海洋音響学会誌
Online ISSN : 1881-6819
Print ISSN : 0916-5835
ISSN-L : 0916-5835
50 巻, 3 号
選択された号の論文の1件中1~1を表示しています
論文
  • 田邊 昭子, 佐藤 裕治, 海老原 格, 若槻 尚斗, 水谷 孝一
    2023 年 50 巻 3 号 p. 56-66
    発行日: 2023/07/01
    公開日: 2025/01/25
    ジャーナル フリー

    Acoustic lenses, which focus sound waves in water without using complicated electronic circuits, are attracting attention as a device to realize miniaturization and power saving of underwater acoustic cameras and sonar. The shapes of acoustic lenses vary widely, but they are designed based on optical theory. Therefore, it is often assumed that total reflection occurs when the angle of incidence exceeds the critical angle, and the transmission characteristics of acoustic lenses are often evaluated at the angle of incidence within the critical angle. However, since the thickness of an acoustic lens is thinner than that of an optical lens, the evanescent field may affect the transmission of sound waves through the lens even when the incident angle exceeds the critical angle. In this study, we designed a biconcave acoustic lens with multiple thicknesses and investigated the focusing characteristics of sound waves incident on the lens at angles exceeding the critical angle. Consequently, it was found that when the minimum thickness of the lens is about one-third of the wavelength, the sound wave penetrates the narrow part of the lens significantly, and the lens may function as a lens even beyond the critical angle.

feedback
Top