非本征光纤法珀传感器的振动特性研究

Vibration characteristics of extrinsic fiber Fabry-Perot sensors

针对光纤法珀(Fabry-Perot,FP)超声波传感器振动特性,将传感器薄板振动简化为具有集中参数的二阶振动,推导二阶振动方程的集中参数(力阻抗、等效质量、弹性系数、集中力),获得传感器共振频率、振幅灵敏度与结构参数设计关系。测试直径2.52 mm、厚度150μm玻璃振动薄板在空气、水中的共振频率分别为205 k Hz及115 k Hz,水介质中共振频率振幅灵敏度约18 pm/Pa。制作的传感器可测试局放产生超声波的最小声压约1 Pa。

Vibration characteristics are important for designing ultrasonic fiber Fabry-Perot （FP） sensors used for partial discharge detection. The vibrations of the film in sensors were simplified as the second order vibrations of lumped parametrers systems. The lumped parameters （mechanical impedance, equivalent mass, elastic coefficient, concentrated force） in second order vibration equations of the FP sensors in liquid were derived and the relationships between sensor＇s resonant frequency, amplitude sensitivity and structure parameters were obtained. For a vibration plate with 2.52 ram- diameter and 150 ixm-thickness in the sensor, the resonant frequency is 205 kHz in atmosphere and 115 kHz in water, and the amplitude sensitivity is about 18 μm/Pa at 115 kHz frequency in water. The minimum detectable acoustic pressure of the fabricated sensors is about 1 Pa.