SUCCESS STORY – Hexapods Proven and Tested in Particle Accelerators-- Birgit Schulze --Hexapods Proven and Tested in Particle Accelerators
Applying Extremely Thin Layers in a Vacuum Chamber

Physik Instrumente (PI) GmbH & Co. KG, Auf der Roemerstrasse 1, 76228 Karlsruhe, Germany
Phone +49 721 4846-0, Fax +49 721 4846-1019, Email info@pi.ws, www.pi.ws

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SUCCESS STORY – Hexapods Proven and Tested in Particle Accelerators-- Birgit Schulze --Hexapods
Hexapods allow individual positioning in all six axes. Theirparallel-kinematic structure is considerably more compact
and stiffer than that of serially stacked multi-axis systems.
Moreover, there is no accumulation of guiding errors and tilt
errors of the individual axes. The pivot point can be selected
as desired via software commands and remains independentof the motion.

This results in a much quicker response and significantly
improved dynamics. Furthermore, no cables have to bemoved, which would reduce accuracy due to additional forces
and torques. Hardly surprising, then, that Hexapods have now
opened up fields of application in many industrial sectors,ranging from mechanical engineering and tool machining tosemiconductor manufacturing, astronomy, biotechnology, lifesciences or material research.

Suitable Solutions for a Wide
Range of Tasks
Physik Instrumente (PI) offers a wide range of Hexapods,
which cover almost all possible areas of application. The
Hexapods are based on electromechanical drives, thus making
them much more accurate than hydraulic Hexapods, known
from flight or driving simulators.

Fig. 1

Depending on design, Hexapods can position loads ranging froma few kilograms to a few hundred kilograms or even to several
tons in any desired orientation in space at high precision

Depending on the application requirements, they are driven
by high-precision drive screws and precisely controllable DC
motors or directly by linear motors, e. g. based on piezo
actuators. Matching digital controllers (Fig. 2) and extensive
software support make it easy for the user to solve eachpositioning task without great effort.

This is why Hexapods are often the method of choice for highprecision positioning tasks. With their different designs, they
cover a wide range of applications and, when designed
accordingly, their use in high vacuum does not present aproblem either.
Hexapods are very versatile (Fig. 1), since, depending on
design, they can position loads ranging from a few kilograms
to a few hundred kilograms or even to several tons in any
desired orientation in space, that is, independently of theirmounting direction, at high precision. Since only one platform
is moved, which usually also has a large aperture, the mass
moved by the parallel-kinematic Hexapods is much less lower
than that of serial, stacked multi-axis systems.

Fig. 2

Physik Instrumente (PI) GmbH & Co. KG, Auf der Roemerstrasse 1, 76228 Karlsruhe, Germany
Phone +49 721 4846-0, Fax +49 721 4846-1019, Email info@pi.ws, www.pi.ws

Powerful digital controller with open software architecture

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SUCCESS STORY – Hexapods Proven and Tested in Particle Accelerators-- Birgit Schulze --An example of a particularly compact Hexapod, which has
been tested and proven, for example, also in high-vacuum
applications, is the H-811 (Fig. 3).

To this end, high-energy and short-wave (UV) light is used totake the starting material, a so-called solid target, to the gas
phase and then deposit it as a layer on the substrate.
For direct use in such a beamline, SURFACE has now
developed a new all-in-one system, which impresses inparticular with its compact design (Fig. 4) and has alreadybeen tested and proven in a first project, offering scientificand commercial users the opportunity to further develop
innovative technologies.

Fig. 3The compact Hexapod is available in a version for vacuum
environment of up to 10-6 hPa

At a diameter of only 130 mm and a height of 115 mm, it
provides travel ranges of up to 35 mm in the XY plane and up
to 13 mm in the Z direction. It is in particular the large tilting
angles of up to 20° around the X and Y axes and of up to 40°
around the vertical axis that make this Hexapod so versatile.
In doing so, it can position loads of up to 5 kg and achievevelocities of up to 10 mm/s.
Each individual strut has a positioning resolution of 40 nm,and positioning can be done at a repeatability of better than
1 µm.

Development of Functional ThinLayer Materials
This compact Hexapod has found an interesting application ina PLD system (Pulsed Laser Deposition System), in which it isused in a synchrotron beamline. In particle accelerators of
this type, X-ray diffraction and reflections of the synchrotron
radiation can be used to investigate the structural propertiesof thin films as part of modern material research under highvacuum conditions.

Fig. 4

New beamline PLD system for in-situ synchrotron diffraction(Image: SURFACE)

The transfer mechanism integrated into this PLD systemenables it to be installed on a goniometer in the synchrotron
beam within a few minutes. This allows the entire system tobe moved, without changing the position of the sample.
Accordingly, PLD growth processes can be optimized ex situ,
while the synchrotron is only occupied during the actual insitu analysis.

