Glossary
1
Voltage
Flexible membrane
Fixed frame
Time
Clamped table
Guiding rod
2
Flexible mem-
brane supports
the piezo and the
axis
SLIP
Flexible membrane
Fixed frame
Time
2
Guiding rod
2
Time
STICK
Time
STICK
STICK
3 SLIPPING PHASE
AT REST
Piezoelectric actuator
3
Time
Flexible mem-
brane supports
the piezo and the
axis
SLIP
∆x
net step is
completed
3
Time
Time
1
PHASE
2 STICKING
AT REST
Time
Clamped table
working principle stepping positioners AT REST
1
1
Piezoelectric actuator
∆x
1
net step is
completed
SLIP
3
Time
The moving table is spring-clamped to the
driving element moved by a piezoelectric
ceramic. The clamping force and the
coating on both sides of the frictional
contact have been carefully chosen for the
respective environment. There is no voltage
applied to the piezo, the table is held
in place by the friction with the driving
element.
2
A sawtooth shaped pulse is applied to
the piezo. During the phase of the slow
flank the movable table sticks to the drive
element and is moved over a distance Δx.
The achieved expansion Δx is proportional
to the applied maximum voltage. The
typical minimum step size for positioners is
50 nm at room temperature.
By repeating this procedure the table can be moved over large distances
with nanometer precision. The range is only restricted by the mechanical
dimensions of the bearings. Additionally to this stepping motion you can
achieve infinitesimal small movements by applying a DC voltage to the piezo
3 By applying the steep flank of the voltage
pulse to the piezo, the drive element is
accelerated very rapidly over a short period
of time, so that the inertia of the movable
table overcomes friction. This way, the
table disengages from the accelerated drive
element and remains nearly non-displaced.
The net step Δx is now completed and the
table remains fixed again at zero voltage.
(fine positioning mode). Our closed-loop controllers will apply this voltage
automatically. You can however power off the controller going back to the last
full step.