NDLI: Sound fields focused by a biconcave acoustic lens for normal and oblique incidence

Content Provider	IEEE Xplore Digital Library
Author	Nakamura, T. Hashimoto, M. Mori, K. Kamakura, T. Anada, T.
Copyright Year	2005
Description	Author affiliation: Nat. Defense Acad., Yokosuka, Japan (Nakamura, T.; Hashimoto, M.; Mori, K.)
Abstract	In this report, a sound pressure field focused by a biconcave lens was investigated using the wave theory and the numerical methods of the parabolic equation (PE) method and finite difference time domain (FDTD) method for normal incidence. For oblique incidence, the hybrid method which combines ray theory and wave theory was used in the calculation. The experimental data were compared with the theoretical results shown above. The experimental on-axis characteristics around the focal point agreed well with the calculated results but disagreed with the results for in front and behind the focal region. It was found that the second peak existed behind the focal point for normal incidence, though there is no second peak in the theoretical results by the analytical method and the FDTD method. After the numerical analysis by the hybrid method and the PE method, the second peak was found at the same position as the experiment. This was thought to be caused by the influence of the edge of the lens, which has a finite size. The dependence of convergent characteristics for oblique incidence was also compared with the results by the hybrid method.
Starting Page	62
Ending Page	67
File Size	973863
Page Count	6
File Format	PDF
ISBN	0780391039
DOI	10.1109/OCEANSE.2005.1511685
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2005-06-20
Publisher Place	France
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Lenses Finite difference methods Acoustic imaging Optical imaging Acoustic waves Focusing Time domain analysis Acoustic arrays Sonar equipment Acoustic beams
Content Type	Text
Resource Type	Article

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