空气背衬芯轴型光纤水听器加速度性能研究

对用于水声探测的光纤水听器,加速度相移灵敏度是一个重要的参数。本文采用有限元法对空气背衬芯轴型光纤水听器的加速度相移灵敏度进行了理论分析,并通过实验验证,得到了空气背衬芯轴型光纤水听器加速度相移灵敏度的优化规律,提高芯轴壳体的硬度可有效降低光纤水听器的加速度相移灵敏度,而改变芯轴壳体的厚度对水听器加速度灵敏度影响不大。     

关于光纤水听器灵敏度的讨论

本文先简略介绍了干涉型光纤水听器的基本原理与检测信号的基本方法，由此给出了光纤水听器相位归一化灵敏度、相位灵敏度、电压灵敏度的定义。在分析它们的物理意义以及相互之间关系的基础上，给出一组能反映它们对应关系的一组数据，以及一光纤水听器探头频率响应曲线。     

低加速度灵敏度水听器

本文介绍了一种用于拖曳线列阵声呐的压电陶瓷型水听器，我们在提高水听器工作稳定性与可靠性，并确保水听器有较高接收灵敏度的前提下，进行了水听器的结构方案优化设计，以降低水听器的加速度灵敏度，研制的水听器接收灵敏度为－１９３ｄＢ，在２０－１０００Ｈｚ频段内灵敏度起伏为１．２ｄＢ，加速度灵敏为－７０ｄＢ。     

Applications of angled-mirror in fiber-optic sensors

An angled-mirror as fiber-optic sensor's reflective modulator is introduced. This paper reports two optical-fiber sensors based on the angled-mirror reflective modulator. One is fiber-optic sliding sensor, the other is called fiber-optic three-states-position sensor.     

灵敏度可调式压电薄膜水听器

本文介绍一种灵敏度可调式压电薄膜水听器，采用PVDF薄膜作为换能材料，聚碳酸脂作为背衬，薄膜粘贴在背衬的内壁，软性的背衬在声压的作用下形变。从而带动薄膜形变，产生电信号输出。水听器内装有前置放大器，调节放大器的负载电阻可调节水听器的灵敏度，灵敏度变化范围为出，水听器内装有前置放大器，100Hz-16kHz。     

脉冲声测量技术在光纤水听器测量中的应用

本文介绍了脉冲声测量技术在非消声水池中光纤水听器测量中的应用。理论上分析了脉冲宽度的选择标准，并搭建了实验系统，对某一光纤水听器的声压灵敏度进行了测量，实验结果验证了该技术用于光纤水听器测量的可行性。     

A fiber-optic voltage sensor based on macrobending structure

We propose and demonstrate an optical voltage sensing scheme based on a macrobending optical fiber in a ratiometric power measurement system. This novel approach to sensing has not been utilized before and has the advantage that the sensor involves simple fabrication compared to existing fiber-optic voltage sensors. To prove the feasibility of such a fiber-optic sensor, a sensor for a voltage range from 0∼100 V is demonstrated, with a resolution of 0.5 V. The sensor is robust, linear, and shows a competitive measurement resolution. The sensor can be easily scaled to suit other voltage levels and be effectively combined with optical current sensors.     

Light intensity modulation fiber-optic sensor for curvature measurement

A light intensity modulation fiber-optic sensor, which can measure curvature directly, has been developed. It is suitable for the measurement of thin, embedded or highly flexible structures. An experimental analysis on the static and dynamic characteristics of sensor has been undertaken. The results show that the output voltage has polarity and a good linear relationship with curvature when the curvature radius is larger than 60 mm. The mathematical model relating the relative output loss, parameters of sensitive zone’s configuration (depth, number, height and half angle of tooth) and bending radius is described analytically based on the geometric optics. Curvature fiber-optic sensors can be used to build a quasi-distributed fiber-optic sensor system, which can measure curvature and torsion angle simultaneously.     

