OPTICAL FIBER TYPE UNDERWATER SOUND DETECTOR

PURPOSE:To obtain an optical fiber type underwater sound detector having directivity by connecting plural pieces of detectors formed by winding optical fibers on anisotropic pressure sensitive elements in series, and detecting the change in the back scattered light of incident pulse light by sound pressure. CONSTITUTION:Plural pieces of detecting elements each consisting of optical fibers 11, 11' wound on anisotropic pressure sensitive elements 12, 12' of LiNbO3, etc. are connected in series and are so arranged as to sense only the sound pressures in X-, Y- and Z directions. The pulse light from laser light sources 31, 31' driven by a pulse generator 38 are made incident through semictransparent films 32, 32' to optical fibers 33, 33'. Since the distortion in the sound pressure increases in the winding parts of said fibers, the back scattering intensity increases. The back scattered light are reflected by the films 32, 32' and are made incident to photodetectors 37, 37'. The outputs thereof are converted to sound pressure intensities by a processing circuit 41, and said intensities are displayed on a display 42 via a timing generating circuit 39 and a masking circuit 40. The optical fiber type underwater sound detector having directivity is thus obtd.