Detection of Subsurface Defect by Photoacoustic Method

Abstract

In this study, the imaging of simulated subsurface defect using a photoacoustic (PA) microscope has been demonstrated. Two types of subsurface defects were fabricated in an aluminum plate specimen mechanically. The first subsurface defect has a cylindrical shape with length and diameter d of 2.0mm and 0.4mm, respectively and aligned parallel to the sample surface. The second subsurface defect had concave top shape, with lateral length of 6.0mm and aligned parallel to the specimen surface. The obtained PA image clearly showed the location and the size of both subsurface defects. The estimated specimen shape obtained from PA signal intensity distribution showed good agreement with the embedded actual specimen shape.