Scanning Acoustic Microscopy

Abstract

This article is an overview of scanning acoustic microscopy, which is one of the more advanced ultrasonic imaging technologies. The scanning acoustic microscope (SAM) uses ultrasound to produce enlarged images of the microscopic structures of materials. In other words, the SAM is an instrument that subjects an object to ultrasound and detects the variations of the elastic properties of the object. The elastic properties are determined by the molecular arrangement of the material, molecule size, intermolecular force or the like, and each material has its unique characteristics. Accordingly, each object reacts in its own peculiar way when subjected to ultrasonic waves. The waves received from the object can be converted into an image. Because ultrasonic waves can penetrate into an object's interior, the surface and also the interior can be visualized. The contents of this article are as follows: First, the need in industry for this process is described. Second, the history of the development of the SAM is illustrated in brief. Third, the basic theory of ultrasonic imaging used in the SAM is depicted, as well as the basic theory of the implements used in the SAM. Furthermore, the V ( z ) curve method for material characterization is described. Selected images are given for a better understanding of the sections.

Determination of sound velocity and acoustic impedance of thin chitosan films by phase-sensitive acoustic microscopy

“…Tittmann and Miyasaka also presented a method for the evaluation of the longitudinal acoustic velocity of a soft layer on a hard substrate by comparing the SAW velocities from simulated and experimentally obtained V(z) curves 14 . In this work, Tittmann's method was implemented introducing the expression for the V(z) as described by Sheppard and Wilson 15 for the theoretical simulation of the V(z) curves.…”

Acoustic emission technique for monitoring the pyrolysis of composites for process control

“…The variation of the transducer voltage as the vertical (z-axis) of the focal point varies, is controlled by the movement of the acoustic lens along the z-axis and is expressed as [21] V ðzÞ ¼ 2p…”

“…f is the front focal distance, k 0 is the wave number in the coupling medium and r and h are the spatial coordinates. The details of this derivation are given elsewhere [21,22].…”

“…By using an acoustic lens of 120°full aperture angle, leaky surface acoustic waves (SAW) can be generated on the surface of the specimen at the location being examined [21]. These waves are known to be very sensitive to surface breaking cracks.…”

Systematic approach to study of thinly and thickly sectioned melanoma tissues with scanning acoustic microscopy

“…The longitudinal wave of the velocity and other valuable parameters can be obtained by methods described previously [14][15][16][17][18][19][20].…”