Time of Flight Diffraction

Time of Flight Diffraction

TOFD technique uses two probes, one for transmitting and the other for receiving The UT beam produces a diffracted signal from the flaw extremities, which act as point sources, as well as a reflected signal. The diffracted signals appear as signals arriving at different times at the receiver. This technique is used to improve the depth sizing estimates of a flaw based on geometrical calculations of the signal arrival times. The disadvantages are where the different signals cannot be resolved in time (small flaws, flaws close to the inspection surface) and the amplitude of the diffracted signals can be low.