CN107040315B

CN107040315B - Laser underwater sound generator

Info

Publication number: CN107040315B
Application number: CN201710227997.8A
Authority: CN
Inventors: 肖林; 侯晓帆; 韩龙; 其他发明人请求不公开姓名
Original assignee: Beijing Huaxia Guanggu Photoelectric Technology Co ltd
Current assignee: Beijing Huaxia Guanggu Photoelectric Technology Co ltd
Priority date: 2017-04-10
Filing date: 2017-04-10
Publication date: 2020-10-30
Anticipated expiration: 2037-04-10
Also published as: CN107040315A

Abstract

The invention relates to a laser underwater sound generator. The underwater laser acoustic generator utilizes the super-strong absorption effect of a water medium on laser with a specific laser wavelength, such as 2-3 microns, and a specific laser pulse shape to convert laser energy into acoustic energy with a certain frequency range to the maximum extent under water, becomes an underwater laser acoustic generator without the cooperation of other acoustic transducers, and is particularly suitable for an underwater maneuvering platform. The laser underwater acoustic generator can be composed of a plurality of single wavelength lasers within the range of 2-3 microns. When the underwater acoustic field signal generator and the underwater acoustic field signal generator work synchronously, underwater strong acoustic field signals can be generated; when the underwater acoustic signals work in a staggered mode, underwater low-acoustic-frequency signals can be generated; by changing the pulse energy or repetition frequency of the laser, underwater bubbles with different sizes or different acoustic frequencies can be generated; by changing the shape of the output end face of the conducting optical fiber, the transmission direction of the sound wave can be controlled.

Description

Laser underwater sound generator

Technical Field

The invention belongs to the technical field of laser underwater sounding. The device utilizes the super-strong absorption characteristic of a water medium to 2.79-micron and/or 2.94-micron waveband laser, directly and efficiently converts laser energy into sound wave signals in a certain frequency range, is an underwater laser sound generator without the cooperation of a special sound transducer, and is suitable for an underwater maneuvering platform.

Background

Sonar has long been the primary, even the only, means of underwater detection/communication. In the last two decades, with the urgent demands for underwater networking communication and detection of an anechoic target, some non-acoustic detection technologies and technologies combining non-acoustic detection have been gaining attention.

It is well known that since the last 70 th century, blue-green laser submarine detection technology has been developed. In decades of efforts, some typical onboard laser detection systems are put into use, but even in a good water area in deep sea, the direct detection distance under the laser is not more than one hundred meters. In order to solve the problem, a laser underwater sound generating technology combining laser and sound detection is proposed in recent years abroad, underwater sound generating effect research of 0.532 micron, 1.06 micron and 10.6 micron lasers is carried out successively, but a sound wave signal can be generated under the matching of a special laser-sound transducer, and the sound wave signal is in a high-frequency sound wave range of dozens of kilohertz to megahertz, and the whole system is complex, so that no practical application is reported so far.

The invention provides a novel underwater sound-making method based on 2.79/2.94 micron laser. The method makes full use of the super-strong absorption of water medium to the laser with the wave band (see figure 1, 3 μm is located at the absorption peak of water, and the absorption coefficient reaches 13200cm^-1) Once the laser enters water, the energy of the laser is completely absorbed by the water, so that the laser-sound conversion efficiency can be greatly improved, the bearing pressure of the underwater platform is reduced, and any other auxiliary sound transducer is not required to be matched, and the underwater mobile platform is particularly suitable for being dragged and used by the underwater mobile platform. In addition, the low-frequency and strong-field acoustic signals which are needed urgently underwater at present can be generated by changing the emission combination mode, the output power and the pulse width of the laser group, so that the underwater detection distance is increased.

At present, the main technology for realizing the laser underwater sound generator of the invention tends to mature. Wherein the content of the first and second substances,

lasers with 2.79/2.94 μm wavelength have been produced in several varieties, such as lamp pumped Er: YAG laser with wavelength of 2.94 micron, repetition frequency of 20Hz and power up to 130W; LD pumped 2.79 micron lasers are also commercially available with pulse energies on the order of hundreds of millijoules or joules and repetition rates of up to several kilohertz.

The product is suitable for the recent product reports of the transmission optical fiber suitable for the wave band of 3 microns, is made of sapphire or other fluoride materials, and is high in price at present, wherein each meter of the transmission optical fiber is thousands to tens of thousands of RMB.

Disclosure of Invention

The invention aims at the requirements of underwater low-acoustic-frequency detection or communication and designs an underwater laser sound generator without an acoustic transducer, which can strongly absorb laser by water.