Experimental research on a novel fiber-optic cantilever-type inclinometer

Experimental setup for tilt measurement and a novel signal detection method for demodulation of fiber Bragg grating (FBG) wavelength shift are proposed. Being attached, respectively, on the upper and lower surface of only one single pendulum-type cantilever element, only a couple of matched FBGs are used for both tilt angle sensing and wavelength shift signal demodulating. So the received light power will change due to the split of the two reflected spectra of FBGs, which corresponds to the tilt angle. In addition, the cross-sensitivity effect of FBG-based sensors will be solved automatically due to a differential signal process method. Experimental results indicate the measurement accuracy is about ± 0.03°, and measurement resolution is estimated to be about 0.002°.     

Determination of low-level water content in ethanol by fiber-optic evanescent absorption sensor

Evanescent field absorption spectroscopy in the infrared range of coiled fiber-optic sensor has been applied to determine the low-level water content in ethanol. Principal component regression and classical least square models have been utilized to build the calibration model and predict the water concentrations. The standard errors of predictions of water concentrations in ethanol were 3.16% and 0.42% respectively. Some methods to improve the accuracy of predicted water concentration in ethanol were suggested. The predicted concentration of water is acceptably accurate and cost-effective. The study demonstrates that the coiled fiber-optic sensor based on evanescent absorption spectroscopy is a feasible technology for prediction of the low-level water content in bio-ethanol and other industries in both on-line and remote situation.     

带空气腔芯轴型光纤水听器特性研究

对带空气腔芯轴型光纤水听器进行了研究和试验验证.分别建立了二维和三维模型对水听器性能进行分析,给出了两种模型下的水听器相移灵敏度计算公式;小批量制作了22个该结构的水听器并进行了测试.试验数据与模型计算结果十分吻合.结果表明,三维模型计算结果比二维模型更为准确,频带内均方根偏差大部分都小于0.3(dB·re·rad)/μPa.试验采用的水听器相移灵敏度为－153(dB·re·rad)/μPa,其归一化相移灵敏度达到－308(dB·re·1)/μPa.同时,该模型可以更好地根据实际需要来设计不同尺寸和性能的水听器结构.     

芯轴型光纤水听器声压相移灵敏度响应分析

提出了一种带空气腔芯轴型光纤水听器的结构模型,并对其声压相移灵敏度的响应特性进行了研究.通过对空气腔芯轴型光纤水听器的基本原理和结构进行分析,得出光纤与弹性筒作用的相互关系;建立了动力学等效模型,得出带空气腔芯轴型光纤水听器声压相移灵敏度表达式以及频率特性的理论模型;利用有限元方法,得到芯轴型光纤水听器的响应模型.根据提出的结构和确定的参量制作出相应的探头,经过试验测试,其3 dB带宽约为30 kHz,测试结果验证了提出的理论模型与有限元模型的正确性.     

一种新型Sagnac式光纤电流传感器

为了消除震动对Sagnac式电流传感器测量结果的影响,提出一种光路改进方法来消除传感器对震动的敏感性,其基本原理是抵消Sagnac效应而不影响法拉第磁光效应.利用琼斯矩阵对改进后的光路结构进行了偏振态分析,理论分析和实验结果吻合,表明改进后的传感器其输出与震动无关.耦合半波片后Sagnac式光纤电流传感器的震动敏感性被消除了,为Sagnac式光纤电流传感器的工程化实现提供了一种可行的方法.     

