CN100507602C - Method and device for detecting underwater acoustic signal by coherent laser remote sensing - Google Patents

Method and device for detecting underwater acoustic signal by coherent laser remote sensing Download PDF

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CN100507602C
CN100507602C CNB2007100427774A CN200710042777A CN100507602C CN 100507602 C CN100507602 C CN 100507602C CN B2007100427774 A CNB2007100427774 A CN B2007100427774A CN 200710042777 A CN200710042777 A CN 200710042777A CN 100507602 C CN100507602 C CN 100507602C
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light
frequency
water surface
optical
heterodyne
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CN101082671A (en
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贺岩
陈卫标
尚建华
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Naijing Zhongke Shenguang Technology Co Ltd
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Shanghai Institute of Optics and Fine Mechanics of CAS
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Abstract

A coherent laser remote sensing method and device for detecting underwater acoustic signals, the method is to divide single frequency laser into detection light and reference light, the detection light is emitted to the water surface after optical heterodyne; the sound wave emitted by the underwater instrument makes the water surface form forced vibration, and the vibration frequency and amplitude are respectively consistent with the frequency and intensity of the underwater sound wave; the frequency of the reflected light of the detection light on the water surface is modulated by the forced vibration speed of the water surface, the reflected light is coherent with the reference light, the reflected light is detected by the photoelectric detector, the vibration speed of the water surface is demodulated by the electric heterodyne demodulator, and then the waveform of the underwater sound wave is obtained, so that the detection of the underwater sound signal is realized. The invention has the advantages of high sensitivity, long distance measurement, flexible light path, reliable structure and easy adjustment.

