Fast Demodulation Algorithm With Lower Spectral Leakage for Fabry-Pérot Interferometric Sensors

In this paper, we propose a new method of fast demodulation that can greatly alleviate the spectral leakage effect. We discuss the signal's frequency expression and illustrate our approach to solving it. The algorithm uses the ratio of two values in a non-zero-padding coarse Fourier amplitude distribution to solve the peak position, and uses the Fourier phase distribution to refine the result. With this method, we can precisely acquire the cavity length of our sensor within a large range of variation. Using a nanopositioning scanner, we successfully solve the OPD in a scanning range from 200 μm to 750 μm. Our algorithm also achieves 60.3 pm high-resolution and 17 kHz execution speed, which are suitable for precise detection in a large dynamic range.