UACE2023: Preliminary Analysis of Sound Field Converged by Convex Acoustic Lens for Installing in Small AUV's Bow



    • Session:
      Acoustic imaging
    • Paper:
      Preliminary Analysis of Sound Field Converged by Convex Acoustic Lens for Installing in Small AUV's Bow
    • Author(s):
      Hiroyuki Kawahara, Hanako Ogasawara, Kazuyoshi Mori
    • Abstract:
      AUVs haves been developed to conduct underwater surveys in unexplored areas such as those around marine volcanoes and in frozen seas that are dangerous and difficult to investigate with manned submersibles. Many AUVs are comparatively small, with various mounted measuring devices; thus, their power supply and mounting space are limited. Under such circumstances, an acoustic lens mounted on the bow of the AUV, was proposed for use as an underwater imaging sonar for obstacle avoidance. Recently, this acoustic lens system has attracted renewed attention due to its fast frame rate, compact size, and low power consumption by utilizing its own refraction effect.\n In this study, we investigated the aberration and converged sound field of a convex acoustic lens for installation in an AUV bow. It was assumed that the lens consisted of solid shell and inner liquid. Aberration was analyzed by the ray tracing method, and converged sound field was computed by the finite difference time domain method. In order to minimize the aberration and maximize the focused sound pressure, material combinations and shell shapes were investigated for optimal lens design. The preliminary analysis results showed that an effective convergence performance was obtained by a shell combining a spherical outer surface and aspherical inner surfaces, and with a material combination of syntactic foam and silicone oil or syntactic foam and fluorinert.
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    Contact details

    • Contact person:
      Mr Hiroyuki Kawahara
    • e-mail:
    • Affiliation:
      National Defence Academy of Japan, Master Course Earth Science and Civil Engineering
    • Country:
      Japan