Piezo Nano Positioning
2014/2015

PIEZO

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POSITIONING

Contents
About PI

starting from page4

Piezo Positioning Systems

starting from page 17
Piezo Scanners for Nano-Precision Positioning in 1 to 6 Axes

Page 18

Z Piezo Scanners for Microscopy

Page 44

Precision Motion Control: Piezo Amplifiers and Controllers for
Nanopositioning

Page 56

Nanometrology

Page 72

Nanopositioning Technology

Page 76

Piezo Drives

starting from page 99
Piezomotors

Page 100

Piezomotor Technologies

Page 104

Piezo Actuators with Guiding and Preload

Page 110

Technology: Guiding and Preload

Page 116

Piezo Actuators and Piezo Components

Page 118

Fundamentals of Piezo Technology

Page 126

2

W W W. P I . W SHexapod and SpaceFAB: Parallel Kinematics with 6 Motion Axes

starting from page 159

Hexapod and SpaceFAB

Page 160

Controller for Hexapod Positioning Systems

Page 176

Accessories

Page 178

Technology of Parallel-Kinematic Precision Positioning Systems

Page 180

Motorized Positioning Systems

starting from page 191
Precision Linear Stages

Page 192

Precision XY Stages

Page 216

Precision Rotary Stages

Page 222

Motorized Precision Linear Actuators

Page 234

Motion Controllers

Page 244

Basics of Motorized Positioning Systems

Page 252

Patents

Page 268

Imprint

Page 269

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PIEZO

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POSITIONINGPI GroupNo other company in the world offers a broader and deeper portfolio of precision motion
technologies than the PI Group. Continuous growth through the development of novel
products and technologies is one of the main characteristics of the PI Group.
With more than 700 highly qualified employees all over the world, research and manufacturing
centers on three continents and subsidiaries in 13 countries, the PI Group is in a position to fulfill
almost any requirement with regard to innovative precision motion technology.

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W W W. P I . W S

Typical for PI: PIFOC® objective scanner –nanometer resolution for precision focus
control in microscopy

PICMA® multilayer piezo actuators fromPI Ceramic with all-ceramic coating for
optimum reliability and lifetime

SpaceFAB positioning system from PI miCos.
Parallel kinematics for positioning in up to six
degrees of freedom

Unique in Piezo Technology andPrecision Positioning
Physik Instrumente (PI) – Precision Positioning for Industry and Research
PI was founded more than four decades ago and is considered today a global market andtechnology leader in the field of precision positioning technology with accuracies to the subnanometer range. At the development and manufacturing site in Karlsruhe, more than 350
employees work on high-resolution drive systems and positioning solutions.
PI Ceramic – Piezo Technology Specialist
PI Ceramic currently employs 200 people. It was founded in Lederhose (Thuringia, Germany) in
1992 as development and manufacturing site for piezoelectric transducers. Today, it is one of theworld leaders in the field of piezo actuators and sensors used for wealth of applications, reachingfrom precision positioning to metrology, and from ultrasound generation to energy recovery.
PI miCos – Motion Control and Systems Integration
PI miCos, founded in 1990 in Eschbach, Germany, joined the PI Group in 2011. With currently
more than 60 employees, the company develops, produces and markets unique systems andcomponents for high-precision positioning applications throughout the world. It mainly focuseson positioning technology under vacuum conditions, air-bearing solutions, linear motors andintegration of complex systems such as used in beamline instrumentation.

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EUROPE

ASIA

PI UK
PI France
PI ItalymiCos Iberia

PI Japan
PI Shanghai(with R&D and production)
PI Singapore
PI Korea

AMERICAGERMANYPI USAPI Karlsruhe
PI Ceramic
PI miCos

Locations for R&D, production, sales and service
Locations for sales and service

The PI Group is present in all key technology regions worldwide. Customers beneﬁt fromits local representations around the globe in many ways:■

Service facilities for diagnosis and repair as well as metrology equipment for tests, systemcalibration and quality assurance■

R&D departments, which are able to react promptly to the demands of the local markets
and ensure a direct dialog with the customers■

Sample and prototype construction – in close contact with development departments andcustomers■

Sales and application engineers – experts for the entire product portfolio of the PI Groupand your contact for customized developments – from the initial consultation to the delivery■

Market and business development experts who listen to what customers in specific market
segments want and enable the PI Group to develop products that fulfill these requirements

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W W W. P I . W S

Well-Positioned
All Over the World

2004 Market launch of PICMA® multilayer

1970 PI founding year

piezo stack actuators1977 PI moved its headquarters to2004 Market launch of NEXLINE®

Waldbronn, Germany

high-performance piezo linear drives

1991 Market launch of 6-axis parallel-kinematics
positioning systems (Hexapods)

2007 Market launch of NEXACT® piezo linear
drives1992 Foundation of PI Ceramic, Thuringia,

2010 More space for growth: Acquisition

Germany; crucial step towards market
leadership in nanopositioningof the expansion site next to the PI headquarters

1994 Market launch of capacitive position

2011 Acquisition of the majority sharessensorsof miCos GmbH

1998 Market launch of digital control

2012 Extension of the PI headquarters andelectronics

PI Ceramic company buildings

2001 Market launch of PILine®

2012 Introduction of PIMag 6D magnetic

ultrasonic piezomotors

levitation positioning system

2001 New company building in Karlsruhe,2013 Market launch of PiezoMike linear

Germany

2002 PI Ceramic company building extended

actuators based on PIShift inertia drives

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Dear customers,

PI is a synonym for top performance in precision motion technologies. We wish to inspire
you with our products and we believe that we have exactly what it takes. PI offers a technological spectrum that is beyond competition worldwide. Piezo actuator technology, voice-coildrives, magnetic levitation technology, nanometrology sensors and digital controllers – we
can implement all of these technologies for any high-precision motion task. Piezo ceramics
are such an elementary part of our portfolio that we founded an entire company to produce
the highest quality piezo materials in the world: PI Ceramic. This way, we are independent
from general purpose components available on the market and can offer all key technologies from one source. This is what makes PI different and unique. And we need to be
unique to satisfy your speciﬁc requirements in drive and positioning technology.
However, technology is not our only strength. Even more important are all the people
working for and with PI. Permanent improvement of the workﬂow, ﬂat hierarchies, directcommunication, both internally and with our customers, are a very good basis. Our employees are looking forward to working for you. We wish to delight you with our solutions.
Yours sincerely,

Dr. Karl Spanner, President of PI

From the Mission Statement of
Physik Instrumente (PI) GmbHThe ”Wall of Fame“: Far more than 100
patents and patent pending technologies iin
the fifieldspositioningth
ld off nanopositioning,
iti i
iti i
controllers and piezoelectric drive systems
Integrated management system: Quality
control, environmental protection and protection of health and safety at work, certified to ISO 9001, ISO 14001, OHSAS 18001

8

W W W. P I . W S”PI is a strongly expanding, privately owned company. PI stands for quality in products, processes
and service. The development and manufacture iscompletely under the control and responsibility of
PI. Profitability is required for financial independence and a prerequisite for reinvestments in newtechnologies. It guarantees stability and a reliable
partnership with our customers.
We, at PI, want to be our customers‘ partners andlook for long-term customer relationships. Conditions to achieve this goal are fair prices and a mutual support when it comes to solving problems.“

Unconventional Ways

The PI Group can respond precisely to the customers‘ needs:
eds:Speciﬁc requirements can often only be fulﬁlled by customomized solutions – solutions that can only be found by meanseans
of unconventional and creative thinking.
Unique Solutions, Broadest and Deepest Portfolio in Precision Motion Technologies
PI feels at home where unconventional solutions are of the essence in both industry and research.
Today nanotechnology is also present in standardized industrial processes. With unconventional
thinking and the broadest and deepest portfolio of precision motion technologies at hand, PI
is in a position to offer solutions that far exceed the performance of general purpose systems.
Understanding the customers‘ requirements is essential in finding a creative, sometimes surprisingly unconventional solution. The technological range available to PI always permits different
approaches not limited to one single technology right from the start, an advantage that turns
into a considerable competitive edge for the customer.
Why Scientists Rely on PI: Creativity for Research and Development

Precision steering mirror for
an astronomical project requiring ultra-high stability andresolution. For this project,long-travel PI NEXLINE® linear
drives were combined withabsolute-measuring sensors

Thousands of scientific publications cite PI products because our systems help researchers
achieve outstanding results faster. Custom developments for research customers are a daily
business for PI. The spectrum reaches from modifications of standard products to special designs
for extreme ambient conditions. Important fields of research are, for example, beamline instrumentation, micro systems and nanotechnology.
OEM Customers Benefit from Our Integrated Management System
Optimized processes allow PI to provide customized products in quantities up to several 100 000
units cost-efficiently with exact adherence to supply deadlines. The range of OEM products
offered by the PI Group varies, from ”compact actuators“ and sensors to highly integrated
parallel-kinematic positioning systems with custom digital controllers and software. Evaluationof pre-production run samples, test procedures, production processes and quality management
are all included in the development process.
The complete control over the design and manufacturing process provides the customer withsignificant advantages, because PI can modify and customize its products in all areas: Mechanics,
electronics, metrology systems and software. Such solutions often go beyond the state-of-theart, providing customers the competitive edge that is necessary to be successful in the market.
Control of All System-Critical Processes and Design Steps
The PI Group controls the design and manufacturing steps of all critical components from thepiezo material to the mechanical construction, from the nanometrology sensors to the digital
control circuits and software. This approach not only yields superior system performance but
also allows us to support our systems for many years in the future, a fact that is appreciated bycustomers in research and industry alike.

Small, smaller, smallest:
Customer-specific drive solutions manufactured by the
PI Group include a 30 mm wide
positioner with electro-magnetic
gear motor, a piezomotor-driven
camera focus unit for mobile
devices and piezo chip actuators
manufactured in large quantities
at low cost

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PIEZO

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Complex three-dimensional
structure: A 300 μm Statueof Liberty was manufactured
with 3D laser lithography
by Nanoscribe (Photo:
Nanoscribe GmbH)structure: Cells settle on ”handles“Three-dimensional structu
Bastmeyer, Zoological Institu(Photo: B. Richter and M. B
Technology (KIT))te, Karlsruhe Institute of Te

Drives that are both small and accurate improve
imaging processes e.g. in medical technology.
(Photo: SCHÖLLY FIBEROPTIC GmbH)

Hexapods in automation. IIn addition to PLC connecstandardized G-Code commands istion, control over standard
possible to allow for even higher flexibility

Curiosity investigates the geology on Mars supported
by PI drive motion systems (Photo: NASA/JPL)

Small and Large-Scale Precision
What does nanolithography have in common with astronomy? As different as they seem to be,both require precision motion with accuracy down to nanometers. With its decades of engineering and manufacturing experience in nanopositioning and drive systems, PI has been working
with world-class leaders in industry and research in these particular fields and many others.
Semiconductor Technology
The semiconductor industry is a pioneer when it comes to commercializing nanotechnology.
Modern computer chips already require structures which are only a few nanometers wide.
PI‘s piezomotor and actuator systems help to precisely align wafers, imaging optics and mask.
Semiconductor test and inspection systems equally rely on the performance characteristics of
PI positioning systems.

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W W W. P I . W S

Vacuum-Compatible, Non-Magnetic and Suitable for Low Temperatures
PI‘s piezoelectric drive systems can be modified to cope with extreme ambient conditions, suchas ultrahigh vacuum, strong magnetic fields or extremely low temperatures. Piezoceramics are
intrinsically compatible with these extreme conditions, but the selection of the right systemcomponents and the assembly process requires a lot of experience. PI miCos is an expert inclassical drive technologies for UHV, in particular when it comes to designing complex multi-axis
systems for high loads and long travel ranges.
Medical Technology
Piezo ceramics to generate ultrasonic waves, actuators for microdosing and the production of
nanoliter drops as well as miniature piezomotors for mobile medication devices – all these aretasks for which the PI Group has been offering solutions for many years. For imaging processes,
such as OCT, focusing or miniature zoom lenses, small and reliable drive systems are increasingly required. PI can offer products for all of these applications.

Endothelial cells as seen
under the microscope(Photo: Lemke Group, EMBL
Heidelberg)

Biotechnology
Biotechnological applications using precise positioning system from PI are not only limited
to typical optical procedures, such as focusing, or to moving and manipulation of samples in
microscopy or in genome sequencers. Also for nano dosing and microfluidics, PI drive systems
are unbeatable. For example, they allow the dosing of smallest volumes, with both high speed
and high precision, in procedures such as PipeJet, or the design of the finest structures by meansof nanoimprint or 3D lithography.
Microscopy
Optical methods have been relying on PI positioning systems for years, e.g. for aligning opticalsystems or samples. Piezo actuators and motors are increasingly replacing conventional drive
systems because they are more compact, more precise and faster. Other non-optical microscopic
processes, such as SEM (scanning electron microscope) and AFM (atomic force microscope),
use PI systems due to their high accuracy and dynamics.
Imaging Methods
Nowadays, numerous industries depend on faster and more precise imaging methods. In all
markets, the required tasks are focusing, zoom, object alignment and higher resolution. This
ranges from the inspection of surface structures on semiconductors or flat screens with whitelight interferometry to optical microscopy, and from the digitalization of documents to image
stabilization for aerial photography and astronomy. In all of these fields, the PI Group is present
with its precise, highly stable and dynamic positioning systems.

Low-profile, cost-efficientpiezo scanner for biometrics:
The CCD chip is moved
dynamically in two axes toincrease the pixel resolution

Industrial Automation
PI positioning systems can communicate directly with a PLC through fieldbus interfaces. They
can be integrated in virtually every automated production line. A synchronized clock with otherautomated components can easily be achieved. Hexapod parallel-kinematic positioners can also
be used in automated manufacturing processes and for precision alignment.
Astronomy and Aerospace Research
Highest precision and dynamics are required in astronomy to follow the motion of stars or tocompensate atmospheric interferences. Hexapods from PI align secondary mirrors of telescopeswith a precision of 1 μm or better; piezo-driven active mirrors increase the optical resolution andalign the elements of large segmented mirrors. Today the PI Group is even present on Mars with
two of its systems: Piezo actuators separate rock samples, motorized drives focus a camera andlaser spectrometer on the Mars rover Curiosity science lab.

SpaceFAB:
6-axis positioning
system for 10-6 hPa

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POSITIONINGPI Ceramic Piezo Technology
PI Ceramic is considered a global leading player in the field of piezo actuators and sensors. The
product range includes various piezo ceramic elements manufactured in both multilayer andpressing technology. Piezo ceramic components are manufactured in a large number of forms
and sizes and with different motion characteristics.
The broad range of expertise in the complex development and manufacturing process of functional ceramic components combined with state-of-the-art production equipment ensure highquality, flexibility and adherence to supply deadlines. Prototypes and small production runs ofcustom-engineered piezo components are available after very short processing times. PI Ceramic
also has the capacity to manufacture medium-sized to large series in automated lines.

Instruments for the removalof tartar with ultrasound,OEM product. The individual
piezo disks can be clearlyseen

PI Ceramic provides■ Piezo ceramic materials■ Miniature piezo actuators■ Lead-free piezoelectric materials■ PICMA® multilayer bending actuators■ Piezo ceramic components■ PICA high-load piezo actuators■ Customized and application-specific■ PT piezo tube actuatorstransducers / ultrasonic transducers■ PICMA® monolithic multilayer piezo

actuators

12■ Preloaded actuators with case
■ Piezocomposites – DuraAct patch

transducers

DuraAct transducers can beused as sensors, actuators andfor energy harvesting

W W W. P I . W S

PI miCos Motion Control
Frequently, the complete integration of multiple axes of high-precision positioning systems isrequired. Some examples are the preparation of experiments in large research facilities, opticalmeasurement technology, photonics automation as well as test and calibration facilities in industrial applications. PI miCos delivers turn-key solutions from one source. All critical mechanicalcomponents are manufactured in-house at PI miCos achieving the highest performance characteristics.
The product range includes linear and rotation stages, multi-axis SpaceFAB robot systems andmatching motion controllers with corresponding software. Furthermore, PI miCos offers special
product lines for use in vacuum up to 10-10 hPa or under cryogenic conditions.
Typical examples for successfully integrated system solutions are found in flexible positioning
systems with linear motors and air-bearing technology as well as in robotics systems that allow
motions with six degrees of freedom and have been specially developed for optical measurement technology and photonics automation.

Positioning in vacuum in up
to six axes is one of the fields
of expertise of PI miCos

Top performance for excellent results: Research
institutions rely on the unique combination oftechnical know-how and perfect implementation, which guarantees, for example,
mple, a highresolution rotary stage motion
without wobble and backlash

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Everything Under One RoofTechnology Under Control
Customer and application-specific product developments are the basis for the success of the
PI Group. Requirements have to be understood and a technological solution has to be found.
Since the PI Group manufactures all key technologies in-house, technology and production canbe adapted perfectly to fulfill the requirements. Evidence is provided by our products.
The Good Feeling When Your Expectations Are Met
Customers should know the performance of the system they use. Therefore, an informative
measurement log is part of every supplied closed-loop nanopositioning system. All measurements are made with external, traceable measurement devices, such as high-resolution interferometers.

The combined lift and swivel
unit carries up to seven tons
and permits 360° rotations.
This allows us to qualify, forexample, high-load Hexapods with load in the exact
same orientation as in thecustomer‘s application

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W W W. P I . W S

A seismic, electromagnetic and thermal isolationof the test laboratories
guarantees a stable temperature with a variationof less than 0.25°C in
24 hours. Measuring
accuracies down to picometers set standards
in the measurement of
nanopositioning equipment

High-precision piezo
positioning systems aremeasured using highquality calibrated interferometers

Visit Uson the Web atwww.pi.ws
For detailed technicalspecifications, drawings,
CAD files and additional
products not shown
here, visit our website atwww.pi.ws. There you will
also find our newslettersand updates on the latest
developments and applications as well as general
information on the PI Group.
Downloading Softwareand User Manuals
PI provides a wealth of software tools along with richdocumentation and detailed
user manuals. Visit our website frequently to stay up to
date. Actually, our PI Update
Finder will help you identify
the PI software on your computer automatically, compare
it to the versions available on
the PI server and direct you tothe latest release.

Qualification in a Wide Range
The product range from a two-ton Hexapod to a 10-gram nanopositioner requires that
PI can both manufacture and qualify these systems. At our Karlsruhe headquarters,a heavy-load shop floor was recently added, in which masses up to five tons can behandled. Special measurement devices, such as high-resolution 6D laser trackers,
qualify the heavy-load precision positioning systems in every orientation.
Nanopositioning systems require stable measurement conditions for qualification.
Measuring rooms with stable climatic conditions, isolated from the building foundation and thus from external vibrations, provide ideal ambient conditions for the highresolution measurement devices, such as interferometers and capacitive sensors.
Complete Systems
PI positioning systems are complete solutions, i.e. they are delivered with everything
required for operation. This includes, unless otherwise specified, power supplies,
cables, mains and network cables, and, of course, the software. A plethora of programlibraries, examples and drivers facilitate integration and programming of the systems
e.g. under Linux, Windows, MATLAB or LabVIEW. In addition, every controller comeswith the PIMikroMove graphical user interface program for easy start-up and system optimization.

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P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

Piezo Positioning Systems

Products

Page 18–75

Technology

Page 76–95

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Piezo Scanners for Nano-Precision Positioning
In 1 to 6 Axes

Three-dimensional structure: Cells
settle on "handles".
(Photo: B. Richter and M. Bastmeyer,
Zoological Institute, Karlsruhe Institute of Technology (KIT))

Nanotechnology is already part of everyday life. The use of high-precision positioning systems in biotechnology, microscopy
or semiconductor technology allows resolution of very fine structures in production and inspection. This allows productionof more and more powerful integrated electronic components and investigation of new diagnostic and therapeutic methods
in life sciences.

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P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

Single-Axis Piezo Scanning Stages

Page 20

Reference-Class Nanopositioning Systems

Piezo Z Scanners

Page 22Compact Positioning Stage for the Vertical Axis

Piezo Scanning Stages for 1 to 3 Axes

Page 26

Precision Positioning Stage for up to 6 Axes

Page 38

Reference-Class Piezo Systems

PicoCube® XYZ Piezo Scanners for AFM

Page 40

Fast Tip/Tilt Mirrors

Page 42

Active Optics

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Single-Axis Piezo Scanning Stages
Reference-Class Nanopositioning Systems

P-753

Highlights■ Excellent precision■ For dynamic applications■ PICMA® piezo actuators for maximum reliability■ Capacitive position sensors for positioning accuracy

and stability in the nanometer range■ Frictionless and zero-backlash flexure guides

Applications
PI‘s piezo-actuator linear stages combine nanometer-precision resolution and guiding precision with minimum crosstalk.
This makes them particularly suitable for reference applications in metrology, for microscopic processes, for interferometry or in inspection systems for semiconductor chip production.

