DIFFRACTION LOSS IN ULTRASONIC MEASUREMENTS ON HALF CYLINDERS AND HALF SPHERES

Abstract

In order to be able to obtain precise results from ultrasonic measurements on solid materials, the diffraction loss in the sound field of the transducer must be known. A simple plane parallel plate makes a suitable test body only if the contact transducer radiates the ultrasonic wave strictly perpendicularly through its front surface. Half cylinders and half spheres are more useful, because they allow the necessary adjustment of the reflecting bottom surface to be performed. The diffraction losses of the half cylinder and half sphere have therefore been calculated. In the case of the half cylinder, measurements were also performed. They are in good agreement with the calculated diffraction loss. These calculated diffraction losses are important for the calibration of contact transducers and many other precise pulse-echo measurements on solid materials.