Ultrasonic Three-Dimensional Imaging Using a Circular-Array Transducer for Inspection

Abstract

A new ultrasonic three-dimensional imaging method is described for inspection. We developed a new two-dimensional ultrasonic scanning method using a circular-array transducer in which numbers of small piezoelectric elements were arranged in a circle. By computer simulation, it was proved that circular-array had lower grating-lobe level and made more uniform scanning in space than a matrix-array. To obtain 3-D data, we proposed two-dimensional electronic scanning method which was made the best use of the geometric characteristic of a circular array transducer. The results of experiments for generation of an ultrasonic beam and 2-D imaging using a trial transducer confirmed directivity of the transducer and possibility of 3-D imaging by the circular array transducer. Obtained data in a ultrasonic testing is 4-dimensions, this is echo position(x, y, z) and sound intensity. To express the data, we proposed a new color conversion technique. Hue and brightness were used as a parameter of perspective and sound intensity, respectively. We evaluated the method with the off-line system to develop the real-time 3-D imaging system.