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P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

P-752

P-753

P-750

P-622

P-752

P-753

P-750

P-620
to
P-629

Excellent guiding
accuracy

LISA actuator and nanoscanning stage: forvertical and horizontaluse

For high loads

PIHera: XY and Z
versions available

66 to 84 × 40 × 13.5

44 to 80 × 30 × 15

115 × 115 × 25

30 × 30 × 12 to
100 × 100 × 22.5

15 to 30

12 to 3875

50 to 1 500

30

100 vertical,
20 horizontal

100

10

up to 0.1

0.05 to 0.2

1

up to 0.2

Linearity error in %

0.03

0.03

0.03

up to 0.02

Repeatability in nm±1 to ±2

±1 to ±3

±3

up to ±1

±1

±5 to ±10±10

±3 to ±10

up to 30

up to 45

12.5

up to 0.4

up to 3 200

up to 5 600

600

up to 1 100

Dimensions in mm
Closed-loop travel range
in μm
Load capacity in N
Closed-loop resolution
in nm

Crosstalk θY/ θZ in μrad
Stiffness in N/μm
Unloaded resonant
frequency in Hz

All product details can be found at www.pi.ws

PIEZO

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Piezo Z Scanners
Compact Positioning Stages for the Vertical Axis

P-622

Highlights■ Frictionless and zero-backlash flexure guides■ PICMA® piezo actuators for maximum reliability■ Open-loop designs available

Applications
Vertical piezo positioning stages are used for the alignment of optics in laser metrology and also for focusing samples in
microscopy or in test systems. PI offers vertical positioning stages in different designs for a wide range of applications.

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P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

P-611.Z

P-612.Z

S-303.BL

P-611.Z

P-612.Z

S-303

High precision in
combination with long
travel ranges

Cost-efficientCompact with clear
aperture

Highly dynamic piezo
phase shift stage

PIHera: XY und Z
versions available

X, XY or XZ
versions available

XY versions
available

version with Picoactuator® drive for highlinearity in open-loop
operation

30 × 30 × 15 to
50 × 50 × 17.5

44 × 44 × 27

60 × 60 × 27

Ø 30 × 10, open-loop
with Ø 8 mm clear
aperture

up to 250

100

100

2

10

15

15

0.5

Sensorcapacitive

SGS

SGS

capacitive

Closed-loop resolution
in nm

up to 0.1

2

1.5

0.03

Linearity error in %

0.02

0.1

0.2

1

Repeatability in nm

±1

<10

±4

0.7

Crosstalk θY/θZ in μrad

<80

±20

–

–

Stiffness in N/μm

up to 0.6

0.45

0.63

–

Unloaded resonant
frequency in Hz

up to 1 000

460

490

25 000P-620.Z
P-621.ZP-622.Z

Options

Dimensions in mm

Closed-loop travel range
in μm
Load capacity in N

All product details can be found at www.pi.ws

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Z and Tip/Tilt Piezo Scanning Stages
With Large Clear Aperture

P-733

Highlights■ Fast step-and-settle in the ms range■ Parallel kinematics for best possible precision with multi-axis motion■ Frictionless and zero-backlash flexure guides■ PICMA® piezo actuators for maximum reliability

Applications
PI‘s vertical positioning stages with large clear aperture are available with different features to fit each individual application. The main areas of application include various microscopic processes for alignment and Z-stacking of samples. In
addition, PI offers special scanning stages for commercially available microscopes.

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P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

P-541

P-518

P-541.ZC
P-541.TC

P-541.ZS
P-541.TS

Reference class

Precision class

Reference class: High
guiding accuracy

Reference class:High dynamics in Z
and tip/tilt axes

XY versions
available

XY versions
available

XY and XYZ
versions, vacuum
versions available

XY and XYZ
versions, vacuum
versions available

150 × 150 × 16.5

150 × 150 × 16.5

100 × 100 × 25

150 × 150 × 30

Active axes

Z, θx, θyZ, θx, θyZ

Z and Z, θX, θY

Clear aperture in mm

66 × 66

66 × 66

50 × 50

66 × 66

Closed-loop travel range
in μm

100

100

100

up to 200

Closed-loop tip/tilt range
θX, θY
in mrad

±0.6

±0.6

–

up to ±1

50

50

50

100

capacitive

SGS

capacitive

capacitive

Closed-loop resolution
in nm

0.5

2.5

0.3

1

Resolution in the
tip/tilt range in μrad

0.08

0.25

–

up to 0.05

Linearity error in %

0.03

0.2

0.03

0.03

Repeatability in nm

±2

±10

±2

up to ±5

Crosstalk θY/ θZ
in μrad

<15

<15

<5

<100

Stiffness in N/μm

0.8

0.8

2.5

up to 4

Unloaded resonant
frequency in Hz

410

410

700

up to 570

Options
Dimensions in mm

Load capacity in N
Sensor

P-733.Z

P-518
P-528
P-558

All product details can be found at www.pi.ws

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Low-Cost 1- and 2-Axis Piezo Scanning Stages
Standard Class of High Dynamics

P-713

Highlights■ Fast piezo stages■ SGS position sensors optimized for high linearity■ Serial and parallel-kinematic designs■ Highly dynamic through direct drive■ Frictionless and zero-backlash flexure guides■ PICMA® piezo actuators for maximum reliability

Applications
Fast X and XY piezo scanners for small loads are frequently used for microstepping processes. Their rapid step-and-settle
improve the resolution of optical systems. These include imaging processes in camera technology and image recognition,for example for biometrics or document archiving.

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P-712

P-712

P-713

P-915KXYS

P-915KHDS

P-915K
XYS

P-915KHDS

Large clear aperture
12 × 15 mm²Large clear aperture
15 × 15 mm²

Customized model

Customized modelwith large clear
aperture 30 × 45 mm²

X

X, Y

X, Y

X, Y

40 × 40 × 6

45 × 45 × 6

40 × 60 × 7

85 × 54 × 12.5

20 × 15

15 × 15–30 × 45

SGS

SGS

–

–

Closed-loop travel range
in μm

30

15 x 15

4 × 4 open-loop

15 × 15 open-loop

Closed-loop resolution
in nm

2

1

0.4 open-loop

0.1 open-loop

Linearity error in %

0.3

0.3

–

–

Repeatability in nm

±5

±4

–

–

±5 / ±20±1 to ±5 / ±40 to ±50

up to ±50–

Stiffness in N/μm

0.6

0.8

–

10

Unloaded resonant
frequency
in Hz

1 550

2 250

> 2 000

1 850

Load capacity in N

5

2

0.5

5

Active axes
Dimensions in mm
Clear aperture in mm
SensorCrosstalk θY/θZ in μrad

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

27

NanoCube®
Cost-Efficient Positioning in up to 3 Axes, Precision-Class

P-611

Highlights■ Cost-efficient■ Modular design of multi-axis systems■ SGS position sensors■ PICMA® piezo actuators for maximum reliability

Applications
The NanoCube® is an all-rounder in nanopositioning technology, offering the best possible alternative to referenceclass systems. Its applications include sample adjustment, handling in microsystem technology, sample handling, fiber
positioning and photonics.

28

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

P-611.2, P-611.XZ

P-611.3

P-612

P-611.1

P-611.2
P-611.XZ

P-611.3

P-612

X

X, Y or X, Z

X, Y, Z

X, Y

44 × 44 × 17

44 × 44 × 34

44 × 44 × 44.2

60 × 60 × 18

–

–

–

38 × 38

Sensor

SGS

SGS

SGS

SGS

Closed-loop travel range
in μm

100

100

100

100

Closed-loop resolution
in nm

2

2

2

5

Linearity error in %

0.1

0.1

0.1

0.4

Repeatability in nm

<10

<10

<10

<10

Crosstalk in μrad

max. ±20max. ±20max. ±20max. ±50

Stiffness in N/μm

0.2

0.2 to 0.35

0.3

0.15

Unloaded resonant
frequency in Hz

400

up to 340

up to 350

400

Load capacity in N

15

15

15

15

Active axes
Dimensions in mm
Clear aperture in mm

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

29

PIHera Nanopositioning Stages for 1 to 3 Axes
Large Variety of Reference-Class Piezo Scanning Stages

P-622

Highlights■ High-precision piezo positioning systems with travel ranges of up to 1 500 μm■ Short response and settling times in the millisecond range■ Capacitive position sensors for maximum positioning accuracy and stability■ PICMA® piezo actuators for maximum reliability■ Frictionless and zero-backlash flexure guides

Applications
The piezo scanners of the PIHera range show in exemplary fashion the history of success of PI‘s nanopositioning systems.
Their compact design makes them suitable for universal use and allows serial assembly of multi-axis systems at low cost.
Their applications include, for example, optical metrology, biotechnology and atomic force microscopy.

30

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

P-621.2CD

P-622.ZCD

P-763.22C

P-620.1
toP-629.1

P-620.2
toP-629.2

P-620.Z
P-621.ZP-622.Z

P-763

1 axisXY axes

Z axisXY axeswith clear aperture,
preliminary data

30 × 30 × 12 to
100 × 100 × 22.5

30 × 30 × 21.5 to
100 × 100 × 40

30 × 30 × 15 to
50 × 50 × 17.5

60 × 60 × 22

–

–

–

30 × 30

50 to 1 500

50 to 1 500

50 to 250

200

0.2 to 3

0.2 to 3.5

0.2 to 1

0.7

Linearity error in %up to 0.02

up to 0.02

0.02

0.02

Repeatability in nm±1 to ±14

±2 to ±14±1±2Crosstalk in μrad

±3 to ±10

±3 to ±30

<20 to <80±50

Unloaded resonant
frequency in Hz

up to 1 100

up to 800

up to 1 000

up to 200

Load capacity in N

10

10

10

3

Dimensions in mm
Clear aperture in mm
Closed-loop travel range
in μm
Closed-loop resolution
in nm

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

31

Low-Proﬁle XY Piezo Scanners
With Large Clear Aperture for Microscopy

P-541

Highlights■ Flexible adjustment possible, e.g. for microscopes■ Particularly low profile■ Large selection of position sensors■ Backlash-free flexure guides■ PICMA® piezo actuators for excellent reliability

Applications
The nanopositioning stages of the P-540 series are designed for applications in microscopy. Their typical low-profile
design allows easy integration into existing structures. Depending on the task at hand, the drive system ranges frombeing particularly dynamic for tracking applications to long travel ranges for superresolution microscopy.

32

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

P-545

P-541.C
P-542.C

P-541.SP-542.S

P-541.2
DD

P-545
PInano®

High precision
through
capacitive sensors

Cost-efficient version
with SGS sensors

Directly driven
and dynamic

Low-cost for microscopy, up to 3 axes

Precision-class

Reference-class

Precision-class

X, Y

X, Y

X, Y

X, Y,( Z)

150 × 150 × 16.5

150 × 150 × 16.5

150 × 150 × 16.5

217 × 150 × 20

80 × 80

80 × 80

80 × 80

82 × 65

Sensorcapacitive

SGS

capacitive

piezoresistive,
capacitive

Closed-loop travel range
in μm

100 to 200

100 to 200

45

70 to 200

Closed-loop resolution
in nm

0.3 to 0.7

2.5 to 4

0.3<1Linearity error in %

0.03

0.2

0.03

0.1

Repeatability in nm

<±5

<±10

<±5

–

Crosstalk in μrad<±5 to ±10<±5 to ±10<±3–Kinematic design

parallelparallelparallelserialUnloaded resonant
frequency in Hz

up to 255

up to 255

1 550

1 000 (X, Y), 800 (Z)Load capacity in N

20

20

20

5

Reference-class
Active axes
Dimensions in mm
Clear aperture in mm

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

33

2-Axis Flexure Scanners
with Excellent Travel Accuracy
Reference-Class Piezo Systems

P-733

Highlights■ Motion in X and Y■ Optimized travel accuracy■ Parallel kinematics with capacitive sensors■ Backlash-free flexure guides■ PICMA® piezo actuators for excellent reliability■ Large clear aperture

Applications
Reference-class nanopositioning stages are suitable for sample positioning in high-resolution, non-optical microscopy.

34

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

P-517, P-527

P-734

P-733.2
DD

P-517.2
P-527.2

P-734

Compact and precise

Directly driven
and dynamic

Travel range of up to
200 μmTravel flatness <5 nm

100 × 100 × 25

100 × 100 × 20

150 × 150 × 30

130 × 130 × 30

50 × 50

50 × 50

66 × 66

56 × 56

Closed-loop travel range
in μm

100

30

100 to 200

100

Closed-loop resolution
in nm

0.3

0.1

1 to 20.3

Linearity error in %

0.03

0.03

0.03

0.03

Repeatability in nm

<±2

<±2

±5 to ±10<±2.5<±3 to ±10<±5 to ±10–<±3 to ±10

Unloaded resonant
frequency in Hz

500

2 230

up to 450500

Load capacity in N

50

50

50

20

P-733.2

Dimensions in mm
Clear aperture in mm

Crosstalk in μrad

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

35

3-Axis Piezo Scanning Stages
Reference-Class Piezo Systems

P-563

Highlights■ Motion in X, Y and Z■ High travel accuracy■ Large clear aperture■ Parallel kinematics with capacitive sensors■ Backlash-free flexure guides■ PICMA® piezo actuators for excellent reliability

Applications
Three-axis nanopositioning stages scan a sample in-plane both in optical and non-optical microscopy and adjust it
along the measuring axis. Further fields of application include interferometry, 3D laser lithography and nano imprint
technologies.

36

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

P-733

P-517

P-733.3

P-517.3
P-527.3

Compact and precise
Highly dynamic Z axis

High dynamics
to up to 200 μm

P-561
P-562
P-563

PIMars series, alsoavailable for 6 axes

P-561.3
DD

Directly driven highdynamics PIMars

Highly dynamic Z axis

Long travel range
also in Z

100 × 100 × 25

150 × 150 × 30

150 × 150 × 30

150 × 150 × 30

Clear aperture in mm

40 × 40

66 × 66

66 × 66

66 × 66

Closed-loop Z travel
range in μm

1020

100 to 300

15100 × 100

100 × 100 to
200 × 200

100 × 100 to
300 × 300

45 × 45

Closed-loop X, Y
resolution in nm

0.3

1 to 2

0.8 to 2

0.2

Closed-loop Z resolution
in nm

0.2

0.1

0.8 to 2

0.2

Linearity error in %

0.03

0.03

0.03

0.01

Repeatability in nm<2±1 to ±1022Crosstalk in μrad

<±10

–

±6 to ±10±3Crosstalk around X, Y
with motion in Z in μrad<±5–

±15 to ±25±3Resonant frequency X, Y
in Hz

460

up to 450

up to 190

920

Resonant frequency Z
in Hz

1 400

1 100

up to 380

1 050

50

50

50

50

Dimensions in mm

Closed-loop X, Y travel
range in μm

Load capacity in N

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING37

Precision Positioning Stages for up to 6 Axes
Reference-Class Piezo Systems

P-518

Highlights■ Parallel kinematics with capacitive sensors■ Capacitive position sensors of maximum linearity■ PICMA® piezo actuators for maximum reliability

Applications
Differential operation of the actuators for one direction of motion combined with a digital motion controller allows
samples or measuring sensors to be aligned not only in the linear axes but also additionally in tilt and rotary angles.

38

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

P-517

P-563

P-587

P-587

P-517.R
P-527.RP-518.TP-562.6

Rotational axes withclear aperture

Tip/tilt axes with clear
aperture

PIMars,

X, Y, θzZ, θx, θy

X, Y, Z, θx, θy, θz

X, Y, Z, θx, θy, θz

150 × 150 × 30

150 × 150 × 30

150 × 150 × 30

240 × 240 × 50

66 × 66

66 × 66

66 × 66–

100 to 200

50 to 200

200

800, 800, 200

Closed-loop resolution
in nm

0.3 to 1

up to 0.5

1

0.7 to 2.2

Closed-loop tilt angle in
mrad

±1

±0.25 to ±1

±0.5

±0.5

Closed-loop angle
resolution in μrad

0.01

0.05

0.1

up to 0.1

Linearity error X, Y, Z /θx, θy, θz in %

0.03

0.03

0.01 / 0.1

0.01 / 0.1

Repeatability
X, Y / Z in nm±5±5 to ±10±2 / ±3±3 /±2

Repeatability
θx, θy / θz in μrad

±0.5

up to ±0.03±0.1 / ±0.15±0.1 / ±0.15

Unloaded resonant frequency X / Y / Z in Hz

450

up to 570

110 / 110 / 190

103 / 130 / 235

Load capacity in N

50

100

50

50

Active axes
Dimensions in mm
Clear aperture in mm
Closed-loop travel range
in μm

compact design

Large travel ranges

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

39

PicoCube® XYZ Piezo Scanners for AFM

P-313

Highlights■ Picometer resolution■ Parallel-kinematic design■ High dynamics through direct drive■ Nonmagnetic and UHV versions available

Applications
Atomic force microscopy (AFM) permits surface inspection with highest resolution, even down to atomic levels. It entersdimensions that light microscopes can no longer resolve. This method can provide information on the topography, chemical surface condition, defects, etc. Typical areas of application include life science technologies, materials research andsemiconductor inspection. Piezo-based scanning systems provide the required precision in the positioning of measuring
tip and sample, thus ensuring the desired high spatial resolution and high dynamics.

40

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

P-313

P-363

E-536

P-363

E-536
PicoCube®
Piezo
Controller

Picoactuator® technology for highly linear
displacement without
position sensor■ With or without servo

X, Y, Z

X, Y, Z■ Output voltage

30 × 30 × 29.4

30 × 30 × 29.4

■ Peak current per channel–

capacitive

up to 15–

0.1

Linearity error in %

0.2

0.05

Crosstalk in μrad–

0.5

Crosstalk withmotion in Z in μrad–

0.2

4 000 / 11 000

3 100 / 9 800

10

10

±250

±250

Active axes
Dimensions in mm
SensorClosed-loop travel range
in μm
Closed-loop resolution
in nm

Unloaded resonant frequency X, Y / Z in Hz
Load capacity in N
Operating voltage in V

control■ With or without digitalinterfaces-250 to +250 V
up to 200 mA, <3 ms■ Bandwidth,

small signal 10 kHz■ Ripple, noise,

0 to 100 kHz <0.8 mVrms

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

41

Fast Tip/Tilt Mirrors
Active Optics

S-334

Highlights■ Two orthogonal, parallel-kinematic tip/tilt axes with common pivot point■ Optional linear axis for adjustment of the optical path length■ Compact design■ Operating frequencies from 100 Hz to >1 kHz■ PICMA® piezo actuators for maximum reliability■ Optional strain gauge sensors for high accuracy■ Frictionless and zero-backlash flexure guides

Applications
Due to their high dynamics and the two tip/tilt axes featuring a common pivot point, tip/tilt mirrors are used for laser
beam steering and control. Applications include industrial materials processing and medical technology, for example
in ophthalmology or dermatology. Image stabilization is a further field of application, which benefits from the highdynamics of the system.

42

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

S-330

S-325

S-330

S-334

S-325

S-340

Fast and flexible tilt
angles

Large tilt angles withpre-mounted mirror

High speed due toadditional closed-loop
Z axisWide range of different materials suchas invar, aluminum,titaniumØ 25 × 37 to 91

25 × 33 × 38

Ø 25 × 50

60 × 60 × 56

Active axes

θX, θYθX, θYθX, θY, Z

θX, θY

Integrated sensor

SGS

SGS

SGS

SGS

Closed-loop tilt angle*
in mradup to 1025 and 50

52

Closed-loop resolution
in μrad0.05 to 0.5

1 and 50.05

0.2

Linearity error in %

0.25

0.05

0.05

0.1

Unloaded resonant
frequency
in kHzup to 3.7

1 and 3
with mirror

2

1.4

Platform diameter in mm

25

12.5

25

59

Closed-loop Z travel
range in μm

–

–

30

–

Closed-loop Z resolution
in nm

–

–

0.6

–

Dimensions in mm

S-340*Mechanical angle: The optical beam deflection is twice as high.

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING43

Z Piezo Scanners for Microscopy
Fast and Precise Positioning of Objective and Sample

PIFOC® in Inverse Microscope
PIFOC® objective scanners with piezo drive achieve settling times of up to 10 ms on travel ranges of up to 1 mm. QuickLockthread inserts allow objectives to be replaced quickly and easily. The figure shows a PIFOC® in an inverted microscope, where
the beam is guided onto the sample from below.

44

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

Positioning Tasks in Microscopy

Page 46

PIFOC® Objective Scanner with Settling Time in Milliseconds

Page 48

High-Speed Z Sample Positioning for
Fast Focus Control and Imaging

Page 52

Microscopic Scanner with Large Clear ApertureHigh-Precision Multi-Axis Sample Positioning with PInano®

Page 54

Up to 200 μm in XY and XYZPrecision XY Stages

Page 216

For Microscopy and Inspection Tasks

45

PIEZO

NANO

POSITIONINGZ Positioning Tasks in Microscopy

Depending on the method used, optical microscopy has different positioning stage and scanner requirements forobjectives and samples. The application determines which axes are moved as well as their stroke and the required
accuracy. The examination of a sample frequently requires many individual scans within a very short period of time,or screenings require high throughputs – both methods have high demands in terms of the systems‘ dynamics andthe smooth behavior during the scan. In addition, their size must ﬁt existing microscopes and must not adversely
affect the beam path.

