Simultaneous measurement of distance and speed using frequency-modulated continuous-wave self-mixing interferometry and all-phase fast Fourier transform

In this work, we propose a method using frequency-modulated continuous-wave (FMCW) self-mixing interferometry (SMI) and all-phase fast Fourier transform (APFFT) for simultaneous measurement of speed and distance. APFFT offers superior accuracy in frequency determination by mitigating issues like the fence effect and spectrum leakage, contributing to the high-accuracy measurement for speed and distance. Both simulations and experiments have demonstrated relative errors at the levels of 10−4 and 10−3 for distance and speed measurements, respectively. Furthermore, factors impacting measurement performance have been discussed. The proposed method provides a high-performance and cost-effective solution for distance and speed measurements, applicable across scientific research and various industrial domains.