An Iterative Algorithm for Scanning Tomographic Acoustic Microscopy

Abstract

Acoustic microscopy is capable of providing high-resolution images of small objects. When such a microscope operates in the transmission mode, it produces simply a shadowgraph of all the structures encountered by the acoustic wave passing through the object. The resultant images are difficult to comprehend because of diffraction and overlapping of complex structures. Scanning tomographic acoustic microscopy (STAM) overcomes these difficulties and produces unambiguous micrographs of objects of substantial thickness and complexity. STAM uses the back-and-forth propagation algorithm to reconstruct tomograms of various layers to be imaged. When these layers are physically close to one another, ambiguities appear in the reconstructed images. Using an iterative algorithm eliminates these ambiguities and resolves layers that are only two wavelengths apart.