摘要
本文报道了一套利用斐索光纤干涉仪对固体声表面波进行准确检测的系统。该系统基于小波变换去噪,能够实现对超声波在固体表面上引起微弱振动的准确检测。斐索干涉仪基于共光路干涉原理设计,克服了其它干涉仪对光纤臂长要求严格且易受温度影响等缺点,具有结构简单、容易调节、灵敏度高和检测面积小等诸多优点。然而,由于较高的检测灵敏度,该表面波检测装置也极易受外界扰动影响,导致信号不稳定、信噪比低等问题。本文利用小波变换方法对干涉仪输出信号进行去噪,极大地提高了该检测方法的信噪比,为固体声表面波的检测提供了高灵敏度和高信噪比的实验系统。
We report a Fizeau fiber interferometer system to detect the ultrasonic surface wave accurately. The system is capable of detecting the micro-vibration produced by ultrasonic wave propagating on the surface of solid. The Fizeau fiber interferometer system avoids the disadvantages of other fiber interferometers for surface ultrasonic wave by using the principle of common light path. The interferometer has some advantages such as simplicity of structure, easiness of control, high sensitivity and capability of detecting the vibration of micro area, but at the same time, has some disadvantages such as instability by disturbance of external environment and low signal noise ratio. We implemented the wavelet transformation to the signals of ultrasonic waves to increase the signal noise ratio significantly. For the measurements of ultrasonic surface waves, the proposed experimental system is highly sensitive and the signal noise ratio is definitely improved by the signal processing method.
引文
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