Aplanatic Acoustic Lens for Underwater Imaging
In this paper, we describe the characteristics of an aplanatic lens which can eliminate both spherical and coma aberrations for improving the picture quality of underwater imaging sonar by the use of acoustic lens system. An aplanatic singlet with two aspherical concave surfaces was designed using a ray theory in paraxial area. The two aplanatic lenses with different aperture of 160 and 400 mm in diameter were made by acrylic resin and sound pressure fields were measured in a water tank for the on-axis characteristics and beam patterns on the focal planes of them in normal incidence on the frequency of 500 kHz. The difference of the convergence characteristics between two aplanatic lenses with different aperture was discussed. As a result, the beam width of the large aplanatic lens had the same characteristics as the small lens after correction of the F number of each lens. It may be concluded that the small lens with the ratio of the aperture to the wave length of 50 is sufficient to obtain the proper convergent performance of an acoustic lens system.
Toshiaki Nakamura Yuji Sato Kazuyoshi Mori
National Defense Academy,Yokosuka 239-8686,Japan Tsukuba University,Tsukuba,305-8573,Japan
国际会议
The 10th Western Pacific Acoustics Conference(第十届西太平洋声学会议WESPAC X)
北京
英文
1-8
2009-09-21（万方平台首次上网日期，不代表论文的发表时间）