Physik Instrumente (PI) GmbH & Co. KG, Auf der Roemerstrasse 1, 76228 Karlsruhe, Germany
Phone +49 721 4846-0, Fax +49 721 4846-1019, Email info@pi.ws, www.pi.ws

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SUCCESS STORY – Hexapods Proven and Tested in Particle Accelerators-- Birgit Schulze --"Further characteristics of our beamline PLD system are thelaser heating, which can heat the substrates up to 1200 °C,
and the simple loading," adds Wolfgang Stein (Fig. 5),
managing director and owner of SURFACE. "In addition, thevacuum chamber can be opened, for example formaintenance work, without changing the alignment of thesample to the goniometer.
Another special feature is the sample manipulator, whichallows due to its small size a wide angle range of the X-rayseven at low substrate heights.”

Fig. 5

Dipl.-Ing. Wolfgang Stein, managing director of SURFACE: "TheHexapod, designed by PI for use in high vacuum, positions thesample, relative to the incident X-rays." (Image: SURFACE)

Hexapod in the Sample
Manipulator

To give the appropriate commands to the Hexapod system,
the Hexapod controller communicates with the superior
control of the PLD system. All motion commands are specified
in Cartesian coordinates, while all transformations to thesingle drives are effected by the controller.
"Any desired point in space can be set as center of rotation
via software commands. This freely definable pivot point ismaintained independently of the motion, thus allowing themotion of the Hexapod platform to be tuned precisely to eachpositioning task," concludes Stein.

Fig. 6The sample manipulator allows a wide angle range of the X-rays
due to its small size even at low substrate heights (Image:SURFACE)

Author

The sample manipulator (Fig. 6) holds the 10 × 10 mm²
substrates. "The Hexapod, designed by PI for use in highvacuum, positions the sample, relative to the incident X-rays,"
explains Wolfgang Stein. This allows the sample to be tilted by+/-5° around the X and Y axes at a resolution of 0.001°. Inaddition, to compensate for different layer thicknesses, it canbe moved in the direction of the Z axis, i. e., vertically to thesample surface, by up to 3 mm.
"Motions of +/ 6 mm in the X and Y directions allow scans atdifferent positions of the sample surface," continues Stein.
The Hexapod is mounted on a rotary stage, which canperform further positioning tasks if required, for example, inorder to carry out so-called RHEED measurements (Reflection
High-Energy Electron Diffraction) during the growth process
or orienting the sample holder towards the lock chamberwhen preparing a sample change.

Dipl.-Phys. Birgit Schulze, Market & Products at PI (PhysikInstrumente)

Physik Instrumente (PI) GmbH & Co. KG, Auf der Roemerstrasse 1, 76228 Karlsruhe, Germany
Phone +49 721 4846-0, Fax +49 721 4846-1019, Email info@pi.ws, www.pi.ws

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SUCCESS STORY – Hexapods Proven and Tested in Particle Accelerators-- Birgit Schulze --About PI
In the past four decades, PI (Physik Instrumente) with
headquarters in Karlsruhe, Germany has become the leading
manufacturer of nanopositioning systems with accuracies in
the nanometer range. With four company sites in Germany
and fifteen sales and service offices abroad, the privately
managed company operates globally. Over 850 highly
qualified employees around the world enable the PI Group to
meet almost any requirement in the field of innovative
precision positioning technology. All key technologies aredeveloped in-house. This allows the company to control every
step of the process, from design right down to shipment:precision mechanics and electronics as well as positionsensors.
The required piezoceramic elements are manufactured by its
subsidiary PI Ceramic in Lederhose, Germany, one of the
global leaders for piezo actuator and sensor products.
PI miCos GmbH in Eschbach near Freiburg, Germany, is a
specialist for positioning systems for ultrahigh vacuum
applications as well as parallel-kinematic positioning systems
with six degrees of freedom and custom-made designs.

About SURFACE
SURFACE, based in Hückelhoven, in the Cologne-DüsseldorfAachen triangle in North-Western Germany, is one of theleading manufacturers of Pulsed Laser Deposition systems.
This thin-layer technology has become firmly established inbasic research, due to the fact that it allows deposition ofcomplex materials very flexibly and with high precision.
Since 1996, the company has also been active in the field of
nanometrology and has been operating the SURFACE
NanoLab since 1998, a highly advanced laboratory fully
equipped with nanoindentation and SPM tools.
This laboratory is also a service provider that offers a wide
range of methods for quantitative characterization of diverse
surface properties. For this field, SURFACE is also amanufacturer of diode-laser-based sample heating systems
for electron microscopy.

Physik Instrumente (PI) GmbH & Co. KG, Auf der Roemerstrasse 1, 76228 Karlsruhe, Germany
Phone +49 721 4846-0, Fax +49 721 4846-1019, Email info@pi.ws, www.pi.ws

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