last modified
May 8, 2018 - 10:19 CEST

# Other software

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Estimation of PEA deformation through interferometry

## Description

### PEA driving system

coming soon...### Estimation of PEA deformation through interferometry

In order to train a hysteresis/creep model, measurements of the PEA (Piezoelectric Actuator) applied voltage*v*and corresponding deformation

*z*are necessary.

If the Atomic Force Microscope (AFM) is not equipped with deformation sensor, signal

*z*cannot be masured.

Nevertheless, it can be estimated starting from the measurement of the deflection signal

*x*[1], according to the following procedure:

- a mirror is placed instead of the AFM sample;
- the cantilever is moved up and down by applying a triangular signal, ensuring that no contact occurs between the cantilever tip and the mirror;
- by properly regulating the inclination angle of the mirror, an interference pattern
*x(t)*is obtained; - in the time interval between two extrema of
*x(t)*, the PEA vertically moves of a quantity*Δz=λ/4*, being*λ*the wavelength of the laser beam; this information can be exploited to estimate signal*z(t)*[1].

- estim_z.m: MATLAB function which generates signal
*z(t)*starting from the PEA applied voltage*v(t)*and the interference signal*x(t)*. - example.m: demo file which employs function estim_z.
- data.mat: contains the measurements of signals
*v(t)*and*z(t)*necessary to run demo example.m.

### References

- Oliveri A., Lodi M., Storace M., Raiteri R., "Application of a low-cost piezoelectric displacement estimation technique based on laser interferometry for hysteresis open-loop compensation in an AFM scanner", Physica B: Condensed Matter, in press.