Scanning Laser Acoustic Microscopy with some Applications to Adhesion

Abstract

Acoustic microscopy became a powerful new tool in non-destructive evaluation (nde) of surfaces and subsurface imaging of optically opaque materials, in imaging of cells in biology, and a vast variety of other applications. Two different techniques have emerged for acoustic microscopy. In the Scanning Acoustic Microscope (SAM) a diffraction limited spot of an acoustic beam is obtained by an acoustic lens in direct analogy to optical microscopy. Imaging is performed by measuring the acoustic reflectance or transmission of an object in the focused spot/1/. In contrast, Scanning Laser Acoustic Microscopy (SLAM) utilizes plane waves. Both methods have the ability to penetrate materials provided the sound absorption is sufficiently small at the employed frequency. Scanning Laser Acoustic Microscopy became commercially available some years ago as a tool for non-destructive evaluation of ceramics, tissue characterization of biological materials, and testing of adhesive bonds. We shall first discuss its principle, and then present applications related to adhesion.