Abstract
Surface and subsurface layers of structured materials were observed as the amplitude and phase images of X-ray photoacoustic signals. An X-ray beam from synchrotron radiation was narrowed with the use of a lead slit and allowed to irradiate the sample in the photoacoustic cell. A laminated sheet of aluminum and lead foils and a flexible print circuit board were used as samples. For the laminated sample, the empty space in the subsurface lead layer was clearly visualized in the images of both amplitude and phase delay. The results were compared with those of the photoacoustic measurement in the visible region. For the flexible print-circuit board, the printed copper strips were observed in both the amplitude and the phase images. The circuit pattern below the surface polymer layer was observed as signals with large phase delays.