Description

The method and apparatus of detecting underwater acoustic signal with coherent laser remote sense
Technical field
The present invention relates to laser remote sensing, a kind of method and apparatus of detecting underwater acoustic signal with coherent laser remote sense particularly, realize at a distance, detecting underwater acoustic signal non-contactly, can be as the receiving end of instrument under water to the telecommunication of wireless, the non-relay equipment of above water platform.
Background technology
Because the characteristic impedance difference of aqueous vapor, most of underwater sound wave is being reflected at the interface, the sound wave loss that is penetrated on the water surface is very big, for detecting underwater acoustic signal, receiving transducer must be immersed in the water, send the acoustical signal that detects to above water platform with cable or wireless system again, this detection mode that has a green end relaying has limited the maneuverability of above water platform detecting underwater acoustic signal.In order to overcome this difficult problem, the method for a kind of laser remote sensing detecting underwater acoustic signal of current employing---incoherent laser remote sensing detecting underwater acoustic signal method [1,2]See also document: 1. mulberry state is bright, Tian Zuoxi, He Jinlin, Cui Guihua, the applied research of laser eavesdropping technology in UNDERWATER ACOUSTIC SIGNAL DETECTION, the marine electronic engineering, 1999 the 6th phases and 2. her thick meetings, Sun Jinzuo utilizes the laser acquisition theoretical research of sound field under water, University Of Yantai's journal, Vol.16No.4Oct.2003.
The principle of this method as shown in Figure 1, with fixed angle incident water surface 03, the water surface fluctuation meeting that causes of the acoustical signal sent of acoustical generator 04 is under water carried out the orientation modulation to laser-bounce light to laser instrument 01 with laser.For the laser pick-off detector 02 of fixed position, catoptrical orientation changes the intensity modulated that will form laser on the detector face, thereby the modulation intelligence of sound wave is delivered on the laser pick-off detector 02, like this, utilizes the intensity modulated information of laser can detecting underwater acoustic signal.
This method is the amplitude modulation(PAM) that Laser Measurement is subjected to water surface, and light source adopts common lasers to get final product, and realizes that difficulty is lower.But there is following shortcoming in this method:
(1) detection sensitivity is directly proportional with the cosine value cos (θ) of laser incident angle, and when the laser incident angle was very little, detection sensitivity reduced greatly.And, be difficult to realize the wide-angle measurement for the long-range detection underwater signal, therefore, this method can't realize remote detection.
(2) transmitting and receiving the angle of machine must strict coupling, and it is big that light path is regulated difficulty.
Summary of the invention
Purpose of the present invention is exactly the deficiency that will remedy above-mentioned existing incoherent laser remote sensing detecting underwater acoustic signal method, a kind of detecting underwater acoustic signal with coherent laser remote sense method and device are provided, realizing the long-range detection underwater signal, and this device should have detection sensitivity height, far measuring distance, light path flexibly, reliable in structure, adjusting be easy to advantage.
Technical solution of the present invention is as follows:
A kind of method of detecting underwater acoustic signal with coherent laser remote sense is characterised in that this method is the single-frequency laser that single-frequency laser is exported to be divided into survey light and reference light, surveys light and is transmitted into the water surface to be measured through after the optical heterodyne modulation; The sound wave that sends of instrument makes water surface to be measured form forced vibration under water, and the frequency of the sound wave that the vibration frequency of this forced vibration and amplitude are sent with instrument under water respectively is consistent with intensity; Described detection light is modulated by the vibration velocity of the water surface to be measured in the catoptrical frequency that the water surface to be measured forms, reflected light and reference light are relevant, receive through photodetector, electricity heterodyne demodulation device demodulates the vibration velocity of water surface to be measured, and then the waveform of acquisition underwater sound wave, realize detection to underwater signal.
Realize the device of the detecting underwater acoustic signal with coherent laser remote sense of said method, comprise laser instrument, beam splitter, optical frequency shifter, optical circulator, telescope, combiner device, photodetector, electric heterodyne demodulation device, heterodyne signal driving amplifier, its position relation is: the laser instrument emitted laser is divided into through beam splitter surveys light and reference light, surveys light and enters optical frequency shifter; Electricity heterodyne demodulation device output heterodyne electric signal amplifies the rear drive optical frequency shifter through the heterodyne signal driving amplifier, makes by the detection light generation of optical frequency shifter and the frequency displacement of heterodyne signal same frequency; Detection light behind the shift frequency enters first port of optical circulator, from the output of second port, is transmitted into the water surface to be measured through telescope again; The reflected light of the water surface is received by this telescope again, enter optical circulator from second port of optical circulator, export from the 3rd port, reflected light and reference light close bundle in the combiner device, survey coherent light signal by photodetector, and be translated into electric signal, demodulate the waveform of underwater signal through electric heterodyne demodulation device.
Described laser instrument is a single frequency optical fiber laser.
Described optical frequency shifter is an acousto-optic frequency shifters.
Described beam splitter and combiner device are optical fiber structure.
Described photodetector is a PIN photodiode.
Described each optical device all adopts optical fiber interface, between light path constitute by single-mode fiber, telescopical aperture and focal length ratio are greater than 2 times of the single-mode fiber numerical aperture.
The laser instrument emitted laser is divided into through beam splitter surveys light and reference light, transmits and receives all and will have bigger decay through the reflection loss of telescopical coupling loss and target because survey light, and therefore, the detection light of telling should be greater than reference light.
