The Research On Ultrasonic Phased Array Dynamic Focusing Technology

By controlling the delay time of the ultrasonic phased array phased array probe to achieve the sound beam deflection and focusing, in order to achieve fast and efficient detection of the work piece. The key technology of the Ultrasonic phased array system is by controlling the transmission and reception’s time and space of the beam effectively, to obtain high-quality sound beam and sound field. Phased array technology, including digital phase delay, dynamic focusing, dynamic apodization, dynamic aperture, coded transmitter, etc., and dynamic focusing technology is a technology which is more critical. Dynamic focusing technology can improve the depth of focal area of the focus, reducing the width of the focus, so it can improve the consistency and the spatial resolution of the acoustic beam, and then provide a more reliable basis for detecting defects.In this paper, the principle of ultrasonic phased array focusing technology and the factors which affecting the accuracy of the phased array is studied. I have proposed a method to improve the phase delay and conventional focused beam resolution, and use dynamic focusing technology in ultrasonic phased array system.This paper completed the following tasks:1. Discussing the ultrasonic phased array inspection related theories, including transducer array radiation theory, and the beam control method in ultrasound detection, based on the phased array’s acoustic radiation theory, establishing a one-dimensional array transducer sound field model, analysis the effects that various parameters in the model to focused acoustic beam systematic, gives the parameter selection basis of improved dynamic focusing of ultrasonic phased array imaging quality.2. The simulation shows that, under the premise that the parameters of the transducer array has been given, the delay accuracy is an important factor which affecting the dynamic beam focus.3. Compression method of dynamic focusing delay parameters is proposed. Firstly, delay parameters are decomposed into relative delay parameters of adjacent array elements and are quantification; and then the initial values and the change locations of relative delay parameters are stored to achieve the compression storage. Atlast, the storage data in the process of dynamic focusing is decompressed to achieve real-time generation of delay parameters required. Performance analysis shows this method significantly reduces the storage of delay parameters.4. Designing high precision ultrasonic phased array transmitter module by using FPGA, under the premise of improving the accuracy of the delay to solve the problem of synchronization between the plates.