reflected by the underwater target object 6 and converting the received acoustic wave signal into an electric signal. In this embodiment, in order to facilitate recovery of the hydrophone 4, as shown in fig. 2, the hydrophone 4 is fixedly mounted on the outer wall of the extension cylinder 33. In this embodiment, the hydrophone 4 is fixed to the outer wall of the extension cylinder 33 by the fixture 7. In order to improve the receiving effect of the acoustic wave signal, the number of the hydrophones 4 is preferably set to be multiple, specifically 4 in this embodiment, and the 4 hydrophones 4 are uniformly distributed on the outer wall of the extension cylinder 33 around the circumference of the extension cylinder 33.
The master control upper computer 5 is in communication connection with the laser 1 and the hydrophone 4 respectively to control the laser signal output of the laser 1, receive the electric signal uploaded by the hydrophone 4 and modulate and demodulate the electric signal, so that the position and the depth of the underwater target object 6 are accurately obtained.
The working process of the high-directivity laser induced sound underwater target detection system is as follows: the detector 3 is placed under water, the laser 1 generates a strong pulse laser signal, the laser signal is divided into a plurality of sub-laser signals with equal energy through the beam splitter 2, each sub-laser signal is focused at the spherical center of the reflecting shell 31 of the detector 3 through the beam expanding and focusing device 32 arranged on the detector 3, water generates a light breakdown effect at the spherical center, so that a sound wave signal is generated, after the sound wave signal is generated, part of sound wave information is directly transmitted, part of the sound wave signal reflects and restricts the propagation direction through the inner surface of the reflecting shell 31, so that the sound wave signal is converted into a plane wave signal with high directivity, when the sound wave signal meets an underwater target 6, the sound wave signal reflected by the underwater target 6 is reflected, collected and received by the hydrophone 4 and is uploaded to the main control upper computer 5, and the main control upper computer 5 modulates and demodulates the signal uploaded by the hydrophone 4, the position and the depth of the underwater target object 6 can be obtained, and the detection of the underwater target object 6 is realized.
The following briefly describes the influence factors for realizing the accurate positioning of underwater target detection: the size of the reflecting shell of the detector is an important condition for determining the emission of the sound wave signal within a certain angle, and is also an important factor for realizing high directivity of the sound wave. Derived from the radiation characteristic of the acoustic far field, the expression of the acoustic wave direction b (theta) is as follows:
in formula (1): l is the radius of the reflective shell of the detector; k is the wave number of the laser induced sound; theta is the direction angle of the acoustic field; j. the design is a square1Is a bessel function of order 1.
The expression for the sound source level SL of the laser induced acoustic signal is as follows:
in formula (2): t is time; p (t) is the acoustic intensity of the laser induced sound; tau is0The length of time for which the laser is acoustically active; p is a radical ofrIs a reference sound pressure.
The expression for the target strength TS of an underwater target is as follows:
TS＝10log(ab/λ)2 (3)
in formula (3): a. b is the length and width of the target, and λ is the wavelength of the acoustic signal.
Assuming a plane as a receiving matrix, the receiving directivity index DIrThe expression of (a) is as follows:
in formula (4): thetarIs the beam width of the acoustic signal.
According to the equations (2), (3) and (4), the detection equation under the noise background can be obtained as follows:
2PL＝SL+TS-N+DIr+10lg(τa)-5lg(d)+5lg(n) (5)
in formula (5): PL is the propagation loss; n is environmental noise; tau isaWidth of the laser induced acoustic signal; d is a detection index; n is the number of acoustic pulses.
The propagation loss PL is related to the probe distance L by the following equation:
PL＝20lg(L)+αL×10-3 (6)
in formula (6): and alpha is an absorption coefficient.
The expression for the distance resolution Δ R of laser induced acoustics is as follows:
in the formula: f is the acoustic frequency; p (f) is the fourier transform of the signal; c is the speed of sound in water; a. theτIs a time delay resolution constant; χ is a distance-ambiguity function of the distance,
wherein t isP (t) is the acoustic intensity of the laser-induced sound, p*(t) is the conjugate function of p (t), τ is the time delay, ξ is the Doppler shift, and j is the imaginary unit.
