Measurements of Three-dimensional Sound Pressure Distribution of Ultrasonic wave by Holographic Interferometry with BSO crystal

利用光折变BSO晶体的实时频闪全息干涉仪，根据超声波作用下水的折射率变化的干涉条纹，实现了三维超声波声压分布的测量。作为这项研究的结果，澄清了以下几点。作为改善BSO晶体全息记录特性的理论和实验检验，对不同熔体成分生长的同一晶体进行了两次混频实验。将单能级和双载流子输运理论模型应用于实验结果，确定了影响全息图记录特性的各种参数。用150 ns的激光脉冲与超声波振荡同步辐射500 kHz水中的超声波。超声波WE-…的全息干涉条纹采用BSO晶体的实时频闪全息干涉光学系统，通过光脉冲形成更多的光脉冲。将干涉条纹图像从CCD摄像机输入到图像采集板，用高灵敏度干涉条纹分析方法(傅里叶变换法)对图像进行分析。根据光波的相变值，得到了较好的超声波前可视化图像和超声波声压分布。利用NPL认证的水听器对该超声波声压场进行了测量，并与声压值进行了对比，取得了较好的一致性，验证了该测量方法的正确性。对于轴对称声压场，应用该技术，对相变量投影数据进行阿贝尔变换，得到三维声压分布。利用该技术测量了圆孔和衍射体辐射的超声波前，得到了与菲涅耳绕射理论得到的衍射像具有较好一致性的三维声压分布作为灰度图像。制作了声透镜，并对其产生的超声波会聚声场进行了应用，观察到会聚和出射声场为三维声压分布。这项技术还被应用于观测瞬变现象，以测量这种稳态现象，并观察到了由水排放引起的气泡破裂所产生的冲击波。通过对冲击波速度的测量，有可能估算出冲击波阵面的压力。较少

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 … More 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