WO2018082208A1 - Optical fiber hydrophone array system, acceleration sensor array system and measurement method - Google Patents

Optical fiber hydrophone array system, acceleration sensor array system and measurement method Download PDF

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WO2018082208A1
WO2018082208A1 PCT/CN2017/070363 CN2017070363W WO2018082208A1 WO 2018082208 A1 WO2018082208 A1 WO 2018082208A1 CN 2017070363 W CN2017070363 W CN 2017070363W WO 2018082208 A1 WO2018082208 A1 WO 2018082208A1
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heterodyne
signal
frequency
pulse
fiber
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PCT/CN2017/070363
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French (fr)
Chinese (zh)
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张敏
何向阁
邱晓康
刘飞
古利娟
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北京大学
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
    • G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means

Definitions

  • the present invention relates to optical fiber sensing technology, and in particular to a fiber optic hydrophone array system and an acceleration sensor array system and a measuring method.
  • fiber-optic hydrophones have received more and more attention and research as a sensor capable of detecting, locating and identifying underwater targets.
  • the sound wave acts on the fiber optic hydrophone probe
  • the phase, intensity and other parameters of the optical wave field in the optical fiber will change, and the external acoustic wave field can be obtained by a certain demodulation method.
  • Currently used fiber optic hydrophones are generally constructed based on the Mach-Zehnder or Michelson interferometer structure.
  • time division multiplexing is the simplest and most effective scheme, and it is easy to be combined with wavelength division multiplexing technology to realize large-scale arraying of hydrophones, which is favored by researchers all over the world.
  • the hydrophone probe multiplexed in the scheme adopts a Michelson interferometer structure.
  • a hydrophone probe includes a splitter coupler, a length of L fiber, a Faraday mirror and a hydrophone probe skeleton.
  • the L long fiber is wound around the hydrophone probe skeleton to sense the external sound wave signal.
  • the time delay of the pulse reflected by different probes is different to realize the misalignment interference of the pulse, and the external acoustic signal can be obtained by demodulating the interference signal.
  • a hydrophone probe includes at least one splitter coupler, a length of L long fiber, a Faraday mirror and a hydrophone probe skeleton.
  • the splitter ratio of the coupler needs to be rationally designed.
  • the Faraday mirror is added, but in some special application environments (such as high temperature environment), the performance of the Faraday mirror is highly demanded.
  • the present invention proposes a fiber optic hydrophone array system with a simple and easy to implement structure and a measuring method thereof, which greatly simplifies the complexity of the existing system.
  • the fiber optic hydrophone array system of the present invention comprises: a narrow linewidth laser, a hydrophone array, a first coupler, a first acousto-optic modulator, a second acousto-optic modulator, a delay fiber, a second coupler, An erbium doped fiber amplifier, a circulator, a second erbium doped fiber amplifier, a filter, a photodetector, a data acquisition card, and an industrial computer; wherein the fiber is wound around a hydrophone probe skeleton to form a hydrophone probe, an optical fiber sequentially wound on a plurality of hydrophone unit matrix forming an array of hydrophones; narrow linewidth laser emits continuous laser; after a first coupler is divided into two evenly all the way through the first acousto-optic modulator is frequency shift f 1 and modulated into a first light pulse, the other way through the second acousto-optical modulator is modulated frequency shift f 2 and a second optical pulse,
  • the vibration information caused by the external acoustic wave signal is modulated by the elastic cylinder on the skeleton of the hydrophone probe to the back-scattered Rayleigh scattering signal, and then modulated to the heterodyne frequency of the heterodyne signal by interference; the heterodyne signal passes through the circulator
  • the three ports enter the second erbium-doped fiber amplifier, and after being amplified by the second erbium-doped fiber amplifier, the noise is filtered through the filter; then, the photodetector is reached, the signal is collected by the high-speed data acquisition card, and finally the signal is sent out on the industrial computer.
  • the difference is demodulated to obtain an external acoustic wave signal, where f 1 ⁇ f 2 , L d >0.
  • the sampling frequency of the heterodyne signal that is, the pulse repetition frequency should be more than 4 times the heterodyne frequency ⁇ f, and the heterodyne frequency should be as large as possible, so the relationship of 4 times is generally selected; the interval L d of the heterodyne pulse pair is larger than the pulse width w, In order to ensure that the two pulses do not overlap, the interval should be as small as possible on this basis.
  • the upper limit of the frequency of the detectable external sound wave signal is half of the heterodyne frequency
  • the lower limit of the frequency of the detectable external sound wave signal is determined by the number of backscattering curves used for time domain reconstruction, and the lower frequency limit is f s / M, where f s is the pulse repetition frequency and M is the number of backscatter curves for time domain reconstruction.
  • the invention adopts an optical fiber directly wound on a plurality of hydrophone probe skeletons to form a hydrophone array, and the heterodyne pulse pair generates a back Rayleigh scattering signal in the optical fiber of the hydrophone array as a heterodyne signal, and the external sound wave
  • the signal deforms the elastic cylinder on the skeleton of the hydrophone probe, which causes the deformation of the optical fiber, so that the phase of the back-scattered Rayleigh scattering signal changes in the optical fiber; and then the external acoustic signal is modulated to the heterodyne frequency of the heterodyne signal by interference.
  • the external acoustic signal is obtained by heterodyne demodulation.
  • the invention only uses one optical fiber, and does not need to add a coupler, a Faraday mirror, etc., compared with the present Some technologies have been greatly simplified.
  • Pulse width The continuous light is modulated into the width of the pulsed light after passing through the acousto-optic modulator.
  • the pulse width in the time domain is ⁇
  • the pulse width in the spatial domain is w
  • the pulse width of the two pulses in the heterodyne pulse pair is it's the same.
  • Pulse repetition frequency Each time a pulse is generated, a heterodyne pulse pair is generated at the same time.
  • the pulse repetition frequency is the frequency at which the heterodyne pulse pair is generated.
  • the sampling frequency of the heterodyne signal the sampling frequency of the back-range Rayleigh scattering signal reconstructed in the time domain at a position on the fiber of the hydrophone array, and the sampling frequency of the heterodyne signal is equal to the pulse repetition frequency.
  • Sampling frequency of the data acquisition card The rate at which the data acquisition card collects data.
  • the sampling frequency is related to the spatial resolution.
  • Sampling depth The length of the data collected by the data acquisition card after one trigger. This value is related to the length of the fiber of the hydrophone array and the sampling frequency of the data acquisition card.
  • Another object of the present invention is to provide a method of measuring a fiber optic hydrophone array system and an acceleration sensor array system.
  • the measuring method of the fiber optic hydrophone array system of the present invention comprises the following steps:
  • the length of the fiber of the hydrophone array is L, and the pulse repetition frequency is f s , then f s ⁇ c/2nL, where c is the speed of light in the vacuum and n is the refractive index of the fiber of the hydrophone array.
  • narrow linewidth laser emits a continuous laser, after the first coupler is divided into two evenly all the way through the first acousto-optical modulator and modulated by frequency shift f 1 into a first light pulse, the other all the way through the second acoustic
  • the second pulsed light passes through the length
  • the delay fiber of L d is separated from the first pulsed light in the time domain; after the first pulsed light and the second pulsed light are combined by the second coupler, two pulses are obtained one after the other to form an outer
  • the difference pulse pair, the heterodyne pulse pair has a heterodyne frequency of ⁇ f, and the heterodyne pulse pair has an interval of L d ;
  • the heterodyne pulse pair is first amplified by the first erbium-doped fiber amplifier, enters the circulator through the first port, and is injected into the fiber of the hydrophone array through the second port of the circulator; the heterodyne pulse pair is in the hydrophone array.
  • the back-direction Rayleigh scattering signal is generated in the optical fiber.
  • the hydrophone array receives the external acoustic wave signal in the water and then modulates the vibration information caused by the external acoustic wave signal to the back-rear by the elastic cylinder on the skeleton of the hydrophone probe.
  • the scatter signal is modulated by interference to the heterodyne frequency of the heterodyne signal, enters the second erbium-doped fiber amplifier through the third port of the circulator, is amplified by the second erbium-doped fiber amplifier, and is filtered by the filter. Then arrive at the photodetector, and the high-speed data acquisition card collects the signal and transmits it to the industrial computer;
  • a heterodyne pulse pair obtains a backscattering curve, and continuously collects M backscattering curves, M ⁇ 50;
  • the signal to be demodulated y s B cos [2 ⁇ ft + ⁇ (t)] is obtained, and then the demodulated signal is subjected to a heterodyne demodulation algorithm, and finally the variation of the optical phase is obtained. (t), thereby obtaining the amplitude and frequency of the external acoustic signal.
  • a method for measuring a fiber optic acceleration sensor array system includes the following steps:
  • the length of the fiber of the acceleration sensor array is L, and the pulse repetition frequency is f s , then f s ⁇ c/2nL, where c is the speed of light in the vacuum, n is the refractive index of the fiber of the acceleration sensor array, data acquisition
  • narrow linewidth laser emits a continuous laser, after the first coupler is divided into two evenly all the way through the first acousto-optical modulator and modulated by frequency shift f 1 into a first light pulse, the other all the way through the second acoustic
  • the second pulsed light passes through the length
  • the delay fiber of L d is separated from the first pulsed light in the time domain; after the first pulsed light and the second pulsed light are combined by the second coupler, two pulses are obtained one after the other to form an outer
  • the difference pulse pair, the heterodyne pulse pair has a heterodyne frequency of ⁇ f, and the heterodyne pulse pair has an interval of L d ;
  • the heterodyne pulse pair is first amplified by the first erbium-doped fiber amplifier, enters the circulator through the first port, and is injected into the optical fiber of the acceleration sensor array through the second port of the circulator; the heterodyne pulse pair is in the fiber of the acceleration sensor array.
  • the back-reverse Rayleigh scattering signal is generated.
