Fig. 4.

Principle of scanning acoustic microscopy in acoustic impedance mode. The acoustic waves reflected from the surfaces of water and the tissue are collected by the same transducer and then combined for the calculation of the acoustic impedance of the tissue. S₀ is the generated signal by the 80 MHz transducer, Z_ref is the acoustic impedance of water, Z_sub is the polystyrene substrate’s acoustic impedance, Z_target is tissue’s acoustic impedance