Time of Flight Diffraction (TOFD) uses the time of flight of an ultrasonic pulse to determine the position and size of a reflector. When a crack is present, there is a diffraction of the ultrasonic wave from the tip of the crack. Using the measured time of flight of the pulse, the depth of a crack tips can be calculated automatically by simple trigonometry.

Eddy current testing is the process of running electronic probes through the length of various types of tubes or along the surfaces of materials in order to find flaws in them. An eddy current is a current that runs opposite to the current introduced by a probe into a conductive material.

Phased arrays are used to detect the image defects including cracks, voids, and pits caused by corrosion. They are used to measure material and coating thickness and to detect changes in material properties.