In a confocal microscope that resolves
single molecules, piezo scanners ensure
the best possible repeatability. PIFOC®
objective stages provide rapid focus
alignment. The required high scanninglinearity is achieved by suitable digitalalgorithms in the control. The figure
shows a single molecule image consisting of immobilized Atto655 and Cy5
molecules. The individual molecules canbe readily distinguished by means of theirdifferent fluorescence lifetimes. (Photo:
PicoQuant)

Z Motion in the Direction of the Optical Axis
For light microscopes, PI products offer fine adjustment in Z for different areasof application, such as fast optical sectioning (Z stacks, image stacks) for 3D processes, confocal or multiphoton microscopy, or autofocus applications and driftcompensation. The required step size, for example in Z-stack acquisition, is in therange of the resolution limit of the microscope.
This can in general be achieved by adjusting either the sample or the objective. The
high precision and short settling time requirements of the application are identical.
With upright microscopy and large or very sensitive samples, the trend is toward
adjusting the objective, and with inverted microscopy and small samples toward
adjusting the sample.
Systems with travel ranges of up to 500 μm, upon request even up to 2 mm, areavailable. Even with large objectives, short settling times of approx. 10 ms and thus
high throughputs are achieved. Especially for macro-objectives of large numeric
aperture (NA), PIFOC® stages are available with a clear aperture of up to 29 mmwith a M32 thread.

QuickLock adapters facilitate the mounting of
the objective scanner on the microscope

PIFOC® objective scanners with their freely exchangeable PI QuickLock threadinserts can be coupled to the microscope using different thread types and in different angles. The PIFOC® are simply inserted between the revolving nosepiece ofthe microscope and the objective using the QuickLock. Then the adapter is screwed
into the revolving nosepiece and the PIFOC® is fastened in the desired direction.
Since the objective positioner itself does not have to be rotated, cabling is nolonger an issue.

46

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

Objective or Sample Adjustment

Fields of Application

Apart from objective stages, several piezo stage series of very low profile anddifferent clear apertures are available for sample adjustment. They are tuned to
3x1" slides or inserts of up to 160 mm x 110 mm. The stroke is up to 500 μm.
For additional tracking or fine adjustment tasks perpendicular to the optical axis,
PI offers integrated piezo-based XYZ scanners.

■ Fast picometer-precision 3D

surface inspection■ Fast focusing for Z-stackacquisition■ Autofocusing■ Drift compensation down to thenanometer range

Autofocus or Externally Specified Target Position
The autofocus signal can be used as control parameter for a constant distance
between sample and objective, thus allowing material drift compensation. Bychanging a single control parameter in the electronics, the piezo stage can bereferenced again to the internal sensor and then used, e. g. for Z-stack scans.

■ 3D laser lithography in biotech-

nology and medical technology

The piezo-based nanopositioning systemmoves the entire revolving nosepiece containing the different objectives in the direction of
the Z axis (Photo: Nikon Instech / PI)

47

PIEZO

NANO

POSITIONINGPIFOC® Objective Scanners
Focusing Microscope Objectives with Nanometer Precision

P-725

Highlights■ Scans and positions objectives with sub-nm resolution and ms settling time
■ Maximum linearity through direct metrology with capacitive sensors■ Minimum objective offset and excellent focus stability through backlash-free parallel flexure guiding■ Outstanding lifetime due to PICMA® piezo actuators■ Longer travel ranges for multiphoton microscopy

Applications
In addition to all common microscopic processes, the applications also include 3D lithography and industrial surface
inspection with white light interferometry (WLI) methods. For all models, a series of QuickLock thread inserts ofdifferent thread dimensions are available, which facilitate mounting. For many models, cost-efficient scanning systems,
including digital motion controllers, are available.

48

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

P-721

P-721

P-725

P-725KHDS

P-726

P-725K
HDS

P-726

Cost-efficient, in asystem combined with
controller

Different travel ranges,
in a system combinedwith controller

40 × 49.5 × 65

46 × 40.5 × 68

Max. objective diameter
in mm

39

39

39

M-32

Closed-loop travel range
in μm

100

100, 250, 400

400

100

Max. dimensions
in mm

SensorCustomized model ofhigh dynamics

Very stiff, for heavy
objectives

Ø 65 × 50.7

capacitive

SGS

capacitive

capacitive

capacitive

Closed-loop resolution
in nm

0.7

5

up to 0.65

1.2

0.4

Linearity error in %

0.03

0.2

0.03

0.03

0.02

Repeatability in nm

±5

±10

±5

±5

±3

100 / 20100 / 20100 / 20100 / 50

Unloaded resonant
frequency in Hz

580

up to 470

up to 620

1 120

Stiffness in N/μm

0.3

up to 0.23

up to 0.4

3.4

Crosstalk in X, Y in nm

100

20 per 100 μm oftravel range

20 per 100 μm oftravel range

50

Push / pull force
capacity in N

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

49

PIFOC® Objective Scanner
Maximum Dynamics for Revolving Nosepieces

P-721K(Photo: Nikon Instech / PI)

Highlights■ Maximum accuracy through direct metrology■ Minimum objective offset and excellent focus stability through backlash-free parallel flexure guiding■ Outstanding lifetime due to PICMA® piezo actuators

Applications
Different microscopic techniques require different dynamics, travel ranges and flexibility of the piezo Z drives. For
high-velocity metrology, as used e.g. in surface and material inspection, focus stability over long travel ranges
and high dynamics are crucial. Often one revolving nosepiece can carry different exchangeable objectives. Herespecial requirements have to be met by the Z scanning method as the different focusing levels have to be approachedwith higher loads.

50

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

P-725.DD

N-725

P-721KTPZ

P-721KPTZ

P-725.DD

N-725

P-721K
TPZ

P-721K
PTZ

Very short step-andsettle of below 5 ms
with microscope
objective

2 mm travel range
with piezo linear
motor

Customized version
for revolving
nosepiece

Customized version
for revolving
nosepiece

52 × 71 × 40.5

52 × 75 × 40

44.5 × 42 × 53

Clear aperture in mm

34

21

Closed-loop travel in μm

18

2 000

80

150

capacitive, SGS

linear encoder

capacitive

capacitive

Closed-loop resolution
in nm

up to 0.2

20

10

2

Linearity error in %up to 0.04

0.1

0.03

0.03

Repeatability in nm

to ±1.5

±25

±10

±10

Push / pull force capacity
in N

100 / 20

10

20

20

Unloaded resonant
frequency in Hz

1 180

-

215, fully loaded

410

Stiffness in N/μm

1.5

0.5

Crosstalk in X, Y in nm

150

<100

Dimensions in mm

SensorAll product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

51

High-Speed Sample Positioning
for Fast Focus Control and Imaging
Microscopic Scanner with Large Clear Aperture

P-737

Highlights■ High positioning stability of objective slides, including micro titer plates■ Response times of a few milliseconds■ PICMA® piezo actuators for high reliability even in permanently high humidity environments■ Minimum offset and excellent focus stability through backlash-free parallel flexure guiding

Applications
Creating Z stacks for 3D imaging applications or fluorescence microscopy requires ultra-high precision and dynamics.
Piezo-driven sample scanners usually are 10 to 20 times faster than conventional stepper motors. This allows for shorter
throughput times and higher data acquisition rates. Also autofocus and drift compensation functions are significantly
more performant.

52

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

P-736

P-737

P-736

P-736

E-709

P-736

P-737

E-709

PInano® microscopy
scanner

PInano® microscopy
scanner for Nikon andOlympus

PIFOC® focusing stage,
perfect mechanical ﬁtwith XY stages ofleading manufacturers

110 × 160 × 20

156 × 237 × 20

138 to 150 × 156 × 27

65 × 93 for objective
slides110 × 160 for microtiterplates90 × 128■ Software drivers for

100, 200

220

100, 250, 500■ Supports

5

20

24 to 50, dependingon travel range

piezoresistive

capacitive, piezoresistive

SGS

Closed-loop resolution
in nm

up to 0.4

1

2.5 to 5

Recommended load for
dynamic operation in kg

0.5

0.5

0.5

Dimensions in mm
Clear aperture in mm
Closed-loop travel in μm
Step-and-settle at 10% step
size in ms, with sample
holder (load <100 g)
SensorDigital piezo servo
controller■ Included in deliveryof P-736 systems■ Digital interfaces■ Analog input

LabVIEW
MetaMorph,μManager, MATLAB■ Wide range offunctions, such asfunction generator,
data recorder, macro
programming, auto
zero, trigger I/O■ Dimensions

160 mm × 96 mm
× 33 mm

Accessories such as corresponding objective slides available.

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

53

High-Precision Multi-Axis Sample
Positioning with PInano®
Up to 200 μm in XY and XYZ

P-545 PInano®

Highlights■ Low-profile with 20 mm for space-saving integration in the microscope■ Counter-sunk insertion frames, for unhindered turning of revolving nosepiece■ Large central aperture for objective slides and petri dishes■ PICMA® piezo actuators for high reliability even in permanently high humidity environments■ Extendable with manual XY stage for 25 mm × 25 mm placement

Applications
Screening applications, confocal microscopy or biotechnology benefit from the sample adjustment in the nanometer
range. The corresponding multi-axis controller is included in delivery and can be controlled digitally or via analog signal.

54

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

P-545 PInano®

Clear aperture in mm
Closed-loop travel in μm
Sensor

E-545

P-545
PInano®
Cap

P-545.R
PInano®

P-545
PInano®
TRAK

Perfectly suited forsuperresolution
microscopy

Cost-efﬁcient design
due to piezoresistive
sensors

Highly dynamic piezo
tracker

90 × 60

90 × 60

90 × 60

200 × 200 × 200

200 × 200 × 200

70 × 70 × 50

capacitive

piezoresistive

piezoresistive■ BNC analog input■ Software drivers

for LabVIEW■ Supports

1

1

<1

Recommended load for
dynamic operation in kg

0.5

0.5

0.5

150 × 182 to
200 × 217

150 × 182 to
200 × 217

150 × 182 to
200 × 217

Accessories such as corresponding objective slides available.

PInano® piezo
servo controller,
included in delivery of
P-545 systems■ Digital interfaces

Closed-loop resolutionin nm

Footprint in mm

E-545

MetaMorph,μManager, MATLAB■ Wide range offunctions, such asfunction generator,
data recorder, macro
programming, auto
zero, trigger I/O

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

55

Precision Motion Control
Piezo Amplifiers and Controllers for Nanopositioning

Selection Criteria for Piezo Amplifiers and Controllers from PI
The decision for a piezo controller depends on the specific application situation. Diverse criteria, such as limited installation
space, the number of axes or the type of control, determine which amplifier or controller is best suited for the application.

Your Application Requires…

Which is the Suitable Controller?

Frequent change in load orchange of operating mode

Change parameters simply using software:
Any digital controller from PI, also E-609 series

Cost-effectiveness

Digital: E-709 or E-609; analog: E-610, E-625, E-621

3 to 6 channels

Digital: E-725, E-712; analog: E-500, E-612

More than 6 channels

Networkable controllers, such as E-621, E-625, E-665;
modular controllers, such as E-712

High resolution

Digital high-end solutions from PI, such as E-753, E-712, E-725;
any analog controller from PI

Highest dynamic linearity

Digital high-end solutions from PI with DDL option

Long-term stability (thermal)

All piezo controllers und drivers from PI

High linearity / accuracy

Any digital controller from PI, also E-709 series:
Digitization for 5th order polynomials, additional DDL option

Control with analog input signal

Any analog controller from PI
E-709, E-609, E-753, E-725 digital servo controllers or E-712 withanalog IN option

Real-time commands

Digital with PIO Option; SPI interface,
TCP/IP for transfer rates of up to 1 kHz;all controllers via analog I/O

Control in real time or with high servo rates

Any analog controller from PI;
E-712, E-753, E-725

Fast, non-periodic motion in several axes, tracking

E-712

Virtual axes multi-axis synchronization

Digital multi-axis controller, such as E-712, E-725

Digital communication interfaces;
user-defined periodic motion profiles; data recorderAny digital controller from PI; E-625, E-621, E-665;
modular controller with E-517 digital control unit

Stand-alone functionality with macros

Modular controller with E-517 digital control unit

Trigger I/Os

Any digital controller from PI; and also E-625, E-621, E-665;
modular controller with E-517 digital control unit

56

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

Digital and Analog Controllers for Piezo Nanopositioning Stages

Page 58

OEM Piezo Amplifier Modules

Page 64

Piezo Drivers / Controllers with High Dynamics

Page 66

For Piezo Actuators with a Control Voltage of up to 1 000 V

Piezo Axes with Special Output Voltage
P

Page 68

Pre-Configured Multi- and Single-Axis Controllers
P

Digital Controllers for Piezomotors
D

Page 70

System Optimization and Ease of Operation: Plug-and-Play
S

57

PIEZO

NANO

POSITIONING

Digital Controllers for Single-Axis
Piezo Nanopositioning Stages
System Optimization and Ease of Operation

E-753

Highlights■ Digital controller with linearization algorithms, parameter settings via softwareand notch filter for suppression of oscillations■ Servo-control for capacitive, SGS and PRS sensors■ ID chip support for automatic calibration of the controller to the piezo mechanics■ Wave generator, data recorder, auto zero, trigger I/O■ Additional high-bandwidth analog control input / sensor input

58

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

E-609,E-709 OEM version

E-709 bench-top device

E-709.CHG

E-709

E-709.
CHG

E-753

E-609

Cost-efficient digitalpiezo controller, foruniversal use

Digital high-performance controller forhigh dynamics

High-efficiency
processor for
linearization algorithms
of higher order, 24 bit
D/A transducer

Analog, USB, digital
RS-232, fast serialinterface with up to
25 Mbit/s.
E-609 OEM piezo controller available withdigital controller andanalog input

Analog, USB, digital
RS-232, fast serialinterface with up to
25 Mbit/s

Analog, Ethernet (TCP/
IP) interface for remotecontrol capability,
RS-232

Sampling rate, servocontrol

10 kHz

10 kHz

25 kHzSupported sensor type

capacitive, SGS, PRS

capacitive

capacitive-30 to +130

-30 to +130

-30 to +135

Peak current in mA

100

500

110

Average current in mA

50

160

40

Amplifier bandwidth,
small signal in kHz

50

50

50

160 × 96 × 33

320 × 150 × 80

264 × 125 × 48

Interfaces /Communication

Output voltage range in V

Dimensions in mm

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

59

Analog Controllers for Single-Axis Piezo
Nanopositioning Stages
Cost-Efficient with Versatile Interfaces

E-625

Highlights■ For high-dynamics applications of several kHz to static applications■ Servo-control for capacitive and SGS sensors■ Analog interfaces■ Optional digital interface60

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

E-610

E-621

E-610

E-621

E-625

E-665

Universal piezo control, OEM module

Piezo controller module, board for up to 12
axes in 19“ rackE-621 digital piezo
controller as benchtop device

High-performancepiezo controller forhigh dynamics

analogdigital interface withadditional digital
functions, such asdata recorder, wave
generator, etc.

digital interface withadditional digital
functions, such asdata recorder, wave
generator, etc.

digital interface withadditional digital
functions, such asdata recorder, wave
generator, etc.

capacitive, SGS

capacitive, SGS

capacitive, SGS

capacitive, SGS-30 to 130-30 to 130-30 to 130-30 to 130

Peak current in mA

180

120

120

360

Average current in mA

100

60

60

120

100 × 160

100 × 160

105 × 205 × 60

236 × 88 × 273

Interface /communication

Supported sensor typeOutput voltage range in V

Dimensions in mm

E-665

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

61

Controllers for Multi-Axis
Nanopositioning Stages
For 3 and More Axes

E-712.6CDA

Highlights■ Versatile solutions for all piezoelectric drives from PI■ For high-dynamics applications of several kHz to static applications■ Servo-control for incremental, capacitive and SGS sensors■ Digital controller for highest system optimization and ease of operation with ID chip support for automatic calibration of

the controller to the piezo mechanics■ Analog controller system with digital interface submodule for wave generator, data recorder and display

62

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W SInterfaces /Communication
Sampling rate, servocontrol
DAC/ADC resolution in bit
Supported sensor type

E-500

E-725

E-712

E-500

E-725

E-712

Modular controller
with analog driver, up
to three axes, optionalwith digital interface
and additional digital
functions, such asdata recorder, wave
generator, etc.

Available Options
for E-712
3-axis digital
controller

Ethernet (TCP/IP),
USB, RS-232, IEEE 488

Ethernet (TCP/IP) USB,
RS-232Ethernet (TCP/IP) USB,
RS-23225 kHz (with digitalinterface)

20 kHz

20 to 50 kHz

24/18

24

20

capacitive, SGS

capacitive

capacitive, PISeca capacitive, incremental

Freely configurable,
modular digital controller for three axes
and more

3- and 6-axis
controllers-30 to 135

140 to 10 000

190

140

Average current in mA

40 to 215 (different
performance classesof piezo amplifier
modules)

120

60

Amplifier bandwidth,
small signal in kHz

50

50

15

9.5 or 19“ casing

263 × 89 × 302 mm³9.5 or 19“ casing

Dimensions■ Additional

interfaces: Analog,
parallel I/O■ Linearization

algorithms of higherorder-30 to 135

Peak current in mA

nanopositioners
and piezomotors■ Pre-conﬁgured-30 to 130
to 1 100

Output voltage range in V

■ Ampliﬁers for piezo■ Real-time operation

system■ Digital sensor-signaltransmission overlonger travel ranges

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

63

OEM Piezo Ampliﬁer Modules

40-Channel Electronics
Based on E-831

Highlights■ Individual multi-channel solutions can be designed on the basis of these piezo amplifiers■ Separate power supply (DC/DC converter) for one or several amplifier modules■ Bench-top versions for fast start-up of piezo actuators in applications with very low dynamics

64

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

E-610

E-831

E-610

E-831

E-660

E-462

Universal piezo controller, OEM module,
optionally with servoloop for capacitive or
SGS sensors

Miniature modules

For quasi-static
applications

For quasi-static
applications-30 to 130-30 to 130

5 to 110

10 to 1 000

Peak current in mA

180

100 to 250

20

0.5

Average current in mA

100

50 to 10010

0.3

Amplifier bandwidth,
small signal in kHz

up to 30

3.5 to 15

quasi-static

quasi-static

Noise, 0 to 100 kHz inmVrms

0.5 to 1.6<0.15 to 0.8

550Eurocard

60 × 28 × 6 mm3160 × 90 × 60 mm3
bench-top device orplug-in module forcircuit board

205 × 150 × 73 mm3bench-top device or
67 × 38 × 20 mm3 OEM
plug-in module

DC/DC transducer,
already integrated

optional withintegrated DC/DC
transducer

DC/DC transducer
already integrated

DC/DC transducer
already integrated

Output voltage range in V

Available designs

Power source

E-660, E-462
OEM plug-in module

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

65

Piezo Drivers / Controllers with High Dynamics
For Piezo Actuators with a Control Voltage of up to 1 000 V

E-481

Highlights■ High dynamics, also for piezo actuators with high electrical capacitance■ Integrated overtemperature protection prevents overheating of the piezo actuator■ Additional options: Servo-control for long-term stability, digital interfaces■ For dynamic scanning in continuous operation, fast switching, active vibration damping

66

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

E-618

E-617

E-506

E-618

E-617

E-506

E-481
E-482

Short rise times due
to high piezo charging
current of up to 20 A

Low power consumption due to switched
control principle withenergy recovery

High linearity of piezo
displacement due tocharge control, deviation <2%

Low power consumption due to switched
control principle withenergy recovery-30 to 130-30 to +130

-30 to 130

0 to +1 100,
bipolar selectable

Peak current in mA

20 (<0.3 ms)

2 (<5 ms)

2 (<2.5 ms)

0.5 to 6 (<5 ms)

Average current in mA

0.8 (>0.3 ms)

1 (> 5 ms)

0.2

0.1 to 2

Amplifier bandwidth,
small signal in kHz

up to 15

3.5

15

several kHz even withhigh actuator capacitance

Noise, 0 to 100 kHz inmVrms

200 mVpp / 24 mVrms(without load), 2 mVrms(1 μF)<30 mVrms <100 mVpp

<0.6 mVrms<25 to 300 mVrms

9.5 or 19“ rack unit

design for top-hat rail
mounting or E-504
module for E-500
controller system

plug-in module
for E-500 controller
system19“ rack unit.
E-421, E-470 piezo
controllers /linear
amplifiers available
for 1 or 2 axes

Output voltage range in V

Available designs

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

67

Piezo Axes with Special Output Voltage
Pre-Configured Multi- and Single-Axis Controllers

E-413.00

Highlights■ Special piezo actuators and piezo scanners require specific output voltages:

Different controllers and drivers for tip/tilt mirrors, multi-axis scanners, bimorph piezo benders, DuraAct andshear actuators■ Internal coordinate transformation of tilt angle for parallel-kinematic multi-axis design■ Large variety of designs, bench-top devices, rack units, individual modules, OEM versions

68

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

E-616

E-536

E-650

E-835

E-616

E-536

E-650

E-413

E-651

E-835

For tip/tilt mirror
systems with tripod ordifferential drive

For PicoCube® 3-axis
piezo scanner

For PICMA® Benders
with or without servocontrol

Bipolar output
voltage, for DuraAct
or shear actuators

SGS

capacitive

SGS or open-loop–-20 to +120-250 to +250

0 to 60

350 to 500 V
voltage range

Peak current in mA

100

100 to 200

up to 300 open-loop
for maximum dynamics

100

Average current in mA

50

15 to 30

<100

<50

Bandwidth in kHz

3 (small signal)

2 to 10 (small signal)

6 (large signal)

up to 4 (small signal)

Available designs

bench-top device or
eurocard rack unit

19“ rack, optional withdigital interface

bench-top device or
OEM plug-in modulebench-top device orcompact OEM designs

Supported sensor typeOutput voltage range in V

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

69

Digital Controllers for Piezomotors
System Optimization and Ease of Operation: Plug-and-Play

E-871

Highlights■ Extensive software support, e.g. for LabVIEW, shared libraries for Windows and Linux.

