Performance of concave transducers in acoustic microscopy

The performance of a scanning reflection acoustic microscope system using concave transducers has been investigated numerically and experimentally. V(z) characteristics that contain information about leaky surface acoustic waves (LSAWs) at the water/sample boundary can be used to analyze the performance of the system. Numerical analyses of V(z) curves are made via the transfer function of the system using a concave transducer based on field theory, taking a fused quartz as a typical sample. The experiments are performed at a frequency of 375 MHz. It is revealed that the amplitude response of the V(z) curve contains a rapid periodic variation in the defocus region that is not directly related to the propagation properties of LSAW, whereas the phase response of the V(z) curve depends strongly on the propagation properties of LSAW.<>