I hope that I understand your question correctly. Do you want to know the differences between ToFD and "ordinary" UT?
There is an interesting paper on this subject on the proknownet website, titled: THE APPLICATION OF THE TIME-OF-FLIGHT-DIFFRACTION INSPECTION TECHNIQUE ON GRP STRUCTURES.
While this paper deals with the technique for use on GRP, the principles remain the same for steels. This paper looks at the fundamentals of the ToFD technique. To see it, follow the link:
www.proknownet.com
Then click on the papers link in the LHS frame. Go to the search papers database page and enter pap-KIOJB as a key-word. (Or type in TOFD)
Hope it helps.
Regards
Niekie Jooste
