Novel Inspection Technique for Simultaneous Visualization of Two Waveforms Obtained by Two-Channel Simultaneous Monitoring

A novel inspection technique for the simultaneous visualization of two waveforms in two-channel simultaneous monitoring using two transducers is proposed. In this technique, the two-channel scattering waves as well as the incident waves from two directions are simultaneously visualized. Compared to the conventional inspection method that uses a single transducer, this technique not only contributes to intuitive and easy interpretation by making use of movies of scattering waves but also halves the inspection time. For a thin aluminum plate with a penetrating slit, scattering phenomena are visualized using two transducers placed at an angle of 90o to the target. For a thick plate with a small rectangular defect on the back surface, waveforms are visualized by two facing transducers. It is shown that the orthogonal positions of the two transducers relative to the target are important, particularly in testing for line-shaped cracks. This technique is a promising candidate for laser-excited ultrasonic inspection.