Fig. 1. Fiber-wrapped thin-walled cylinder. (a) Schematic diagram; (b) physical map

Fig. 2. Diagram of Michelson interference phase extraction calibration device based on 3×3 coupler. (a) Phase extraction calibration device; (b) schematic diagram of demodulation method

Fig. 3. Curves of relation between calculated value of sound pressure sensitivity and (a) material, (b) outer radius, and (c) wall thickness of thin-walled cylinder

Fig. 4. Phase of fiber wrapped on thin-walled cylinder with an outer radius of 25 mm and a wall thickness of 1 mm varies with sound pressure

Fig. 5. Research on acoustic response directivity of thin-walled cylinder. (a) Layout of incident azimuth of sound source in experiment; (b) sensitivity of sound pressure varies with azimuth

Fig. 6. Experimental measurement results of sound pressure sensitivity varies with (a) outer radius and (b) wall thickness of thin-walled cylinder

Fig. 7. Schematic of quasi-DAS system

Fig. 8. Original signals and demodulation results of quasi-DAS system. (a) Space-time diagram of detective signal; (b) time domain diagram and (c) spectrum diagram of demodulated signals in unsensitized sensing area; (d) time domain diagram and (e) spectrum diagram of demodulated signals in sensitized sensing area

Fig. 9. Sound pressure measured by microphone and DAS system

Table 1. Young’s modulus and Poisson’s ratio of different materials

Table 2. Parameters of outer radius and wall thickness of thin-walled cylinders used in experiments