Study On Image Processing And Imaging Technology Of The Ultrasonic Phased Array Testing System

Ultrasonic Testing is a research hotspot in NDT field at present. Through controlling the sound wave interference, it can make the sound beam steer and focus, which enable it be applied in inspecting work object with complicated structure. Now, it is being studied by universities, and research acheivements are applied in industrial NDT filed. As is required by defect testing and recognizing, the quality of defect image has been highly concerned. This thesis focuses on research on plan designing, image processing and imaging technology of ultrasonic phased array system.Firstly, the basic principle and knowledge of ultrasonic phased array are introduced. Civa software is used to simulate the basic properties of ultrasonic phased array system and probe paremeter designing is discussed, which has provided the designing of experiment with theoretical basis. Several kinds of ultrasonic image forming mechanism are introduced, which provides the basis of following imaging part.Secondly, how to improve the quality of image is discussed and experiment is conducted. Aim at the interference noise caused by diffuse reflection, filter is used to finish the denoising. After comparation of results of several algorithms, Lee algorithm has the best result. Then some typical fake defect images are elimated, which improved the quality of image.Thirdly, for the characteristics of ultrasound testing, the defect image is not focused enough, which lead it to have a larger size. Then the synthetic aperture focusing imaging algorithm is used for imaging. But the effect of this algorithm on line defect is not obvious. After analysis, decide to use the result of image adding of point defects as line defect. Rebuild the point image by synthetic aperture focusing imaging algorithm and add these images together each with a displacement of one probe element. Use the result acquired to take the place of line defect image rebuilt by synthetic aperture focusing algorithm. Through simulation and experiment, the method is proved to be feasible, and the defect image rebuilt is more in accordance with the real defect.