THORLABS MNA601/IR, Руководство пользователя

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NanoTrak Autoalignment Controller
E.2 Piezoelectric Controller
E.2.1 The Piezoelectric Effect
Piezoelectricity is the effect whereby certain types of crystal expand reversibly when
subjected to an electric field.
Although the amount of expansion is usually very small (corresponding to less than
1% strain in the material) it can be controlled extremely finely by varying the strength
of the electric field. Piezoelectric materials therefore form the basis of very high
precision actuators. The resolution of these actuators is effectively only limited by the
noise and stability of the drive electronics. Moreover, the force generated by the
expanding piezo is very large, typically hundreds of newtons.
Perhaps the most useful property of these actuators is their ability to produce
oscillating motion at considerable frequencies, usually limited by the mechanical
system driven rather than by the piezo actuator itself. This ability is used to advantage
in the NanoTrak control system, for example.
The electric field gradient needed to produce a useful amount of expansion is quite
large. Thus to avoid excessive drive voltages, the actuator is constructed as a stack,
consisting of lamina of active material sandwiched among electrodes – see Fig. E.6.
In this way, the distance from positive to negative electrodes is very small. A large
field gradient can therefore be obtained with a modest drive voltage (75 V in the case
of Thorlabs actuators).
Fig. E.6 Piezo-electric actuator schematic diagram
expansion
+ve
–ve
drive voltage
piezoelectric
material
electrodes