Time-domain flaw imaging system

Ultrasonic Non Destructive Evaluation of materials is a useful tool for flaw detection and characterization. A typical ultrasonic imaging system may consist of a single transducer or an array of sensors working in a B-scan mode. This mode operates by transmitting a pulse of train of pulses from several locations and detecting the echoes coming from in-homogeneities. The reflected energy can be represented as a map of ultrasonic reflectivity. A time-delay beamformer has been successfully used to reconstruct the image, and localize the inhomogeneities within the scanned medium, by time shifting the signals, and summing them up. This process enables to locate regions at which signals are added constructively. It is however, a time consuming process and requires lambda/2 distance of motor steps or inter-element distance between array elements. An algorithm based on time-domain envelope beamformer is presented here. This algorithm is able to diminish the number of computational operations without losing relevant information about the location of in-homogeneities. A comparison between classical and envelope beam-formers is presented when applied to sets of simulated signals. Lateral and longitudinal resolutions are also computed when two targets are within the scanned medium.