Method of forming the output surface of a focussing ultrasonic transducer and a transducer comprising such an output surface.

摘要

This method is characterised in that it includes the following steps: - a first set of reference points with coordinates x, z in a beam incidence plane is calculated (at 10), by varying the beam aperture angle, and such that the ultrasound times of travel for journeys passing through these points and through the focal point are identical, - analogously, a second set of reference points with coordinates y, z in a plane perpendicular to the incidence plane is calculated (at 10), - two polynomials of degree 4 are defined (at 11) by polynomial interpolation by the method of least squares of these two sets of points: f(x) = ax<4> + bx<3> + cx<2> + dx g(y) = a'y<4> + b'y<3> + c'y<2> + d'y - the coordinates of the points of the output surface are determined (at 12) through the relation: z = f(x) + g(y); and - the output surface is formed (at 12) from these coordinates. <IMAGE>