A novel digital phase detection method for frequency-modulated continuous-wave interferometric fiber-optic displacement sensor

摘要

A novel digital phase detection method is proposed for the high accuracy and large dynamic range interrogation of frequency-modulated continuous-wave (FMCW) interferometric fiber-optic displacement sensors. Firstly, a peak of beat signal is found coarsely, and the range of the peak is obtained. Then golden section is used to find the peak accurately, in which cross-correlation filtering is used to calculate the value of golden section points. The simulation in the MATLAB environment show that the phase discrimination error is 0.073 rad, and displacement error is 9 nm, when the signal-to-noise ratio is 20 dB. In the real-time interrogation of a FMCW fiber-optic displacement sensor, we realized a repeatability error of 3.5 nm, a standard error of 4.5 nm and a linearity of 0.9999. The experimental results show that the method can achieve real-time displacement measurement with high accuracy and large dynamic range.