Real-time displacement reconstruction based on all-fiber Fabry–Perot interferometer

• A real-time displacement measurement technique based on all-fiber Fabry–Perot interferometer. • The quadrature detection algorithm can significantly simplify the data processing process. • Two Fabry-Perot interference signals with a phase shift of π / 2 can be obtained directly. • The object displacement can be reconstructed directly by the quadrature demodulation algorithm. • The structure of the system is simple and compact. A real-time displacement reconstruction method based on an all-fiber Fabry–Perot interferometer (FPI) is proposed, utilizing the fiber end face and the object surface to form an extrinsic FPI. Using the constant phase difference of 90° between the two output ports of the 2 × 2 coupler, two-phase orthogonal FPI signals carrying the object motion information can be detected by two invisible photodetectors, and real-time displacement reconstruction can be realized by adopting inverse tangent and unwrapping processing procedures. Results show that the absolute errors of the experiment are below 80 nm.