Survey light and enter optical frequency shifter, electricity heterodyne demodulation device output heterodyne electric signal, amplify the rear drive optical frequency shifter through the heterodyne signal driving amplifier, make by the detection light generation of optical frequency shifter and the frequency displacement of heterodyne signal same frequency, the water surface vibration velocity that the frequency size of heterodyne signal should cause with reference to measured underwater signal is guaranteed optical frequency shift that vibration velocity the causes frequency less than heterodyne signal.
Detection light behind the shift frequency enters first port of optical circulator, from the output of second port, is transmitted into the water surface through telescope again; The sound wave that sends of instrument makes water surface form forced vibration under water, and vibration frequency is consistent with intensity with the underwateracoustic wave frequency respectively with amplitude, and water surface vibration causes surveying light and produces Doppler shift, frequency shift amount Δ f at the reflected light of the water surface 0V has following relation with water surface vibration velocity:
Δf = 2 V · cos θ λ
In the formula: θ is the angle of direction of motion and direction of observation, and λ is an optical maser wavelength.The water-reflected light of surveying light is received by same telescope, enter second port of optical circulator, from the output of the 3rd port, telescopical aperture and focal length ratio can both pass through telescope more preferably greater than 2 times of the single-mode fiber numerical aperture with the light of guaranteeing the single-mode fiber emission.
Reflected light and reference light close bundle at the combiner device, survey coherent light signal by photodetector, and be translated into electric signal, this electric signal is to be the FM signal of fundamental frequency with the heterodyne signal frequency, the size of modulating frequency is the Doppler shift amount that water surface vibration causes, demodulate modulating frequency through electric heterodyne demodulation device, can obtain the waveform of underwater signal.
Technique effect of the present invention is as follows:
1, the Laser emission of apparatus of the present invention and be received as zero angle is not even descending because of the angle detection sensitivity that causes that diminishes can appear in telemeasurement yet.
2, telescope of apparatus of the present invention transmit-receive sharing is measured light path and is regulated simple.
3, apparatus of the present invention adopt all optical fibre structure, and inner light path is flexible, reliable in structure.
Description of drawings
Fig. 1 is existing incoherent laser remote sensing detecting underwater acoustic signal method principle of work synoptic diagram, and wherein 01 be laser instrument, and 02 is the laser pick-off detector, and 03 is water surface, and 04 is acoustical generator under water.
Fig. 2 is the structural representation of the device embodiment of detecting underwater acoustic signal with coherent laser remote sense of the present invention, and wherein 1 is fiber laser, and 2 is beam splitter, 3 is acousto-optic frequency shifters, and 4 is optical fiber circulator, and 5 is telescope, 6 is the combiner device, and 7 is photodetector, and 8 is electric heterodyne demodulation device, 9 is the heterodyne signal driving amplifier, 10 is optical fiber circulator first port, and 11 is optical fiber circulator second port, and 12 is optical fiber circulator the 3rd port, 13 is water surface, and 14 are acoustical generator under water.
Embodiment
The invention will be further described below in conjunction with drawings and Examples, but should not limit protection scope of the present invention with this.
See also Fig. 2 earlier, Fig. 2 is the structural representation of the device embodiment of detecting underwater acoustic signal with coherent laser remote sense of the present invention.As seen from the figure, the formation of the device of detecting underwater acoustic signal with coherent laser remote sense of the present invention comprises laser instrument 1, beam splitter 2, optical frequency shifter 3, optical circulator 4, telescope 5, combiner device 6, photodetector 7, electric heterodyne demodulation device 8, heterodyne signal driving amplifier 9.Its position relation is: laser instrument 1 emitted laser is divided into through beam splitter 2 surveys light and reference light, surveys light and enters optical frequency shifter 3; Electricity heterodyne demodulation device 8 is exported the heterodyne electric signal, amplifies rear drive optical frequency shifters 3 through heterodyne signal driving amplifier 9, makes by the detection light generation of optical frequency shifter 3 and the frequency displacement of heterodyne signal same frequency; Detection light behind the shift frequency enters first port one 0 of optical circulator 4, from 1 output of second port one, is transmitted into the water surface 13 through telescope 5 again; The sound wave that sends of acoustical generator 14 causes the water surface to produce the vibration consistent with underwater sound wave under water, and the vibration velocity of the water surface is to the reflected light formation frequency modulation (PFM) of the water surface; The reflected light of frequency modulation is received by this telescope 5 again, enter second port one 1 of optical circulator 4, from 2 outputs of the 3rd port one, reflected light and reference light close bundle at combiner device 6, survey coherent light signal by photodetector 7, and be translated into electric signal, demodulate the waveform of underwater signal through electric heterodyne demodulation device 8.
The described laser instrument 1 of present embodiment is a single frequency optical fiber laser, and optical maser wavelength is 1550nm, live width<8kHz, and power 100mW exports continuously.
Described optical frequency shifter 3 is an acousto-optic frequency shifters, and optical wavelength is 1550nm, and frequency shift amount is 55MHz.
Described beam splitter 2 and combiner device 6 are optical fiber structure, and beam splitter splitting ratio 99:1=surveys light: reference light, combiner device close beam ratio 99:1=and survey light: reference light.
The combination of described optical circulator 4 and telescope 5, realized that single telescope 5 receives and dispatches light signal simultaneously, transmitted and received optical axis zero angle, the output optical fibre end face of second port one 1 of optical circulator 4 is positioned at the place, focal plane of telescope 5, the focal length 100mm of telescope 5, bore 30mm.
Described photodetector 7 is a PIN photodiode, for having the InGaAs G9806 series of preposition enlarging function.
Described each optical device all adopts optical fiber interface, between light path constitute by the single-mode fiber of 1550nm, optical fiber interface is FC/APC.
Show that through on probation the device of detecting underwater acoustic signal with coherent laser remote sense of the present invention has been eliminated Near and the light path accent of the operating distance that existing incoherent laser remote sensing detecting underwater acoustic signal method exists Joint difficulty big shortcoming has realized the long-range detection underwater signal, and have highly sensitive, Light path flexibly, reliable in structure, adjusting be easy to advantage.

