Defect detection system and method

摘要

Detecting a defect in the sample is accomplished by photoacousticly exciting acoustic longitudinal, surface Rayleigh, and shear waves at a first point on a near surface of a sample; photoacoustically detecting acoustic waves at a second point spaced from the excitation first point for intercepting shear waves reflected from the far surface of the sample at approximately the angle of maximum shear wave propagation; and detecting the energy level of the intercepted reflected shear waves representative of the flaw in the sample.