English: Animated diagram showing how an ultrasound imaging array works. It consists of a beamforming oscillator (TX) that produces an electric signal consisting of pulses of sine waves oscillating at an ultrasonic frequency, which is applied to an array of transducers (T) in contact with the skin surface that convert the electric signal into ultrasonic waves traveling through the tissue. The timing of the pulses emitted by each transducer is controlled by programmable delay units (φ) that are controlled by a micropricessor control system (C). The moving red lines are the wavefronts of the ultrasonic waves emitted by each transducer. The wavefronts are spherical, but they combine superpose to form plane waves, creating a beam of sound traveling in a specific direction. Since the pulse from each transducer is progressively delayed going up the line, each transducer emits its pulse after the one below it. This results in a beam of sound waves emitted at an angle to the array. By changing the pulse delays, the computer can scan the beam of ultrasound in a raster pattern across the tissue. The echoes reflected by different density tissue, received by the transducers, build up an image of the underlying structures.