Abstract: An ultrasonic head is a linear array consisting of a plurality of transducer elements. The array is perpendicular to a sectional plane of the object under study and can be rotated about its longitudinal axis. Several groups each consisting of jointly controlled transducer elements are driven to form a beam aperture. Between each two adjacent driven groups there is provided at least one group that is switched off. The ultrasonic tomography unit thus obtained scans several parallel section levels one after the other or even, at least approximately simultaneously, without additional mechanical movement.