  • the acceleration sensor array receives the external vibration signal in the air and then modulates the vibration information caused by the external vibration signal to the back-scattered Rayleigh scattering signal through the elastic cylinder on the acceleration sensor skeleton.
  • the detector collects signals from a high-speed data acquisition card and transmits them to the industrial computer;
  • a heterodyne pulse pair obtains a backscattering curve, and continuously collects M backscattering curves, M ⁇ 50;
  • the signal to be demodulated y s B cos [2 ⁇ ft + ⁇ (t)] is obtained, and then the demodulated signal is subjected to a heterodyne demodulation algorithm, and finally the variation of the optical phase is obtained. (t), thereby obtaining the amplitude and frequency of the external vibration signal.
  • the invention generates a heterodyne pulse pair, modulates the external acoustic wave signal to the heterodyne frequency through interference, and obtains the external acoustic wave signal in the water by heterodyne demodulation; introducing a heterodyne pulse pair in the conventional ⁇ -OTDR system to realize Demodulation of phase information; the invention uses only one optical fiber, and does not need to add a coupler, a Faraday mirror, etc., which is greatly simplified compared to the prior art, and each hydrophone primitive has been obtained. Same detection sensitivity as existing systems.
  • the scheme can also be applied to an optical fiber acceleration sensor array, and an optical fiber is sequentially wound on a plurality of acceleration sensor skeletons to form an acceleration sensor array, thereby detecting an external vibration signal in the air.
  • FIG. 1 is a schematic diagram of one embodiment of a fiber optic hydrophone array system of the present invention.
  • FIG. 2 is a three-dimensional view of a backscattering curve obtained by one embodiment of a method of measuring a fiber optic hydrophone array system in accordance with the present invention.
  • FIG. 3 is a schematic diagram of a heterodyne demodulation algorithm of one embodiment of a method of measuring a fiber optic hydrophone array system in accordance with the present invention.
  • the fiber optic hydrophone array system of the present embodiment includes: a narrow linewidth laser S, a first coupler OC1, a first acousto-optic modulator AOM1, a second acousto-optic modulator AOM2, and a delay fiber DF.
  • a hydrophone probe is formed on the hydrophone probe skeleton HS, and one optical fiber is sequentially wound on a plurality of hydrophone probe skeletons to form a hydrophone array H1 to Hn; the narrow linewidth laser S emits a continuous laser; the first coupling after an OCl, uniformly divided into two, all the way through the first acousto-optic modulator is a frequency shift f AOM1 and modulated into a first light pulse 1, another branch of the second acousto-optical modulator through the AOM2 is shifted and modulated frequency f 2
  • the Rayleigh scatter signal is used as a heterodyne signal, and the external acoustic wave signal received by the hydrophone array is modulated by interference to the heterodyne frequency of the heterodyne signal; the heterodyne signal enters the second erbium through the third port of the circulator C.
  • the fiber amplifier EDFA2 is amplified by the second erbium-doped fiber amplifier EDFA2, and then filtered by the filter F to remove noise; then reaches the photodetector PD, the high-speed data acquisition card DAQ collects the signal, and finally the signal is transmitted on the IPC of the industrial computer Heterodyne demodulation to obtain an external acoustic signal.
  • the first acousto-optic modulator AOM1 and the second acousto-optic modulator AOM2 are respectively connected to the driver AOMD of the acousto-optic modulator.
  • a fiber of length 1km is used to wind the hydrophone array, and each hydrophone probe is wound around 19m fiber, and the two hydrophone probes are spaced 4m apart, and 43 hydrophone probes can be wound. .
  • the narrow linewidth laser emits a continuous laser with a center frequency of f 0 , which is evenly divided into two paths after passing through the first coupler, and is shifted by frequency f 1 and modulated into a first pulsed light by a first acousto-optic modulator.
  • the second pulse light passes through the delay fiber of length L d , which is separated from the first pulse light in the time domain; the first pulse light and the second pulse light After the second coupler is combined, two pulses are obtained one after the other to form a heterodyne pulse pair.
  • the heterodyne frequency ⁇ f of the heterodyne pulse pair is 50 kHz, and the interval of the heterodyne pulse pair is L d ;
  • the heterodyne pulse pair is first amplified by the first erbium-doped fiber amplifier, enters the circulator through the first port, and is injected into the fiber of the hydrophone array through the second port of the circulator; the heterodyne pulse pair is in the hydrophone array.
  • the back-direction Rayleigh scattering signal is generated in the optical fiber, and as the heterodyne signal, the external acoustic wave signal in the water received by the hydrophone array is modulated to the heterodyne frequency of the heterodyne signal by interference, and enters the second through the third port of the circulator.
  • the erbium-doped fiber amplifier is amplified by a second erbium-doped fiber amplifier, filtered through a filter to remove noise; then reaches the photodetector, and the high-speed data acquisition card collects the signal and transmits it to the industrial computer;

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  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)

Abstract

An optical fiber hydrophone array system, an acceleration sensor array system and a measurement method. The optical fiber hydrophone array system comprises: a narrow linewidth laser S, hydrophone arrays H1-Hn, a first coupler OC1, a first acousto-optic modulator AOM1, a second acousto-optic modulator AOM2, a delay fiber DF, a second coupler OC2, a first erbium-doped fiber amplifier EDFA1, a circulator C, a second erbium-doped fiber amplifier EDFA2, a filter F, a photodetector PD, a data acquisition card DAQ and an industrial personal computer IPC. By means of generating a heterodyne pulse pair, an external acoustic signal is modulated onto a heterodyne frequency by means of interference, and an external acoustic signal in the water is obtained by means of heterodyne demodulation. The optical fiber hydrophone array system is greatly simplified, and each hydrophone element achieves the same detection sensitivity as an existing system. The solution can also be applied to an optical fiber acceleration sensor array. An optical fiber is sequentially wound around a plurality of acceleration sensor skeletons to form an acceleration sensor array so as to detect an external vibration signal in the air.

Description

光纤水听器阵列***和加速度传感器阵列***及测量方法Fiber optic hydrophone array system and acceleration sensor array system and measuring method 技术领域Technical field
本发明涉及光纤传感技术，具体涉及一种光纤水听器阵列***和加速度传感器阵列***及测量方法。The present invention relates to optical fiber sensing technology, and in particular to a fiber optic hydrophone array system and an acceleration sensor array system and a measuring method.
背景技术Background technique
随着国家海洋战略的实施以及国防安全的需要，光纤水听器作为一种能够对水下目标进行探测、定位和识别的传感器受到了越来越多的关注与研究。当声波作用到光纤水听器探头上时将会引起光纤中光波场的相位、强度等参量发生变化，通过一定的解调方法即可得到外界的声波场。目前常用的光纤水听器一般都是基于Mach-Zehnder或Michelson干涉仪结构来构建的。此外，由于水下声场的复杂性，单个的水听器探头很难获得目标的详细信息，因此需要多探头的复用，从而组成水听器阵列。目前研究较多的光纤水听器阵列复用技术有：空分复用、时分复用、波分复用、频分复用等。在各种复用技术中，时分复用是最简单有效的方案，并且由于其易与波分复用技术相结合而实现水听器的大规模阵列化，从而备受各国研究者的青睐。With the implementation of the national marine strategy and the need for national defense security, fiber-optic hydrophones have received more and more attention and research as a sensor capable of detecting, locating and identifying underwater targets. When the sound wave acts on the fiber optic hydrophone probe, the phase, intensity and other parameters of the optical wave field in the optical fiber will change, and the external acoustic wave field can be obtained by a certain demodulation method. Currently used fiber optic hydrophones are generally constructed based on the Mach-Zehnder or Michelson interferometer structure. In addition, due to the complexity of the underwater sound field, it is difficult for a single hydrophone probe to obtain detailed information of the target, so multiple probes need to be multiplexed to form a hydrophone array. At present, many fiber optic hydrophone array multiplexing technologies are studied: space division multiplexing, time division multiplexing, wavelength division multiplexing, frequency division multiplexing, and the like. Among various multiplexing technologies, time division multiplexing is the simplest and most effective scheme, and it is easy to be combined with wavelength division multiplexing technology to realize large-scale arraying of hydrophones, which is favored by researchers all over the world.
参考文献“张楠.大规模光纤水听器阵列光学外差及时分复用技术研究[D].国防科学技术大学,2007.”中给出了目前较常用的光纤水听器时分复用阵列***结构图。该方案中复用的水听器探头采用了Michelson干涉仪结构，一个水听器探头包括一个一分二耦合器、一段L长光纤、一个法拉第旋镜和一个水听器探头骨架四部分，其中L长光纤绕在水听器探头骨架上来感测外界声波信号。利用不同探头反射回来脉冲的时延不同实现脉冲的错位干涉，通过对干涉信号的解调即可得到外界的声波信号。References "Zhang Nan. Research on optical heterodyne and time-division multiplexing technology for large-scale fiber-optic hydrophone arrays [D]. National University of Defense Technology, 2007." The current commonly used fiber-optic hydrophone time-division multiplexing arrays are given. System structure diagram. The hydrophone probe multiplexed in the scheme adopts a Michelson interferometer structure. A hydrophone probe includes a splitter coupler, a length of L fiber, a Faraday mirror and a hydrophone probe skeleton. The L long fiber is wound around the hydrophone probe skeleton to sense the external sound wave signal. The time delay of the pulse reflected by different probes is different to realize the misalignment interference of the pulse, and the external acoustic signal can be obtained by demodulating the interference signal.
