带加速度补偿平面型光纤光栅水听器探头技术的研究

针对平面型光纤Bragg光栅(Fiber Bragg Grating,缩写为FBG)水听器探头加速度响应明显,影响它对正常声压进行探测的需求,提出了采用加速度补偿措施进行加速度去敏这一有效方法。从理论和实验上分析研究了带加速度补偿平面型光纤FBG水听器探头的结构灵敏度、灵敏度频率响应特性和加速度响应特性。结果表明:采用加速度补偿措施后,单位加速度(1m·s-2)响应输出的等效作用声压由2.52~3.26 Pa降为0.0758~0.217 Pa。同时,探头结构灵敏度由28 fm/Pa减小为20 fm/Pa,动态谐振频率由6.2 kHz增高为6.52 kHz。谐振频率的增加有助于提高水听器系统的动态响应特性,而结构灵敏度的降低,可以通过提高FBG动态波长解调仪的灵敏度来进行补偿。本来,光纤光栅或光纤光栅激光水听器系统可探测灵敏度主要由解调仪灵敏度决定,而不是由探头结构灵敏度决定。所以,该加速度补偿措施具有很大的实用性。      

Study of the planar optical fiber Bragg grating hydrophone probe with acceleration compensation

Since the probe acceleration response of a planar optical FBG hydrophone is very obvious and has an adverse influence on normal underwater acoustic pressure detection,an acceleration desensitization method employing an acceleration compensation measure is presented here.Results indicate that by utilizing this method,the equivalent pressure output applied by one unit of acceleration(1m·s^-2) is reduced from a range of 2.52-3.26 Pa to 0.0758-0.217 Pa, while the structural sensitivity decreases from 28 fm/Pa to 20 fm/Pa,however,the resonance frequency increases slightly from 6.2 kHz to 6.5 kHz.The increased resonance frequency helps to improve the dynamic frequency characteristics,and while the structural sensitivity is reduced, it can be compensated for by improving the optical FBG dynamic wavelength interrogation sensitivity.The system sensitivity of the optical FBG hydrophone is mainly determined by its wavelength interrogation sensitivity and not the probe structure sensitivity.Therefore,the acceleration compensation method would have broad practical applications.     

光纤Bragg光栅水听器探头的特性及实验研究

论述了FBG水听器探头基元——光纤Bragg光栅(FBG)的传感特性,分析了FBG的耦合系数、反射率、反射带宽和栅长对FBG水听器传感特性的影响。通过改进FBG水听器探头封装结构,增加了其压力敏感系数。并将实验结果与标准水听器(压电型)比较,标定出FBG的声压灵敏度,在1～25KHz的声波检测范围,其响应平坦度好、信号输出稳定,改进措施是有效的。     

光纤Bragg光栅水听器特性及实验研究

论述了光纤Bragg光栅（FBG）水听器探头基元 （FBG）的传感特性,分析了FBG的耦合系数、反射率、反射带宽和栅长对光纤Bragg光栅水听器传感特性的影响.通过改进光纤Bragg光栅水听器探头封装结构,增加了其压力敏感系数.并将实验结果与标准水听器（压电型）比较,标定出光纤Bragg光栅水听器的声压灵敏度;对传感信号进行电路解调,得出了解调结果,结果显示与原始声波信号基本一致.试验表明,在1 kHz~25 kHz的声波检测范围,光纤Bragg光栅水听器响应平坦度好,信号输出稳定,证明文中采取的改进措施是有效的.     

带加速度补偿的DFB光纤激光水听器

针对分布反馈式光纤激光水听器在用于水声探测时极易受加速度效应干扰的问题,设计了一种双膜片对称结构的光纤激光水听器,对该水听器的抗加速度性能进行了研究.建立了双膜片结构水听器的加速度灵敏度理论模型,分析了水听器各部件的尺寸大小、材料参量与水听器加速度灵敏度的关系,实现了对水听器结构的优化设计;加工制作了分布反馈式光纤激光水听器原型样品,并进行了实验研究.测量结果表明,在2.5~10kHz的频率范围内,该结构水听器的平均声压灵敏度为-132.6dB,波动幅度不大于±0.5dB,加速度灵敏度小于-28dB.该水听器在保证了较高声压灵敏度与平坦的响应曲线的同时,抗加速度性能也得了有效改善,可大大提高光纤激光水听器阵列在运动状态下对远距离目标探测的信噪比.     

