Extraction of interference phase in frequency-scanning interferometry based on empirical mode decomposition and Hilbert transform.

Nonlinear optical frequency scanning is inevitable in frequency scanning interferometry with tunable lasers and seriously reduces the accuracy of interference signal phase extraction. To address this, we propose a phase-extraction algorithm based on empirical mode decomposition and Hilbert transformation. The method can effectively eliminate the influence of the optical frequency scanning nonlinearity. The validity and stability of the method have been verified through simulations and experiments. Moreover, the single-cycle relative error of the phase between adjacent peaks and the standard deviation of the measurement system improved to 0.6% and 0.7 μm, respectively, with a 5 MHz sampling rate.