Directional point-focus-beam acoustic microscope system (for materials characterization)

A practical system of directional point-focus beam (PFB) acoustic microscopes with two functions of imaging and quantitative measurements is developed based on the authors' previous work. The construction and performance of the system are described. The system is demonstrated for investigation of a polycrystalline sample of Mn-Zn ferrite with an average grain size of 100 mu m using two directional PFB devices. Directional acoustic images are obtained at 225 MHz and 375 MHz in several different propagation directions of leaky surface acoustic waves (LSAWs). Measurements of LSAW velocity, including the angular dependence in some grains of the sample, are performed according to the procedure of V(z) curve analysis. Anisotropic elastic properties of each grain are characterized both in imaging and in quantitative measurements. >