| Presentation | 2003/11/21 Nonlinearly generated second harmonic component in a focused beam reflected from free surface Shigemi SAITO, Ryuzo KAMURO, Yasuhiro SHIBATA, |
|---|---|
| PDF Download Page | PDF download Page Link |
| Abstract(in Japanese) | (See Japanese page) |
| Abstract(in English) | A second harmonic component nonlinearly generated in the focused sound wave is not so large compared to a plane wave in spite of strong sound concentration at the focus. One of the reasons for this phenomenon lies in the cancellation between the second harmonic components generated in the pre- and post-focal regions due the phase reversal of the sound at the focus. Hence, when another phase reversal is provided at the focal region so that the phase returns to the beginning state together with the effect of natural phase reversal, enhancement of the second harmonic generation is expected. To attain this, the reflection of the focused beam at a water surface set in the focal region is experimentally observed using a focusing source to receive the reflected second harmonic sound by itself, which employs a LiNbO_3 plate with domain inversion. The experimental result is compared with the theoretical calculation based on the Khokhlov-Zabolotskaya-Kuznetsov equation, where the condition of the phase reversal for both the fundamental and second harmonic components is assumed at the free surface. Although the theory predicts the second harmonic amplitude increased by over 2 times, the experiment reveals a significantly small amplitude of the second harmonic particularly in the small amplitude region. The cause of the disagreement is not clarified yet even through some discussion. |
| Keyword(in Japanese) | (See Japanese page) |
| Keyword(in English) | Nonlinear acoustics / Focused sound / Second harmonic sound / Diffraction effect / Reflection |
| Paper # | US2003-78 |
| Date of Issue |
| Conference Information | |
| Committee | US |
|---|---|
| Conference Date | 2003/11/21(1days) |
| Place (in Japanese) | (See Japanese page) |
| Place (in English) | |
| Topics (in Japanese) | (See Japanese page) |
| Topics (in English) | |
| Chair | |
| Vice Chair | |
| Secretary | |
| Assistant | |
| Paper Information | |
| Registration To | Ultrasonics (US) |
|---|---|
| Language | JPN |
| Title (in Japanese) | (See Japanese page) |
| Sub Title (in Japanese) | (See Japanese page) |
| Title (in English) | Nonlinearly generated second harmonic component in a focused beam reflected from free surface |
| Sub Title (in English) | |
| Keyword(1) | Nonlinear acoustics |
| Keyword(2) | Focused sound |
| Keyword(3) | Second harmonic sound |
| Keyword(4) | Diffraction effect |
| Keyword(5) | Reflection |
| 1st Author's Name | Shigemi SAITO |
| 1st Author's Affiliation | School of Marine Science and Technology, Tokai University() |
| 2nd Author's Name | Ryuzo KAMURO |
| 2nd Author's Affiliation | School of Marine Science and Technology, Tokai University |
| 3rd Author's Name | Yasuhiro SHIBATA |
| 3rd Author's Affiliation | School of Marine Science and Technology, Tokai University |
| Date | 2003/11/21 |
| Paper # | US2003-78 |
| Volume (vol) | vol.103 |
| Number (no) | 485 |
| Page | pp.pp.- |
| #Pages | 6 |
| Date of Issue | |