Micro-vibration measurement based on current modulation and secondary feedback self-mixing interference technology

摘要

The secondary feedback self-mixing interference (2FSMI) technology used to measure the micro-vibrations of objects is more accurate than the self-mixing interference (SMI) technique, and current modulation is a commonly used modulation method. Therefore, current modulation and 2FSMI technology are combined to measure micro-vibrations with different amplitudes within a wavelength. First, the interference signal is current-modulated by a sawtooth wave. Second, the collected signal is preprocessed. Third, the preprocessed signal is subject to fast Fourier transform spectrum analysis. Finally, the micro-displacement of the vibrating object is reconstructed. Experimental results show that the maximum error of this method in reconstructing the micro-displacement of a vibrating object is less than 13nm, which is approximately half that of the SMI technique. Moreover, this method can reconstruct not only sinusoidal vibrations but also arbitrary waveform vibrations. Therefore, using this method to measure object vibration can yield high measurement accuracy without increasing the experimental device.