Selected Applications
IDS Sensors
Synchronous Data Acquisition for Detecting Vibration
Propagation
In high precision systems for moving objects in nanometer ranges, error
motions and vibration propagation are crucial information for the motion
accuracy. Due to this, synchrotron facilities continue to develop and upgrade
different components to keep pace with the latest available technologies.
The beamline I08 recently upgraded the end-station using attocube interferometers
IDS3010 with BiSS-C interface. An experimental setup at the Diamond
Light Source is synchronously triggering and tracking the movement of
eight different linear axes. These eight axes were controlled by the Delta Tau
“GeoBrick” controller, which ensures the accurate timestamped data from
all eight axes, i.e. three IDS3010 devices.
Rough sketch of the setup. The eight sensor heads M12/C1.6 are shown monitoring the 3 modules,
each module consist of 3-dimentional X, Y, and Z movements. The complete setup is in high vacuum.
The parasitic movement during the incremental steps of the X-axis (red line) is shown for disabled
axes Y (blue line) and Z (green line).
The setup consists of three motion modules as shown in a simplified
version in the upper figure: from the bottom one manual positioner, on top
of it one stepper motor for more coarse adjustments, and finally on top of
that one piezo-based positioner for fine motions. All three modules can
move in X-, Y-, and Z-direction, i.e. the complete setup consists of 9 linear
movements, and is being tracked by 8-axes consisting of M12/C1.6 high
vacuum compatible sensor heads. Since the sample’s position is relevant
for each movement of the three modules, every motion axis needs to be
tracked. There are two kinds of error motions (parasitic movements) relevant
for the sample’s position: vibrations caused by moving the positioner that
spread to connecting positioners and the sample, as well as uneven mo-
tions caused by non-parallel mountings between the positioners.
One measurement example is shown in the lower figuer, which only involves
the X, Y, and Z piezo-based positioners in the upper module. The two parasitic
movements are shown while moving the fine piezo positioner in the X-direction
using 5 nm step sizes. The red line (X-axis) shows the positioner moving in
one direction, after 10 steps, the positioner is moving back with one 50 nm
step. The blue line (Y-axis) shows the error motions of the fine positioner
orthogonal to the motion of the positioner in the horizontal level. The noised
oscillations are caused by vibration propagation emerging from the posi-
tioner’s motions. This line shows a linear offset of 10 pm for every step.
This offset originates from the not perfect parallel mounting between
the X- and Y- positioners. This non orthogonal mount can be compensated
using the information for the other axes. The green line (Z-axis) shows
the vertical movements of the fine positioner. Only the last step of 50 nm
shows a significant change of the vertical position, presumable due to a rapid
vibration.
(Diamond Light Source Limited, 2017)
attoSENSORICS
Ultra Precision Sensors
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