现有技术中，一个水听器探头至少包括一个一分二耦合器、一段L长光纤、一个法拉第旋镜和一个水听器探头骨架四部分。首先为了保持各基元反射回来信号光强的大小基本一致，耦合器的分光比需要进行合理的设计。其次为了各反射脉冲能够准确的对上进行干涉，需要较精确的控制光纤的长度。最后为了消除偏振态对干涉信号的影响，因此加入了法拉第旋镜，但在一些特殊应用环境中(比如高温环境)，对法拉第旋镜的性能有较高的要求。这些都增加了***设计的复杂度与困难。 In the prior art, a hydrophone probe includes at least one splitter coupler, a length of L long fiber, a Faraday mirror and a hydrophone probe skeleton. Firstly, in order to keep the signal intensity of each element reflected substantially the same, the splitter ratio of the coupler needs to be rationally designed. Secondly, in order to accurately interfere with each of the reflected pulses, it is necessary to control the length of the optical fiber more accurately. Finally, in order to eliminate the influence of the polarization state on the interference signal, the Faraday mirror is added, but in some special application environments (such as high temperature environment), the performance of the Faraday mirror is highly demanded. These all add to the complexity and difficulty of system design.
发明内容Summary of the invention
针对以上现有技术中存在的问题，本发明提出了一种结构简单易实现的光纤水听器阵列***及其测量方法，大大简化现有***的复杂度。In view of the above problems in the prior art, the present invention proposes a fiber optic hydrophone array system with a simple and easy to implement structure and a measuring method thereof, which greatly simplifies the complexity of the existing system.
本发明的一个目的在于提出一种光纤水听器阵列***和加速度传感器阵列***。It is an object of the present invention to provide a fiber optic hydrophone array system and an acceleration sensor array system.
本发明的光纤水听器阵列***包括：窄线宽激光器、水听器阵列、第一耦合器、第一声光调制器、第二声光调制器、延时光纤、第二耦合器、第一掺铒光纤放大器、环形器、第二掺铒光纤放大器、滤波器、光电探测器、数据采集卡和工控机；其中，光纤缠绕在水听器探头骨架上形成水听器探头，一根光纤依次缠绕在多个水听器探头骨架上形成水听器阵列；窄线宽激光器发出连续激光；经第一耦合器后，均匀分成两路，一路经过第一声光调制器被移频f1并被调制成第一脉冲光，另外一路经过第二声光调制器被移频f2并被调制成第二脉冲光，第一脉冲光与第二脉冲光之间的频率差Δf＝f1-f2即为外差频率；第二脉冲光经过长度为Ld的延时光纤，与第一脉冲光在时域上分开；第一脉冲光和第二脉冲光经过第二耦合器合光后，得到一前一后的两个脉冲，形成一个外差脉冲对，外差脉冲对的外差频率为Δf，外差脉冲对的间隔为Ld；外差脉冲对先经过第一掺铒光纤放大器放大后，通过第一口进入环形器，通过环形器的第二口注入水听器阵列；外差脉冲对在水听器阵列的光纤中产生背向瑞利散射信号，作为外差信号，水听器阵列接收到水中的外界声波信号后通过水听器探头骨架上的弹性筒将外界声波信号引起的振动信息调制到背向瑞利散射信号上，进而通过干涉调制到外差信号的外差频率上；外差信号通过环形器的第三口进入第二掺铒光纤放大器，经过第二掺铒光纤放大器放大后，经过滤波器滤除噪声；然后到达光电探测器，由高速的数据采集卡采集信号，最后在工控机上进行信号的外差解调，从而得到外界声波信号，其中，f1≠f2，Ld>0。The fiber optic hydrophone array system of the present invention comprises: a narrow linewidth laser, a hydrophone array, a first coupler, a first acousto-optic modulator, a second acousto-optic modulator, a delay fiber, a second coupler, An erbium doped fiber amplifier, a circulator, a second erbium doped fiber amplifier, a filter, a photodetector, a data acquisition card, and an industrial computer; wherein the fiber is wound around a hydrophone probe skeleton to form a hydrophone probe, an optical fiber sequentially wound on a plurality of hydrophone unit matrix forming an array of hydrophones; narrow linewidth laser emits continuous laser; after a first coupler is divided into two evenly all the way through the first acousto-optic modulator is frequency shift f 1 and modulated into a first light pulse, the other way through the second acousto-optical modulator is modulated frequency shift f 2 and a second optical pulse, the frequency difference Δf between the first and the second light pulse light pulse = f 1 -f 2 is the heterodyne frequency; the second pulsed light passes through the delay fiber of length L d , and is separated from the first pulsed light in the time domain; the first pulsed light and the second pulsed light are combined by the second coupler After that, get two pulses in tandem, shape A heterodyne pulse, heterodyne frequency of the heterodyne pulse [Delta] f, the heterodyne pulse interval of the L d; heterodyne after the first pulse of a first erbium-doped fiber amplifier, through the first port into the annular, The hydrophone array is injected through the second port of the circulator; the heterodyne pulse pair generates a back-reverse scatter signal in the fiber of the hydrophone array as a heterodyne signal, and the hydrophone array receives the external acoustic wave signal in the water. The vibration information caused by the external acoustic wave signal is modulated by the elastic cylinder on the skeleton of the hydrophone probe to the back-scattered Rayleigh scattering signal, and then modulated to the heterodyne frequency of the heterodyne signal by interference; the heterodyne signal passes through the circulator The three ports enter the second erbium-doped fiber amplifier, and after being amplified by the second erbium-doped fiber amplifier, the noise is filtered through the filter; then, the photodetector is reached, the signal is collected by the high-speed data acquisition card, and finally the signal is sent out on the industrial computer. The difference is demodulated to obtain an external acoustic wave signal, where f 1 ≠f 2 , L d >0.
外差信号的采样频率即脉冲重复频率应该是外差频率Δf的4倍以上，外差频率要尽量的大，因此一般选4倍关系；外差脉冲对的间隔Ld要大于脉冲宽度w，以保障两个脉冲没有重叠，在这个基础上间隔要尽量小。可探测的外界声波信号的频率的上限为外差频率的一半，可探测的外界声波信号的频率的下限由用于时域重构的背向散射曲线的条数决定，频率下限为fs/M，其中fs为脉冲重复频率，M为用于时域重构的背向散射曲线的条数。The sampling frequency of the heterodyne signal, that is, the pulse repetition frequency should be more than 4 times the heterodyne frequency Δf, and the heterodyne frequency should be as large as possible, so the relationship of 4 times is generally selected; the interval L d of the heterodyne pulse pair is larger than the pulse width w, In order to ensure that the two pulses do not overlap, the interval should be as small as possible on this basis. The upper limit of the frequency of the detectable external sound wave signal is half of the heterodyne frequency, and the lower limit of the frequency of the detectable external sound wave signal is determined by the number of backscattering curves used for time domain reconstruction, and the lower frequency limit is f s / M, where f s is the pulse repetition frequency and M is the number of backscatter curves for time domain reconstruction.
本发明采用一根光纤直接缠绕在多个水听器探头骨架上形成水听器阵列，外差脉冲对在水听器阵列的光纤中产生背向瑞利散射信号，作为外差信号，外界声波信号使得水听器探头骨架上的弹性筒发生形变，进而引起光纤的形变，使得光纤中背向瑞利散射信号的相位发生变化；进而通过干涉将外界声波信号调制到外差信号的外差频率上，通过外差解调，得到外界声波信号。本发明只采用一根光纤，完全不用添加耦合器、法拉第旋镜等器件，相比于现 有的技术有了大大的简化。The invention adopts an optical fiber directly wound on a plurality of hydrophone probe skeletons to form a hydrophone array, and the heterodyne pulse pair generates a back Rayleigh scattering signal in the optical fiber of the hydrophone array as a heterodyne signal, and the external sound wave The signal deforms the elastic cylinder on the skeleton of the hydrophone probe, which causes the deformation of the optical fiber, so that the phase of the back-scattered Rayleigh scattering signal changes in the optical fiber; and then the external acoustic signal is modulated to the heterodyne frequency of the heterodyne signal by interference. On the other hand, the external acoustic signal is obtained by heterodyne demodulation. The invention only uses one optical fiber, and does not need to add a coupler, a Faraday mirror, etc., compared with the present Some technologies have been greatly simplified.
