Tip diffraction method is well known as a very exact sizing technique. Many researches for the technique have been done and several instruments have been developed. But almost all of the techniques require special instruments for it and so it is not easy to apply the techniques in field test where common ultrasonic flaw detector is used.

It is true that common flaw detector is not suitable to perform the tip diffraction methods in many applications. But in some cases, especially in sizing linear cracks, the common flaw detector is enough to measure the size of crack by tip diffraction signal with less precision.