Data recorder, e.g. for position values■ Processing of incremental sensors■ Analog I/O, e.g. for connection to joystick, and digital I/O for automation applications■ Integrated drivers, optimized for the corresponding drive type, e.g. with auto-resonant ultrasonic frequencies

or concerted displacement of shear and longitudinal actuators■ Alternative: Driver electronics without integrated control for designing an external servo loop

70

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

E-755

E-861

C-867

E-755

E-861

E-871

C-867

For NEXLINE®
piezo stepping drives

For NEXACT®
piezo stepping drives

For PIShiftpiezo inertia drives

For PILine®
ultrasonic drives

Special featureslinearization with polynomials for perfectlinearity of motion,
deviation approx.
0.001% over the entire
travel range of the
NEXLINE® nanopositioning stage

supports all motion
modes: Point-to-pointmotion, analog modefor nanometer-precise
positioning at target
position. Non-volatile
macro memory

supports all motion
modes: Point-to-pointmotion, analog modefor nanometer-precise
positioning at target
position. Non-volatile
macro memory

supports all motion
modes: Point-to-pointmotion, slow motion
at μm/s, precise stepand-settle. Non-volatile macro memory

Interfaces /Communication

RS-232

USB, RS-232

USB, RS-232

USB, RS-232

Multi-axis control

up to 16 units
via daisy chain.
E-712 modular multiaxis controller fordifferent drive modes
available

up to 16 units
via daisy chain.
E-712 multi-axis
controller

up to 16 units
via daisy chain

up to 16 units via
daisy chain. 2-axis
controller available

Open-loop designs /drive electronics

open-loop designs
available

E-862 OEM drive electronics available

E-870 OEM drive electronics available

OEM version in eurocard format or C-872
OEM driver electronics
available

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING71

Nanometrology
High Precision for Nanopositioning Technology

PIMag™ 6D, the positioning system based on magnetic levitation: Th
hepassive platform levitates on a magnetic field which actively guides
it. In this way, objects can be moved linearly or rotationally on a plannewith a previously unattained guiding accuracy. The six-axis motion iss
controlled by a 6D sensor, that combines high-resolution capacitive andincremental sensors

72

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W SCapacitive and Incremental Sensors

Page 74

Nanometrology in PI Piezo Nanopositioning Systems

73

PIEZO

NANO

POSITIONING

Capacitive and Incremental Sensors
Nanometrology in PI Piezo Nanopositioning Systems

PIOne Sensor
Head and Scale

Highlights■ Noncontact distance measurement■ For applications with highest precision requirements■ Direct position measurement compensates for mechanical deviation: Direct metrology

Applications
For its reference-class nanopositioning stages, PI uses noncontact position measurement methods. The most important
specifications for selecting a suitable method are linearity, resolution (sensitivity), stability, bandwidth and, last but notleast, the costs. In addition, it is important that the selected method is capable of directly measuring the platform's motion, so that any position change of the platform is captured by the controller relatively to the base body. Here, accuracies
in the sub-nanometer range are possible.

74

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

D-015

D-510

D-015
D-050

D-510
PISeca

D-711
PIOne

Single-electrode capacitive sensors withexcellent resolution

Incremental sensor
with interferometricmeasuring principle fornanopositioning

D-100

Capacitive sensors
with resolution in the
sub-nanometer range

Area of application

integrated in the piezo
nanopositioning
stages from PI
For use in UHV
up to 10-9 hPa

easy integration,
available as individual
product for designing
an external servo loopwith E-852 electronics
Also for vibration
measurement

integrated in PI
nanopositioners withtravel range>1 mm

Resolution

0.0005% of themeasurement range,
typically
0.5 nm to 10 pm

0.001% of themeasurement range,
typically
1 to 5 nm

up to 20 pm RMS;
0.12 nm peak-to-peak

Bandwidth

10 kHz

10 kHz1 MHz

up to 1 000 μm

20 to 500 μm,
millimeter on request

10 to 130 mm,
depending on the
scale

up to 0.01% of themeasurement
range, typically 10 to
50 nm

up to 0.1% of themeasurement
range, typically 100 to
500 nm<20 nm-20 to +80°C-20 to +100°C

10 to +50°C

aluminumother, e.g. Invar on
requestaluminumother, e.g. Invar on
requestmixture,glass scale

15 × 8 × 4 to
20 × 20 × 5

Ø 8 to 20 × 30

23 x 12 x 9.5

Measurement range

Linearity error

Operating temperature
range

Material

Dimensions sensor
in mm

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

75

Nanopositioning Technology

Piezo Actuators as Drives for Nanopositioning

Page 77

Highly Reliable PICMA® Piezo Actuators – Nanopositioning with Piezomotors over Long Travel Ranges:
PiezoWalk®, PILine®, PIShift
Excellent Guiding Accuracy through Flexure Joints

Page 79

No Wear – Flexures as Levers – Sub-Nanometer Accuracy
Parallel Kinematics Optimizes Motion in Multiple Axes

Page 80

Parallel or Serial Multi-Axis Design
Kinematics of Multi-Axis Tip/Tilt Systems

Page 81

Tip/Tilt System with Tripod Piezo Drive – Tip/Tilt System with Differential Piezo Drive (Tetrapod) –Dynamics of a Piezo Tip/Tilt Mirror
Use in Vacuum

Page 83

Vacuum Classification at PI
Special Ambient Conditions

Page 83

Magnetic Fields – Low Temperatures
Sensor Technology for Nanopositioning Technology

Page 84

Maximum Accuracy through Direct Metrology – Capacitive Sensors – PIOne Linear Encoders: Small andPicometer Resolution – Indirect Position Measurement with Strain Gauge Sensors – Direct Parallel Metrology:
Multi-Axis Measurements using a Fixed Reference
Precision Motion Control

Page 88

Control Electronics Optimizes System Properties – Advantages and Disadvantages of Position Control –Resolution with Closed-Loop and Open-Loop Control – Flexible Controllers to Match the Mechanics –Controller Tuning
Digital Controllers Provide Precision, Dynamics and Ease of Operation

Page 91

Linearization of the Electronics – Controllers and Controlling Methods – Linearization of the
Mechanical System – Dynamic Linearization – Additional Functions of Digital Controllers
Motion Control Software

Page 93

Universal Command Set – Host Software PIMikroMove for Fast Start-Up®

Page 96

ServiceScope of Delivery – Customization – Updated Firmware, Software and User Manuals

76

Glossary

Page 97

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

Piezo Actuators as Drives
for Nanopositioning

Low-profile two-axis piezo scanner

Piezo actuators have excellent drive
properties:■ The motion of piezo actuators is based onsolid-state effects, which makes their resolution in general unlimited■ Their stiffness is very high, enabling highforce generation by piezo stepping drives■ Their rapid response time in the micro-

second range is a result of their high resonant frequency of several hundred kilohertz■ The available travel range is a few hundred

micrometers

The motion of piezo actuators is not straight.
To avoid lateral migration, a guiding system isrequired. In piezo stages manufactured by PI,
friction and backlash-free flexure joints ensure high-stiffness guiding and optimum travel
accuracy. They also enlarge the travel range tothe millimeter range.
Solid state effects in the piezoelectric material
account for a nonlinear motion with hysteresis.
To achieve the excellent stability, linearity andrepeatability required for nanopositioning, aposition control is used.

Highly Reliable PICMA® Piezo Actuators
PICMA ® piezo actuators fromm PI are theonly monolithic, multilayer piezo
actuators
zo actutuat
a ors
in the world which are completely
ely encapsuencapssulated in a ceramic insulation layer.
yer. Decadesof experience with PICMA® seriesries in various applications show that the lifetime has
been increased by at least a fac
factorcto
tor of 10
compared to conventional, polymer-coated,
mer-co
oat
ated
ed,,
multilayer piezo actuators. In lifetime
tests,
fetime teststs,s,more than 100 billion cycles without
sinthout a sin
in-gle failure have been demonstrated.
strated. The
PICMA® technology is patented.
d.

The position control eliminates the nonlinear behaviorof the piezo actuator. The possible travel range, however, is longer without position control

PIEZO

Due to their ultra-high performance and reliability, PICMA®
piezo actuators with all-ceramic
insulation were chosen for tests
carried out by NASA on Mars

77

NANO

POSITIONING

Nanopositioning with Piezomotors over Long
Travel Ranges: PiezoWalk®, PILine®, PIShift

Piezomotor Properties

For travel ranges over 1 mm, PI uses piezomotors as drives, which also feature high stiffness
and resolutions in the nanometer range. Piezomotors do not generate magnetic fields nor are
they affected by them.

■ Self-locking when at rest with maxi-

Piezomotors are optimally suited for using thespecific properties of piezo actuators to achieve
longer travel ranges. Adapted to the required
force and velocity development, PI provides
a series of different piezomotor technologies,
each of which focuses on different features.

■ Different technologies optimized formum holding force■ Variable travel ranges■ Nanometer-precision resolution■ Easy mechanical integrationhigh velocities or for high forces

Piezo stack actuators in multi- PiezoWalk®
layer or pressing technology
piezo stepping drive

PILine®
ultrasonic piezomotor

PIShift
piezo inertia drive

Sub-nanometer resolution

Sub-nanometer resolution

Sub-micron resolution

Sub-nanometer resolution

Fast response within a few
microseconds

Velocity up to 10 mm/s
High-dynamics scan mode

Very high operating frequency
Noiseless driveHigh velocity of up to several
100 mm/s

Very high operating frequency
Noiseless drive
Velocity of more than 10 mm/s

Travel ranges of up to approx.
300 μm directly and 2 mm withlever ampliﬁcation

Long travel ranges, only limitedby the runner lengthLong travel ranges, only limitedby the runner lengthLong travel ranges, only limitedby the runner length

High stiffness
Force generation of up to 100 kN

Very high forces of up to 800 N(NEXLINE®)
Self-locking at rest

Forces up to 40 N
self-locking at rest

Forces up to 10 N
self-locking at rest

Control via analog voltage
Voltage range 150 V (PICMA®
multilayer actuators),
1 100 V (PICA high-load actuators)

Multi-actuator drive generates
stepping motion
Voltage range 55 V (NEXACT®),
500 V (NEXLINE®)

Single-actuator drive
Control via high-frequency alternating voltage (sinus)
Voltage range 120 V, 200 V. Minimotors substantially lower

Single-actuator drive
Control via high-frequency
alternating voltage (modiﬁed
sawtooth)
Voltage range <48 V■ Nanometer-precise positioning■ Nanometer-precise■ Positioning with sub-μm■ Nanometer-precision

with high dynamics■ Lever-amplified and guided
systems■ Piezo scanners■ Fine adjustment■ Force generation■ Active vibration insulation

positioning■ Quasi-static applications athigh holding force■ Travel ranges of up to afew mm■ Coarse and fine adjustment■ Force generation■ Active vibration insulation■ Operation at constantly
low velocity

accuracy■ Fast step-and-settle■ Scan mode with highvelocities■ Operation at constantly
low velocity

positioning stable over a
prolonged period■ Quasi-static applications at
low to medium holding force

Ideal for:78

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W SExcellent Guiding Accuracy
through Flexure Joints

A piezo stage with integrated
flexure guide achieves a guiding accuracy of only a few
nanometers or microradiansand excellent flatness

Flexure guides from PI have proven their worth
for nanopositioning tasks down to 2 mm.
The motion of a flexure joint is based on theelastic deformation of a solid. Therefore, there
is no static, rolling or sliding friction.
No Wear
Their advantages are the high stiffness, load
capacity and wear-resistance. Flexures aremaintenance-free, can be manufactured fromnonmagnetic materials, require no lubricants
or consumables and hence also function in a
vacuum without any problem.

Sub-Nanometer Accuracy
Flexures allow motions with extremely highpath accuracy. In order to compensate forheight or transversal offset, PI uses special
multi-link flexure guides. These guiding systems, which are implemented in most nanopositioning systems from PI, allow a flatness
and straightness in the sub-nanometer or
microradian range.

Flexures as Levers
The displacement of a piezo actuator can also
be multiplied by integrating a lever mechanism. The actuator is mechanically integrated
in a flexure joint in such a way that the travel
range is extended to up to 2 mm. Since simple
lever structures lose a considerable amount of
guiding accuracy and stiffness, however, thedesign requires much more complex geometries.
This lever mechanism with flexure guides transforms
the actuator travel range (vertical) to an even, straightmotion (horizontal)

The deformation of the flexure guides is checked with
FEM stress simulations

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Parallel Kinematics Optimizes Motionin Multiple Axes

In a parallel-kinematic multi-axis system, allactuators act directly on one moving platform.
This means that all axes move the same minimized mass and can be designed with identical dynamic properties. Parallel-kinematic
systems have additional advantages overserially stacked or nested systems, including
more-compact construction and no cumulative
error or weight from the different axes. Parallel-kinematic systems can be operated with up
to six degrees of freedom with low inertia andexcellent dynamic performance.

In a parallel-kinematic structure, all drives act on thesame moving platform so that the individual axes havethe same dynamic behavior. Consequently, higher
dynamics and higher scanning frequencies, improved
guiding accuracy, repeatability and stability can beachieved than with serial axes systems

A serial multi-axis system, whether nested or stacked,
assigns exactly one direction of motion to each actuatorand each sensor. The stage axes carry the next mounted
axis so that the dynamic properties deteriorate andthe overall stiffness decreases. Moreover, the runoutsof the individual axes add up to a lower accuracy andrepeatability. Serial-kinematic systems have a simpler
structure and can often be manufactured at lower costs

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Kinematics of Multi-Axis Tip/Tilt Systems

Piezo tip/tilt mirror systems from PI are based on parallel kinematics with a single movable
platform for all directions of motion. The systems achieve a higher linearity than can beattained by switching two single-axis systems in succession, as is the case with galvanoscanners, for example, and therefore, are very compact.

Horse head nebula(Photo: Brian Lula)

The tilt angle andthe travel in Z arecalculated using thefollowing formulas:θXθY = 2A –

θY

(B+C)
2a

θX =

(B-C)
b

Z=

(A+B+C)
3

A, B, C is the linear
displacement of therelevant actuators.

Arrangement of the actuators of a tripod piezo drive

PI offers a large range from compact systems
for laser beam steering up to large units used
for astronomy.
Tip/Tilt System with Tripod Piezo Drive
The platform is driven by three piezo actuatorsthat are located in 120° angles to one another.
By means of coordinate transformation, themotion can be split among the different actuators.

The platform is driven by two pairs of piezo
actuators located in 90° angles to one another.
Four actuators are controlled differentially inpairs, depending on the tilt direction. The tilt
axes θX and θY are arranged orthogonally sothat a coordinate transformation is not necessary.
This concludes in an excellent stability in linear
and angular positioning for a wide temperature range.

Piezo

They allow for an optical beam deflection up
to 100 mrad, extremely short response times
from milliseconds to microseconds and resolutions down to nanoradians.

Tip/Tilt System with Differential Piezo Drive(Tetrapod)

Piezo

Piezo-actuated tip/tilt mirrors and platforms
are suitable both for highly dynamic operation,such as tracking, scanning, image stabilization,
elimination of drift and vibration, and for static
positioning of optical systems and samples.

Principle of a tilt system withdifferential piezo drive

Just as the tripod, the differential version guarantees an optimum angular stability over alarge temperature range. For position controlled versions, the differential evaluation of
two sensors per axis provides an improved
linearity and resolution.

In addition to tilting, the platform may also be
used linearly in Z direction, which is important,for example, for correcting optical path lengths(phase shifters).

PIEZO

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Dynamics of a Piezo Tip/Tilt Mirror

The maximum operating frequency of a piezo
tip/tilt system strongly depends on its mechanical resonant frequency. The propertiesof amplifier, controller and sensor are also
important. To estimate the effective resonant
frequency of the system – a combination of
platform and mirror – it is necessary to calculate the moment of inertia of the mirror substrate first.
Moment of inertia of a rotationally symmetricmirror:
IM = m

[

2R2 + H2
12

+

(

H
2

)]

IM = m

[

12

+

+T

( )]
H
2

f' = mf0
1 + IM/I0

Resonant frequency of a piezo tip/tilt systemwith mirror
with:

2

Moment of inertia of a rectangular mirror:

L2 + H2

The resonant frequency of the system is calculated with resonant frequency of the platform(see technical data) and moment of inertia ofthe mirror substrate using the following formula:2+T

f' = resonant frequency of platform with mirror [Hz]f0 = resonant frequency of platform without
mirror [Hz]I0 = moment of inertia of platform (see technical data) [g × mm²]]
IM = moment of inertia of mirror[g × mm²]with:
m = mirror weight [g]IM = moment of inertia of a mirror[g × mm²]
L = mirror length orthogonally to tilt axis[mm]
H = mirror thickness [mm]T = distance of pivot point to platform surface(see technical data of individual models)[mm]
R = mirror radius [mm]82

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Use in Vacuum

Piezo stages use technologies that are basically perfect for being used in a vacuum: Piezo
actuators, capacitive position sensors and flexure guides. Furthermore, they need no lubricant or grease for operation.
The PICMA® piezo actuators in all PI nanopositioning systems are manufactured without
polymers and, consequently, have particularly low gas emissions. They can be baked out
at up to 150°C. The materials used for vacuum positioning stages are aluminum alloys,
stainless steels or titanium. The surfaces are
not coated but electropolished. Vacuum cableinsulation is made of PTFE or FEP (Teflon), on
request also of polyimide (Kapton) or PEEK.
The use of plastics and adhesives is reduced
as far as possible.

This piezo six-axis stage was developed for Physikalisch-Technische Bundesanstalt (PTB), the German
national metrology institute, as object slide in an atomic
force microscope (AFM); it is designed for use in UHV.
The linear travel ranges are 12 μm × 12 μm × 10 μm; anactive correction of the travel accuracy is possible bycontrolling the tilt axes. With a load of 300 g, it achieves
a resonant frequency of over 2 kHz

Vacuum Classification at PI
High vacuum (HV)

For a number of positioning stage series,
PI offers UHV versions as catalog products.
Design and manufacture for ranges beyond
these limits are offered on request. The
vacuum feedthroughs are not included in
the scope of delivery and may be orderedseparately, if required.

10-3 to 10-6 hPa

Ultrahigh vacuum (UHV) 10 to 10 hPa-7-9

1 hPa = 1 mbar

Special Ambient Conditions
Magnetic Fields

Low Temperatures

PICMA® piezo actuators are excellently suitedfor being used in very strong magnetic fields.
Piezo positioning systems can be manufactured without ferromagnetic materials.

Piezo actuators show displacements to thecryogenic range. Special models of PICMA®
actuators can be used down to -271°C but
with a considerably reduced travel range. For
designing a nanopositioning system, it is also
important to select suitable materials and components.

Piezomotors can also be used in magnetic
fields, because they do not generate magnetic
fields nor are they affected by them.

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Sensor Technology for
Nanopositioning Technology

The PIOne linear encoder is used in PI's high-resolution
nanopositioning system, such as N-664. This linear
positioner is driven by NEXACT® piezo linear motors
and, depending on the motion controller, can achieve
a position resolution of less than one nanometer at
30 mm travel range

PI offers the widest range of high-dynamics
and high-resolution nanopositioning systems
worldwide. Their linearity and repeatability
would not be possible without highest-resolution measuring devices.
Accuracies in the range of a few nanometers
and below require a position measurement
method that can also detect motion in this range. The most important specifications for selecting a suitable method are linearity, resolution(sensitivity), stability, bandwidth and, last but
not least, the costs. Another important factor isthe ability to directly record the motion of theplatform. The contact with the movable parts
also affects the measuring result; therefore, PI
uses noncontact measurement methods as far
as possible. Furthermore, the sensors need tobe small and may not heat up.
PI nanopositioning systems use three different
types of sensors: Capacitive sensors and linear
encoders for direct metrology as well as strain
gauges for indirect position measurement.

