| 摘要 |
<p>For digital ultrasound echography beams are produced by piezoelectric transducers, with varying delays and phase shifts. These are controlled, offering specific dynamically controlled delays and phase shifts, using tables of data relating to each of the transducers in use. The digital ultrasound echography technique uses a network of piezoelectric ultrasound transducers, producing beams which focus at a distance. The beams are produced with varying delays and phase shifts. The process for controlling the production of delays, for these ultrasound beams, includes memorizing in three tables (5,6,7), parameters relating to each of the transducers of the echographic probe. These parameters include the inverse of reception times (1/t - tau00), the shift values (tau00) and the corresponding indices (ND). The parameters also include values (DELTA2) which are a function of the square of the distance from the element (K) which is taken to be the central reference. The delay (tauk(t)) is calculated by applying, at each instant, t, the formula: tau(t) = tau00 - (DELTA2 tau-02) / (t - tau00).</p> |
