Pulse-echo ultrasound ($z=ct/2$)

An emitted acoustic pulse is followed by detection of returning echoes. Travel time estimates depth under a declared sound-speed and path model, while echo amplitudes depend on interfaces and propagation losses.

A depth-versus-time display from repeated acquisition along one pulse-echo beam line.

A brightness-coded spatial image assembled from pulse-echo beam lines.

An amplitude-versus-depth representation of a single pulse-echo beam line.