A - Scan
"A" means Amplitude-Scan. The A-Scan shows the reflected ultrasonic echo
over the time. The information is contained in the way the acoustic wave is
from the specimen. Time of
flight ("TOF"), Amplitude and Phase of the reflected echo are the base for
the acoustic image.
Only certain parts of the echo signal are image-relevant. They can be
selected by setting gates within the A-Scan histogram. Position and length
of these gates define depth and thickness of the investigated layers.