本发明的光纤加速度传感器阵列***包括：窄线宽激光器、加速度传感器阵列、第一耦合器、第一声光调制器、第二声光调制器、延时光纤、第二耦合器、第一掺铒光纤放大器、环形器、第二掺铒光纤放大器、滤波器、光电探测器、数据采集卡和工控机；其中，光纤缠绕在加速度传感器骨架上形成加速度传感器，一根光纤依次缠绕在多个加速度传感器骨架上形成加速度传感器阵列；窄线宽激光器发出连续激光；经第一耦合器后，均匀分成两路，一路经过第一声光调制器被移频f1并被调制成第一脉冲光，另外一路经过第二声光调制器被移频f2并被调制成第二脉冲光，第一脉冲光与第二脉冲光之间的频率差Δf＝f1-f2即为外差频率；第二脉冲光经过长度为Ld的延时光纤，与第一脉冲光在时域上分开；第一脉冲光和第二脉冲光经过第二耦合器合光后，得到一前一后的两个脉冲，形成一个外差脉冲对，外差脉冲对的外差频率为Δf，外差脉冲对的间隔为Ld；外差脉冲对先经过第一掺铒光纤放大器放大后，通过第一口进入环形器，通过环形器的第二口注入加速度传感器阵列；外差脉冲对在加速度传感器阵列的光纤中产生背向瑞利散射信号，作为外差信号，加速度传感器阵列接收到空气中的外界振动信号后通过加速度传感器骨架上的弹性筒将外界振动信号引起的振动信息调制到背向瑞利散射信号上，进而通过干涉调制到外差信号的外差频率上；外差信号通过环形器的第三口进入第二掺铒光纤放大器，经过第二掺铒光纤放大器放大后，经过滤波器滤除噪声；然后到达光电探测器，由高速的数据采集卡采集信号，最后在工控机上进行信号的外差解调，从而得到外界振动信号，其中，f1≠f2，Ld>0。The optical fiber acceleration sensor array system of the present invention comprises: a narrow linewidth laser, an acceleration sensor array, a first coupler, a first acousto-optic modulator, a second acousto-optic modulator, a delay fiber, a second coupler, and a first blend铒 fiber amplifier, circulator, second erbium-doped fiber amplifier, filter, photodetector, data acquisition card and industrial computer; wherein the fiber is wound on the acceleration sensor skeleton to form an acceleration sensor, and one fiber is wound in multiple accelerations in sequence an acceleration sensor is formed on the sensor array skeleton; narrow linewidth laser emits continuous laser; after a first coupler is divided into two evenly all the way through the first acousto-optical modulator and modulated by frequency shift f 1 into a first light pulse, Also the way through the second acousto-optical modulator is modulated frequency shift f 2 and a second optical pulse, the first pulse frequency difference Δf between the light and the second optical pulse = f 1 -f 2 is the heterodyne frequency; the second pulse of light passes through a length L d of the delay optical fiber, separate from the first light pulse in the time domain; a first pulse of light after the second pulse of light passes through the second optical coupler together to give A one after the two pulses forming a heterodyne pulse, pulse heterodyne heterodyning frequency [Delta] f, the heterodyne pulse interval of L d; heterodyne pulse to pass through the first erbium-doped fiber amplifier After entering the circulator through the first port, the acceleration sensor array is injected through the second port of the circulator; the heterodyne pulse pair generates a back-reverse scatter signal in the fiber of the acceleration sensor array as a heterodyne signal, and the acceleration sensor array receives After the external vibration signal in the air, the vibration information caused by the external vibration signal is modulated by the elastic cylinder on the skeleton of the acceleration sensor to the back Rayleigh scattering signal, and then modulated to the heterodyne frequency of the heterodyne signal by interference; The signal enters the second erbium-doped fiber amplifier through the third port of the circulator, is amplified by the second erbium-doped fiber amplifier, and is filtered by the filter to remove noise; then reaches the photodetector, and the signal is collected by the high-speed data acquisition card, and finally The heterodyne demodulation of the signal is performed on the industrial computer to obtain an external vibration signal, where f 1 ≠f 2 , L d >0.
下面明确几个基本概念：Here are a few basic concepts:
脉冲宽度：连续光经过声光调制器后被调制成脉冲光的宽度，时域上表示的脉冲宽度为τ，空间域上表示的脉冲宽度为w，外差脉冲对中两个脉冲的脉冲宽度是一样的。Pulse width: The continuous light is modulated into the width of the pulsed light after passing through the acousto-optic modulator. The pulse width in the time domain is τ, the pulse width in the spatial domain is w, and the pulse width of the two pulses in the heterodyne pulse pair. it's the same.
脉冲重复频率：每次生成脉冲都会同时生成一个外差脉冲对，脉冲重复频率即为生成外差脉冲对的频率。Pulse repetition frequency: Each time a pulse is generated, a heterodyne pulse pair is generated at the same time. The pulse repetition frequency is the frequency at which the heterodyne pulse pair is generated.
外差信号的采样频率：水听器阵列的光纤上一个位置的背向瑞利散射信号在时域上重构后的采样频率，外差信号的采样频率与脉冲重复频率相等。The sampling frequency of the heterodyne signal: the sampling frequency of the back-range Rayleigh scattering signal reconstructed in the time domain at a position on the fiber of the hydrophone array, and the sampling frequency of the heterodyne signal is equal to the pulse repetition frequency.
数据采集卡的采样频率：数据采集卡采集数据的速率，该采样频率与空间分辨率有关。Sampling frequency of the data acquisition card: The rate at which the data acquisition card collects data. The sampling frequency is related to the spatial resolution.
采样深度：数据采集卡一次触发后采集数据的长度，该值与水听器阵列的光纤的长度和数据采集卡的采样频率有关。Sampling depth: The length of the data collected by the data acquisition card after one trigger. This value is related to the length of the fiber of the hydrophone array and the sampling frequency of the data acquisition card.
本发明的另一个目的在于提供一种光纤水听器阵列***和加速度传感器阵列***的测量方法。 Another object of the present invention is to provide a method of measuring a fiber optic hydrophone array system and an acceleration sensor array system.
本发明的光纤水听器阵列***的测量方法，包括以下步骤：The measuring method of the fiber optic hydrophone array system of the present invention comprises the following steps:
1)水听器阵列的光纤的长度为L，脉冲重复频率为fs，则有fs＜c/2nL，其中，c为真空中的光速，n为水听器阵列的光纤的折射率，数据采集卡的采样频率为fc，采样深度为N，则有N＝fc/fs；1) The length of the fiber of the hydrophone array is L, and the pulse repetition frequency is f s , then f s <c/2nL, where c is the speed of light in the vacuum and n is the refractive index of the fiber of the hydrophone array. The sampling frequency of the data acquisition card is f c , and the sampling depth is N, then there is N=f c /f s ;
2)窄线宽激光器发出连续激光，经第一耦合器后，均匀分成两路，一路经过第一声光调制器被移频f1并被调制成第一脉冲光，另外一路经过第二声光调制器被移频f2并被调制成第二脉冲光，第一脉冲光与第二脉冲光之间的频率差Δf＝f1-f2即为外差频率；第二脉冲光经过长度为Ld的延时光纤，与第一脉冲光在时域上分开；第一脉冲光和第二脉冲光经过第二耦合器合光后，得到一前一后的两个脉冲，形成一个外差脉冲对，外差脉冲对的外差频率为Δf，外差脉冲对的间隔为Ld；2) narrow linewidth laser emits a continuous laser, after the first coupler is divided into two evenly all the way through the first acousto-optical modulator and modulated by frequency shift f 1 into a first light pulse, the other all the way through the second acoustic The optical modulator is frequency-shifted f 2 and modulated into a second pulsed light, and the frequency difference Δf=f 1 -f 2 between the first pulsed light and the second pulsed light is a heterodyne frequency; the second pulsed light passes through the length The delay fiber of L d is separated from the first pulsed light in the time domain; after the first pulsed light and the second pulsed light are combined by the second coupler, two pulses are obtained one after the other to form an outer The difference pulse pair, the heterodyne pulse pair has a heterodyne frequency of Δf, and the heterodyne pulse pair has an interval of L d ;
3)外差脉冲对先经过第一掺铒光纤放大器放大后，通过第一口进入环形器，通过环形器的第二口注入水听器阵列的光纤；外差脉冲对在水听器阵列的光纤中产生背向瑞利散射信号，作为外差信号，水听器阵列接收到水中的外界声波信号后通过水听器探头骨架上的弹性筒将外界声波信号引起的振动信息调制到背向瑞利散射信号上，进而通过干涉调制到外差信号的外差频率上，通过环形器的第三口进入第二掺铒光纤放大器，经过第二掺铒光纤放大器放大后，经过滤波器滤除噪声；然后到达光电探测器，由高速的数据采集卡来采集信号，传输至工控机；3) The heterodyne pulse pair is first amplified by the first erbium-doped fiber amplifier, enters the circulator through the first port, and is injected into the fiber of the hydrophone array through the second port of the circulator; the heterodyne pulse pair is in the hydrophone array. The back-direction Rayleigh scattering signal is generated in the optical fiber. As the heterodyne signal, the hydrophone array receives the external acoustic wave signal in the water and then modulates the vibration information caused by the external acoustic wave signal to the back-rear by the elastic cylinder on the skeleton of the hydrophone probe. The scatter signal is modulated by interference to the heterodyne frequency of the heterodyne signal, enters the second erbium-doped fiber amplifier through the third port of the circulator, is amplified by the second erbium-doped fiber amplifier, and is filtered by the filter. Then arrive at the photodetector, and the high-speed data acquisition card collects the signal and transmits it to the industrial computer;
4)一个外差脉冲对得到一条背向散射曲线，连续采集M条背向散射曲线，M≥50；4) A heterodyne pulse pair obtains a backscattering curve, and continuously collects M backscattering curves, M≥50;
5)选取所有背向散射曲线的同一位置处的信号进行时域重构，将会得到同一位置处随时间变化的信号，该信号的表达式为：I＝A+B cos[2πΔft+Φ(t)]，其中Δf为外差频率，Φ(t)为外界声波信号引起水听器阵列的光纤中光相位的变化量，Φ(t)与外界声波信号的幅度成正比，该比值即为水听器探头的灵敏度，Φ(t)的频率与外界声波信号的频率一致；5) Selecting the signal at the same position of all backscattering curves for time domain reconstruction will result in a signal that changes with time at the same position. The expression of the signal is: I=A+B cos[2πΔft+Φ( t)], where Δf is the heterodyne frequency, Φ(t) is the amount of change in the optical phase of the fiber in the hydrophone array caused by the external acoustic signal, and Φ(t) is proportional to the amplitude of the external acoustic signal, which is The sensitivity of the hydrophone probe, the frequency of Φ(t) is consistent with the frequency of the external acoustic signal;
6)将上述信号滤除直流成分后将得到待解调信号ys＝B cos[2πΔft+Φ(t)]，然后对待解调信号进行外差解调算法，最后得到光相位的变化量Φ(t)，从而得到外界声波信号的幅度和频率。6) After filtering the DC component of the above signal, the signal to be demodulated y s = B cos [2πΔft + Φ(t)] is obtained, and then the demodulated signal is subjected to a heterodyne demodulation algorithm, and finally the variation of the optical phase is obtained. (t), thereby obtaining the amplitude and frequency of the external acoustic signal.
