An Algorithm for Measuring Vibration Frequency of Self-Mixing Interference Signal Based on Fast Fourier Transform

摘要

Optical feedback self-mixing interference (OFSMI) technology can be used to measure the micro-vibration of the object. Existing algorithms have problems such as small frequency measurement range, low precision, and unstable under different optical feedback level factors. In order to extract the vibration frequency accurately, this paper proposes a measurement algorithm based on Fast Fourier Transform. By analyzing the frequency domain characteristics of the self-mixing interference signal, the algorithm can accurately extract the vibration frequency of the object from the fundamental spectral component. The spectrum optimization algorithm and filter algorithm effectively reduce the impact of noise and other interference on the measurement results. Finally, the computer simulations and actual vibration measurements are carried out for different vibration frequencies. It is proved that the higher the frequency is, the higher the accuracy is. And the relative deviation can be controlled within 2% when the vibration frequency is higher than 100 Hz.