基于光纤水听器的声场水平相关性研究

中科院声学研究所声场声信息国家重点实验室与长沙国防科技大学合作研制出了一条32阵元的光纤水听器阵,并于2002年8月在渤海进行了一次海上实验。本文利用光纤水听器阵获得的气枪声信号进行了声场的水平相关性分析,并与理论结果进行了比较,实验和理论结果基本符合。     

压电陶瓷水听器加速度响应的有限元分析

本文用有限元法分析了压电陶瓷圆柱形水听器的材料参数与几何尺寸对其加速度响应的影响。针对理论分析，进行了水听器加速度响应实验，实验结果与理论分析基本相符。     

光纤阵与压电阵的海试比较

为了检验光纤水听器阵在低频(100Hz~1kHz)/甚低频段(100Hz)的测量性能,在南海海试中,我们将一16元光纤阵与16元常规压电水听器阵平行安装在同一基阵框架上并沿舷侧布放,使得两阵受到基本相同的振动干扰。通过单频和宽带脉冲信号的传播实验,对双阵接收信号进行比较。试验结果表明,光纤阵具有更好的抗振动加速度性能,因此在甚低频段检测中具有明显的优势。     

Novel mechanical antialiasing fiber-optic hydrophone with a fourth-order acoustic low-pass filter

A novel mechanical antialiasing interferometric fiber-optic hydrophone with a fourth-order acoustic low-pass filter has been fabricated and demonstrated for the first time to the best of our knowledge. The low-frequency lumped parameters model of the hydrophone is constructed based on the theories of an electroacoustic analogy, and the acoustic performance is predicted by the circuit analysis methods. The measured low-frequency response is very flat, and the acoustic sensitivity is about -140 dB with regard to 1 rad/microPa. The system has two measured resonant frequencies, i.e., 850 and 4000 Hz, which is in agreement with the simulation results. It is expected that this new type of fiber-optic hydrophone will become an important class of sensors used to eliminate the aliasing in future sonar systems.     

基于最小二乘法的光纤法布里-珀罗传感器相位校正解调算法

为了提高光纤法布里-珀罗传感器的解调精度和效率,利用干涉光谱中的波峰计算出一系列光程差,根据最小二乘法求出该组光程差中方差最小的解作为粗略解调结果,并计算出光谱附加相位;在光谱附加相位基础上进行校正,得到补偿光程差,两者之和为最终解调结果.仿真结果表明,该算法的解调误差在±2.5nm内.光纤法布里-珀罗蓝宝石高温传感实验表明,从室温升到1000℃时,该算法解调光程差精度为5.4nm,对应温度的精度为±0.36‰F.S.,同等条件下计算速度比FFT-MMSE快400倍,具有计算精度高,计算速度快的优点.     

Cost-effective assembly of a basic fiber-optic hydrophone for measurement of high-amplitude therapeutic ultrasound fields

Design considerations, assembly details, and operating procedures of one version of a cost-effective basic fiber-optic probe hydrophone (FOPH) are described in order to convey practical information to groups interested in constructing a similar device. The use of fiber optic hydrophones can overcome some of the limitations associated with traditional polyvinylidene difluoride (PVDF) hydrophones for calibration of acoustic fields. Compared to standard PVDF hydrophones, FOPH systems generally have larger bandwidths, enhanced spatial resolution, reduced directionality, and greater immunity to electromagnetic interference, though they can be limited by significantly lower sensitivities. The FOPH system presently described employs a 100-microm multimode optical fiber as the sensing element and incorporates a 1-W laser diode module, 2 x 2 optical coupler, and general-purpose 50-MHz silicon p-i-n photodetector. Wave forms generated using the FOPH system and a reference PVDF hydrophone are compared, and intrinsic and substitution methods for calibrating the FOPH system are discussed. The voltage-to-pressure transfer factor is approximately 0.8 mV/MPa (-302 dB re 1 V/microPa), though straightforward modifications to the optical components in the FOPH system are discussed that can significantly increase this value. Recommendations are presented to guide the choice of optical components and to provide practical insight into the routine usage of the FOPH device.     

超高压光纤压力传感器理论和实验研究

本文提出了一种新型超高压光纤压力传感器.并用一种几何光学计算方法,用来计算该传感器的耦合系数曲线.在此基础上,设计并加工出一种具有新特点的超高压光纤压力传感器.这种传感器的实验研究结果与理论分析一致.