According to the mechanism of the interferometric fiber-optic sensor, an optical orthogonal heterodyne demodulation technology has been investigated in this paper. A variable fiber delay line was used to adjust the optical phase delay to obtain optical orthogonal heterodyne demodulation, so that the low-frequency noise in the photo-detector can be reduced. Comparing with the conventional heterodyne demodulation schemes, the additional noise as well as temperature-related drift induced by the electronic phase drift devices can be eliminated by using the proposed demodulation technology. An experiment system was set up to measure the optical phase change induced by the piezoelectric ceramic (PZT) vibration. The result shows that the proposed scheme can demodulate the sensing signal efficiently, and a minimum detectable phase shift of 9.2×10-5 rad can be achieved.%针对干涉型光纤传感器信号传感的原理特点,本文提出了一种光正交外差解调技术.该方法使用可调光纤延时线进行传感光信号延迟的精确调整以实现正交外差解调,从而减少了光电探测器的低频噪声影响.与常规的外差解调技术相比,提出的解调结构方案消除了电子移相元件所带来的额外电子噪声与环境温度变换引起的相位漂移.通过压电陶瓷环谐振特性测量实验,表明了提出的基于光正交外差的干涉型光纤传感器解调技术可以有效地进行干涉振动信号的解调,实验取得的最小可探测相移量可达到9.2× 10-5 rad.
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