Throughout my 40 years in nondestructive testing (NDT), thickness gages have gone through a tremendous journey. From analog to highly intelligent digital gages, the transformation has been amazing.
Ultrasonic thickness gages operate as a system consisting of a gage with a pulser/receiver, a transducer and cable. The transducer transforms electrical energy into mechanical energy, or vibrations. The time it takes these vibrations to enter a homogeneous material, reflect off an interface, and return to the transducer, at a given sound speed (velocity), is calculated as a thickness.