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

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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.