光纤光栅水听器的研究

发布时间：2018-03-03 23:25

本文选题：光纤光栅　切入点：水听器探头　出处：《东北大学》2014年硕士论文　论文类型：学位论文

【摘要】：声波是海洋远距离传输的有效载体,光纤水听器是一种把水下声信号转换成光信号的换能器,是水声学中最重要的测量仪器,现已经在海洋石油、海洋渔业、天然气勘探、医学测量等方面得到的广泛的研究和应用。为了解决传统压电结构水听器抗电磁干扰差等问题,论文以光纤光栅为传感元件设计了基于等强度悬臂梁结构的光纤光栅水听器,并对其特性进行了分析和测试,主要研究内容如下：(1)从光纤光栅加速度传感理论出发,采用等强度悬臂梁设计了一种新型的光纤光栅水听器探头结构,并且针对其交叉敏感特性提出了双光栅差动结构的温度补偿设计。通过仿真实验确定探头的尺寸。(2)通过ANSYS对结构进行有限元分析。分析结果表明：该结构沿x、y、z轴三个方向的灵敏度分别为13.55pm/g、0.0296pm/g和0.00037pm/g,横向灵敏度均达不到敏感灵敏度的1%,具有良好的横向抗干扰能力；在敏感方向上一阶模态起到主要作用,并且受其他模态影响很小,可以避免交叉耦合现象。(3)对所设计的FBG水听器探头结构进行封装,并对其性能进行测试。静力实验表明所设计的水听器探头的压力灵敏度为1.1547nm/N,光纤光栅中心波长与应力之间存在良好的线性关系,并未出现啁啾现象；振动测试表明该结构具有较高的振动灵敏度；温度补偿实验验证了探头的温度补偿特性。(4)通过光纤光栅F-P振动解调系统,将振动信号转换为电压信号,将测量得到的电压信号转换为加速度信号,该方法的扫描速度是传统光谱仪解调法的300倍。解调得到FBG水听器的加速度灵敏度为11.9pm/g。本文所设计的水听器加速度灵敏度为11.9pm/g,并且具有良好的横向抗干扰能力；固有频率为50.98Hz,具有较好的低频测量特性；双光栅差动结构的设计能够有效避免温度变化对测量结果的影响。综上,本文所设计的光纤光栅水听器可以满足水下声压信号的测量需求。
[Abstract]:Acoustic wave is an effective carrier of ocean long-distance transmission, fiber optic hydrophone is a kind of transducer to convert underwater acoustic signal into optical signal, it is the most important measuring instrument in underwater acoustics, which has been used in offshore oil, offshore fishery and natural gas exploration. In order to solve the problem of electromagnetic interference difference of traditional piezoelectric hydrophone, a fiber Bragg grating hydrophone based on equal strength cantilever beam structure is designed based on fiber grating as sensing element. The main research contents are as follows: (1) based on the acceleration sensing theory of fiber Bragg grating, a new type of fiber grating hydrophone probe structure is designed by using an equal-strength cantilever beam. The temperature compensation design of double grating differential structure is put forward according to its cross sensitivity. The size of probe is determined by simulation experiment. The finite element analysis of the structure is carried out by ANSYS. The results show that the structure is along the xyyong z axis. The sensitivity of the three directions is 13.55 pm / g 0.0296 pm / g and 0.00037 pm / g respectively. The first mode plays a major role in the sensitive direction, and is little affected by other modes, which can avoid the cross coupling phenomenon. It can encapsulate the designed FBG hydrophone probe structure. The static experiment shows that the pressure sensitivity of the hydrophone probe is 1.1547 nm / N, and there is a good linear relationship between the center wavelength and the stress of the fiber grating. The vibration test shows that the structure has high vibration sensitivity, and the temperature compensation experiment verifies the temperature compensation characteristic of the probe. 4) the vibration signal is converted into the voltage signal through the fiber Bragg grating F-P vibration demodulation system. The measured voltage signal is converted into an acceleration signal, The scanning speed of this method is 300 times that of the traditional spectrometer demodulation method. The acceleration sensitivity of the FBG hydrophone is 11.9pm / g. The acceleration sensitivity of the hydrophone designed in this paper is 11.9pm / g and has good transverse anti-jamming ability. The natural frequency is 50.98 Hz, which has good low frequency measurement characteristics. The design of double grating differential structure can effectively avoid the influence of temperature change on the measurement results. The fiber Bragg grating hydrophone designed in this paper can meet the need of underwater acoustic pressure signal measurement.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB565.1

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