Measurements have confirmed the excellent repeatability of the piezo positioning system with capacitive
sensors with 1.4 nm (1 σ value) of standard deviation

Maximum Accuracy through Direct Metrology
When directly measuring positions with noncontact sensors, each change in position of
the moving platform is directly captured by the controller relatively to the base body.
There are no drive or guiding elements, which would affect the measurement, between
measured point and moving platform. This method allows a bandwidth in kilohertz range,
resolution in sub-nanometer range and excellent stability.
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■ Vacuum compatible down to 10-9 hPa■ Maintenance-free, no wear
■ High bandwidth up to 10 kHz■ High temperature and long-term stability(<0.1 nm/3 h)■ Invar versions for highest temperature stabi-lity (5 × 10-6/K)■ Compact one and two-electrode sensors,custom designs■ Processing electronics in various configura-

Capacitive Sensors

tion levels, from analog OEM versions to amodular digital controller system that can be
expanded at any time

Nanopositioning systems from PI are driven
by translation piezo actuators and have travel
ranges of a few hundred micrometers up to
one millimeter. Capacitive sensors achieve
a position resolution in the sub-nanometer
range, high stability and bandwidth, as well as
the best linearity and accuracy.
Capacitive sensors from PI determine thedistance between two plate electrodes without
contact. An active guard ring electrode generates a homogenous field in the measurement
area. This and the very precise parallel adjustment of the two electrodes guarantees the best
possible linearity of the sensor signals overthe entire measuring range. These sensors areintegrated in the nanopositioning system insuch a way that no effects on size and mass(inertia) are to be expected. With a corresponding arrangement, they directly detect the
motion of the platform (direct metrology).

c = ε0 · εr ·AdOperating principle of a capacitive sensor. The capacitance C is proportional to the active
sensor area A, d is the measuring range (distance from sensor to target surface), ε0 isconstant, εr is the dielectric constant of the material between the plates, generally air.
The measured quantity is the change in capacitance of the electric field. An active guard
ring electrode generates a homogenous field in the measurement area

PISeca single-plate capacitive sensors measure against all kinds of conductive surfaces
and are easier to handle mechanically, forexample during installation or cable routing.
Their employment is also more versatile, e.g.
for detecting motions perpendicular to thedirection of measurement. The quality of thesensor signals, however, strongly depends on
the parallelism and condition of the surface
measured.
■ Noncontact absolute measurement of

distance, motion and vibration■ Measuring ranges from a few 10 μm to2 mm feasible■ Only minimum heating, no scattered light■ Direct metrology: Direct position measure-ment of moving objects

PISeca single-electrode capacitive sensors measure against all kinds of conductive surfaces and are easier to handle mechanically, for example during installation or cablerouting. Their employment is also more versatile, e.g. for detecting motions perpendicular to the direction of measurement. The E-852 stand-alone processing electronics for
PISeca only shows minimum noise and integrates a linearization system. All systems
are calibrated at PI and optimized for the intended bandwidth and the measuring range

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Small with Picometer Resolution
The capacitive measuring systems reach theirlimits with larger travel ranges: Either sensor
areas become larger or resolution and linearity deteriorate. Nanopositioning systemwith piezomotors, which have travel rangesof several 10 millimeters, use linear encoders
as posi tion sensors. These are incremental
measuring systems that consist of a scale andsensor head. The high-resolution linear sensor
PIOne ensures a position resolution of far lessthan a nanometer with adequate processing of
the measurement.

The sensor head of the PIOne contains a MachZehnder interferometer, which is moved along
a linear scale. Sine and cosine signals are
generated from the signals of the reflections
at the grid. Additional interpolation accounts
for the demonstrably small resolution of thesystem. The sensor head also generates adirection-sensing reference. The sensor head
here measures 23 x 12 x 9.5 mm³. PIOne uses
a patented technology.

■ Resolution to 20 picometer RMS;

0.12 nanometer peak-to-peak■ Velocities up to 0.5 m/s at maximum

resolution■ Compact dimensions

23 mm × 12 mm × 9.5 mm■ Sine, cosine or quadrature output signals■ Low power consumption and low heatdissipation■ Bakeout temperature up to 80°C

Noise measurement of a positioning system with the PIOne at 1 MHz bandwidth and 18-bit resolution of the sensor input: 16 picometer RMS and 100 picometer peak-to-peak86

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Indirect Position Measurementwith Strain Gauge Sensors
Strain gauge sensors consist of a thin metal(SGS) or semiconductor foil (piezo-resistant,
PRS), which is attached to the piezoceramics
or, for improved precision, to the guiding
system of a flexure stage. This type of position measurement is done with contact andindirectly, since the position of the moving

platform is derived from a measurement on
the lever, guide or piezo stack. Strain gauge
sensors derive the position information fromtheir expansion. Full-bridge circuits with several strain gauge sensors per axis improve thermal stability.

Sensor type

Sensitivity/
Resolution*

Linearity*

Stability/
Repeatability

Bandwidth*

Measurement
methodMeasurement
range

Capacitive

excellent

excellent

excellent

excellent

direct / noncontact<2 mm

Strain gauge
sensors made ofmetal foil (SGS)very goodvery good

goodvery goodindirect / withcontact<2 mm

Piezoresistive
strain gauge sensors (PRS)

excellent

goodaveragevery goodindirect / withcontact<1 mm

Linear encoders

excellentvery good

excellentvery good

direct / noncontact

up to >100 mm* The classifications refer to the characteristics of the nanopositioning system. The information on resolution, linearity and repeatability in therespective data sheet reflects the specifications of the overall system, including controller, mechanical system and sensor. They are tested using
external measuring instruments (Zygo interferometer)

Direct Parallel Metrology: Multi-Axis
Measurements using a Fixed Reference
A multi-axis stage design with parallel kinematics allows you to use direct parallel metrology, measuring all degrees of freedom of themoving platform in relation to a fixed reference. Unintended crosstalk of the motion intoa different axis, e.g. as a result of an external
force, can thus be detected and actively corrected in real time. This so-called active guiding can keep the deviation from the trajectory
down to a few nanometers, even in dynamic
operation.

Parallel-kinematic nanopositioning system with capacitive sensors, parallel-metrology
arrangement and reduced inertia. The arrows show the signal flow from the sensor to theclosed-loop control. Red: X axis, blue: Y axis

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Precision Motion Control

Closed-loop PI piezo controllers feature:■ High linearity■ Positioning with sub-nanometer accuracy■ Excellent long-term stability■ Noise approx. 1 mV (RMS value)■ Low power consumption■ Notch filter for higher bandwidth■ Output voltages adapted to various piezo

actuators and piezo drives■ Analog interfaces for fast direct command-

OEM piezo controller card. The piezo control voltages
are generated on-board, operation only requires a stabilized voltage between 12 and 24 V

Flexible Controllers to Match the Mechanics
PI offers the world’s largest portfolio of precision motion technologies for positioning in theaccuracy range from one micrometer down tobelow one nanometer. Fast settling or extremely smooth low speed motion, high positional
stability, high resolution and high dynamics –the requirements placed on piezo mechanisms
vary greatly and need drivers and controllers
with a high degree of flexibility. PI provides abroad spectrum of piezo electronics from versatile general purpose controllers to highly
specialized devices. Units come in different
levels of integration from customized OEM
boards and a plug & play bench-top devices tomodular controllers to scalable to almost any
number of axes.

ing in real time
■ Short-circuit strength

Piezo mechanisms directly respond to thesmallest change in the drive voltage with achange in displacement. Response times of afew microseconds are possible, depending on
the mechanical design and the performance ofthe piezo controller.
In static operation, i.e. when a certain positionis held, the stability of the power supply is alsodecisive because piezo actuators react even to
the minutest change in voltage with a motion.
Therefore, noise or drifting must be avoided asmuch as possible.

This high-performance piezo controller delivers
peak power of up to 6 kW. A digital interface
module offers extended functionalities, such asrecorder and function generator
data reco

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P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W SControlIn
Overflow

Slew Rate

Servo OFFON+

The performance of a piezo mechanism not
only depends on the mechanical design but
also largely on the capabilities of its controller. PI's low-noise, drift-free piezo amplifiers
ensure optimum stability and resolution. Highbandwidth allows for rapid response times andhigh scanning frequencies.
Closed-loop position control compares thetarget position with the information provided
by the position feedback sensor (actual value)
and automatically compensates for nonlinearity, hysteresis and drift.
The servo-control part of most analog piezo
controllers manufactured by PI is identical: A
proportional integral control loop specifically
optimized for piezo operation. One or moreadjustable notch filters considerably improveusable bandwidth and dynamics because
resonances are suppressed before they canaffect the system stability. In digital controllers,
optimized control algorithms further minimize
settling times and increase bandwidth and stability. High-end closed-loop piezo positioning
systems can achieve a repeatability down to
the sub-nanometer range and bandwidths to
10 kHz.

Proportional Integral
Term
Term

PZT
Out

PZT
Monitor

DCOffset

Optimized Control Design Improves
System Properties

PZT
Amplifier

NotchFilter

PZT
Sensor–SensorMonitorSensorGain

SensorRange
Bandwidth Adjustment

ZeroAdjust

SensorIn

Block diagram of a typical closed-loop piezo controller

Resolution in Closed-Loop and Open-Loop
Control
Closed-loop piezo systems guarantee higher linearity and repeatability than open-loopsystems. The position resolution of piezo
actuators and flexure-based piezo mechanisms
is not limited by friction but influenced by electrical noise at the sub-nanometer level.
Because of the additional sensor and the servo
circuit, the noise is slightly higher in closedloop operation compared to open-loop control,
where only the piezo amplifier contributes toelectrical noise. If high-quality components areused, sub-nanometer positional noise levels
are possible in closed-loop operation. Capacitive position sensors achieve the best resolution, linearity and stability.

Advantages and Disadvantages of Position Control
Most precision positioning applications greatly benefit from closed-loop control.
When maximum bandwidth is crucial, open-loop may be worth a consideration:
A closed-loop controller always operates in the linear range of voltages and currents. Since
the peak current is limited in time and is therefore nonlinear, it cannot be used for a stable selection of control parameters. As a result, position control limits the bandwidth anddoes not allow for pulse-mode operation. In switching applications, it may not be possible
to attain the necessary positional stability and linearity with position control. Open-loop
operation may be a better choice here with linearization obtained by means of chargecontrolled amplifiers or by numerical correction methods.
In closed-loop operation, the maximum safe operating frequency is also limited by the phaseand amplitude response of the system. Rule of thumb: The higher the resonant frequency ofthe mechanical system, the higher the control bandwidth can be set. The sensor bandwidthand performance of the servo (digital or analog, filter and controller type, bandwidth) also
limit the operating bandwidth of the positioning system.

PIEZO

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Standardized Measurements Logs:
The Good Feeling When Your Expectations Are Met
Nanopositioning systems are an essential but
costly component in applications. PI therefore individually tests and optimizes the static and dynamic parameters of every system.
The measurement log is delivered with thesystem. The customer can thus retrace theperformance of the system at delivery andwhich system components belong together at
any time.
PI continually invests in improving the testing
methods and testing equipment in order to beable to supply systems of even higher quality. Closed-loop nanopositioning systems aretested exclusively with high-quality calibrated interferometers. The test laboratories are
insulated against seismic, electromagnetic andthermal effects, temperature stability is better
than 0.25°C in 24 hours. PI thus sets the standard in the testing and specification of nanopositioning products.

Controller Tuning
To optimize the system performance, information about the application is required, suchas the desired operating frequency, step-andsettle, the size and weight of the payload, orthe spring constant of a preload in relation towhich the piezo actuator is operated.

Highly dynamic, closed-loop nanopositioning system: A piezo scanner achieves
the full travel range of 100 μm in only a few milliseconds

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Digital Controllers Provide Precision,
Dynamics and Ease of Operation

Digital piezo controllers have several advantages over analog servo circuits: Linearity andsettling behavior can be specifically influenced
by digital algorithms allowing much greater
flexibility than analog circuits. The result ishigher precision and better dynamic performance.
Linearization of the Electronics
With digital servo controllers it is possible to
upload calibration data quickly and remotely.
PI piezo stages can store optimized parametersin an ID chip. With this combination, controllers and mechanics can be swapped without
performance losses, because the controller
recognizes the mechanics and reads specificlinearization and calibration data when it ispowered up.

Modular, digital multi-axis controls withintegrated coordinate transformation simplify the operation of complex parallelkinematics systems, such as this Hexapod
with NEXLINE® piezo stepping drives

Controllers and Servo Techniques
TargetValue

The task of a servo loop is to correct deviations between the actual position and the target position. Commonly, this is done with P-I(proportional-integral) controllers. Dependingon the application, however, advanced control
techniques in combination with linearization
algorithms can yield better results. Digital filters avoid undesired mechanical excitation,
suppress noise and, with that, increase theresolution and system bandwidth.
Linearization of the Mechanical System+
Slew Rate–
Controller

Band-Stop
FilterDAC

Low-Pass Filter

ADC

Amplifier

ActuatorandSensorSensor Electronics

Block diagram of a digital piezo servo controller

The linearity of the entire system is one criterion for its positioning accuracy. Piezo actuators typically show a nonlinearity of 10 to 15%,
which has to be compensated by the control
loop. Digital controllers use higher-order polynomials to reduce the motion nonlinearity tovalues below 0.001%, which, for a typical travel
range of 100 μm, corresponds to an accuracyof one nanometer and better.

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Dynamic·Linearization: Following a Moving
TargetElliptical scan (for laser micro bore applications) with an XY piezo scanning stage
and conventional PID controller. The outercurve shows the desired position, theinner curve shows the actual motion

The same scan as before but with a DDL
controller. The tracking error is reduced toa few nanometers, target and actual position cannot be distinguished in the graph

Dynamic digital linearization (DDL) reduces the
dynamic tracking errors of periodic trajectories.
This is relevant for scanning applications,where a specific position must be identified
on the fly and later be approached with highprecision, or for applications where a trajectorymust be followed at very high speed with minimum deviation for processing steps.

Additional Functions of Digital Controllers
Computing power and memory size which go
hand in hand with digital controllers allow usefuladditional functions to be implemented.
■ Software access to all motion parameters

and the graphic display of the results■ Coordinate transformation for parallel kine-

matics for simple control in Cartesian coordinates■ Macro memory to store and retrieve

motions which can be triggered externally■ Function generator and waveform memory

for the retrieval of predefined trajectories
and the generation of customized waveforms■ Data recorders record sensor and control

data for subsequent processing■ The ID chip permits the flexible exchangeof controllers and nanopositioners without
the need to retune the operational parameters
Not all controllers provide the above-listedfunctions. The individual ranges of functions
are listed in the relevant datasheets.

The standard interfaces for digital nanopositioning
controllers are RS-232, USB and TCP/IP. Additionally, PI
offers digital I/O lines, options for analog interfaces andreal-time PIO

92

Complex motion profiles can be generated, saved andimplemented with the function generator

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W SMotion Control Software from PI
Effective and Comfortable Solutions

Parallel Kinematics

Nanopositioning

UP TO 6 DEGREES OF FREEDOMSUB-NANOMETER RESOLUTIONGCS
MOTION CONTROL

Drive Technology

Micropositioning

DC, STEPPER, PIEZO, MAGNETIC

LONG TRAVEL RANGESAll digital controllers made by PI are accompanied by a comprehensive software package. PI
supports users as well as programmers withdetailed online help and manuals which easeinitiation of the inexperienced but still answer
the detailed questions of the professional.
Updated software and drivers are always
available to PI customers free of charge via
the Internet.
PI software covers all aspects of the applicationfrom the easy start-up to convenient system
operation via a graphical interface and fast andcomprehensive integration in customer written
application programs.

Universal Command Set Simplifies
Commissioning and Programming
PI developed the PI General Command Set(GCS) that is used to control all nano- andmicro-positioning systems regardless of thedrives and motion controllers used. GCS withits many preprogrammed functions accelerates
the orientation phase and the application development process significantly while reducing
the chance of errors, because the commands
for all supported devices are identical in syntax
and function.

Supported Operating Systems■ Windows XP (SP3)■ Windows VISTA■ Windows 7 32/64 bit■ Linux 32/64 bit■ Windows 8 32/64 bit

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Start-Up
PIMikroMove is PI’s convenient graphical userinterface for any type of digital controller andpositioning system, regardless of whether
piezoelectric, linear motors, or classical electrical motor drives are used and independentof the configuration and number of axes.
All connected controllers and axes are displayed and controlled consistently with thesame graphical interface. For a multi-axis
application, various controllers can be usedand commands can still be issued via PIMikroMove in the same window. Two or more independent axes can be controlled by the position
pad using a mouse or joystick; Hexapod sixaxis positioning systems are also displayed
graphically.
Macro programs simplify repetitive tasks forexample in automated processes. The macros
are created as GCS command sets that can be
executed directly on the controller, e.g. as astart-up macro that allows stand-alone operation; they can also be processed by the host PC.

function of position for later evaluation withexternal software. They can also automaticallyfind the global maximum of, for example, thecoupling efficiency of optical devices.
Depending on the specific controller, PIMikroMove supports a number of additional functions. A data recorder can record system parameters and other variables during motion forlater analysis.
Optimizing System Behavior
When the mechanical properties of a positioning system are changed, e.g. by applying a
different load, motion control parameters often
need to be adapted. PI software provides tools
for optimization of the system response andstability. Different parameter sets can be saved
for later recall, also accessible from custom
application programs.

Scan and align algorithms can record analog
values, e.g. the output of a power meter as a

The flexibly configurable data recorder records data,such as position, sensor signal or output voltage in
relation to time

94

Convenient operation and performance optimization
with PI software: The parameter setting tool shows
the frequency response of a nanopositioning stage in
Bode plot

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W SMotion Control Software from PI
Fast Integration of PI Controllers in Third-Party Programming Languages andSoftware Environments

Currently, many applications are producedin LabVIEW, e.g. in measuring and control
technology and automation engineering. PI
provides complete LabVIEW drivers sets tofacilitate programming. A controller-specificConfiguration_Setup VI is integrated at thestart of the LabVIEW application and includes
all system information and initiation steps
required for start-up. The application itself is
implemented with controller-independent VIs.
In case of a controller change or upgrade, it isusually only necessary to exchange the Configuration_Setup VI , whereas the applicationspecific code remains identical due to the consistent GCS command set structure.
The driver set includes many specific programming examples, e.g. comprehensive scan andalign routines that can be used as template forcustomer-specific programs. Moreover, theopen source code of many VIs allows for rapid
adaptation to the user needs.

These libraries support all common programming languages and all PI positioning systems,
allowing the PI GCS command set functions to
be integrated seamlessly in external programs.
Third-Party Software Packages
Drivers for the PI GCS commands have now
been integrated in many third-party software
packages. This allows for the seamless integration of PI positioning systems in software suites
such as MetaMorph, μManager, MATLAB and
ScanImage. Moreover, EPICS and TANGO
drivers are available for integration into experiments of large-scale research facilities.
The drivers for μManager, MATLAB and a largepart of the EPICS drivers are being developedand serviced in-house by PI.

Flexible Integration in Text-Based Programming Languages
The integration of PI positioning systems intext-based programming languages under
Microsoft Windows or Linux is simplified byprogram libraries and exemplary codes.

Supported Languages and Software
Environments■ C, C++, Python, Visual C++, Visual

Basic, Delphi■ LabVIEW, MATLAB, μManager, EPICS,TANGO, MetaMorph■ and all programming environmentsthat support the loading of DLLs
95

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Service

The scope of delivery of a PI system consistingof controller and stage includes everything
required for its operation.
■ External power supplies■ All power, communication and system cab-les
■ The comprehensive user manual in printed

form■ Software CD with set-up function

When developing the instruments, top priority is given to the use of state-of-the-art components. This ensures a long availability andreplaceability of the systems even beyond the
product lifecycle. All positioning systems fromPI’s standard range fulfill the CE and RoHS provisions.
Customized product developments and adaptations are an important part of our technicalprogress.

We offer you:
■ The complete range of our product spec-

trum from electronic components and complete devices as an OEM circuit board
through to the modular encased system■ Production of small batches and large

series■ Product development according to special

product standards (national or market-specific standards such as the German Medical
Device Act, for example) and the corresponding certification■ Adaptation of the systems to special envi-

ronmental conditions (vacuum, space,clean room)■ Copy-exactly agreements

The current versions of firmware, softwareand user manuals are available on the internet
free of charge. Firmware updates can easily be
carried out via the standard interfaces of thecontroller. PI offers comprehensive software
support. PI software is included in the scopeof delivery for digital equipment and is used
to start up the system and also to analyze andoptimize the system’s behavior. DLLs, LabVIEW drivers or the support of MATLAB makeit easier to program the system.

