V(Z) CURVES OF LAYERED ANISOTROPIC MATERIALS FOR THE LINE-FOCUS ACOUSTIC MICROSCOPE

V(z) curves for a line-focus acoustic microscope have been calculated in terms of the characteristic functions of the acoustic lens and the reflectance function of the fluid-loaded specimen. More accurate expressions for the characteristic functions of the acoustic lens are presented by taking account of attenuation in the coupling fluid, of the angular dependence of transmission by the antireflection coating on the lens surface, and by making a better estimate of the focal length. The reflectance function has been calculated for anisotropic layers deposited on anisotropic substrates. The calculated V(z) curves have been compared with measurements for isotropic and anisotropic materials, and layered anisotropic materials. The surface acoustic wave velocities obtained from the theoretical and the measured V(z) curves have been compared for the full range of directions of wave propagation. The comparisons of V(z) curves and surface acoustic wave velocities show excellent agreement between theoretical and experimental results.