Real-time displacement reconstruction by an orthogonal Fabry–Perot interferometer

A real-time reconstruction of the displacement method based on an orthogonal Fabry–Perot interferometer is presented. Two orthogonal polarization signals with a phase shift of π / 2 are obtained using a He–Ne laser with internal-mirror multilayer coatings. The displacement of the vibration target is reconstructed in real time using the arctangent and unwrapping algorithm for two quadrature signals. Meanwhile, two quadrature signals are used to discriminate the direction of motion. The experimental results under different peak-to-peak amplitudes and frequencies show that the reconstruction errors are less than 58 nm.