Fig. 1. Structure of vibration sensor and elastic diaphragm. (a) Three-dimensional model of vibration sensor; (b) side view of vibration sensor; (c) plan view of elastic diaphragm

Fig. 2. Simulation results of mass block and crossbeam of elastic diaphragm. (a) Simulation of resonant frequencies for different mass block radius and thickness; (b) simulation of resonant frequencies for different beam width and thickness

Fig. 3. Simulation results of elastic diaphragm. (a) Simulated deformation with acceleration of 1g and frequency of 600 Hz; (b) simulation results of frequency response of elastic diaphragm

Fig. 4. Fabrication steps of vibration sensor. (a) Diaphragm embedded in ceramic bracket; (b) dimensional drawing of ceramic shell with pressure block; (c) integrated diagram of ceramic ferrule and optic fiber; (d) side dimension diagram of vibration sensor; (e) overall physical image of vibration sensor

Fig. 5. Comprehensive schematic diagram of vibration measurement system. (a) Model of acceleration measuring device; (b) hardware architecture based on FPGA; (c) physical image of circuit and FP demodulator; (d) interference spectrum of vibration sensor

Fig. 6. Demodulation rate testing of FP demodulator. (a) Diagram of demodulation rate testing device; (b) variations of cavity length at frequencies of 1, 5, and 10 kHz when a voltage of 5 V is applied

Fig. 7. Stability testing of vibration sensor under static conditions. (a) Relative variation of FP cavity length within 60 s; (b) histogram of relative variation distribution of cavity length

Fig. 8. Measurement results of frequency response of vibration sensor. (a) Time domain response waveforms at different frequencies under acceleration of 1g; (b) axial deformation from 200 to 5000 Hz under acceleration of 1g

Fig. 9. Shock response experiment of vibration sensor. (a) Free shock response time domain signal; (b) FFT result

Fig. 10. Measured time domain waveforms of cavity length under different accelerations at 200, 400, and 600 Hz

Fig. 11. Linear fitting curves of cavity length versus acceleration at 200, 400, and 600 Hz

Fig. 12. Linear fitting curve of vibration sensor with three repeated tests at 600 Hz

Fig. 13. Interference immunity. (a) Time domain waveform with a frequency of 600 Hz and an acceleration of 4g; (b) linear response of vibration sensor when vibration direction is axial direction and cross direction, respectively

Fig. 14. Large scale impact test. (a) Impact test bench; (b) 200g impact test results of vibration sensor