Fig. 1. Schematic diagram of displacement measurement.

Fig. 2. Schematic diagram of displacement reconstruction: (a) SMI signal; (b) derivative of SMI signal; (c) result of fringe counting method; (d) result of interpolation method.

Fig. 3. SMI experimental system of displacement measurement.

Fig. 4. (a) Experimental SMI signal of PZT vibration; (b) local amplification of experimental SMI signal of PZT vibration.

Fig. 5. EEMD result of the experimental SMI signal.

Fig. 6. Comparison of filtered signals with different IMFs.

Fig. 7. (a) Envelope of filtered SMI signal; (b) normalized SMI signal; (c) reconstructed displacement signal; (d) error of reconstruction displacement.

Fig. 8. (a) Experimental SMI signal of linear displacement table; (b) derivative of experimental SMI signal.

Fig. 9. (a) Envelope of filtered SMI signal; (b) normalized SMI signal; (c) derivative of normalized SMI signal; (d) reconstructed displacement signal; (e) relative error of reconstruction displacement.