Fig. 1. Schematic of the improved PGC demodulation algorithm for laser vibrometers

Fig. 2. Fitting results of the two algorithms for the simulated data

Fig. 3. Experimental setup

Fig. 4. Lissajous figures under different amplitudes of the LFM

Fig. 5. Waveform and spectrum of the voltage signal corresponding to interference light detected by PD

Fig. 6. Time domain waveform of two quadrature signals after low pass filtering

Fig. 7. Lissajous figures before and after ellipse fitting under different LFM

Fig. 8. Spectra of demodulated signals under the stimulating amplitude of 100 mV and different amplitudes of LFM

Fig. 9. Spectrum comparison of demodulated signals of two algorithms

Fig. 10. Lissajous figures of the quadrature signals with different C values

Fig. 11. SINAD and THD of demodulated signal under different C values

Fig. 12. Response linearity and noise floor of the system and waveform and spectrum diagrams of the demodulated signal when THD=1%

Fig. 13. Frequency response of the system's output amplitude

Fig. 14. Waveform and spectrum diagrams of the two demodulated vibration signals of the system