新型光纤光栅水声传感器的研究

提出了一种新型的光纤布拉格光栅(FBG)水声传感探头结构以及光纤光栅传感信号的自解调方法。利用一对匹配光栅构成推挽结构,实现了传感-解调的合二为一,大大地减小了系统的复杂度;并通过筒状弹性体结构,解决了裸光纤光栅测量水声信号的灵敏度过小的问题,并具有温度补偿作用。仿真与初步实验结果表明,该水听器探头的测量动态范围超过100 dB,在100~200 dB re 1μPa的水声压范围内,测量灵敏度为0.36 nm/Mpa。     

Development of an optical fiber hydrophone with fiber Bragg grating

A new type of optical fiber hydrophone is constructed with a fiber Bragg grating (FBG) based on the intensity modulation of laser light in an FBG under the influence of sound pressure. The FBG hydrophone shows linearity, with dynamic range about 70 dB. It can measure amplitude and phase of an acoustic field in real time, and operates in a wide range of acoustic frequency, at least from 1 kHz to 3 MHz. No signal distortion is observed in the detected signal. Because of the simplicity in its operating principle and geometry, an FBG hydrophone is expected to be an acoustic sensor of high practicality compared to a conventional optical fiber hydrophone.     

100kHz～500kHz压电复合材料标准水听器

本文介绍了一种我们制作的可应用于100kHz～500kHz频段的标准水听器,水听器敏感元件采用1-3型压电复合材料,通过对敏感元件及水听器结构进行合理设计,从工艺上保证水听器性能的稳定、可靠,制作完成的标准水听器满足高频标准的所有技术指标要求。测试结果表明,水听器的接收灵敏度大于-194dB,频段内灵敏度起伏为2.9dB,最高使用频率-3dB波束宽度大于20度;稳定性考核表明,水听器有良好的温度、时间稳定性,是一种比较理想的中高频标准水听器,适合于水声的校准和中高频声信号测试。     

High-sensitivity,fiber-optic,flexural disk hydrophone with reduced acceleration response

Abstract

A hydrophone consisting of a hollow cylinder whose flexible, circular end plates are bonded to pairs of pat, spiral wound coils of optical fiber is described. When the end plate/disk is deformed due to a pressure difference, the outer and inner fiber coils experience opposite strains resulting in a “push—pull” optical path length difference which is detected in an all-fiber Michelson interferometer. The close proximity of the interferometric fiber coils, separated by the thin thermally conducting end plate, rejects thermal gradient-induced signals. The addition of a second identical end plate and fiber coil pair at the opposite end of the cylinder will double the acoustic sensitivity while canceling acceleration induced signals. The calculated and measured optical strain of a single simply supported plate, single-coil sensor (8.0 cm diameter, 3.0 mm thickness) using static pressure, acoustic pressure, and acceleration are in good agreement and yield a sensitivity of 0.21 rad/Pa (ΔΦ/ΦΔP = -301 dB re I μPa-1) below its resonance frequency of 3 kHz. The calculated and measured strain for a dual clamped disk (4.5 cm diameter, 1.0 mm thickness) acceleration-canceling sensor with four 8-m coils are in good agreement also and yield a sensitivity of 1.0 rad/Pa (ΔΦ/ΦpΔP = -291 dB re 1 μPa^?1) below the disk resonance frequency of 4.5 kHz. These are the highest fiber-optic, omnidirectional hydrophone sensitivities reported to date.     

基于球形压电陶瓷的耐压水听器

利用球形压电陶瓷自身所具有的耐压能力,采用径向极化空气背衬压电球壳换能器作为声学接收敏感元件,设计并制作了一种球形耐压水听器。首先对其低频开路接收灵敏度和谐振频率等声学特性进行了分析和有限元仿真,然后对其强度和稳定性等耐压性能进行了分析和有限元仿真,最后对其声学性能和耐压能力进行了测试。测试表明,该球形耐压水听器的直径为36 mm,工作频段为50 Hz～10 kHz,低频接收灵敏度为-198.4 dB (0 dB=1 V/μPa),等效自噪声谱级为46.5 dB@1 kHz,其耐压深度可达3000 m。该耐压水听器为大深度水听器设计提供了参考,在深水声学领域具有重要的应用价值。     

