| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 1999: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1998: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
The measurements of the tree-dimensional ultrasonic wave sound pressure distribution were realized from the interference fringe pattern of the refractive index variation of the water by ultrasonic wave by real time stroboscope holographic interferometer with photorefractive BSO crystal. As a result of this study, following points were clarified.
1. As theoretical and experimental examination on the improvement on the hologram recording characteristics of the BSO crystal, the two wave mixing experiments were carried out on same crystals grown from various melt composition. The single-level and two carrier band transport theoretical model were applied to the experimental results, and the various parameters which contributed in the hologram recording characteristics, were determined.
2. Ultrasonic waves of 500kHz in water were irradiated with the laser pulse of 150ns duration by synchronizing to the ultrasonic wave oscillations. The holographic interference fringes of the ultrasonic wave we
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re formed by the light pulse with the real time stroboscope holographic interferometry optical system using the BSO crystal. The interference fringe images were input into the frame grabber board from CCD camera, and the images were analyzed by high sensitive interference fringe analysis method ( Fourier transformation method ). The good ultrasonic wavefront visualized images and the ultrasonic wave sound pressure distributions were obtained from values of phase change of the light wave.
3. Using the hydrophone of NPL certified, this ultrasonic wave sound pressure field was measured, and the good coincidence was obtained in comparison with sound pressure value by this technique, and the correctness of this measuring method was verified.
4. For the axisymmetric sound pressure field, this technique was applied, and Abelian conversion was carried out from projection data of the phase change quantity, and the three-dimensional sound pressure distribution was obtained. The ultrasonic wavefront that it radiated from circular aperture and diffracts was measured by this technique, and three-dimensional sound pressure distribution which shows the good coincidence with diffraction image got in fresnel diffraction theory was obtained as a grayscale image. And, the acoustic lens was manufactured, and convergence sound field of the ultrasonic wave by it was also applied, and the converged and effusing sound field was observed as a three-dimensional sound pressure distribution.
5. This technique was also applied to the observation of transient phenomenon for the measurement of such steady phenomenon, and the shock wave by a collapse of the bubble, which was made to arise by the water discharge, was observed. It was possible to estimate the pressure of the shock wave front from the measurement of the shock-wave velocity. Less
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