Vn. Belyi et al., ULTRASONIC BEAM FOCUSING IN FERROELECTRIC CERAMICS BY APPLICATION OF A NONUNIFORM ELECTRIC-FIELD, Ultrasonics, 33(4), 1995, pp. 295-299
Citations number
14
Categorie Soggetti
Acoustics,"Radiology,Nuclear Medicine & Medical Imaging
A new solution to the problem of controllable focussing of ultrasonic
beams is given. It results from the fact that the application of a non
-uniform electric field, of a special configuration, in ferroelectric
ceramics causes a quadratic change of the velocity in the cross-sectio
n of an ultrasonic beam. A new type of a controllable device for acous
tic beam focussing - an electroacoustic lens - has been made. The desi
gns of lenses have been calculated on the basis of the quadratic elect
roacoustic effect and the results are presented of the first experimen
tal observation of the phenomenon of ultrasonic beam focussing in non-
uniform electric fields of special configurations. The dependence has
been established of the focal length on the lens length and the apertu
re, as well as on the control voltage value and the electroacoustic pa
rameters of the material. The lens was made of ferroelectric ceramics
lead-zirconate-niobate, (PbZn1/3NbO3)-based, and had a focal length of
15 cm at a control voltage of 5 kV.