The Characterization of the Cylindrical Ultrasonic Transducer Surface Vibration Using Far-field Acoustical Holography

The paper presents the results of investigation on the distribution of vibrational velocity on the surface of the cylindrical piezoelectric ultrasound transducers using far-field acoustical holography. In contrast to the plane and focused transducers, for which method of acoustic holography using the Rayleigh integral is applicable [1], cylindrical sources require scanning over a closed surface surrounding the source itself. This fact makes it difficult to use the Rayleigh integral. Therefore, the method of treatment based on the use of cylindrical functions and the Hankel transform is used. In the cylindrical case registration of evanescent waves in the tangential direction is required, even in the far field. It is shown that the accuracy of the method is limited by the standard diffraction limit of half the wavelength in the medium.