Ultrafast hardware-based focal law calculator for automatic focusing

Phased array ultrasonic imaging of arbitrarily shaped components at high scanning speed demands computing an adapted set of focal laws before each new image. This requires computing the individual time-of-flight (TOF) from array elements to foci in a two media scenario. Most precedent approaches to this problem were based on iterative search for the minimum TOF in a sampled interface (Fermat׳s principle). This work follows a different approach by implementing a specialized processor that performs TOF computations. Several algorithms are implemented using High Level Synthesis (HLS) for state-of-theart FPGAs: Fermat iterative search, Newton–Raphson, Illinois and a combination of the latter.