The main application of SAM uses focused sound waves in the ultrasonic frequency band, commonly in the range between 5 and 200 MHz. Upon a trigger signal, a spike pulse is produced that excites a piezo element, which is contained in an ultrasonic transducer, to a broadband oscillation. The bandwidth of that oscillation depends on the mechanical and structural specifics of the transducer element. It is commonly desired to excite short pulses since that allows for an increased axial resolution. The number of oscillations and the frequency of the excited wave define the pulse length and, thus, limit the axial resolution. However, since acoustic microscopes are intended and capable of covering a broad frequency range, the actual inspection frequency and the pulse specifics can be adjusted upon selecting a most appropriate transducer for a specific inspection task. As may become clear from the descriptions above, acoustic waves can be focused just like other wave types. However, since the sound velocity in a solid usually exceeds the values in gases or fluids, acoustic lenses are commonly concave in order to provide the radially decreasing phase shift required for focusing. In case of an acoustic lens, the numerical aperture, which includes the radius of curvature and the opening angle, defines the achievable lateral resolution. However, due to the difference in sound velocity between the coupling medium and a solid sample, the theoretical value of the lateral resolution deviates from the actual achievable value inside the solid. A short pulse of focused sound waves is then transmitted from the acoustic lens into the coupling medium and further into the sample, where it undergoes reflection and scattering that send parts of the insonated waves back into the direction of the transducer. In acoustic inspection in pulse-echo mode, the same focusing ultrasonic transducer that transmits the acoustic pulse is also used for receiving echoes occurring at boundaries between materials/structures of differing acoustic impedance values. The reflectivity of those interfaces is defined by the acoustic impedance mismatch resulting from the differences in mass density and sound velocity, representing the material’s elastic properties. In case of delamination, the resulting reflectivity is close to one, caused by the immense difference in mass density and elastic properties between the solid sample and the gaseous layer originating the delamination. This fact enables acoustic microscopy to detect delamination defects even with lateral dimensions much below the actual resolution, hence requiring the discrimination between detection and resolution limit.