Distributed optical fiber sound wave detection device

A distributed optical fiber sound wave detection device that uses an optical fiber as a sensor, comprising:

• an optical pulse emission unit that causes an optical pulse to be incident into the optical fiber from one end of the optical fiber;
• and
• a Rayleigh scattered light reception unit that receives Rayleigh scattered light produced inside the optical fiber by the incidence of the optical pulse, wherein
• the optical pulse emission unit outputs the optical pulse that is modulated using a code sequence which has a predetermined length based on a length dimension of the optical fiber and by which the optical pulse is divided into a plurality of cells of a predetermined width, and
• the Rayleigh scattered light reception unit includes:
• a phase variation derivation unit that performs demodulation corresponding to the modulation in the optical pulse emission unit on the Rayleigh scattered light and determines a phase variation thereof from the demodulated Rayleigh scattered light;
• and
• a sound wave detection unit that determines a sound wave that has struck the optical fiber from the phase variation determined by the phase variation derivation unit.