一种光纤加速度传感器阵列***的测量方法，包括以下步骤：A method for measuring a fiber optic acceleration sensor array system includes the following steps:
1)加速度传感器阵列的光纤的长度为L，脉冲重复频率为fs，则有fs＜c/2nL，其中，c为真空中的光速，n为加速度传感器阵列的光纤的折射率，数据采集卡的采样频率为fc，采样深度为N，则有N＝fc/fs； 1) The length of the fiber of the acceleration sensor array is L, and the pulse repetition frequency is f s , then f s <c/2nL, where c is the speed of light in the vacuum, n is the refractive index of the fiber of the acceleration sensor array, data acquisition The sampling frequency of the card is f c , and the sampling depth is N, then there is N=f c /f s ;
2)窄线宽激光器发出连续激光，经第一耦合器后，均匀分成两路，一路经过第一声光调制器被移频f1并被调制成第一脉冲光，另外一路经过第二声光调制器被移频f2并被调制成第二脉冲光，第一脉冲光与第二脉冲光之间的频率差Δf＝f1-f2即为外差频率；第二脉冲光经过长度为Ld的延时光纤，与第一脉冲光在时域上分开；第一脉冲光和第二脉冲光经过第二耦合器合光后，得到一前一后的两个脉冲，形成一个外差脉冲对，外差脉冲对的外差频率为Δf，外差脉冲对的间隔为Ld；2) narrow linewidth laser emits a continuous laser, after the first coupler is divided into two evenly all the way through the first acousto-optical modulator and modulated by frequency shift f 1 into a first light pulse, the other all the way through the second acoustic The optical modulator is frequency-shifted f 2 and modulated into a second pulsed light, and the frequency difference Δf=f 1 -f 2 between the first pulsed light and the second pulsed light is a heterodyne frequency; the second pulsed light passes through the length The delay fiber of L d is separated from the first pulsed light in the time domain; after the first pulsed light and the second pulsed light are combined by the second coupler, two pulses are obtained one after the other to form an outer The difference pulse pair, the heterodyne pulse pair has a heterodyne frequency of Δf, and the heterodyne pulse pair has an interval of L d ;
3)外差脉冲对先经过第一掺铒光纤放大器放大后，通过第一口进入环形器，通过环形器的第二口注入加速度传感器阵列的光纤；外差脉冲对在加速度传感器阵列的光纤中产生背向瑞利散射信号，作为外差信号，加速度传感器阵列接收到空气中的外界振动信号后通过加速度传感器骨架上的弹性筒将外界振动信号引起的振动信息调制到背向瑞利散射信号上，进而通过干涉调制到外差信号的外差频率上，通过环形器的第三口进入第二掺铒光纤放大器，经过第二掺铒光纤放大器放大后，经过滤波器滤除噪声；然后到达光电探测器，由高速的数据采集卡来采集信号，传输至工控机；3) The heterodyne pulse pair is first amplified by the first erbium-doped fiber amplifier, enters the circulator through the first port, and is injected into the optical fiber of the acceleration sensor array through the second port of the circulator; the heterodyne pulse pair is in the fiber of the acceleration sensor array. The back-reverse Rayleigh scattering signal is generated. As the heterodyne signal, the acceleration sensor array receives the external vibration signal in the air and then modulates the vibration information caused by the external vibration signal to the back-scattered Rayleigh scattering signal through the elastic cylinder on the acceleration sensor skeleton. And then interfering to the heterodyne frequency of the heterodyne signal, through the third port of the circulator into the second erbium-doped fiber amplifier, after being amplified by the second erbium-doped fiber amplifier, filtering the noise through the filter; The detector collects signals from a high-speed data acquisition card and transmits them to the industrial computer;
4)一个外差脉冲对得到一条背向散射曲线，连续采集M条背向散射曲线，M≥50；4) A heterodyne pulse pair obtains a backscattering curve, and continuously collects M backscattering curves, M≥50;
5)选取所有背向散射曲线的同一位置处的信号进行时域重构，将会得到同一位置处随时间变化的信号，该信号的表达式为：I＝A+B cos[2πΔft+Φ(t)]，其中Δf为外差频率，Φ(t)为外界振动信号引起加速度传感器阵列的光纤中光相位的变化量，Φ(t)与外界振动信号的幅度成正比，该比值即为加速度传感器的灵敏度，Φ(t)的频率与外界振动信号的频率一致；5) Selecting the signal at the same position of all backscattering curves for time domain reconstruction will result in a signal that changes with time at the same position. The expression of the signal is: I=A+B cos[2πΔft+Φ( t)], where Δf is the heterodyne frequency, Φ(t) is the amount of change in the optical phase of the optical fiber of the acceleration sensor array caused by the external vibration signal, and Φ(t) is proportional to the amplitude of the external vibration signal, which is the acceleration The sensitivity of the sensor, the frequency of Φ(t) is consistent with the frequency of the external vibration signal;
6)将上述信号滤除直流成分后将得到待解调信号ys＝B cos[2πΔft+Φ(t)]，然后对待解调信号进行外差解调算法，最后得到光相位的变化量Φ(t)，从而得到外界振动信号的幅度和频率。6) After filtering the DC component of the above signal, the signal to be demodulated y s = B cos [2πΔft + Φ(t)] is obtained, and then the demodulated signal is subjected to a heterodyne demodulation algorithm, and finally the variation of the optical phase is obtained. (t), thereby obtaining the amplitude and frequency of the external vibration signal.
本发明的优点：Advantages of the invention:
本发明产生外差脉冲对，通过干涉将外界声波信号调制到外差频率上，通过外差解调，得到水中的外界声波信号；在传统的Φ-OTDR***中引入了外差脉冲对，实现了相位信息的解调；本发明只采用一根光纤，完全不用添加耦合器、法拉第旋镜等器件，相比于现有的技术有了大大的简化，并且每个水听器基元取得了与现有***相同的探测灵敏度。另外该方案同样可以使用于光纤加速度传感器阵列，将一根光纤依次绕制在多个加速度传感器骨架上则形成加速度传感器阵列，从而探测空气中的外界振动信号。 The invention generates a heterodyne pulse pair, modulates the external acoustic wave signal to the heterodyne frequency through interference, and obtains the external acoustic wave signal in the water by heterodyne demodulation; introducing a heterodyne pulse pair in the conventional Φ-OTDR system to realize Demodulation of phase information; the invention uses only one optical fiber, and does not need to add a coupler, a Faraday mirror, etc., which is greatly simplified compared to the prior art, and each hydrophone primitive has been obtained. Same detection sensitivity as existing systems. In addition, the scheme can also be applied to an optical fiber acceleration sensor array, and an optical fiber is sequentially wound on a plurality of acceleration sensor skeletons to form an acceleration sensor array, thereby detecting an external vibration signal in the air.
附图说明DRAWINGS
图1为本发明的光纤水听器阵列***的一个实施例的示意图。1 is a schematic diagram of one embodiment of a fiber optic hydrophone array system of the present invention.
图2为根据本发明的光纤水听器阵列***的测量方法的一个实施例得到的背向散射曲线的三维视图。2 is a three-dimensional view of a backscattering curve obtained by one embodiment of a method of measuring a fiber optic hydrophone array system in accordance with the present invention.
图3为根据本发明的光纤水听器阵列***的测量方法的一个实施例的外差解调算法的示意图。3 is a schematic diagram of a heterodyne demodulation algorithm of one embodiment of a method of measuring a fiber optic hydrophone array system in accordance with the present invention.
具体实施方式detailed description
下面结合附图，通过具体实施例，进一步阐述本发明。The invention will be further illustrated by the following examples in conjunction with the accompanying drawings.
如图1所示，本实施例的光纤水听器阵列***包括：窄线宽激光器S、第一耦合器OC1、第一声光调制器AOM1、第二声光调制器AOM2、延时光纤DF、第二耦合器OC2、第一掺铒光纤放大器EDFA1、环形器C、第二掺铒光纤放大器EDFA2、滤波器F、光电探测器PD、数据采集卡DAQ和工控机IPC；其中，光纤OF缠绕在水听器探头骨架HS上形成水听器探头，一根光纤依次缠绕在多个水听器探头骨架上形成水听器阵列H1～Hn；窄线宽激光器S发出连续激光；经第一耦合器OC1后，均匀分成两路，一路经过第一声光调制器AOM1被移频f1并被调制成第一脉冲光，另外一路经过第二声光调制器AOM2被移频f2并被调制成第二脉冲光，第一脉冲光与第二脉冲光之间的频率差Δf＝f1-f2即为外差频率；第二脉冲光经过长度为Ld的延时光纤DF，与第一脉冲光在时域上分开；第一脉冲光和第二脉冲光经过第二耦合器OC2合光后，得到一前一后的两个脉冲，形成一个外差脉冲对，外差脉冲对的外差频率为Δf，外差脉冲对的间隔为Ld；外差脉冲对先经过第一掺铒光纤放大器EDFA1放大后，通过第一口进入环形器C，通过环形器C的第二口注入水听器阵列的光纤；外差脉冲对在水听器阵列的光纤中产生背向瑞利散射信号，作为外差信号，水听器阵列接收到的外界声波信号通过干涉调制到外差信号的外差频率上；外差信号通过环形器C的第三口进入第二掺铒光纤放大器EDFA2，经过第二掺铒光纤放大器EDFA2放大后，经过滤波器F滤除噪声；然后到达光电探测器PD，由高速的数据采集卡DAQ来采集信号，最后在工控机IPC上进行信号的外差解调，从而得到外界声波信号。第一声光调制器AOM1和第二声光调制器AOM2分别连接至声光调制器的驱动器AOMD。As shown in FIG. 1, the fiber optic hydrophone array system of the present embodiment includes: a narrow linewidth laser S, a first coupler OC1, a first acousto-optic modulator AOM1, a second acousto-optic modulator AOM2, and a delay fiber DF. , second coupler OC2, first erbium doped fiber amplifier EDFA1, circulator C, second erbium doped fiber amplifier EDFA2, filter F, photodetector PD, data acquisition card DAQ and IPC IPC; among them, fiber OF winding A hydrophone probe is formed on the hydrophone probe skeleton HS, and one optical fiber is sequentially wound on a plurality of hydrophone probe skeletons to form a hydrophone array H1 to Hn; the narrow linewidth laser S emits a continuous laser; the first coupling after an OCl, uniformly divided into two, all the way through the first acousto-optic modulator is a frequency shift f AOM1 and modulated into a first light pulse 1, another branch of the second acousto-optical modulator through the AOM2 is shifted and modulated frequency f 2 The second pulse light, the frequency difference Δf=f 1 -f 2 between the first pulse light and the second pulse light is the heterodyne frequency; the second pulse light passes through the delay fiber DF of length L d , and the a pulse of light is separated in the time domain; the first pulsed light and the second pulsed light pass through the first After closing the optical coupler OC2 obtain two one after the pulse, differential pulse forming an outer pair of heterodyne frequency of the heterodyne pulse [Delta] f, the heterodyne pulse interval of L d; Heterodyne first pulse After being amplified by the first erbium-doped fiber amplifier EDFA1, the first port is introduced into the circulator C, and the second port of the circulator C is injected into the fiber of the hydrophone array; the heterodyne pulse pair is generated in the fiber of the hydrophone array. The Rayleigh scatter signal is used as a heterodyne signal, and the external acoustic wave signal received by the hydrophone array is modulated by interference to the heterodyne frequency of the heterodyne signal; the heterodyne signal enters the second erbium through the third port of the circulator C. The fiber amplifier EDFA2 is amplified by the second erbium-doped fiber amplifier EDFA2, and then filtered by the filter F to remove noise; then reaches the photodetector PD, the high-speed data acquisition card DAQ collects the signal, and finally the signal is transmitted on the IPC of the industrial computer Heterodyne demodulation to obtain an external acoustic signal. The first acousto-optic modulator AOM1 and the second acousto-optic modulator AOM2 are respectively connected to the driver AOMD of the acousto-optic modulator.
