Pulse-echo imaging
= Pulse-echo imaging
<Pulse-echo imaging> sends a short acoustic pulse and records echoes returning from interfaces or scatterers. If <sound speed> is approximately constant and the path is straight, an echo delay $t$ corresponds to range $r=ct/2$, because sound travels to the scatterer and back.
Scanning beam direction and measuring echo strength produces an image. Pulse duration and bandwidth affect <axial resolution>, while beam width affects transverse resolution. Incorrect sound-speed assumptions distort inferred positions, and multiple reflections can create echoes that do not correspond to a single direct round trip.