Novel imaging method in scanning acoustic microscopy for thin films

A novel virtual cavity scanning acoustic microscope (VSAM), in which a resonating acoustic cavity is formed by a PZT plate mirror and an acoustic lens, has been developed. Resonance conditions were obtained by placing a PZT mirror in the focal plane of the acoustic lens and air bubble samples were examined. Practical geometry conditions and expressions for the acoustic resonance quality factor and loss, are given. This resonance phenomenon is used for high amplification of small acoustic signals and for the signature identification of surface and subsurface soft features in acoustic microscopy. A dedicated 3D image processing software has been used to extract detailed images of the scanned objects in resonance.