本实施例中，一根长度为1km的光纤来绕制水听器阵列，每个水听器探头上绕19m光纤，两个水听器探头间隔4m，即可绕制43个水听器探头。In this embodiment, a fiber of length 1km is used to wind the hydrophone array, and each hydrophone probe is wound around 19m fiber, and the two hydrophone probes are spaced 4m apart, and 43 hydrophone probes can be wound. .
本实施的光纤水听器阵列***的测量方法，包括以下步骤： The measuring method of the fiber optic hydrophone array system of the present embodiment includes the following steps:
1)窄线宽激光器发出连续激光，中心频率为f0，经第一耦合器后，均匀分成两路，一路经过第一声光调制器被移频f1并被调制成第一脉冲光，频率为f0+f1，另外一路经过第二声光调制器被移频f2并被调制成第二脉冲光，频率为f0+f2，第一脉冲光与第二脉冲光之间的频率差Δf＝f1-f2即为外差频率；第二脉冲光经过长度为Ld的延时光纤，与第一脉冲光在时域上分开；第一脉冲光和第二脉冲光经过第二耦合器合光后，得到一前一后的两个脉冲，形成一个外差脉冲对，外差脉冲对的外差频率Δf为50kHz，外差脉冲对的间隔为Ld；1) The narrow linewidth laser emits a continuous laser with a center frequency of f 0 , which is evenly divided into two paths after passing through the first coupler, and is shifted by frequency f 1 and modulated into a first pulsed light by a first acousto-optic modulator. frequency of f 0 + f 1, all the way through additional second acousto-optical modulator is modulated frequency shift f 2 and a second light pulse, a frequency f 0 + f 2, between the first and the second light pulse light pulse The frequency difference Δf=f 1 -f 2 is the heterodyne frequency; the second pulse light passes through the delay fiber of length L d , which is separated from the first pulse light in the time domain; the first pulse light and the second pulse light After the second coupler is combined, two pulses are obtained one after the other to form a heterodyne pulse pair. The heterodyne frequency Δf of the heterodyne pulse pair is 50 kHz, and the interval of the heterodyne pulse pair is L d ;
2)外差脉冲对先经过第一掺铒光纤放大器放大后，通过第一口进入环形器，通过环形器的第二口注入水听器阵列的光纤；外差脉冲对在水听器阵列的光纤中产生背向瑞利散射信号，作为外差信号，水听器阵列接收到的水中的外界声波信号通过干涉调制到外差信号的外差频率上，通过环形器的第三口进入第二掺铒光纤放大器，经过第二掺铒光纤放大器放大后，经过滤波器滤除噪声；然后到达光电探测器，由高速的数据采集卡来采集信号，传输至工控机；2) The heterodyne pulse pair is first amplified by the first erbium-doped fiber amplifier, enters the circulator through the first port, and is injected into the fiber of the hydrophone array through the second port of the circulator; the heterodyne pulse pair is in the hydrophone array. The back-direction Rayleigh scattering signal is generated in the optical fiber, and as the heterodyne signal, the external acoustic wave signal in the water received by the hydrophone array is modulated to the heterodyne frequency of the heterodyne signal by interference, and enters the second through the third port of the circulator. The erbium-doped fiber amplifier is amplified by a second erbium-doped fiber amplifier, filtered through a filter to remove noise; then reaches the photodetector, and the high-speed data acquisition card collects the signal and transmits it to the industrial computer;
3)一个外差脉冲对得到一条背向散射曲线，连续采集M条背向散射曲线，M＝100，如图2所示；3) A heterodyne pulse pair obtains a backscattering curve, and continuously collects M backscattering curves, M=100, as shown in Fig. 2;
4)选取所有背向散射曲线的同一位置处的信号进行时域重构，将会得到同一位置处随时间变化的信号，该信号的表达式为：I＝A+B cos[2πΔft+Φ(t)]，其中Δf为外差频率，Φ(t)为外界声波信号引起水听器阵列的光纤中光相位的变化量，Φ(t)与外界声波信号幅度成正比，Φ(t)的频率与外界声波信号的频率一致；4) Selecting all the signals at the same position of the backscattering curve for time domain reconstruction will result in a signal that changes with time at the same position. The expression of the signal is: I=A+B cos[2πΔft+Φ( t)], where Δf is the heterodyne frequency, Φ(t) is the amount of change in the optical phase of the fiber in the hydrophone array caused by the external acoustic signal, Φ(t) is proportional to the amplitude of the external acoustic signal, Φ(t) The frequency is consistent with the frequency of the external acoustic signal;
5)将上述信号滤除直流成分后将得到待解调信号ys＝B cos[2πΔft+Φ(t)]，然后对待解调信号进行外差解调算法，如图3所示，具体算法过程为：将待解调信号ys分别与正弦信号sin(2πΔft)和余弦信号cos(2πΔft)进行混频并分别经过低通滤波器LPF(滤波器的截止频率≤Δf)，然后两者相除得到两者的比值，最后经过反正切arctan运算即可得到光相位的变化量Φ(t)。5) After filtering the DC component of the above signal, the signal to be demodulated y s =B cos[2πΔft+Φ(t)] is obtained, and then the heterodyne demodulation algorithm is performed on the demodulated signal, as shown in FIG. 3, the specific algorithm The process is: mixing the signal y s to be demodulated with the sinusoidal signal sin(2πΔft) and the cosine signal cos(2πΔft), respectively, and passing through the low-pass filter LPF (cutoff frequency of the filter ≤ Δf), and then the two phases In addition to obtaining the ratio of the two, the optical phase change amount Φ(t) is obtained by the inverse tangent arctan operation.
最后需要注意的是，公布实施例的目的在于帮助进一步理解本发明，但是本领域的技术人员可以理解：在不脱离本发明及所附的权利要求的精神和范围内，各种替换和修改都是可能的。因此，本发明不应局限于实施例所公开的内容，本发明要求保护的范围以权利要求书界定的范围为准。 It is to be understood that the present invention is intended to be a further understanding of the invention, and it is understood by those skilled in the art that various modifications and changes can be made without departing from the spirit and scope of the invention and the appended claims It is possible. Therefore, the invention should not be limited by the scope of the invention, and the scope of the invention is defined by the scope of the claims.

