Atomic force acoustic microscopy

The principal difference between AFAM and other forms of SPM is the addition of a transducer at the bottom of the sample which induces longitudinal out-of-plane vibrations in the specimen.

The figure shown here is the clear schematic of AFAM principle here B is the magnified version of the tip and sample placed on the transducer and tip having some optical coating generally gold coating to reflect the laser light on to the photodiode.

The frequency used sweeps from some few kHz to MHz, keeping the sine wave amplitude constant.

This deflection of the reflected laser beam from the cantilever (probe) indicates the flexural and torsional parameters of the specimen.

Since the development of atomic force microscopy many modes and related techniques have emerged.

CRFM techniques depend principally on the calculation of contact resonance frequencies and how they shift with variations (like precipitates and matrix) in the sample.

Atomic force acoustic microscopy (AFAM) was originally developed by Rabe and Arnold [1] from the Fraunhofer Institute of Nondestructive Testing in 1994.

Such a technique allows one to determine the Young's modulus from the contact stiffness with a resolution of a few tens of nanometers, mode sensitivity is about 5%.