An apparatus for detecting the structure of a weld, comprising: a plurality of sensors (1052) for generating a series of periodic ultrasonic waves for transmission in a welded body, which receiver (1052) are provided in a two-dimensional array; a multiplexer for directing transmission of an ultrasonic wave from each of the transducer (1052) and for receiving return signals from the transducer (1052); a transition time stretch (1054) for contacting a surface of the welded body; a computer control system that is configured to direct the transmission of the ultrasonic waves and for receiving and interpreting signals received from the sensors data; and a display unit for visually displaying the interpreted data from the computer control system, wherein the computer control system the data received from the receivers data processed to a indentation depth under each sensor (1052) from both sides of the weld for the purpose of reconstruction of an impression shape and calculation of a pickup tilt value for each to determine receiver (1052).