Claims (10)

  1. 一种光纤水听器阵列***，包括：窄线宽激光器、水听器阵列、第一耦合器、第一声光调制器、第二声光调制器、延时光纤、第二耦合器、第一掺铒光纤放大器、环形器、第二掺铒光纤放大器、滤波器、光电探测器、数据采集卡和工控机；其中，光纤缠绕在水听器探头骨架上形成水听器探头，一根光纤依次缠绕在多个水听器探头骨架上形成水听器阵列；所述窄线宽激光器发出连续激光，经第一耦合器后，均匀分成两路，一路经过第一声光调制器被移频f1并被调制成第一脉冲光，另外一路经过第二声光调制器被移频f2并被调制成第二脉冲光，第一脉冲光与第二脉冲光之间的频率差Δf＝f1-f2；第二脉冲光经过长度为Ld的延时光纤，与第一脉冲光在时域上分开；第一脉冲光和第二脉冲光经过第二耦合器合光后，得到一前一后的两个脉冲，形成一个外差脉冲对，外差脉冲对的外差频率为Δf，外差脉冲对的间隔为Ld；外差脉冲对先经过第一掺铒光纤放大器放大后，通过环形器的第一口进入环形器，再通过环形器的第二口注入水听器阵列；外差脉冲对在水听器阵列的光纤中产生背向瑞利散射信号，作为外差信号，水听器阵列接收到水中的外界声波信号后通过水听器探头骨架上的弹性筒将外界声波信号引起的振动信息调制到背向瑞利散射信号上，进而通过干涉调制到外差信号的外差频率上；外差信号通过环形器的第三口进入第二掺铒光纤放大器，经过第二掺铒光纤放大器放大后，经过滤波器滤除噪声，然后到达光电探测器，由数据采集卡采集信号，最后在工控机上进行信号的外差解调，从而得到外界声波信号，其中，f1≠f2，Ld>0。A fiber optic hydrophone array system comprising: a narrow linewidth laser, a hydrophone array, a first coupler, a first acousto-optic modulator, a second acousto-optic modulator, a delay fiber, a second coupler, An erbium doped fiber amplifier, a circulator, a second erbium doped fiber amplifier, a filter, a photodetector, a data acquisition card, and an industrial computer; wherein the fiber is wound around a hydrophone probe skeleton to form a hydrophone probe, an optical fiber And sequentially winding on a plurality of hydrophone probe skeletons to form a hydrophone array; the narrow linewidth laser emits a continuous laser, which is evenly divided into two paths after being passed through the first coupler, and is frequency-shifted by the first acousto-optic modulator f 1 and is modulated into a first light pulse, the other way through the second acousto-optical modulator 2 and is moved into the second pulse modulated optical frequency F, a frequency difference Δf between the first pulse and the second pulse of light = light f 1 -f 2 ; the second pulse light passes through the delay fiber of length L d , and is separated from the first pulse light in the time domain; the first pulse light and the second pulse light are combined by the second coupler to obtain Two pulses in tandem to form a heterodyne For red, heterodyne frequency of the heterodyne pulse [Delta] f, the heterodyne pulse interval of L d; Heterodyne first pulse after a first erbium-doped fiber amplifier via a first circulator port enters the circulator, Then, the second port of the circulator is injected into the hydrophone array; the heterodyne pulse generates a back Rayleigh scattering signal in the fiber of the hydrophone array as a heterodyne signal, and the hydrophone array receives the external sound wave signal in the water. Afterwards, the vibration information caused by the external acoustic wave signal is modulated by the elastic cylinder on the skeleton of the hydrophone probe to the back Rayleigh scattering signal, and then modulated to the heterodyne frequency of the heterodyne signal by interference; the heterodyne signal passes through the circulator The third port enters the second erbium-doped fiber amplifier, and after being amplified by the second erbium-doped fiber amplifier, the noise is filtered through the filter, and then reaches the photodetector, the signal is collected by the data acquisition card, and finally the heterodyne of the signal is performed on the industrial computer. Demodulation, thereby obtaining an external acoustic wave signal, where f 1 ≠f 2 , L d >0.
  2. 如权利要求1所述的光纤水听器阵列***，其特征在于，外差信号的采样频率即脉冲重复频率为外差频率Δf的4倍以上；外差脉冲对的间隔Ld大于脉冲宽度w，在这个基础上间隔要尽量小。Fiber optic hydrophone array system as claimed in claim 1, wherein the sampling frequency of the heterodyne signal, i.e. pulse repetition frequency of 4 times or more of the heterodyne frequency Δf; heterodyne interval L d is greater than the pulse width of the pulse w On this basis, the interval should be as small as possible.
  3. 如权利要求1所述的光纤水听器阵列***，其特征在于，可探测的外界声波信号的频率的上限为外差频率的一半，下限由用于时域重构的背向散射曲线的条数决定，频率下限为fs/M，其中fs为脉冲重复频率，M为用于时域重构的背向散射曲线的条数。A fiber optic hydrophone array system according to claim 1, wherein the upper limit of the frequency of the detectable external acoustic wave signal is half of the heterodyne frequency, and the lower limit is the strip of the backscattering curve for time domain reconstruction. The number determines that the lower frequency limit is f s /M, where f s is the pulse repetition frequency and M is the number of backscatter curves used for time domain reconstruction.
  4. 一种光纤加速度传感器阵列***，包括：窄线宽激光器、加速度传感器阵列、第一耦合器、第一声光调制器、第二声光调制器、延时光纤、第二耦合器、第一掺铒光纤放大器、环形器、第二掺铒光纤放大器、滤波器、光电探测器、数据采集卡和工控机；其中，光纤缠绕 在加速度传感器骨架上形成加速度传感器，一根光纤依次缠绕在多个加速度传感器骨架上形成加速度传感器阵列；窄线宽激光器发出连续激光，经第一耦合器后，均匀分成两路，一路经过第一声光调制器被移频f1并被调制成第一脉冲光，另外一路经过第二声光调制器被移频f2并被调制成第二脉冲光，第一脉冲光与第二脉冲光之间的频率差Δf＝f1-f2；第二脉冲光经过长度为Ld的延时光纤，与第一脉冲光在时域上分开；第一脉冲光和第二脉冲光经过第二耦合器合光后，得到一前一后的两个脉冲，形成一个外差脉冲对，外差脉冲对的外差频率为Δf，外差脉冲对的间隔为Ld；外差脉冲对先经过第一掺铒光纤放大器放大后，通过环形器的第一口进入环形器，再通过环形器的第二口注入加速度传感器阵列；外差脉冲对在加速度传感器阵列的光纤中产生背向瑞利散射信号，作为外差信号，加速度传感器阵列接收到空气中的外界振动信号后通过加速度传感器骨架上的弹性筒将外界振动信号引起的振动信息调制到背向瑞利散射信号上，进而通过干涉调制到外差信号的外差频率上；外差信号通过环形器的第三口进入第二掺铒光纤放大器，经过第二掺铒光纤放大器放大后，经过滤波器滤除噪声，然后到达光电探测器，由数据采集卡采集信号，最后在工控机上进行信号的外差解调，从而得到外界振动信号，其中，f1≠f2，Ld>0。A fiber accelerometer array system, comprising: a narrow linewidth laser, an acceleration sensor array, a first coupler, a first acousto-optic modulator, a second acousto-optic modulator, a delay fiber, a second coupler, and a first blend铒 fiber amplifier, circulator, second erbium-doped fiber amplifier, filter, photodetector, data acquisition card and industrial computer; wherein the fiber is wound on the acceleration sensor skeleton to form an acceleration sensor, and one fiber is wound in multiple accelerations in sequence an acceleration sensor matrix forming the sensor array; narrow linewidth laser emits a continuous laser, after the first coupler is divided into two evenly all the way through the first acousto-optical modulator and modulated frequency shift f 1 into a first light pulse, Also the way through the second acousto-optical modulator is modulated frequency shift f 2 and a second optical pulse, the first pulse frequency difference Δf between the light and the second optical pulse = f 1 -f 2; second pulse light passes The delay fiber of length L d is separated from the first pulsed light in the time domain; the first pulsed light and the second pulsed light are combined by the second coupler to obtain two before and after Pulses form a heterodyne pulse pair, the heterodyne pulse pair has a heterodyne frequency of Δf, and the heterodyne pulse pair has an interval of L d ; the heterodyne pulse pair is first amplified by the first erbium-doped fiber amplifier and passed through the circulator The first port enters the circulator, and then the second sensor of the circulator is injected into the acceleration sensor array; the heterodyne pulse pair generates a back Rayleigh scattering signal in the fiber of the acceleration sensor array, and the acceleration sensor array receives the air as a heterodyne signal. After the external vibration signal, the vibration information caused by the external vibration signal is modulated by the elastic tube on the skeleton of the acceleration sensor to the back Rayleigh scattering signal, and then modulated to the heterodyne frequency of the heterodyne signal by interference; the heterodyne signal passes The third port of the circulator enters the second erbium-doped fiber amplifier, and after being amplified by the second erbium-doped fiber amplifier, the noise is filtered through the filter, and then reaches the photodetector, the signal is collected by the data acquisition card, and finally the signal is transmitted on the industrial computer. The heterodyne is demodulated to obtain an external vibration signal, where f 1 ≠f 2 , L d >0.
  5. 如权利要求4所述的光纤加速度传感器阵列***，其特征在于，外差信号的采样频率即脉冲重复频率为外差频率Δf的4倍以上；外差脉冲对的间隔Ld大于脉冲宽度w，在这个基础上间隔要尽量小。Fiber acceleration sensor array system according to claim 4, characterized in that the sampling frequency of the heterodyne signal, i.e. pulse repetition frequency of 4 times or more of the heterodyne frequency Δf; heterodyne interval L d is greater than the pulse width of the pulse w, On this basis, the interval should be as small as possible.
