Keysight 5500 SPM
User’s Guide
9
Closed-Loop Scanners
In an open-loop scanner, a voltage is applied to the piezo actuators in
extremely precise increments to move the probe accurately in all three
axes. Nevertheless, inherent material properties of the piezo ceramics,
such as hysteresis, creep, and aging may cause the piezoes to drift from
these expected positions.
Keysight closed-loop scanners include high-precision, inductive
positioning sensors to measure, compare, and correct the actual scanner
position to the expected position. Closed-loop scanning improves scan
linearity, provides more accurate probe positioning, and overcomes the
effects of creep, hysteresis, etc.
Scanner Types
Two types of closed-loop scanners are available for the Keysight 5500
SPM: Z-axis closed-loop, and X/Y/Z closed-loop.
Z-Axis Closed-Loop Scanner
The Z-axis closed-loop scanner provides exceptional Z-axis positioning
for very linear vertical positioning. Z-axis closed-loop is useful and
more accurate when generating force curves as the sensor eliminates
hysteresis and controls the piezo position to a much higher degree.
Positional drift that may be present in an open-loop system is
continuously corrected with the closed-loop sensor.
In the position tab of the Servo dialog box, you can select the
Set Z
Position Using
check box to precisely maintain the cantilever at a