The invention relates to an underwater laser sound-producing device, which is realized according to the following scheme, and utilizes a 2.79 micron and/or 2.94 micron laser group positioned in a peak wave band of light absorption of water as an underwater sound-producing laser source, so as to play the super-strong absorption function of a water medium on the laser energy of the wave band, and directly convert the laser energy entering water into underwater sound waves without the cooperation of an acoustic transducer through the thermal expansion effect generated between the laser and the water medium; the head-to-tail connection of pulse signals output by each laser is realized by controlling the emission delay time of each laser in a 2.79 micron and/or 2.94 micron laser group, and a condition is created for underwater low-frequency acoustic signals by utilizing a method for expanding the total pulse width output by the laser group.

The underwater laser sound generator without the sound transducer has the advantages that:

the super-absorption effect of the water medium on 2.79/2.94 micron laser is utilized, the conversion efficiency of laser underwater sound is greatly improved, and the pressure for bearing and supplying power to an underwater small platform is reduced; the method for increasing the total pulse width of the laser group is beneficial to generating underwater low-frequency sound wave signals and improving the underwater detection/communication action distance.

Drawings

FIG. 1 absorption curves of hemoglobin, melanin and water for light

FIG. 2 is a schematic block diagram of an underwater laser microphone without an acoustic transducer according to the present invention

FIG. 3 is a schematic diagram of the output structure of the underwater laser sound-producing device without the acoustic transducer according to the present invention

Detailed Description

The invention relates to an underwater laser sound-producing device without an acoustic transducer. FIG. 2 shows a schematic block diagram of an underwater laser microphone without the need for a special acoustic transducer; fig. 3 shows a schematic diagram of an underwater laser sound generator without a sound transducer. In fig. 2 and 3, the laser group is exemplified by 5 lasers. The following detailed description is made with reference to the accompanying drawings.

The underwater sound generator is composed of a 2-3 micron laser group 1, a laser power supply 2, an optical fiber coupler group 3, a conducting optical fiber group 4, a control box 5 and a support 6. Wherein the content of the first and second substances,

the 2-3 micron laser group 1 consists of 5 hosts of 2 micron solid pulse lasers, wherein the output wavelength of each laser is 2.01 microns, the pulse energy is 0.1-5J, the repetition frequency is 1-40Hz, the pulse width is 0.3ms, and a xenon lamp pumping mode is adopted.

The laser power supply 2 has the power supply capacity of ensuring 5 lasers to work simultaneously, and the maximum trigger frequency can reach 200 Hz. By varying the power supply parameters of the laser, the output shape of the laser pulses can be varied, such as bell-shaped, rectangular, steep front and steep back, or steep front and back, etc.

The controller 5 is the control center of the whole underwater laser sound generator, and can change the pulse emission time, pulse energy, repetition frequency and pulse shape of each laser by controlling the power supply 2 of the laser, the time control precision is better than 10 microseconds, and the variable pulse waveforms are not less than 3.

The optical fiber coupler group 3 comprises 5 optical fiber couplers, the conducting optical fiber group 4 comprises 5 conducting optical fibers matched with the optical fiber couplers, and each laser in the laser group 1 corresponds to 1 optical fiber coupler and 1 conducting optical fiber respectively. The conducting optical fiber is made of low-OH material suitable for 2-micron laser transmission, or is a solid optical fiber or a hollow conduit. The output end face of the conducting optical fiber can be processed into a round lens or a reflecting surface such as an inclined plane, a paraboloid and the like, and the control of the laser induced acoustic signal propagation direction is realized by changing the direction of the laser emitted by the conducting optical fiber.

The output ends of the 5 conducting fibres are bundled together and fixedly mounted on an output support 6, which is either placed near the optical window of the underwater load-bearing platform or can be inserted directly into the water.

Claims

1. A kind of laser underwater sound-making device, apply to the underwater detection and communication technical field, characterized by that, the said laser underwater sound-making device, produce the underwater sound wave under the condition of not having the acoustic transducer, the said laser underwater sound-making device includes:

the laser device comprises a laser group, a laser module and a control module, wherein the laser group comprises a plurality of lasers, and each laser is used for outputting 2.94 micrometers of laser;

a laser power supply for powering the set of lasers;

and the controller is used for controlling the power supply of the laser to control the emission time of each laser in the laser group, so that the emission time of each laser is sequentially connected to increase the total width of the output pulse of the laser group.

2. The laser underwater sound generator of claim 1, wherein a fiber coupler group comprises a plurality of fiber couplers, and the fiber couplers correspond to the lasers one to one;

and the input ends of the conducting optical fibers are respectively coupled to the output ports of the corresponding lasers in the laser group through the optical fiber couplers.

3. The laser underwater phonograph of claim 1 wherein the laser group includes 5 lasers.

4. The laser underwater sonicator of claim 1, wherein the controller is further configured to control a pulse output shape of the laser by varying the laser power supply parameter.

5. The laser underwater sonotrode of claim 1, characterized in that the pulse energy of said laser ranges from 0.1J to 5J, inclusive, the repetition rate of said laser ranges from 1Hz to 40Hz, inclusive, and the pulse width ranges from 10ns to 0.3ms, inclusive.