Claims (7)

1, a kind of method of detecting underwater acoustic signal with coherent laser remote sense is characterised in that this method is single-frequency laser to be divided into survey light and reference light, surveys light and is transmitted into the water surface to be measured through after the optical heterodyne modulation; The sound wave that sends of instrument makes water surface to be measured form forced vibration under water, and the frequency of the sound wave that the vibration frequency of this forced vibration and amplitude are sent with instrument under water respectively is consistent with intensity; Described detection light is modulated by the vibration velocity of the water surface to be measured in the catoptrical frequency that the water surface to be measured forms, this reflected light and reference light are relevant, receive through photodetector, electricity heterodyne demodulation device demodulates the vibration velocity of water surface to be measured, and then the waveform of acquisition underwater sound wave, realize detection to underwater signal.
2, realize the device of the detecting underwater acoustic signal of the described method of claim 1, it is characterized in that this device comprises laser instrument (1), beam splitter (2), optical frequency shifter (3), optical circulator (4), telescope (5), combiner device (6), photodetector (7), electric heterodyne demodulation device (8), heterodyne signal driving amplifier (9), its position relation is: laser instrument (1) emitted laser is divided into through beam splitter (2) surveys light and reference light, surveys light and enters optical frequency shifter (3); Electricity heterodyne demodulation device (8) output heterodyne electric signal amplifies rear drive optical frequency shifter (3) through heterodyne signal driving amplifier (9), makes by the detection light generation of optical frequency shifter (3) and the frequency displacement of heterodyne signal same frequency; Detection light behind the shift frequency enters first port (10) of optical circulator (4), export from second port (11), pass through telescope (5) again and be transmitted into the water surface, the reflected light of the water surface is received by this telescope (5) again, enter second port (11) of optical circulator (4), from its 3rd port (12) output, reflected light and reference light close bundle in combiner device (6), survey coherent light signal by photodetector (7), and be translated into electric signal, demodulate the waveform of underwater signal through electric heterodyne demodulation device (8).
3, the device of detecting underwater acoustic signal according to claim 2 is characterized in that described laser instrument (1) is a single frequency optical fiber laser.
4, the device of detecting underwater acoustic signal according to claim 2 is characterized in that described optical frequency shifter (3) is acousto-optic frequency shifters.
5, the device of detecting underwater acoustic signal according to claim 2 is characterized in that described beam splitter (2) and combiner device (6) are optical fiber structure.
6, the device of detecting underwater acoustic signal according to claim 2 is characterized in that described photodetector (7) is PIN photodiode.
7, according to the device of the described detecting underwater acoustic signal of claim 2 to 6, it is characterized in that described each optical device all adopts optical fiber interface, between light path constitute by single-mode fiber, the aperture of described telescope (5) and focal length ratio are greater than 2 times of described single-mode fiber numerical aperture.
CNB2007100427774A 2007-06-27 2007-06-27 Method and device for detecting underwater acoustic signal by coherent laser remote sensing Active CN100507602C (en)

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CN107340523B (en) * 2017-06-11 2020-08-18 宁波飞芯电子科技有限公司 Speed and distance measuring system and method based on laser heterodyne detection
CN107966205A (en) * 2017-10-20 2018-04-27 哈尔滨工业大学(威海) A kind of underwater target acoustic detection method and device based on coherent laser
CN109586807A (en) * 2018-11-09 2019-04-05 北京华夏光谷光电科技有限公司 Sky-water means of communication and device
CN109507683A (en) * 2018-11-09 2019-03-22 北京华夏光谷光电科技有限公司 The laser acquisition method and device of the airborne shallow water depth of water
CN110132396A (en) * 2019-04-29 2019-08-16 中国科学院光电技术研究所 A kind of highly sensitive underwater sound wave detection device and method based on telescopic system
CN113432702B (en) * 2021-05-25 2023-01-31 天津大学 Ocean cross-cavitation-layer acoustic signal detection system and method based on optical heterodyne

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3790278A (en) * 1972-04-26 1974-02-05 United Aircraft Corp Peaked power coherent pulsed laser transmitter/receiver system
US5024528A (en) * 1989-11-13 1991-06-18 Bar Ilan University Alignment apparatus employing a laser light scatterer
WO1993011449A1 (en) * 1991-11-27 1993-06-10 United Technologies Corporation Laser diode liquid-level/distance measurement
WO1999040398A1 (en) * 1998-02-06 1999-08-12 Marconi Electronic Systems Limited Improvements in or relating to sound detection
US6724467B1 (en) * 2002-04-19 2004-04-20 Richard I. Billmers System for viewing objects at a fire scene and method of use
CN201083836Y (en) * 2007-06-27 2008-07-09 中国科学院上海光学精密机械研究所 Device for detecting underwater acoustic signal by coherent laser remote sensing

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3790278A (en) * 1972-04-26 1974-02-05 United Aircraft Corp Peaked power coherent pulsed laser transmitter/receiver system
US5024528A (en) * 1989-11-13 1991-06-18 Bar Ilan University Alignment apparatus employing a laser light scatterer
WO1993011449A1 (en) * 1991-11-27 1993-06-10 United Technologies Corporation Laser diode liquid-level/distance measurement
WO1999040398A1 (en) * 1998-02-06 1999-08-12 Marconi Electronic Systems Limited Improvements in or relating to sound detection
US6724467B1 (en) * 2002-04-19 2004-04-20 Richard I. Billmers System for viewing objects at a fire scene and method of use
CN201083836Y (en) * 2007-06-27 2008-07-09 中国科学院上海光学精密机械研究所 Device for detecting underwater acoustic signal by coherent laser remote sensing

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
水下目标光学隐蔽深度遥感获取方法. 朱海等.中国激光,第35卷第5期. 2007 *
激光多]普勒振动计用于水下声光通信. 贺岩等.中国激光,第34卷第5期. 2007 *

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