Abstract:Damage imaging based on laser-induced surface acoustice wave is one of the difficult points of laser ultrasonie nondestruetivetesting. There exist the problems such as low imaging resolution, poor imaging efect and high equipment requirements. Aiming at theseproblems, propose that the 2D time-delay superposition imaging algorithm is adopted to improve the imaging quality. Firstly, throughexperiment and simulation, a variely of signals generated in the process of laser ultrasonie scanning are systematically analyzed. Based onthis, the imaging algorithm of laser-induced surface acoustie wave is improved. In this paper, the reetangular erack defects and circulardefeets with depth gradient are set up. Then, the defeets are scanned, detected and imaged with the laser ultrasonic scanning platform.In the images, the morphologies of the rectangular crack defects and circular defects are clearly reflected. The imaging results show thatthe resolution of the 2D time-delay superposition imaging algprithm is significantly improved compared with that of the energy method.The full width at half maximum is no more than 0.3 mm; and the measurement erors of the radius of the cireular defects and the lengthof reetangular erack defects are no more than 0.4 mm. And the algorihm also has certain measurement ability for the defeet depth.