Through right the utility model provides a high directive property laser sends sound target detection system's explanation under water can see the utility model provides a high directive property laser sends sound target detection system under water and has following one or more advantage at least:
1. the laser is matched with the beam splitter to generate a plurality of beams of laser, the beams of laser are focused to the spherical center of a reflecting shell of the detector through a beam expanding and focusing device arranged on the detector, the laser energy is converted into sound wave energy by utilizing the optical breakdown effect of water, and the sound waves are reflected by utilizing the hemispherical reflecting shell to form a plane wave signal with high directivity, so that the directivity of underwater target detection is enhanced, and the underwater target detection precision and sensitivity are improved;
2. the multi-beam laser signals jointly act on the spherical center position of the reflecting shell of the detector, so that the breakdown effect is more favorably generated, and a sound source generated at the spherical center position has better quality and has the characteristics of high sound pressure level and wide frequency spectrum;
3. the detector has simple structure and small volume, can move underwater, enhances the mobility of sound source signals and improves the maneuverability of underwater target detection.
Finally, it should be noted that: the embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The above embodiments are only used to illustrate the technical solution of the present invention and not to limit it; although the present invention has been described in detail with reference to preferred embodiments, it should be understood by those skilled in the art that: the invention can be modified or equivalent substituted for some technical features; without departing from the spirit of the present invention, it should be understood that the scope of the claims is intended to cover all such modifications and variations.
Claims (9)
1. A highly directional laser induced acoustic underwater target detection system comprising:
a laser for generating a laser signal;
the hydrophone is used for receiving the acoustic wave signal reflected by the underwater target object;
the master control upper computer is in communication connection with the laser and the hydrophone respectively;
it is characterized by also comprising:
a beam splitter for dividing the laser signal generated by the laser into a plurality of divided laser signals, which are connected to the laser;
the detector, the detector includes that one is the reflection casing of hemisphere bowl form and is used for right divide laser signal to expand the beam focusing device with the focus, expand beam focusing device with divide laser signal quantity unanimous and one-to-one setting, expand beam focusing device's laser outlet all to the centre of sphere position department of reflection casing is in order to be all divide laser signal to assemble in reflection casing's centre of sphere position department, the internal surface of reflection casing sets up to the acoustic reflection face is in with restraint water the propagation direction of the sound wave signal that produces when the optical breakdown effect takes place in centre of sphere position department.
2. The highly directional laser induced acoustic underwater target detection system of claim 1, wherein said laser is a fiber laser.
3. The highly directional laser induced acoustic underwater target detection system of claim 2, wherein said beam splitter is a fiber beam splitter.
4. The highly directional laser induced acoustic underwater target detection system as claimed in claim 1, wherein said beam expanding and focusing devices are mounted on said reflection housing and disposed close to an edge of an open side of said reflection housing, said beam expanding and focusing devices being uniformly distributed along a circumferential direction of the open side of said reflection housing.
5. The highly directional laser induced acoustic underwater object detection system of claim 1, wherein said detector further comprises an extension cylinder interfacing with the open side of said reflector housing.
6. The highly directional laser induced acoustic underwater target detection system as claimed in claim 5, wherein said beam expanding and focusing devices are mounted on said extension cylinder and disposed close to an open side edge of said reflection housing, said beam expanding and focusing devices being uniformly distributed along a circumferential direction of said extension cylinder.
7. The highly directional laser induced acoustic underwater target detection system as claimed in claim 1, 4 or 6, wherein said beam expanding and focusing means comprises a beam expanding member for expanding beams and a focusing member for focusing.
8. The highly directional laser induced acoustic underwater target detection system as claimed in claim 5, wherein said hydrophone is fixedly mounted to an outer wall of said extension cylinder.
9. The highly directional laser induced acoustic underwater target detection system as claimed in claim 8, wherein the number of the hydrophones is plural, and the plural hydrophones are uniformly distributed on the outer wall of the extension cylinder body around the circumference of the extension cylinder body.
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