圆柱形超高静水压水听器设计与测试

(本文介绍了一种应用于20Hz~20kHz频段、最大工作深度5000米的超高静水压水听器,水听器敏感元件采用厚壁压电陶瓷圆管,高强度复合泡沫去耦,通过对敏感元件及水听器结构进行合理设计,保证水听器具有高的耐压强度。设计了一种圆柱形高静压耦合腔,根据耦合腔声学和力学条件,确定了腔体尺寸及厚度,在国内首次实现了最高50MPa压力下的水听器低频灵敏度测试。测试结果表明,水听器常压下接收灵敏度响应平坦,在常压到50MPa压力范围内,水听器低频接收灵敏度最大变化小于2dB,表明该型水听器具有良好的压力稳定性,可在深海资源勘测、深海通讯等方面获得广泛应用。)     

夹层式光纤激光水听器探头优化设计

为改善分布反馈式(DFB)光纤激光器水声探测性能,利用有限元软件ANSYS,以相对加速度灵敏度为目标函数,结构尺寸参数为设计变量,结构第一阶固有频率和探头声压灵敏度为状态变量,对夹层式封装结构进行了优化设计,对其声压探测及抗加速度机理进行了分析。分析表明,基于优化结果设计的探头在采用100m非平衡干涉仪时,其声压灵敏度约为-135.1dB,相对加速度灵敏度可达到-19.6dB。结果表明,基于封装结构敏感部分分别承受声压激励和加速度激励时的不同响应机理,对夹层式封装结构关键部位尺寸进行优化设计后,通过合理选择承压梁与中间变形梁的厚度以及上下连接点的位置,封装制得的光纤激光水听器具有较高的声压灵敏度和良好的抗加速度性能。     

基于密集波分复用技术的Bragg光栅水听器

论述了用Bragg光栅制作水听器的原理和意义,利用光纤通信的密集波分技术,实现声压信号动态解调.采用压力增敏材料对Bragg光栅封装来增加其响应灵敏度,为避免温度变化引起光栅交叉敏感,在室温23±1℃条件下进行试验,给出实验结果.实验表明:基元水听器的频率响应平坦度好,信号输出稳定.同时采用密集波分技术动态解调声信号方案是可行的.     

High-sensitivity, fiber-optic, flexural disk hydrophone with reduced acceleration response

A hydrophone consisting of a hollow cylinder whose flexible, circular end plates are bonded to pairs of pat, spiral wound coils of optical fiber is described. When the end plate/disk is deformed due to a pressure difference, the outer and inner fiber coils experience opposite strains resulting in a “push—pull” optical path length difference which is detected in an all-fiber Michelson interferometer. The close proximity of the interferometric fiber coils, separated by the thin thermally conducting end plate, rejects thermal gradient-induced signals. The addition of a second identical end plate and fiber coil pair at the opposite end of the cylinder will double the acoustic sensitivity while canceling acceleration induced signals. The calculated and measured optical strain of a single simply supported plate, single-coil sensor (8.0 cm diameter, 3.0 mm thickness) using static pressure, acoustic pressure, and acceleration are in good agreement and yield a sensitivity of 0.21 rad/Pa (ΔΦ/ΦΔP = -301 dB re I μPa-1) below its resonance frequency of 3 kHz. The calculated and measured strain for a dual clamped disk (4.5 cm diameter, 1.0 mm thickness) acceleration-canceling sensor with four 8-m coils are in good agreement also and yield a sensitivity of 1.0 rad/Pa (ΔΦ/ΦpΔP = -291 dB re 1 μPa^-1) below the disk resonance frequency of 4.5 kHz. These are the highest fiber-optic, omnidirectional hydrophone sensitivities reported to date.     

一种用于大坝混凝土声层析成像用水听器线阵

声层析成像技术可以用图像的方式精确完整地反映层析面上检测体内部质量,是一种有效的无损检测手段。在大坝混凝土的安全隐患检测中发挥着越来越重要的作用,本研究旨在研制成像用的接收声波的水听器线阵,水听器线阵由12个水听器阵元组成,阵元间隔2m,水听器由直径40mm的接收型压电园管和前置放大器组成,水听器在低于20kHz的频率范围内,自由场接收电压灵敏度为-173±-3dB,在2MPa静水压力下灵敏度下降不超过2dB。制作了二例了具有清晰接收波形、一致性和可靠性好的水听器线阵,最终为客户在现场实地获得了高质量的层析图像。     