96

P I E Z O P O S I T I O N I N G S Y S T E M S | W W W. P I . W SGlossary

Amplifier classification
PI uses the following amplifier classifications:
Charge-controlled, switched (class D), linear.

Amplifier resolution
Only for digitally controlled amplifiers: Measurement of the smallest digital output value (LSB)in mV.

Average current
For multi-axis controllers, it is specified perchannel. Measured value. It is available reliably
over a longer period.

Bandwidth
Measured value. The frequency in kHz, withwhich the amplitude decreased by -3 dB, is specified. Large signal values: With maximum output voltage. Small signal values: With output
voltage of 10 Vpp. The values are displayed in theamplifier operating diagram.

Capacitive base load (internal)
For switching amplifiers. Stabilizes the output
voltage even without connected capacitive load(piezo actuator). The possible output power of apiezo controller/driver depends on internal andexternal capacitive loads.

Control input voltage range
Also input voltage; for piezo controller/driver.
Recommended range from -2 to 12 V. The usual
gain value of 10 V leads to an output voltage of-20 to 120 V. Most PI controllers allow for a input
voltage range of -3 to 13 V.

Current consumption
Current consumption of the system on supplyend. It is specified for controller without load.
Alternatively, power consumption.

Current limitation
Short-circuit protection.

Drive typeDefines the types of drive supported by the controller/driver, such as DC motors, piezo stepping
drives, piezo actuators.

Dynamic resolution
For capacitive sensors. Measured in the nominal
measuring range, bandwidth see data table. See
static resolution.

Encoder input
Maximum bandwidth (-3 dB) of the input signals
for the encoder input.

Input level
Permissible input level for digital interfaces.

Limit switches

Peak current

Function: Optical, magnetic.

Only available for very short times, typicallyunder a few milliseconds. It is used to estimate
the possible dynamics with a certain capacitive
load. Note: In this case, the piezo controller/
driver does not necessarily work linearly.

Linearity error
Value gained with external, traceable measuring
device. Defines the maximum deviation from an
ideal straight motion. The value is given as apercentage of the entire measuring range. The
linearity error does not influence the resolution
or repeatability of a measurement.
Measurement of the linearity error: The target
and measured actual values of the positions areplotted against each other, a straight line isdrawn through the first and last data point, andthe maximum absolute deviation from thisstraight line is determined. A linearity error of
0.1% corresponds to an area of ±0.1% aroundthe ideal straight line. Example: A linearity errorof 0.1% over a measuring range of 100 μm produces a possible maximum error of 0.1 μm.

Power consumption
Maximum power consumption under full load.

Profile Generator
Linear interpolation, point-to-point, trapezoid,
double bends. For several axes: Electronic gearing.

Reference point switch
Function: Optical, magnetic.

Resolution

Measurement range extension factor

Position resolution relates to the smallest
change in displacement that can still be detectedby the measuring devices. The uncontrolled
resolution in piezo nanopositioning systems andpiezo actuators is basically unlimited because it
is not limited by static or sliding friction. Instead,the equivalent to electronic noise is specified.

For capacitive sensors, used by PI.

Rise time

Noise

Time constant of the controller/driver. Timerequired for increasing the voltage range from
10% to 90%.

Linearization
Integrated method, e.g. ILS, polynomials to thenth degree, sensor linearization.

For capacitive sensors. In extended measurement ranges, noise is considerably higher thanin the nominal measurement range.

Operating limits
Values measured at an ambient temperature of
20°C. A sine is used as control signal in openloop operation. The amplifier works linearly
within the operating limits, in particular without
thermal limitation.

Operating temperature range
In any case, the device can be operated safely inthe maximum permissible temperature range.
To avoid internal overheating, however, full load
is no longer available above a certain temperature (maximum operating temperature underfull load).

Ripple, noise, 0 to 100 kHz
Ripple of voltage in mVpp with unique frequency.
Noise over the entire frequency range.

Sensor bandwidth
Measured value. The frequency, with which theamplitude decreased by -3 dB, is specified.

Sensor resolution
The sensor can be the critical element in position resolution, for this reason the sensor resolution can be specified separately if necessary.

Static resolution
For capacitive sensors. Measured with a bandwidth of 10 Hz, nominal measuring range.

Operating voltage

Suggested capacitive load

Allowed control input voltage range (also input
frequency) for the supply of the device.

For switching amplifiers. The possible output
power of a piezo controller/driver depends oninternal and external capacitive loads.

Output voltage
The output voltage of piezo controllers shows
variations of only a few millivolt and is particularly stable in the long term.

Overtemperature protection
Switch-off temperature for voltage output. No
automatic restart.

97

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Piezo Drives

Products

Pages 102 – 125

Fundamentals of Piezo Technology

Pages 126 – 157

99

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Piezomotors
Integration Examples of Piezo Linear Motors

PILine® motors act on an annular runner, producing a rapid
rotary motion, e.g. for this Leica TS30 total station for automated angle and distance measurement at high accuracy
and reliability (Photo: Leica Geosystems)

100

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Piezo Linear Motors

Page 102First Integration Levels for OEM Applications

Technologies of Piezomotors

Integration of PILine® ultrasonicultrasonic motors
allows the design of XY stages with particuticularly low height e.g. for microscopy

Page 104

Compact special design of a linear positioning
stage with NEXACT® piezo stepping drive andprecision linear guides. The dimensions are
only 33 mm × 24 mm × 20 mm

PIShift drives adjust
adjustst theth
he tilting
tilting antilt
anglesngles inn a cardanic mirror holder
ho
older

101

PIEZO

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Piezo Linear Motors
First Integration Levels for OEM Applications

N-216

Highlights■ Wide range of different piezomotor technologies: Forces from 10 to 800 N■ Self-locking at maximum force, thus no heat generation at rest
■ The travel range is scalable and limited only by the runner length■ Easy integration, replacement for motor-spindle drives■ Nonmagnetic designs available on request■ Vacuum-compatible up to 10-6 mbar; UHV on request

Applications
Applications range from sample handling in biotechnology to positioning of optical components in imaging processes.
PI uses piezomotors as space-saving and high-resolution drive element in single- and multi-axis positioning systems.
Integration ranges all the way to complex 6D Hexapods, which can also be used under extreme ambient conditions suchas UHV or magnetic fields.

102

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N-111

N-310

U-264

N-422

N-216
N-111

N-310

U-264

N- 422

Versions withhigh-resolution
integrated linear
encoder available

Sub-nm resolution,
velocity controllable toa few nm/s

Cost-efﬁcient and fast

Easy-to-control
1-actuator principlewith sub-nm resolution

Drive type

NEXLINE®
piezo stepping drive

NEXACT®
piezo stepping drive

PILine®
ultrasonic piezomotor

PIShift
Piezo inertia drive

Dimensions in mm

50 × 50 × 80 (N-216)
28 × 40 × 40 (N-111)

25 × 25 × 12

57 × 63 × 10.2

21.5 × 18 × 13

a few nm/s to
1 mm/s maximum

a few nm/s to
20 mm/sa few nm/s to
500 mm/s

a few nm/s to
20 mm/sPush/pull force in N

up to 600

up to 20

up to 40

up to 10De-energized holding
force in N

up to 800 /self-locking

up to 20 /self-locking

up to 40 /self-locking

up to 10 /self-locking

Smallest step size
without sensor in mm

0.03

0.03

50

300 with E-870 driver

Operating voltage-250 / 250 V bipolar

up to 45 V

up to a voltage rangeof 200 V

up to a voltage rangeof 48 V

Travel range in mm

20

up to 125

up to 150

up to 401200 (N-216)
300 (N-111)

<100

<100

<30

E-755, E-712 Motion
Controller incl. driver

E-862 driver, E-861
Motion Controller incl.
driver

C-872 driver, C-867
Motion Controller incl.
driver

E-870 driver, E-871
Motion Controller incl.
driverVelocity

Mass in g

Recommended
controller

All product details can be found at www.pi.ws

PIEZO

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103

PiezoWalk® Piezo Stepping Drives
Nanometer Precision with a High Feed Force■ Forces from 10 to 800 N■ Integration levels from an OEM motor

to a multi-axis positioning system■ Scalable travel range due to scalable

runner length■ Resolution to 0.03 nm■ Self-locking when at rest, no heatgeneration■ Nonmagnetic and vacuum-compatible

operating principle

Why PiezoWalk®?
PiezoWalk® drives
were developed
more than 10 years
ago for the semiconductor industry, which is very
demanding when it
comes to reliability,
position resolution
and long-term stability. PI received
the SEMI Technology Innovation
Showcase Awardfor the PiezoWalk®
technology in 2005.
The drives are continuously developed
further, and a large
number of variants
are now available
for different areas ofapplication.

Directly Driven PiezoWalk® Linear Motors
As essential components, these piezo stepping drives have several piezo actuators thatare preloaded against a guided runner. These
piezo actuators perform a stepping motion
during operation that causes a forward feedof the runner. The piezo actuators can be operated to perform very small stepping and feed
motions so that a high motion resolution of far
below one nanometer is achieved.

With NEXLINE® drives, the stepping motion
is realized via separately controlled, powerful
longitudinal and shear actuators, achieving ahigh stiffness with feed forces of several 100 N.
The more compact NEXACT® drives performthe stepping motion with bending elements.
A suitable selection of the piezo elements optimizes step size, clamping force, velocity andstiffness for the respective requirements.

Piezo stepping drives do not require any
mechanical components such as coupling or
gearhead, which cause friction and backlash
and would considerably limit the precision andreliability of high-resolution motor-spindlebased drive systems.
Stepping Motion Sequence
With PiezoWalk® stepping drives, piezo actuators
work in pairs as clamping and feed elements ona moving runner. Cyclical control induces a stepping motion of the actuators on the runner, andthe runner is moved forwards and backwards.
Motion sequence of a NEXLINE® actuator

104

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Piezomotors are Self-Locking
Preloading the piezoceramic actuators against
the runner ensures self-locking of the drive
when at rest and switched off. As a result, it
does not consume any power, does not heatup, and keeps the position mechanically stable.
Applications with a low duty cycle that requirea high time and temperature stability profit
from these characteristics.
Lifetime and Reliability
The motion of the piezoceramic actuator isbased on crystalline effects and is not subject
to any wear. Unlike other piezomotor principles, the coupling of the piezo actuators to therunner is not subject to sliding friction effects;
the feed is achieved by the physical clamping
and lifting of the actuators.

special versions of the drives are offered.
Piezo stepping drives can also be used inclean rooms or in environments with a hardultraviolet radiation.
Two Technologies for More Flexibility
For the piezo stepping drives, PI uses two different technologies that can be adapted to therespective requirements. NEXLINE® stepping
drives are designed for high push and holding
forces up to 800 N and work with low velocities. The more compact NEXACT ® drives
achieve higher velocities and develop forcesfrom 10 to 20 N.

Piezomotors for Applications – e.g. in a
Vacuum and in Strong Magnetic Fields
Piezomotors from PI are vacuum-compatible
in principle and suitable for operation understrong magnetic fields. For these purposes,

Various designs and sizes of NEXLINE® modules (left and right) as well as NEXACT®
(center)

Constant velocity and smooth driving of a NEXLINE®
drive are best achieved in nanostepping mode, but
the maximum attainable velocity is higher in full-stepmode

OEM piezomotors (from left): N-216 and N-111 with NEXLINE®, N-310 with NEXACT®
drivesSequence of open-loop 1 nm motions of a NEXLINE® drive

105

PIEZO

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POSITIONINGPILine® Ultrasonic Piezomotors
Compact Drives, Fast and Self-Locking■ Integration levels

from an economical OEM motor toa multi-axis positioning system■ Excellent dynamic

properties, fast
step-and-settle■ Basically unlim-

ited travel ranges■ Easy mechanicalintegration■ Self-locking at rest
■ Holding force up

to 15 N
■ Velocity up to

500 mm/s■ Resolution to

0.05 μm (50 nm)

Direct-Driven PILine® Linear Motors

Piezomotors are Self-Locking

These linear drives dispense with the mechanical complexity of classical rotary motor/gear/
leadscrew combinations in favor of costs andreliability.

Preloading the piezoceramic actuators against
the runner ensures self-locking of the drive
when at rest and powered down. As a result,it does not consume any power, does not heatup, and keeps the position mechanically stable. Applications with a low duty cycle, that arebattery-operated or heat-sensitive benefit fromthese characteristics.

These components can be very susceptible towear, especially in miniaturized systems. An
integral part of the ultrasound piezomotor ispiezo ceramics that is pretensioned against a
movably guided runner via a coupling element.
The piezo element is excited to high-frequency
oscillations that cause the runner to move.

Lifetime and Reliability
The motion of the piezoceramic actuator isbased on crystalline effects and is not subject to any wear. The coupling to the runner,on the other hand, is subject to friction
effects. Depend ing on the operating mode,running distances over 2 000 km or a MTBF of
20 000 hours are achieved.
Dynamics in Use
The stiff design, direct coupling and fast
response of the piezo ceramics to electric inputs allows for very fast start / stop behavior
and velocities to hundreds of mm/s.
Patented Technology
The products described in this document are inpart protected by the following patents:
US patent no. 6,765,335B2
European patent no. 1267425B1

The piezoceramic actuator is excited to ultrasonic vibrations with a high-frequency
AC voltage between 100 and 200 kHz. The deformation of the actuator leads to aperiodic diagonal motion of the coupling element to the runner. The created feed isroughly 10 nm per cycle; the high frequencies lead to the high velocities

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PILine® Ultrasonic Piezomotors
OEM Motors, Technical Data

PILine® integration levels (left to right): M-272 closedloop, guided linear actuator, OEM motor and U-264
RodDrive low-profile actuator (unguided)

Different Integration Levels Offer Flexibility
PILine® drives allow the design of positioning
systems with higher dynamics and smaller
dimensions. PI offers various integration levelsof PILine® drives for easier integration into
customer designs:■ RodDrives are unguided, open-loop linear

drives that replace motor-leadscrew combinations. They can easily be coupled to a
guided positioning platform■ The integration of OEM motors requires

more experience and technical knowledge
because the optimal preload between
runner and actuator has to be set up by
the customer■ Positioning stages with integrated PILine®

drives, available in customized designs forOEM

Drive Electronics■ Linear actuators move the load via a

guided rod. Position feedback is available
as an option

Motion and positioning

To produce the ultrasound oscillations in thepiezo actuator, special drive electronics are
required that are also provided by PI. These
range from OEM boards to integrated servo controllers for closed-loop systems.

Drive electronics create theultrasonic vibrations for the
piezoceramic actuator of the
PILine® drive. PI offers universal drivers for all actuatorsizes – as well as specialized,
compact boards

P-661

U-164

Unit

Tolerance

No limit

No limitmmto 1 mm

Min. incremental motion,
open-loop**

0.05

0.05

μm

typ.

Velocity (open-loop)

500

500

mm/s

max.

Travel range*

Mechanical properties
Stiffness, de-energized

0.7

3

N/μm

±10 %

Holding force, de-energized

1.5

3

N

max.

2

4

N

max.

9

18

N

averagelow

Push / pull force
Preloading on friction bar
Integration effort

±10 %
low

Drive properties
Resonant frequency
Motor voltage

210

155

42 Vrms (120 Vpp)

60 Vrms (170 Vpp)

kHz

±2 kHzMiscellaneous
Operating temperature range
Casing material
Weight-20 to +50-20 to +50

Aluminum, anodized

Aluminum, anodized

10

20

°C

g

±5 %

* The travel range of piezo linear motors is practically unlimited. It only depends on the length of the runner** The minimum incremental motion is a typical value which can be reached in open-loop operation. However, it is important to follow the installation guidelines forthe motors

PIEZO

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POSITIONING

107

108

Open-loop step sequence of a PILine® based translation stage. Steps of
approx. 300 nm shown. For repeatable increments closed-loop operation is recommended, because the step size depends on the force
applied from outside

PILine® ultrasonic linear motors provide excellent dynamic properties.
They provide acceleration to several g and can achieve step-and-settleof a few 10 microseconds for small distances

Maximum duty cycle depending on the ambient temperature with acontrol signal level of 100%

Force / velocity motor characteristic of a PILine® motor 6 N
holding force. The percentages refer to the control signal level, which
denotes the coupling of the electric power of the actuator

P-661, dimensions in mm

U-164, dimensions in mm

PIE
P ZI EOZ O
A CDT RU IAVTEOSR |S W
| W
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P I. .PW
I . SW SPIShift Piezo Inertia Drives
Cost-Efficient, Compact Linear Motors■ From OEM drives

to integration intoa multi-axis positioning system■ Basically unlim-

ited travel ranges■ Easy mechanicalintegration■ Self-locking at rest
■ Holding force up

to 10 N
■ Velocity of morethan 5 mm/s
■ Simple, cost-effi-

cient control

PIShift drives are space-saving and cost-efficient piezo-based drives with relatively highholding forces of up to 10 N and a basicallyunlimited travel range. They make use of the
stick-slip effect (inertia effect) – a cyclical alternation of static and sliding friction between amoving runner and the drive element generated by the piezo element – for a continuous
feed of the runner. With an operating frequency above 20 kHz, PIShift drives reach velocities
of more than 5 mm/s.

The PIShift drive principle
is based on a single piezo
actuator that is controlledwith a modified sawtooth
voltage provided by a special
drive electronics. The actuator
expands slowly taking along
the runner. When the piezo
element contracts quickly, therunner cannot follow due toits inertia and remains at its
position

Silent and Energy-Saving
The drive works silently at this frequency.
When at rest, the drive is self-locking andtherefore requires no current and generates
no heat. It holds the position with maximum
force.
Easy Integration
For easy integration, the drive component iseither mounted on a level surface or screwed
in on the front. The load is coupled to themoving runner. Compact drive electron ics
are available in single or multi-channel versions and can be controlled via analog ordigital interfaces. The piezo drive element in
the actuator requires less than 50 V operating
voltage.

A full cycle produces a feed of typically 300 nanometers. The mechanical components are designed so that
there is minimum backstep during the fast contraction

PIEZO

109

NANO

POSITIONING

Piezo Actuators with Guiding and Preload

Translation actuators with and without preload
can be inserted into microvalves while forlarger travel ranges lever-amplified drive
systems are suitable110

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PiezoMove® Flexure Actuators

Page 112

Guided and Preloaded PICMA®
Multilayer Lever-Amplified Piezo Actuators

Preloaded Piezo Stack Actuators

Page 114

for Dynamic Applications

Technology: Guiding and Preload

Page 116

Piezo Stack Actuators

PiezoMove® Flexure Actuators

Travel ranges

up to approx. 300 μm

to 1 mmMoving axes

one

one

Sensor technology

optional SGS

optional SGS

Linearity

up to 99.8 %up to 99.8 %Guidingnone

flexure joints for tilts <10°Space requirement

low

low

Price

low

low

averagelow

Integration effort

111

PIEZO

NANO

POSITIONING

PiezoMove® Flexure Actuators
Guided and Preloaded PICMA®
Multilayer Lever-Amplified Piezo Actuators

P-603
PiezoMove®
Flexure Actuator
Highlights■ Sub-millisecond response time and sub-nanometer resolution■ Versions with SGS sensors for repeatabilities of only a few nanometers■ Cost-efficient OEM solutions for integration■ For high quantities

Applications
For valves, pumps, micro- and nanoliter dosing, active vibration insulation, sample handling and imprint technologies in
microfluidics, biotechnology, medical technology, mechatronics, adaptive systems technology or metrology.

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P-601

P-602

P-601

P-604

P-602

P-603

P-604

Dimensions in mm

16.5 × 12 × 16.5 to82.5 × 12 × 20.5

28 × 17 × 9 to
126 × 34 × 14

33.5 to62 × 21 × 6

19.5 × 13 × 3

Travel range in μm

100 to 400

100 to 1 000

100 to 500

300

Push force capacity inmotion direction in N

15 to 30

100

10 to 40

2

Pull force capacity inmotion direction in N

105

10 to 20

1.5

350 to 750

150 to 1 000

300 to 900

900

1.5 to 5

1.5 to 39

1.5 to 3.7

0.27

Operating voltage range
in V-20 to 120-20 to 120-20 to 120-20 to 120

Versions with SGS
position sensor

available

available

available–

E-610, E-625, E-709

E-610, E-625, E-709

E-610, E-625, E-709

E-610, E-831

Unloaded resonant
frequency in Hz
Electrical capacitancein μF

Recommended
controller

All product details can be found at www.pi.ws

PIEZO

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POSITIONING

113

Preloaded Piezo Stack Actuators
For Dynamic Applications

P-216
PICA Power
Piezo Actuator

Highlights■ Sub-millisecond response time and sub-nanometer resolution■ Compact stainless steel case with variable end pieces■ High stiffness■ UHV versions■ Versions with SGS positioning sensor available

Applications
Highly dynamic applications that also have high precision and force generation requirements can be found in precision
mechanical engineering, in material processing, material forming and others. They include switching and dosing tasks
as well as active compensation of vibrations. Versions for vacuum of up to 10-9 hPa, particularly high or low operating temperatures are available.

