Resolution of electronically controlled ultrasonic scanner - is improved by phase control focussing with outlying members of transducer group advanced or retarded (NL 3.6.77)

摘要

Each spt of the scan is produced by a group of transducers working together. The signal emitted by the outlying elements of the group is smaller in amplitude and earlier in phase than that emitted by the central elements, and the echoes are treated correspondingly. This produces an electronic focussing of the beam, similar to the physical focussing produced by a curved transducer. For heart scanning a circular array of transducers is preferred to a linear one. It emits the outlying signals at a later phase than the central ones.