Fig. 1. Structure of the SPM-LD interferometer for the large-range displacement measurement.

Fig. 2. Curve of Eq. (8) in the interval of (0, 5) and with a 0.1 step.

Fig. 3. Update for the dynamic value of the effective SPM depth using the novel method in the numerical simulations.

Fig. 4. (Color online) (a) Measurement results for 1 mm/s constant-velocity motion in the numerical simulations. (b) Relative errors of the measurement results. (c) Cumulative amplitude spectrum (CAS) of the relative errors.

Fig. 5. Amplitude of the modulated laser with an 8 kHz SPM signal in the experiments.

Fig. 6. (Color online) (a) Update for the dynamic value of the effective SPM depth using the novel method in the experiments. (b) Measurement results for the traditional method and the novel method in the experiments. (c) Relative errors of the measurement results in the experiments.

Fig. 7. (Color online) (a) Relative errors after the high-pass filter in the experiments. (b) CAS of the relative error after the high-pass filter in the experiments.