114

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P-235

P-844

P-820

P-885

P-212
P-216

P-842 to
P-845

P-810
P-830

P-225
P-235

P-840
P-841

P-820

PICA Stack actuatorsfor maximum force
generation

PICMA® Stack
multilayer actuators

PICMA® Stack
multilayer actuators

Encapsulated PICMA®
Stack multilayer
actuators for use inrough environment

Ø 18 to 50
length of up to 199

Ø 12 to 19
length of up to 137

Ø 5.5 to 10
length of up to 76

Ø 11.2 to 18.6
length of up to 40.5

Operating voltage range
in V

0 to 1 000-20 to 120-20 to 120-20 to 120

Travel range in μm

15 to 180

15 to 90

15 to 60

17 to 36

Push force capacity inmotion direction in N

2 000 to 30 000

800 to 3 000

50 to 1 000

800 to 3 000

Pull force capacity inmotion direction in N

300 to 3 500

50 to 700

1 to 10-

Unloaded resonant
frequency in kHz

up to 17

5 to 18

8 to 2235 to 60

Electrical capacitancein μF

0.05 to 8

1.5 to 36

0.3 to 6

1.5 to 6

E-481, E-421

E-610, E-621, E-709

E-610, E-621, E-709

E-831, E-610

Dimensions in mm

Recommended
controller

P-885
P-888

All product details can be found at www.pi.ws and www.piceramic.com

PIEZO

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POSITIONING

115

Technology:
Piezo Actuators with Guiding and Preload

Simple lever amplification.
The point contact decouples
shear forces and thus tensilestress on the piezo ceramic

Preloaded and Cased Actuators
Piezoceramic actuators are insensitive to pushforces, but must be protected from pulling andshearing stress. A case mechanically decouples lateral forces and insulates contacting.
Between the case and the piezo ceramic, apreload can be applied, e.g. by means of aspring, which allows dynamic operation ofhigher loads.
Flexure Guides Direct Motion and Maintain
Stiffness
Precise straight motions require the piezo
actuator to be embedded in a guide. This is
usually a flexure guide, which is frictionless
and allows hysteresis-free motion at the possible travel ranges of up to a few millimeters.
Ideally this mechanical guiding concept also
integrates force decoupling and preloading
without an adverse effect on the system stiffness.

116

Lever Amplification Allows Travel Ranges of
up to 1 mm
The displacements of piezo stack actuators
are typically up to a few ten millimeters anda few 100 micrometers maximum. The flexure
guide can be designed such that it will act likea mechanical lever. This mechanically amplifies the displacement of the piezo actuator andguides it into a different direction, if necessary.
Lever-amplified systems have an extremely
demanding design: On the one hand, they aresupposed to prevent lateral migration and, on
the other, to always guide it in a straight line,
even though the lever always leads througha pivot point. Moreover, increasing the travel
range is at the cost of stiffness.
The flexure guide can be designed such thatfurther integration does not require any additional guide.

The piezo ceramic stack ismechanically preloaded
against the housing by meansof a spring. This preventspull forces, such as the ones
caused by the inert mass of
the load in dynamic operation

P I E Z O D R I V E S | W W W. P I . W SFrom Stack Actuator to 6-Axis Stage
Integration levels of piezo actuators

Stack Actuators

Lever-Amplified
Actuators

Positioning Systems

Travel ranges

up to approx. 300 μm

to 1 mmto 1 mmMoving axes

one

one

up to 3 linear axes and 3 tip/tilt axes

Sensor technology

optional SGS

optional SGS

SGS or direct measuring
capacitive sensors

Linearity

up to 99.8 %up to 99.8 %more than 99.9 %Guidingnone

flexure joints fortilts <10°flexure joints fortilts <2°

Space requirement

low

low

depending on conﬁguration

Price

low

low

depending on configuration

averagelow

lowIntegration effort

PiezoMove® OEM Flexure Actuators with
Built-In Guiding
PiezoMove® actuators combine guided motion
with long travel ranges of up to 1 mm andprovide precision in the 10 nanometer range
if ordered with the position sensor option.
Their high-precision, frictionless flexure
guides achieve very high stiffness and excellent straightness of motion. This makes themeasier to handle than a simple piezo actuator,
but still keeps them extremely compact. The
number and size of the piezo actuators used
determine stiffness and force generation.
These features, their small dimensions andcost-efficient design make PiezoMove® flexure
actuators suitable in particular for OEM applications. For open-loop applications, versions
without sensors are available.
In addition to the standard steel models, special invar and nonmagnetic versions are available on request.
This lever mechanism with flexure guides transforms the actuator travel range (vertical)
to an even, straight motion (horizontal)

117

PIEZO

NANO

POSITIONING

Piezo Actuators and Piezo Components
Direct Drives for Precision Positioning and Precision Production, Micro Dispensing Systems,
Switching Applications, Force and Vibration Generation

Currently PICMA® actuators are being used in the CheMin Instrument of the Mars Rover Curiosity. In dynamic tests carried out by NASA for the Mars
Mission, PICMA® actuators have withstood 100 billion operating cycles without failures and without any significant loss in power (Picture: NASA/JPL)118

PP II EE ZZ OO DDRR II VV EE SS || W
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Page 120

Multilayer Technology or Glued Stack Actuators

PICMA® Bender Multilayer Actuators

Page 122

All-Ceramic Bending Actuators with High Displacement

Unguided Piezo Actuators

Page 124

And Piezo Components

Flexible Adjustment of Actuators and Components
PI Ceramic is one of the worldwide leading manufacturers of piezo technology. Their in-house development laboratories
and installations for prototype construction and for testing the finished elements allow quick and flexible adjustment of thestandard products to special fields of application. Our pressing and multilayer technology enables us to shape products witha short lead time. This also allows large series of up to several 100 000 units per year to be produced.
The in-house manufactured
PICMA® multilayer piezo
actuators combined withhigh-precision sensors andmechanical design are thebasic element. The control
electronics and software
especially developed by PI
convert these products into
first-class nanopositioning
systems

119

PIEZO

NANO

POSITIONING

Longitudinal Piezo Actuators / Translators
Multilayer Technology or Glued Stack Actuators

PICMA®
Multilayer Piezo Actuators
Highlights■ Sub-millisecond response time and sub-nanometer resolution■ High stiffness■ Variable end pieces■ UHV versions■ Optionally with SGS sensors for position control

Applications
The reliablity of PI piezo actuators is required in many areas: In semiconductor industry, precision mechanics and production as well as for switching applications and valve control, e.g. in automotive industry. Piezo actuators are also used in
active vibration damping, nanotechnology, metrology, optics and interferometry.

120

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P-016

P-016

P-010...PtoP-056...P

P-887

P-010...HtoP-025...H
P-007 to
P-056

PL088

PD080

P-882 toP-888

PL022 to
PL088
PD050
PD080

PICA Power high-loadstack actuators

PICA Thru and PICA
Stack actuators withand without inner hole

PICMA® Stack
multilayer piezo
actuators with andwithout inner hole

PICMA® Chip miniature
multilayer actuators,
also available
ring-shapedØ 10 to 56

Ø 7 to 56
hole up to 16

2 × 3 to 10 × 10

2 × 2 to 10 × 10
or Ø 8 × 2.45

9 to 169

8 to 244

9 to 36

2

0 to 1 000

0 to 1 000-20 to 120-20 to 120

Travel range in μm

5 to 180

5 to 300

5 to 38

2

Blocking force in N

1 200 to 78 000

650 to 78 000

190 to 3 800

120 to 2 000

Unloaded resonant
frequency in kHz

7 to 130

5 to 144

40 to 135

600

Electrical capacitancein μF

0.017 to 21

0.011 to 27

0.15 to 13

0.025 to 1.1

Cross-section in mm
Length in mm
Operating voltage range
in V

All product details can be found at www.pi.ws and www.piceramic.com

PIEZO

NANO

POSITIONING

121

PICMA® Bender Multilayer Actuators
All-Ceramic Bending Actuators with High Displacement

PICMA®
Bender Actuators
Highlights■ PICMA® multilayer technology in bimorph structure■ Bidirectional, symmetrical displacement■ Low operating voltage■ UHV versions

Applications
Their reliability and low operating voltage make PICMA® bending actuators ideal for dosing and pumping applications, for
optical beam deflection, and when minimally dimensioned, for use in portable devices. There the piezo elements can beused, for example, as acoustic-mechanical converters.

122

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P-871

P-871

PL112
to
PL140
PD410

Can be manufactured in round (as disk) or
rectangular shape (as plate)
For application to a metal or silicon substrate

PICMA® Benderactuators with SGS
position sensor

18 × 10 × 0.65 to
45 × 11 × 0.60
Ø 44 × 0.65

22 × 10 × 0.65 to
49 × 11 × 0.60

0 to 60

0 to 60

Displacement in μm±80 to ±1 000±80 to ±1 000

Blocking force in N

±0.5 to ±2±0.5 to ±2

Unloaded resonant
frequency in Hz

160 to 2 000

160 to 2 000

Electrical capacitancein μF

2 × 1 to 2 × 4

2 × 1 to 2 × 4

E-650

E-651, E-614

Operating voltage range
in V

Recommended
controller/driverCompletely assembled to customer requirements
For particularly compact OEM solutions
Multilayer Contracting Plates

UHV-compatible
up to 10-9 hPa

Dimensions in mm

Application-Specific Designs

Piezo Element Applied to a
Passive Substrate
Unidirectional displacement, resulting in higher
stiffness and larger relative displacement
Any Desired Contours
Also available with all-ceramic insulated hole

Variable Height of the Active Layers
Up to 15 μm for a control voltage of only 10 V
Miniature Designs
Only 4 × 10 mm² in edge length

All product details can be found at www.pi.ws and www.piceramic.com

PIEZO

NANO

POSITIONING

123

Unguided Piezo Actuators
And Piezo Components

PT120 to PT140

Highlights■ DuraAct piezo patch transducer for application to structural materials■ PT Tube piezo tubes for microdosing, micromanipulation and scanning applications■ Compact PICA Shear actuators for displacement in up to 3 axes
■ Lead-free piezo actuators in Picoactuator® technology■ Large choice of designs

Applications
The products are just as variable as the applications: DuraAct piezo transducers are used for condition monitoring
and adaptive systems. Piezo tubes are suitable for microdosing using, for example, jet technology, as micro- and nanomanipulators and as fiber stretchers. PICA Shear actuators are among the smallest XYZ positioning devices and areavailable in versions for cryogenic environment of down to -269°C and vacuum of as high as 10-9 hPa. The crystalline
Picoactuator® exhibits highly linear displacement even without servo loop, allowing it to use the full dynamic range forpositioning operations.

124

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P-876PT Tube

P-141

P-405

P -876PT Tube

P-111 to
P-151

P-405

DuraAct Piezo
transducer for use as
actuator and sensor

Piezo Tube actuators forradial, lateral and axial
displacement

Highly reliable PICA
Shear actuators
X, XY, XZ and XYZ
versions

Picoactuator® made oflead-free crystalline
material

Available in different
forms and dimensions or as array

UHV-compatible
versions up to 10-9 hPa-50 to +200,-100 to +400 or-250 to +1000

0 to 1 000 or ±250

-250 to 250±500

Lateral contraction
up to 800 μm/m. Displacement dependingon the structural
material

5 to 15 axial,±10 to ±35 lateral

1 to 101

90 to 800

–

–

–

–

–

30 to 530

up to 160

Electrical capacitancein nF

up to 150

3 to 70

0.2 to 230 per axis

<4

Cross-section in mm

61 × 35

Ø 2.2 to 40

3 × 3 to 16 × 16

5 × 5 to 10 × 10

20 to 40

3.5 to 40

up to 19–

E-508, E-413, E-536

E-421

Available designs

Operating voltage range
in V

Travel range in μm

Blocking force indirection of travel in N
Unloaded resonant
frequency in kHz

Length in mm

Recommended
controller/driver

E-835, E-413 for actuator applications
E-821 for energy
harvesting

Versions for cryogenic
and UHV environments

Longitudinal and shear
actuators

All product details can be found at www.pi.ws and www.piceramic.com

PIEZO

NANO

POSITIONING

125

Fundamentals of Piezo Technology

Basic Principles of Piezoelectricity

Page 127

Piezoelectric Effect – Ferroelectric Polarization – Expansion of the Polarized Piezo Ceramic
Piezoelectric Actuator Materials

Page 128

Displacement Modes of Piezoelectric Actuators

Page 129

Manufacturing of Piezo Actuators

Page 134

Multilayer Tape Technology – Pressing Technology – PT Tube Actuators – DuraAct
Properties of Piezoelectric Actuators

Page 137

Displacement Behavior

Page 137

Nonlinearity – Hysteresis – Creep – Position Control
Temperature-Dependent Behavior

Page 140

Forces and Stiffnesses

Page 142

Preload and Load Capacity – Stiffness – Force Generation and Displacement
Page 146

Dynamic Operation
Resonant Frequency – How Fast Can a Piezo Actuator Expand – Dynamic Forces
Electrical Operation

Page 147

Electrical Capacitance – Power Consumption – Continuous Operation – Pulse-Mode Operation
Ambient Conditions

Page 150

Vacuum Environment – Inert Gases – Magnetic Fields – Gamma Radiation – Environments withHigh Humidity – Liquids
Reliability of PICMA® Multilayer Actuators

Page 151

Lifetime when Exposed to DC Voltage – Lifetime in Dynamic Continuous Operation
Amplifier Technology: Piezo Electronics for Operating Piezo Actuators
Characteristic Behavior of Piezo Amplifiers

Page 153
Page 153

Power Requirements – Amplifier Frequency Response Curve – Setting the Control Input Voltage
Solutions for High-Dynamics 24/7 Operation

Page 154

Switched Amplifiers with Energy Recovery – Overtemperature Protection – Charge Control
Handling of Piezo Actuators

Page 156

Mechanical Installation – Electrical Connection – Safe Operation

126

P I E Z O D R I V E S | W W W. P I . W S

Basic Principles of Piezoelectricity

The Piezoelectric EffectFerroelectric Polarization

Pressure generates charges on the surface ofpiezoelectric materials. This so-called direct
piezoelectric effect, also called the generator
or sensor effect, converts mechanical energy
to electrical energy. The inverse piezoelectriceffect in contrast causes this type of materials
to change in length when an electrical voltage
is applied. This effect converts electrical energy
into mechanical energy and is thus employedin actuator technology.

To minimize the internal energy of the material,
ferroelectric domains form in the crystallites of
the ceramic (fig. 2). Within these volume areas,
the orientations of the spontaneous polarization are the same. The different orientations ofbordering domains are separated by domain
walls. A ferroelectric polarization process isrequired to make the ceramic macroscopicallypiezoelectric as well.

The piezoelectric effect occurs in monocrystalline materials as well as in polycrystalline
ferroelectric ceramics. In single crystals, anasymmetry in the structure of the unit cells of
the crystal lattice, i.e. a polar axis that forms
below the Curie temperature Tc, is a sufficient
prerequisite for the effect to occur.
Piezoelectric ceramics also have a spontaneous polarization, i.e. the positive and negative charge concentration of the unit cells are
separate from each other. At the same time,
the axis of the unit cell extends in the directionof the spontaneous polarization and a spontaneous strain occurs (fig. 1).

For this purpose, a strong electric field of several kV/mm is applied to create an asymmetry
in the previously unorganized ceramic compound. The electric field causes a reorientationof the spontaneous polarization. At the sametime, domains with a favorable orientation
to the polarity field direction grow and thosewith an unfavorable orientation shrink. The
domain walls are shifted in the crystal lattice.
After polarization, most of the reorientations
are preserved even without the application ofan electric field (see fig. 3). However, a small
number of the domain walls are shifted backto their original position, e.g. due to internalmechanical stresses.

(1)

(2)

O2
Pb
Ti, ZrFig. 1(1) Unit cell with symmetrical,
cubic structure above theCurie temperature TC(2) Tetragonally distorted
unit cell below the Curie
temperature TC with spontaneous polarization andspontaneous strain

Expansion of the Polarized Piezo Ceramic

The extrinsic effect is based on a reversible
ferroelectric reorientation of the unit cells. It
increases along with the strength of the driving field and is responsible for most of thenonlinear hysteresis and drift characteristics offerroelectric piezoceramics.

–

–

–

–

+

+

+

–

–

–

–

+

+

+

–

–

+

+

+

–

+

–

+

+

–

–

–

–

–

–

+

+

+

+

+

+
+

–

The ceramic expands, whenever an electricfield is applied, which is less strong than theoriginal polarization field. Part of this effect isdue to the piezoelectric shift of the ions in the
crystal lattice and is called the intrinsic effect.

–

+

(1)

(2)
–

+
–

+

–

–

+
–

+
–

–

+
–

+ +
– –

+
–

+
–

+

+

+

(3)

Fig. 3
Orientation of the spontaneous polarization within apiezo ferroelectric ceramic(1) Unpolarized ceramic,(2) Ceramic during polarization and (3) ceramic after
polarization

Fig. 2: A cross-sectional view of a ferroelectric ceramicclearly shows the differently polarized domains within
the individual crystallites(Source: Fraunhofer Institute for Ceramic Technologies
and Systems IKTS, Dresden, Germany)

127

PIEZO

NANO

POSITIONING

Piezoelectric Actuator Materials
Basic Principles of Piezoelectricity

(Z)
3

6

P

5
2(Y)

(X)

1

4

Fig. 4
Orthogonal system todescribe the properties ofa polarized piezo ceramic.
Axis 3 is the direction ofpolarization

Commercially available piezoceramic materials
are mostly based on the lead-zirconate-leadtitanate material system (PZT). By adding othermaterials the properties of the PZT compositions can be influenced.
Ferroelectrically soft piezoceramics with low
polarity reversal field strengths are used
for actuator applications since the extrinsic
domain contributions lead to high overall
piezo moduli. This includes the piezoceramics
PIC151, PIC153, PIC255, PIC252 and PIC251.

Actuator Materials from PI Ceramic

PIC151

PIC153

PIC255/252

PIC050Density ρ [g/cm3]

7.80

7.60

7.80

4.70

Curie temperature Tc [°C]

250

185

350

>500

2 400
1 980

4 200

1 750
1 650

60
85

20

30

20

<1

Physical and Dielectric Properties

Relative permittivity
in polarization direction ε33Τ/ε0perpendicular to polarization
ε11/ε0Dielectric loss factor
tan δ [10-3]

Ferroelectrically hard PZT materials, suchas PIC181 and PIC300, are primarily used inhigh-power ultrasound applications. They
have a higher polarity reversal resistance,high mechanical quality factors as well as
low hysteresis values at reduced piezoelectric
deformation coefficients. The Picoactuator®
series is based on the monocrystalline material
PIC050, which has a highly linear, hysteresisfree characteristic, but with small piezoelectriccoefficients.

PIC151 Modified PZT ceramic with balanced
actuator characteristics. High piezoelectric coupling, average permittivity,
relatively high Curie temperature.
Standard material for the PICA Stack,
PICA Thru and PT Tube product lines.
PIC153 Modified PZT ceramic for large displacements.
High piezoelectric deformation coefficients, high permittivity, relatively low
Curie temperature.
Special material for the PICA Stack and
PICA Thru product lines as well as forglued bending actuators.

Electro-Mechanical Properties
Piezoelectric deformation coefficient, piezo modulus*
d31 [pm/V]
d33 [pm/V]
d15 [pm/V]

- 210
500

600

- 180
400
550

40
80

PIC255 Modified PZT ceramic that is especially suited to bipolar operation, in shear
actuators, or with high ambient temperatures.
High polarity reversal field strength(>1kV/mm), high Curie temperature.
Standard material for the PICA Power,
PICA Shear, PT Tube and DuraAct
product lines

Acousto-Mechanical Properties
Elastic
compliance coefficients11E [10-12 m2 /N]
s33E [10-12 m2 /N]
Mechanical quality factor Qm

15.0
19.0

16.1
20.7
100

50

80

PIC252 Variant of the PIC255 material with alower sintering temperature for use in
the multilayer tape process.

For explanations and further data, see the catalog "Piezoceramic Materials and Components"* The deformation coefficient corresponds to the charge coefficient used with piezo components.
The value depends on the strength of the driving field (fig. 22, p. 137). The information in the tablerefers to very small field strengths (small signal)

PI Ceramic offers a wide range of further materials, including lead-freepiezoceramics that are currently mainly used as ultrasonic transducers.

128

Standard material for the PICMA® Stack,
PICMA ® Chip and PICMA ® Bender
product lines as well as some DuraAct
products.
PIC050 Crystalline material for linear, hysteresis-free positioning with small displacements in an open servo loop.

For application-specific properties, actuators can be manufactured from
special materials, although the technical implementation has to be individually checked. www.piceramic.com

P I E Z O D R I V E S | W W W. P I . W S

Excellent stability, high Curie temperature.
Standard material for the Picoactuator®
product line.

