光学式超音波検出装置における大振幅超音波応答の改善

概要

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An ultrasound detection system with optical heterodynes shows nonlinear behavior in the large-ultrasonic-amplitude region ( >λ/8, λ : wavelength of detecting light), and possesses some problems in the measurement of laser ultrasound (ultrasound generated by laser deposition), especially of thin specimens. We studied the mechanism of the nonlinear response and found a method to improve it. Through experiments, we obtained an improved demodulation method using signal processing techniques to extract actual ultrasonic waveforms in the large-amplitude region, and confirmed its effectiveness. We also carried out numerical experiments on the characteristics of our improved demodulation, method and the standard demodulation method. The results show that compared with the standard demodulation method, our method is more robust against noise of beat signals, and more useful for measuring laser ultrasound even in the small-amplitude region.
一般社団法人日本機械学会の論文
1994-10-25