Miniature photonic-crystal hydrophone optimized for ocean acoustics

This work reports on an optical hydrophone that is insensitive to hydrostatic pressure, yet capable of measuring acoustic pressures as low as the background noise in the ocean in a frequency range of 1 Hz to 100 kHz. The miniature hydrophone consists of a Fabry-Perot interferometer made of a photonic-crystal reflector interrogated with a single-mode fiber and is compatible with existing fiber-optic technologies. Three sensors with different acoustic power ranges placed within a sub-wavelength sized hydrophone head allow a high dynamic range in the excess of 160 dB with a low harmonic distortion of better than -30 dB. A method for suppressing cross-coupling between sensors in the same hydrophone head is also proposed. A prototype was fabricated, assembled, and tested. The sensitivity was measured from 100 Hz to 100 kHz, demonstrating a sound-pressure-equivalent noise spectral density down to 12 μPa/Hz(1/2), a flatband wider than 10 kHz, and very low distortion.     

聚（偏二氟乙烯-三氟乙烯）压电圆管水听器

提出了高灵敏度压电共聚物圆管水听器设计方法,论述了聚(偏二氟乙烯-三氟乙烯)[P (VDF-TrFE)]材料结构与压电特性的关系,利用解析法和有限元法,分析了多振动模式耦合特性对压电共聚物圆管水听器灵敏度响应的影响规律,仿真分析了圆管水听器的耐静水压特性和噪声特性,与相同结构的压电陶瓷和压电均聚物水听器相比,压电共聚物圆管水听器低频段灵敏度分别可提高20 dB和5 dB以上,研制了尺寸为Φ14 mm × 55 mm的压电共聚物圆管水听器样品,经测试,在10 Hz~1 kHz频段内水听器灵敏度响应达到-181.8 dB±1 dB,等效自噪声压低于零级海况海洋环境噪声,与理论模型结果有良好的一致性。结果表明,该设计显著提升了圆管水听器的低频接收灵敏度,并为其耐静水压性能提升提供了思路。      

一种具有声低通滤波特性的无源零差光纤水听器

报道了一种新颖的具有抗混叠功能的无源零差迈克耳孙型光纤水听器.它由一个普通的芯轴型光纤水听器和一个圆柱型亥姆霍兹共振器构成.在驻波罐中对其声压相位灵敏度频响进行了测量,结果表明该光纤水听器具有较好的声低通滤波特性,能有效地抑制声信号中的高频成分,从而实现抗混叠滤波.该光纤水听器的低频声压相位灵敏度主要由传感光纤长度和弹性增敏层的物理特性决定,约为-159 dB(0 dB=1 rad/μPa).在1150 Hz附近出现了一个共振峰,这主要由圆柱型亥姆霍兹共振器的声学特性决定.1150～2280 Hz频段内的灵敏度衰减率约为50 dB/倍频程,1500 Hz以后的灵敏度衰减量大于10 dB.这对于提高我国未来声纳系统的抗干扰能力具有十分重要的意义.     

Fiber Bragg grating hydrophone with high sensitivity

A fiber Bragg grating （FBG） hydrophone with high sensitivity was demonstrated. This hydrophone used a rubber diaphragm and a copper hard core as the sensing element. To compensate the hydrostatic pressure, a capillary tube was fixed at the end of the hydrophone. Theoretical analysis of the acoustic pressure sensitivity was given in this letter. Experiments were carried out to test the frequency response of the hydrophone. The result shows that when the Young＇s modulus of the diaphragm is higher, a flatter frequency response will be obtained.     

一种耐静压分布反馈式光纤激光水听器探头设计

大深度工作环境下，静水压会引起分布反馈式光纤激光水听器反射中心波长漂出解调系统的复用窗口，使水听器无法解调目标声压信号；不同的静水压也会引起分布反馈式光纤激光水听器灵敏度的变化，影响光纤激光水听器阵列的一致性。基于电力声类比理论，提出带静压补偿的分布反馈式光纤激光水听器探头，建立结构的声压传递函数，分析各结构参数对传递函数的影响，为分布反馈式光纤激光水听器探头频率响应平坦化设计提供理论依据。加工制作了耐静压分布反馈式光纤激光水听器样品进行测试，在0 kHz～10 kHz频率范围内声压灵敏度波动范围不大于±2.4 dB，2.3 MPa内出射激光中心波长漂移量不大于0.06 nm，对深水光纤激光水听器的研究具有指导意义。