Fig. 1. Structure of DLP-3D printing optical fiber FPI acoustic emission sensor

Fig. 2. Numerical simulation diagram of relationship among natural frequency, thickness, and effective radius of sensitive diaphragm

Fig. 3. Simulation of extinction ratio under different reflectivity

Fig. 4. Demodulation principle of optical fiber FPI acoustic emission sensor. (a) Schematic of interferometric-intensity demodulation mechanism; (b) variation of reflected light intensity obtained by device with/without acoustic emission signal

Fig. 5. DLP printing technology to prepare optical fiber FPI acoustic emission sensor. (a) Working principle of DLP-3D printer; (b) flow chart of optical fiber FPI acoustic emission sensor printing

Fig. 6. 3D printing sensor head. (a) Physical picture; (b) microscopic image of cross-section of printed diaphragm

Fig. 7. Reflection spectra of 3D printing FPI sensor

Fig. 8. Schematic of experimental system for 3D printing FPI acoustic emission sensor

Fig. 9. Sound pressure frequency response of FPI acoustic emission sensor. (a) Waveform response of 3D printing FPI acoustic emission sensor; (b) corresponding FFT frequency spectra

Fig. 10. Sound pressure intensity response of FPI acoustic emission sensor. (a) Waveform response of FPI sensor under different sound pressures; (b) sound pressure response characteristic