Abstract
UT scanner must have the sampling intervals and a beam spot size smaller than potential flaws in materials in order to be able to detect them. If material longer than 1m must be tested with a pitch of 1mm, more than 1000 scan lines are needed to detect flaws, and the material cannnot be examined in common production lines. The number of horizontal scanning lines must be decreased to reduce testing time. Alternatively, the scanning speed must be increased. This study performs propagation analysis of an acoustic wave emitted from a probe and presents methods and the formulas to reconstruct 3D image of flaws in the sample with fewer horizontal scanning lines.