In this study, the nondestructive detection of an internal defect in the weld metal of an aluminum plate has been demonstrated using a photoacoustic microscope (PAM). The internal defects with actual defect in a specimen were fabricated in the inside of weld metal by the welding. The nondestructive detection of the position and size of the internal defect was carried out using the PAM. In addition, X-ray tomographic imaging was also carried out for comparison with the obtained PAM images. The information on depth direction and size of the internal defects was obtained from photoacoustic (PA) amplitude images and the signal intensity distribution.