  6. 一种光纤水听器阵列***的测量方法，包括以下步骤：A method for measuring a fiber optic hydrophone array system includes the following steps:
    1)水听器阵列的光纤的长度为L，脉冲重复频率为fs，则有fs＜c/2nL，其中，c为真空中的光速，n为水听器阵列的光纤的折射率，数据采集卡的采样频率为fc，采样深度为N，则有N＝fc/fs；1) The length of the fiber of the hydrophone array is L, and the pulse repetition frequency is f s , then f s <c/2nL, where c is the speed of light in the vacuum and n is the refractive index of the fiber of the hydrophone array. The sampling frequency of the data acquisition card is f c , and the sampling depth is N, then there is N=f c /f s ;
    2)窄线宽激光器发出连续激光，经第一耦合器后，均匀分成两路，一路经过第一声光调制器被移频f1并被调制成第一脉冲光，另外一路经过第二声光调制器被移频f2并被调制成第二脉冲光，第一脉冲光与第二脉冲光之间的频率差Δf＝f1-f2；第二脉冲光经过长度为Ld的延时光纤，与第一脉冲光在时域上分开；第一脉冲光和第二脉冲光经过第二耦合器合光后，得到一前一后的两个脉冲，形成一个外差脉冲对，外差脉冲对的外差频率为Δf，外差脉冲对的间隔为Ld； 2) narrow linewidth laser emits a continuous laser, after the first coupler is divided into two evenly all the way through the first acousto-optical modulator and modulated by frequency shift f 1 into a first light pulse, the other all the way through the second acoustic The light modulator is frequency-shifted f 2 and modulated into a second pulsed light, the frequency difference between the first pulsed light and the second pulsed light is Δf = f 1 - f 2 ; the second pulsed light is extended by a length L d The optical fiber is separated from the first pulsed light in the time domain; the first pulsed light and the second pulsed light are combined by the second coupler to obtain two pulses before and after, forming a heterodyne pulse pair, The heterodyne frequency of the difference pulse pair is Δf, and the interval of the heterodyne pulse pair is L d ;
    3)外差脉冲对先经过第一掺铒光纤放大器放大后，通过环形器的第一口进入环形器，再通过环形器的第二口注入水听器阵列的光纤；外差脉冲对在水听器阵列的光纤中产生背向瑞利散射信号，作为外差信号，水听器阵列接收到水中的外界声波信号后通过水听器探头骨架上的弹性筒将外界声波信号引起的振动信息调制到背向瑞利散射信号上，进而通过干涉调制到外差信号的外差频率上，通过环形器的第三口进入第二掺铒光纤放大器，经过第二掺铒光纤放大器放大后，经过滤波器滤除噪声，然后到达光电探测器，由数据采集卡来采集信号，传输至工控机；3) The heterodyne pulse pair is first amplified by the first erbium-doped fiber amplifier, enters the circulator through the first port of the circulator, and then injected into the fiber of the hydrophone array through the second port of the circulator; the heterodyne pulse pair is in the water The back-direction Rayleigh scattering signal is generated in the fiber of the earphone array. As a heterodyne signal, the hydrophone array receives the external acoustic wave signal in the water and modulates the vibration information caused by the external sound wave signal through the elastic tube on the skeleton of the hydrophone probe. Back to the Rayleigh scattering signal, and then interfering to the heterodyne frequency of the heterodyne signal, through the third port of the circulator into the second erbium-doped fiber amplifier, after being amplified by the second erbium-doped fiber amplifier, filtered The device filters out the noise, then reaches the photodetector, and the signal is collected by the data acquisition card and transmitted to the industrial computer;
    4)一个外差脉冲对得到一条背向散射曲线，连续采集M条背向散射曲线；4) A heterodyne pulse pair obtains a backscattering curve and continuously acquires M backscattering curves;
    5)选取所有背向散射曲线的同一位置处的信号进行时域重构，将会得到同一位置处随时间变化的信号，该信号的表达式为：I＝A+B cos[2πΔft+Φ(t)]，其中Δf为外差频率，Φ(t)为外界声波信号引起水听器阵列的光纤中光相位的变化量，Φ(t)与外界声波信号的幅度成正比，Φ(t)的频率与外界声波信号的频率一致；5) Selecting the signal at the same position of all backscattering curves for time domain reconstruction will result in a signal that changes with time at the same position. The expression of the signal is: I=A+B cos[2πΔft+Φ( t)], where Δf is the heterodyne frequency, Φ(t) is the amount of change in the optical phase of the fiber in the hydrophone array caused by the external acoustic signal, and Φ(t) is proportional to the amplitude of the external acoustic signal, Φ(t) The frequency is consistent with the frequency of the external acoustic signal;
    6)将上述信号滤除直流成分后将得到待解调信号ys＝B cos[2πΔft+Φ(t)]，然后对待解调信号进行外差解调算法，最后得到光相位的变化量Φ(t)，从而得到外界声波信号的幅度和频率。6) After filtering the DC component of the above signal, the signal to be demodulated y s = B cos [2πΔft + Φ(t)] is obtained, and then the demodulated signal is subjected to a heterodyne demodulation algorithm, and finally the variation of the optical phase is obtained. (t), thereby obtaining the amplitude and frequency of the external acoustic signal.
  7. 如权利要求6所述的测量方法，其特征在于，在步骤4)中，背向散射曲线的条数M≥50。The measuring method according to claim 6, wherein in the step 4), the number of strips of the backscattering curve is M ≥ 50.
  8. 如权利要求6所述的测量方法，其特征在于，在步骤6)中，对待解调信号进行外差解调算法，具体过程为：将待解调信号ys分别与正弦信号sin(2πΔft)和余弦信号cos(2πΔft)进行混频并分别经过低通滤波器，然后两者相除得到两者的比值，最后经过反正切arctan运算得到光相位的变化量Φ(t)。The measuring method according to claim 6, wherein in step 6), the heterodyne demodulation algorithm is performed on the signal to be demodulated, and the specific process is: respectively, the signal to be demodulated y s and the sinusoidal signal sin(2πΔft) The cosine signal cos(2πΔft) is mixed and passed through a low-pass filter, and then the two are divided to obtain the ratio of the two, and finally the inverse tangent arctan operation is used to obtain the optical phase change amount Φ(t).
  9. 一种光纤加速度传感器阵列***的测量方法，包括以下步骤：A method for measuring a fiber optic acceleration sensor array system includes the following steps:
    1)加速度传感器阵列的光纤的长度为L，脉冲重复频率为fs，则有fs＜c/2nL，其中，c为真空中的光速，n为加速度传感器阵列的光纤的折射率，数据采集卡的采样频率为fc，采样深度为N，则有N＝fc/fs；1) The length of the fiber of the acceleration sensor array is L, and the pulse repetition frequency is f s , then f s <c/2nL, where c is the speed of light in the vacuum, n is the refractive index of the fiber of the acceleration sensor array, data acquisition The sampling frequency of the card is f c , and the sampling depth is N, then there is N=f c /f s ;
    2)窄线宽激光器发出连续激光，经第一耦合器后，均匀分成两路，一路经过第一声光调制器被移频f1并被调制成第一脉冲光，另外一路经过第二声光调制器被移频f2并被调制成第二脉冲光，第一脉冲光与第二脉冲光之间的频率差Δf＝f1-f2；第二脉冲光经过长度为Ld的延时光纤，与第一脉冲光在时域上分开；第一脉冲光和第二脉冲光经过第二耦合器合 光后，得到一前一后的两个脉冲，形成一个外差脉冲对，外差脉冲对的外差频率为Δf，外差脉冲对的间隔为Ld；2) narrow linewidth laser emits a continuous laser, after the first coupler is divided into two evenly all the way through the first acousto-optical modulator and modulated by frequency shift f 1 into a first light pulse, the other all the way through the second acoustic The light modulator is frequency-shifted f 2 and modulated into a second pulsed light, the frequency difference between the first pulsed light and the second pulsed light is Δf = f 1 - f 2 ; the second pulsed light is extended by a length L d The optical fiber is separated from the first pulsed light in the time domain; the first pulsed light and the second pulsed light are combined by the second coupler to obtain two pulses before and after, forming a heterodyne pulse pair, The heterodyne frequency of the difference pulse pair is Δf, and the interval of the heterodyne pulse pair is L d ;
    3)外差脉冲对先经过第一掺铒光纤放大器放大后，通过环形器的第一口进入环形器，通过环形器的第二口注入加速度传感器阵列的光纤；外差脉冲对在加速度传感器阵列的光纤中产生背向瑞利散射信号，作为外差信号，加速度传感器阵列接收到空气中的外界振动信号后通过加速度传感器骨架上的弹性筒将外界振动信号引起的振动信息调制到背向瑞利散射信号上，进而通过干涉调制到外差信号的外差频率上，通过环形器的第三口进入第二掺铒光纤放大器，经过第二掺铒光纤放大器放大后，经过滤波器滤除噪声，然后到达光电探测器，由数据采集卡来采集信号，传输至工控机；3) The heterodyne pulse pair is first amplified by the first erbium-doped fiber amplifier, enters the circulator through the first port of the circulator, and is injected into the optical fiber of the acceleration sensor array through the second port of the circulator; the heterodyne pulse pair is in the acceleration sensor array. The back-direction Rayleigh scattering signal is generated in the optical fiber. As the heterodyne signal, the acceleration sensor array receives the external vibration signal in the air and then modulates the vibration information caused by the external vibration signal to the back Rayleigh through the elastic cylinder on the skeleton of the acceleration sensor. The scatter signal is modulated by interference to the heterodyne frequency of the heterodyne signal, enters the second erbium-doped fiber amplifier through the third port of the circulator, is amplified by the second erbium-doped fiber amplifier, and is filtered by the filter to remove noise. Then arrive at the photodetector, and the signal is collected by the data acquisition card and transmitted to the industrial computer;
    4)一个外差脉冲对得到一条背向散射曲线，连续采集M条背向散射曲线；4) A heterodyne pulse pair obtains a backscattering curve and continuously acquires M backscattering curves;
    5)选取所有背向散射曲线的同一位置处的信号进行时域重构，将会得到同一位置处随时间变化的信号，该信号的表达式为：I＝A+B cos[2πΔft+Φ(t)]，其中Δf为外差频率，Φ(t)为外界振动信号引起加速度传感器阵列的光纤中光相位的变化量，Φ(t)与外界振动信号的幅度成正比，Φ(t)的频率与外界振动信号的频率一致；5) Selecting the signal at the same position of all backscattering curves for time domain reconstruction will result in a signal that changes with time at the same position. The expression of the signal is: I=A+B cos[2πΔft+Φ( t)], where Δf is the heterodyne frequency, Φ(t) is the amount of change in the optical phase of the fiber in the acceleration sensor array caused by the external vibration signal, Φ(t) is proportional to the amplitude of the external vibration signal, Φ(t) The frequency is consistent with the frequency of the external vibration signal;
    6)将上述信号滤除直流成分后将得到待解调信号ys＝B cos[2πΔft+Φ(t)]，然后对待解调信号进行外差解调算法，最后得到光相位的变化量Φ(t)，从而得到外界振动信号的幅度和频率。6) After filtering the DC component of the above signal, the signal to be demodulated y s = B cos [2πΔft + Φ(t)] is obtained, and then the demodulated signal is subjected to a heterodyne demodulation algorithm, and finally the variation of the optical phase is obtained. (t), thereby obtaining the amplitude and frequency of the external vibration signal.
  10. 如权利要求9所述的测量方法，其特征在于，在步骤4)中，背向散射曲线的条数M≥50。 The measuring method according to claim 9, wherein in the step 4), the number of strips of the backscattering curve is M ≥ 50.
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