Fig. 1. Schematics of vibration measurement by a fiber microprobe with internal modulation. (a) Optical part; (b) Signal processing

Fig. 2. Results of nonlinear errors from simulation. (a) Lissajous figures; (b) Phase demodulation error

Fig. 3. Schematic diagram of signal processing based on ellipse fitting

Fig. 4. Microprobe vibration measurement system based on internal modulation

Fig. 5. Measurement results of semi-simulation. (a) Vibration measurement results of 0.5 kHz; (b) Vibration spectrum of 0.5 kHz; (c) Vibration measurement results of 0.8 kHz; (d) Vibration spectrum of 0.8 kHz; (e) Vibration measurement results of 1.0 kHz; (f) Vibration spectrum of 1.0 kHz

Fig. 6. Lissajous figures in phase demodulation. (a) Initial Lissajous figure; (b) Lissajous figures after compensation of each step

Fig. 7. Phase demodulation results after each step. (a) Initial phase demodulation results; (b) First compensation; (c) Second compensation; (d) Third compensation

Fig. 8. Results of static displacement measurement

Fig. 9. Comparison results of linear displacement

Fig. 10. Results of vibration test. (a) Vibration measurement results of 25 Hz; (b) Vibration spectrum of 25 Hz; (c) Vibration measurement results of 50 Hz; (d) Vibration spectrum of 50 Hz; (e) Vibration measurement results of 600 Hz; (f) Vibration spectrum of 600 Hz

Fig. 11. Results of amplitude and THD at different vibration frequencies