Fig. 1. Frequency relationship between reference wave and signal wave in sawtooth wave modulation

Fig. 2. Flow chart of phase demodulation algorithm based on zero-crossing detection method

Fig. 3. Beat signal peak clipping

Fig. 4. Flow chart of the phase demodulation algorithm based on centroid peak-finding method

Fig. 5. Phase error and displacement error corresponding to 10~60 dB signal to noise ratio. (a) Zero-crossing detection method; (b) Centroid peak-finding method

Fig. 6. Schematic diagram of a frequency-modulated continuous-wave laser interference displacement sensor

Fig. 7. Physical drawing of FMCW interferometric displacement measurement system

Fig. 8. Beat signal and sawtooth signal acquired. (a) Sawtooth signal; (b) Beat signal

Fig. 9. Random error and distribution of displacement when the length of the F-P cavity is 44 mm fixed by zero-crossing detection method. (a) Random error of displacement fixed distance; (b) Random error distribution

Fig. 10. The random error and distribution of displacement when the length of the F-P cavity is 44 mm fixed by the centroid peak-finding method. (a) Random error of displacement fixed distance; (b) Random error distribution

Fig. 11. Comparison of the standard deviation of displacement random error between zero-crossing detection method and centroid peak-finding method when F-P cavity length is different