Research On The Synthetic Aperture Focusing Ultrasonic Imaging Technique Applied To The Teaching Experiment

The synthetic aperture focusing ultrasonic imaging technique has been applied to engineering field widely as an ultrasonic flaw detection method,imaging with synthesis of small apertures to produce a large aperture,increasing the lateral resolution of the image.In this paper,the synthetic aperture focusing imaging algorithms was researched and the feasibility of the algorithms was verified according to the experiment,which could be applied to teaching experiment.The experiment plan has been designed.The main work has been done as follows:Firstly,based on the background of synthetic aperture focusing imaging technique,the synthetic aperture focusing imaging algorithms were studied.The calculating methods were brought forward on synthetic aperture length and delay time when ultrasonic wave propagated in two kinds of medium.Three kinds of SAFT imaging algorithms were studied respectively based on original algorithms which are the SAFT delay integer algorithm,SAFT introducing fractional delay coefficient algorithm and SAFT correlation algorithm.Then,based on the theory of the above,the experiment of scanning metal wires which was immersed in water by ultrasonic wave was made,and the experiment of scanning the aluminum sample was done by the ultrasonic instrument.The two experiments were corresponded with ultrasonic wave propagating in one kind of medium or in two kinds of medium respectively using the synthetic aperture focusing imaging algorithms.The feasibility of the synthetic aperture focusing imaging algorithms is verified by the study of the experiment.Finally,the synthetic aperture focusing imaging technique was applied to teaching experiment of college physics based on the study above,designing the teaching experiments which meet the demand of students.To begin with,an observational experiment of water immersion ultrasonic scanning echoes has been designed to make students familiar with laboratory practices and equipment,make students to be well-versed in the operation system with JDUT-1B type ultrasonic scanning imaging software.According to this experiment,students were able to distinguish the echo signal of each part in the waveform figure of the echo signal,and familiar with ultrasonic flaw detection rule by manual scanning.And then,the experiment of scanning wires which was immersed in water by ultrasonic wave and the experiment of scanning the aluminum sample which was immersed in water by ultrasonic wave were been design.Ultrasonic B scanning image was obtained by automatic scanning,which could be observed intuitively and be processed according to the synthetic aperture focusing imaging algorithms by students.The experiments above could deepen the understanding of students to the synthetic aperture focusing imaging technique,achieving the goal of experimental teaching.