Nondestructive evaluation of simulated corrosion by the use of photoacoustic and new photothermal imaging

Nondestructive imaging of surface defects fabricated on a metal plate immersed in an electrolyte has been performed with a new photothermal detection scheme. A periodically modulated beam of an Ar⁺-ion laser is focused onto a sample and scanned two-dimensionally across its surface. An imaging under the environment of electrolyte based on the principle of the detection was carried out with two- and three-terminal configurations. These results were compared with that obtained with a conventional photoacoustic imaging.