TOFD originated from tip diffraction techniques which were first published by Silk and Liddington in 1975 which paved the way for TOFD. Later works on this technique are given in a number of sources which include Harumi et al.
The concept of TOFD (Time-of-Flight Diffraction) originated from tip diffraction techniques first described by Silk and Liddington in 1975. This paved the way for further development of the technique.  Harumi et al.'s work has contributed to the advancement of this method.