Abstract
In ultrasonic pulse-echo measurements with a long waveguide (also known as a buffer rod), the unwanted spurious echoes (often called trailing echoes) are often generated and deteriorate the signal-to noise (S/N) ratio of the main echo. In our previous work, we had proposed and investigated a new method that can reduce such trailing echoes. In the method, the cross-sectional shape perpendicular to the axial direction of the buffer rod is a regular odd polygon in which any side of the rod is not parallel to any of the other sides, so that trailing echoes are hardly generated due to the geometrical effect of the odd polygons. However, unfortunately, small trailing echoes are still generated even for such odd polygons due to symmetry of the cross-sectional shape. In addition, the mechanism for the generation of trailing echoes has not been clarified. In this work, the mechanism to reduce the generation of trailing echoes for buffer rods having the cross-sectional shapes of odd polygons is examined.
