Development of fundamental technique of nonlinear ultrasound phased array system for estimation of aging structure

在分析相控阵探头声场的基础上，利用孔径合成技术将传统的非线性超声系统与商用相控阵系统相结合，实现了超声成像。然后，为了验证LiNbO_3，PMN-PT，PZT和PbTiO_3压电元件的有效性，我们使用上述元件制作超声换能器，并系统地估计每个元件的效率。因此，其他三种元件具有高效率约4至10倍，与LiNbO 3相比，这是我们现在主要用于非线性超声测量。由于LiNbO 3和PMN-PT均为单晶，无晶粒结构，在高压激励下具有更高的可靠性，因此PMN-PT有望成为最有前途的非线性超声测量材料。作为低成本的非线性超声测量系统，采用最大激励电压为600 V的方波脉冲发生器，并对其中的8个方波脉冲发生器进行了改进，研制成8通道相控阵系统。由于PT压电元件阵列的基本设计使用了IV 1 EIVIS光刻设备lb，证实了非线性超声阵列的有效性系统的基础上，应用超声光弹可视化系统对声场进行了观测，结果表明，与传统的非线性超声系统相比，低成本的方波脉冲发生器能够显示出足够大的超声位移幅值。此外，该阵列的声场可以用开发的八通道相控阵系统进行控制，尽管通道数量不够。从另一个角度讲，利用光弹性可视化方法可以建立阵列和阵列系统的评估体系。低成本非线性超声相控阵系统将在近几年进一步实现低成本脉冲发生器、高效率换能器和检测设备相结合的阵列系统。

After the analysis of sound field of a phased array probe, the conventional nonlinear ultrasonic wave system and the commercial phased array system were combined for ultrasonic imaging using aperture synthesis technique. Then, in order to verify the validity of piezo-electric elements of LiNbO3, PMN-PT, PZT and PbTiO3, we fabricate ultrasonic transducers using above elements and estimate the efficiency of each element systematically. Consequently, other three elements had high efficiency about 4 to 10 times comparing with LiNbO3 which is now we mainly used for nonlinear ultrasound measurement. Then PMN-PT can be expected as the most promising for nonlinear ultrasound measurement because LiNbO3 and PMN-PT are single crystal that expected higher reliability for high voltage excitation due to grain free structure. As the low cost nonlinear ultrasonic measurement system, square burst pulser with a maximum excitation voltage of 600V is applied and furthermore eight of these square burst pulser were improved to developed as a 8 channel phased array system.Eight channels array was also made of PMN-PT piezoelectric element due to the basic design of an array using the IV1EIVIS lithography equipment lb confirm the validity of the nonlinear ultrasound array system, ultrasonic photoelastic visualization system was applied to observe a sound field.As the conclusion, low cost square burst pulser shows the enough high amplitude ultrasonic displacement comparing with the conventional nonlinear ultrasonic wave system. In addition to this sound field of the array can control with the developed eight channels phased array system although the number of channels was not enough. From another view, we can establish the estimation system for array and array system by using the photoelastic visualization method. Low cost nonlinear ultrasound phased array system will realize in near further combining the low cost pulser high efficient transducer and estimation equipment of array systems.