2. Principle of the scanning acoustic microscope

While we have detectors to record a luminous flux coming from an object, there are no acoustic receptors analogous to the eye or the photographic plate to fix the acoustic image on a support.

Various transcription devices were therefore sought, leading to the current system, which is partly inspired by the scanning electron microscope.

• In its basic principle, the acoustic microscope comprises an ultrasound generator, consisting of a piezoelectric transducer, which converts an incident electrical signal into an acoustic signal. The frequencies f in acoustics correspond to wavelengths λ of the order of micrometers, given the speed v of ultrasound, which is of the order of several thousand meters per second (λ = v / f). It follows that the maximum spatial resolution achieved, due to diffraction limitation, is of the order...