Displacement Modes ofPiezoelectric Actuators
Basic Principles of Piezoelectricity

Examples of longitudinal stack actuators
are the multilayer
piezo actuators
PICMA® Stack, Encapsulated PICMA®,PICMA® Chip, as
well as the stacked
actuators PICA Stack,
PICA Power, PICA
Thru that are glued
together from individual plates, andthe crystalline
Picoactuator®.

Longitudinal Stack Actuators
In longitudinal piezo actuators, the electricfield in the ceramic layer is applied parallel tothe direction of polarization. This induces an
expansion or displacement in the direction ofpolarization. Individual layers provide relatively low displacements. In order to achieve technically useful displacement values, stack actuators are constructed, where many individual
layers are mechanically connected in series
and electrically connected in parallel (fig. 5).

30 N/mm2 in relation to the cross-sectional areaof the actuator. Values of up to several 10 000
Newton can thus be achieved in the actuator.
Longitudinal stack actuators are excellently
suited for highly dynamic operation due totheir high resonant frequencies. A mechanical preloading of the actuator suppresses
dynamically induced tensile forces in brittle
ceramic material, allowing response times in
the microsecond range and a high mechanicalperformance.

ΔLlong Longitudinal

displacement [m]d33(GS) LongitudinalnVpiezoelectric largesignal deformation
coefficient [m/V]
Number of stacked
ceramic layers
Operatingvoltage [V]longLongitudinal stack actuators are highly efficient in converting electrical to mechanicalenergy. They achieve nominal displacements ofaround 0.1 to 0.15% of the actuator length. The
nominal blocking forces are on the order of

In addition to the expansion in the direction of polarization, which is utilized withlongitudinal actuators, a contraction
always occurs in the piezo actuator thatis orthogonal to its polarization when it isoperated with an electric field parallel tothe direction of polarization.

P

V
GND

E
V

P
P
P
P
P
P
P
P

E
E
E
E
E
E
E
E

GND

Fig. 5∆Llong = n d33(GS) V(Equation 1)

This so-called transversal piezoelectriceffect is used by contracting actuators,
tube actuators, or bending actuators.

PIEZO

129

NANO

POSITIONING

Furthermore, shear stresses cannot be compensated by a mechanical preload. Both, limit
the practical stacking height of shear stacks.

A typical application
for shear actuators
are drive elements
for so-called stickslip motors.

Shear actuators combined with longitudinal
actuators yield very compact XYZ stacks withhigh resonant frequencies.

Shear actuatorsfrom PI Ceramic areoffered as productlines PICA Shear und
Picoactuator®.

Picoactuator® Technology

Shear Actuators
In piezoelectric shear actuators, the electricfield in the ceramic layer is applied orthogonally to the direction of polarization and thedisplacement in the direction of polarization
is utilized. The displacements of the individual
layers add up in stacked actuators here as well
(fig. 6).

shear

V
GND

V

P

P
P
P
P
P
P
P
P

E

E
E
E
E
E
E
E
E

Fig. 6

V

Picoactuator® longitudinal and shear actuators are made of the crystalline piezoelectricmaterial PIC 050. The specific displacement is±0.02% (shear actuators) or ±0.01% (longitudinal piezo actuators) of the actuator length andis thus 10 times lower than for classic piezo
actuators made of lead zirconate - lead titanate(PZT). The displacement here is highly linearwith a deviation of only 0.2%.

The shear deformation coefficients d 15 arenormally the largest piezoelectric coefficients.
When controlled with nominal voltages,
PIC ceramics achieve d 15(GS) values of up to2000 pm/V. The permissible controlling fieldstrength is limited in order to prevent a reversal of the vertically oriented polarization.

GND

When lateral forces act on the actuator, theshear motion is additionally superimposed bya bending. The same effect occurs in dynamic
operation near the resonant frequency.

Fig. 7:
Measured nonlinearity of a Picoactuator®

∆Lshear = n d15(GS) V(Equation 2)

130

P I E Z O D R I V E S | W W W. P I . W S

Tube Actuators
Tube actuators are radially polarized. The electrodes are applied on the outer surfaces, sothat the field parallel to the polarization also
runs in a radial direction. Tube actuators use
the transversal piezoelectric effect to generate displacements. Axial displacements orchanges in length (fig. 8), lateral motions suchas changes in the radius (fig. 9), as well as
bending (fig. 10) are possible.
Axial displacement

ΔLshear Shear

ΔLaxial = d31(GS) l Vtd15(GS) Piezoelectric large-

displacement [m]axial

In order to cause a tube to bend, the outerelectrode is segmented into several sections.
When the respectively opposite electrodes are
driven, the tube bends in a lateral direction.

signal shear deformation coefficient[m/V](Equation 3)

Undesirable tilting or axial motions that occur
during this process can be prevented by more
complex electrode arrangements. For example, an eight-electrode arrangement creates a
counter bending and overall achieves a lateraldisplacement without tilting.

P

V

Operatingvoltage [V]placement [m]ΔLradial Radial tube dis-Fig. 8placement [m]ΔLlateral Lateral tube displacement [m]radialThe following estimation
applies for large radi:∆Lradial ≈ d31(GS)Further application examples are microdosing in the construction of nanoliter
pumps or in inkjet printers.

V

ΔLaxial Axial tube dis-Radial displacement(radius change)

Tube actuators are often used in scanningprobe microscopes to provide dynamic
scanning motions in open-loop operation,
and as fiber stretchers.

Number of
stacked ceramiclayersGND

E

PI Ceramic offers precision tube actuators in
the piezo tube product line.

n

ID + t2td31(GS) Transversal piezo-

electric largesignal deformation
coefficient [m/V]

E

V

P

l
ID

(Equation 4)
GND

V

Tube length [m]Internal tube diameter [m]tTube wall thickness (=(OD-ID)/2)[m]
For all equations, ID >> t.
All tube dimensions, seedata sheet

Fig. 9Bending actuators,
XY scanning tubes∆Llateral = 0.9 d31(GS)laterall2(ID + t)tV

(Equation 5)

P+V

Fig. 10

PIEZO

NANO

P
GND

-V

131

POSITIONING

ΔLtrans Transversal displacement [m]d31(GS) Transversal

l

h
n
V
ΔLbendlf
hp

piezoelectric largesignal deformation
coefficient [m/V]
Length of the piezo
ceramic in the
direction of displacement [m]Height of aceramic layer [m]Number of
stacked ceramiclayersOperatingvoltage [V]Bending
displacement [m]Free bender
length [m]Height piezoceramic element
[m]
lf

P
P

Rh

RE

VF

132

E
E

hP

Ratio of theheights of the substrate (hs) andpiezoceramic element (hp) in acomposite bender(Rh=hs/hp)
Ratio of the elasticity modulus of
the substrate (Es)and the piezoceramic element(Ep) in in a composite bender(RE=Es/Ep)
Fixed voltage forbender actuator
control [V] (V and
VF can be superimposed with anoffset voltage)

Contracting Actuators
Typically, piezo contracting actuators are lowprofile components. Their displacement occurs
perpendicularly to the polarization direction
and to the electric field. The displacement ofcontracting actuators is based on the transversal piezoelectric effect whereby up to approx.
20 μm is nominally achieved.
Multilayer elements offer decisive advantages
over single-layer piezo elements in regard totechnical realization: Due to the larger crosssectional area, they generate higher forces andcan be operated with a lower voltage (fig. 11).

As a result of the contraction, tensile stresses
occur that can cause damage to the brittle
piezo ceramic. A preload is therefore recommended.
For the patch actuators of the DuraAct productgroup, a piezo contractor is laminated into apolymer. This creates a mechanical preloadthat protects the ceramic against breakage.
Multilayer contracting actuators can be re quested as special versions of the PICMA ®
Bender product line.

Fig. 11

ΔLtrans = d31 (GS) l V (Equation 6)
h

V
GND

P

E

L trans

V

P
P
P
P

pi_120137_illustrationen_variante.indd 1

P I E Z O D R I V E S | W W W. P I C E R A M I C . C O M

E
E
E
E

GND

04.04.12 1

change in length into a large bending displacement vertical to the contraction. Depending on
the geometry, translation factors of 30 to 40
are attainable, although at the cost of the conversion efficiency and the force generation.

Attached to a substrate, contracting actuators
act as bending actuators (fig. 12). For the construction of all-ceramic benders, two active
piezoceramic elements are joined and electrically controlled. If a passive substrate made ofmetal or ceramic material, for example, is used,
one speaks of composite benders. The piezoceramic elements can be designed as individual
layers or as multilayer elements.
Piezoelectric bending actuators function
accord ing to the principle of thermostatic
bimetals. When a flat piezo contracting actuator is coupled to a substrate, the driving andcontraction of the ceramic creates a bending
moment that converts the small transversal

With piezoelectric bending actuators, displacements of up to several millimeters can beachieved with response times in the millisecond range. The blocking forces, however, arerelatively low. They are typically in the rangeof millinewtons to a few newtons.

VF+
V
VF-

P
P

E
E

Fig. 17
By selecting a two-sided
restraint with a rotatable
mounting (bottom) instead ofa single-sided fixed restraint(top), the ratio of the displacement and the force of thebender can be changed. The
displacement is reduced
by a factor of four while theblocking force is increased
by a factor of four. Especiallyhigh forces can be attained
when using flat bending
plates or disks with a restraint
on two sides instead of stripshaped benders

bend

Bending Actuators

Fig. 12: Displacement of bending actuators

All-ceramic bending actuator for parallel circuiting
+VF
V
-VF

P
P

E
E

ΔLbend =lf 2
3n d 2 V (Equation 7)
8
hp

ΔLbend =lf 2
3V (Equation 8)
n d31(GS)8
hp2

PI Ceramic offers allceramic multilayer
bending actuatorswith very low piezo
voltages in the
PICMA® Bender
product line. Composite benders canbe manufactured as
special versions, in
multilayer as wellas in single-layer
versions or as adrive element with
DuraAct actuators.

Fig. 13All-ceramic bending actuator for serial circuiting

V
GND

P
P

E
E

(Operation against the polarization direction only
possible with reduced voltage or field strength, p. 49 ff.)
Fig. 14

Two-layer composite bender with one-sided
displacement
V
GND

P

E

Fig. 153l2
2RhRE (1+Rh)
V
ΔLbend = n d31(GS) f 2(1+R)2+0.25(1-Rh2RE)28
hp RhREh(Equation 9)
Application DuraAct, PICMA® Bender(customized versions)Symmetrical three-layer composite bender for parallel circuiting

+VF
V
-VF

P

E

P

E

1+Rh
3
l2
V
ΔLbend = n d31(GS) f 2
8
hp 1+1.5Rh+0.75Rh2+0.125RERh3
Fig. 16(Equation 10)

Equations according to Pfeifer, G.: Piezoelektrische lineare Stellantriebe. Scientific journal series of Chemnitz
University of Technology 6/1982

PIEZO

NANO

POSITIONING

V

P
P
P
P

E
E
E
E

VF+
VF-

Fig. 18
The products of the PICMA®
Bender line are all-ceramicbending actuators with two
piezoceramic elements thateach consist of several active
layers (multilayer actuators)

133

Manufacturing of Piezo Actuators
Basic Principles of Piezoelectricity

Multilayer Tape Technology
Processing of thepiezo ceramic powder
Slurry preparation
Tape casting
Screen printing of the innerelectrodes
Stacking, laminating
Isostatic pressing
Cutting andgreen shaping
Debindering andsintering (cofiring)
Grinding, lapping
Application of thetermination electrodes

Multilayer Tape Technology
The technologies for manufacturing piezo
actuators decisively contribute to their function, quality and efficiency. PI Ceramic is proficient in a wide range of technologies, frommultilayer tape technology for PICMA® stackand bending actuators, through glued stackactuators for longitudinal and shear displacements, up to the construction of crystalline
Picoactuator ® actuators, the DuraAct patch
transducers and piezoceramic tubes.
PI Ceramic multilayer actuators, PICMA® forshort, are manufactured in large batches withtape technology. First, the inner electrode pattern is printed on thin PZT tapes while stillunsintered and these are then laminated intoa multilayer compound. In the subsequent
cofiring process, the ceramic and the innerelectrodes are sintered together. The finishedmonolithic multilayer piezo element has nopolymer content anymore.

The inner electrodes of all PICMA® actuators
are ceramically insulated (fig. 19). PICMA® Stackactuators use a patented structure for this purpose, in which a thin ceramic insulation tapecovers the electrodes without significantly limiting the displacement.
The more fine-grained the ceramic material
used, the thinner the multiple layers that canbe produced. In PICMA® Stack actuators, theheight of the active layers is 60 μm and in
PICMA® Bender actuators around 20 to 30 μm,
so that the benders can be operated with avery low nominal voltage of only 60 V.

Hermetically encapsulated PICMA® were developed for
applications in extremely high humidity and in roughindustrial environments. They are equipped with corrosion-resistant stainless-steel bellows, inert gas filling,
glass feedthroughs and laser welding

Polarization
In the past years, the technologies for processing
actuators in an unsintered state have been continuously developed. For this reason, round geometries or
PICMA® actuators with an inner hole can also be
manufactured

Assembly
Final inspection

Ceramic
insulation
layer

E
0

134

100μm

Fig. 19:
In PICMA® stack actuators,
a ceramic insulation tapecovers the inner electrodes

PICMA® multilayer actuators are produced in different shapes. Depending on the application, they can also be
assembled with adapted ceramic or metal end pieces, additional coating, temperature sensors, etc.

P I E Z O D R I V E S | W W W. P I . W S

Pressing Technology
PICA stack actuators such as PICA Stack,Thru or Shear consist of thin piezoceramic
plates with a standard layer thickness of
0.5 mm. For manufacturing, piezoceramiccylinders or blocks are shaped with pressing technology, sintered and then separated into plates with diamond wafer saws.
Metal electrodes are attached with thin or thickfilm methods depending on the material, andthe ceramic is then polarized.

Picoactuator® piezo actuators consist of crystalline layers with a thickness of 0.38 mm.
In contrast to ceramic, the orientation of the
spontaneous polarization is not determined bya ferroelectric polarization but by the cutting
direction in the monocrystal. All other processing and mounting steps are similar to those forstacked PICA actuators.

Pressing Technology
Processing of thepiezo ceramic powder
Mixing the raw materials
Calcination, presintering
Milling

Completely assembled stackactuators with a metal endpieceand SGS expansion sensor (left),with stranded wires, temperature
sensor and transparent FEP shrink
tubing (right)

Stack actuators are created by gluing theplates together whereby a thin metal contact
plate is placed between each two ceramic
plates in order to contact the attached electrodes. The contact plates are connected witheach other in a soldering step, and the finishedstack is then covered with a protective polymer
layer and possibly an additional shrink tubing.

Spray drying
Pressing and shaping
Debindering and sintering
Lapping, grinding,
diamond slicing
Application of electrodes byscreen printing or sputtering

Polarization
Mounting andassembling technology:
Gluing, poss. ultrasonicdrilling for inner hole,soldering, coating
Final inspection

The final processing of the piezoceramic plates manufactured with pressing technology is adapted to their futureuse. The figure shows different piezo actuator modules

135

PIEZO

NANO

POSITIONING

DuraAct Patch Actuators and Transducers
DuraAct patch actuators use piezoceramic contracting plates as their base product. Depending on the piezoceramic thickness, these plates
are manufactured with pressing technology(>0.2 mm) or tape technology (0.05 to 0.2 mm).
The plates are connected to form a composite
using conductive fabric layers, positioning
tapes, and polyimide cover tapes.
The lamination process is done in an autoclave
in a vacuum, using an injection method. This
results in completely bubble-free laminates of
the highest quality.

Structured electrodes allow specific driving of tube actuators

PT Tube Actuators
PT Tube actuators are manufactured frompiezoceramic cylinders that were previously
produced with the pressing technology. The
outer diameter and the parallelism of the endsurface are precisely set through centerless circular grinding and surface grinding. The innerhole is drilled with an ultrasonic method.

The curing temperature profile of the autoclave
is selected so that a defined internal preload of
the piezoceramic plates will result due to thedifferent thermal expansion coefficients of thematerials involved.
The result of this patented technology arerobust, bendable transducer elements that canbe manufactured in large batches.

The metalization then is done with thin- or
thick-layer electrodes, possibly accompaniedby structuring of the electrodes with a laser
ablation method.
In addition to the described procedure for
manufacturing precision tubes with very
narrow geometric tolerances, the more costefficient extrusion method is also available forsmall diameters.

Different shapes of DuraAct actuators with ceramic
plates in pressing and multilayer technology

Laminated ceramic layers in a DuraActtransducer arrangement (array)136

P I E Z O D R I V E S | W W W. P I . W SProperties of Piezoelectric Actuators
Displacement Behavior

P

S

In the PI and PIC
data sheets, the freedisplacements of theactuators are given
at nominal voltage.

Prem

unipolarsemi-bipolar
unipolarbipolarsemi-bipolar
Srem

bipolar

Ec

-Ec

Ec

E

E

a)

b)

Fig. 20: Displacement of ferroelectric piezo ceramics with different control amplitudes parallel to thedirection of polarization direction. Large-signal curves as a function of the electrical field strength Ea) electromechanical behavior of the longitudinal strain S, b) dielectric behavior of the polarization P

Nonlinearity
The voltage-dependent displacement curvesof piezo actuators have a strongly nonlinear
course that is subject to hysteresis due to the
extrinsic domain contributions. It is therefore
S

ΔS

E
ΔE

d(GS) = ∆S
∆E

(Equation 11)

Fig. 21: Unipolar and semi-bipolar electromechanicalcurves of ferroelectric piezo ceramics and definition of
the piezoelectric large-signal deformation coefficientd(GS) as the slope between the switchover points of apartial hysteresis curve

not possible to interpolate linearly from thenominal displacement to intermediate positions with a particular driving voltage. The
electromechanical and dielectric large-signal
curves of piezo ceramics illustrate the characteristics (fig. 20). The origin of each graph isdefined by the respective thermally depolarized condition.

Piezoelectric Deformation Coefficient(Piezo Modulus)
The gradient ΔS/ΔE
between the two
switchover pointsof the nonlinear
hysteresis curves isdefined as thepiezoelectric largesignal deformation
coefficients d(GS) (fig.
21). As the progressive course of thecurves shows, thesecoefficients normallyincrease along withthe field amplitude(fig. 22).

The shape of both bipolar large-signal curves
is determined by the ferroelectric polarity reversal process when the coercive fieldstrength EC is achieved in the opposing field.
The dielectric curve shows the very large
polari zation changes at these switchover
points. At the same time, the contractionof the ceramic after reversing the polarity turns into an expansion again, since thepolarization and the field strength have thesame orientation once more. This property gives the electromechanical curve its
characteristic butterfly shape. Without theelectric field, the remnant polarizations
Prem /-Prem and the remnant strain Srem remain.
Piezo actuators are usually driven unipolarly.
A semi-bipolar operation increases the strain
amplitude while causing a stronger nonlinearity and hysteresis which result from theincreasing extrinsic domain portions of thedisplacement signal (fig. 21).
137

PIEZO

NANO

POSITIONINGIf the values from fig. 22 are entered into
the equations 3 to 10 (p. 131-133), theattainable displacement at a particularpiezo voltage can be estimated. The fieldstrength can be calculated from the layer heights of the specific component andthe drive voltage VPP. The layer thickness of
the PI Ceramic standard products can befound starting on p. 134.

d15 PIC155 bipolar
d15 PIC255 bipolar
d33 PIC153 unipolar
d33 PIC151 unipolar

1500

d33 PIC255 unipolar
d33 PIC252 unipolar-d31 PIC252 unipolar
1000

500

0
0,0

0,5

1,0

1,5

2,5

Fig. 22: Piezoelectric large-signal deformation coefficients d(GS) for different materials and control modes
at room temperature and with quasistatic control.
With very small field amplitudes, the values of thecoefficients match the material constants on p. 12840%
d15 PIC155 bipolar
35%

ΔL

2,0

EPP [kV/mm]

Hdisp

The free displacement of the componentsthat can actually be attained depends onfurther factors such as the mechanicalpreload, the temperature, the control frequency, the dimensions, and the amountof passive material.

d(GS) [pm/V]

Estimation of the Expected Displacement2000

d15 PIC255 bipolar
d33 PIC151 unipolar30%

d33 PIC252/255 unipolar
d33 PIC153 unipolar

25%
20%
15%

Max Diff ΔL

ΔLmax
10%
5%
0%
0,0

U

0,5

1,0

1,5

2,0

2,5

EPP [kV/mm]

138

Fig. 23: The hysteresis value Hdisp is defined as the ratio
between the maximum opening of the curve and the
maximum displacement

Fig. 24: Displacement hysteresis Hdisp of various actuator materials in open-loop, voltage-controlled operation
for different drive modes at room temperature and withquasistatic control

Hysteresis

Especially high values result for shear actuators or with bipolar control. The reason forthese values is the increasing involvementof extrinsic polarity reversal processes in theoverall signal.

In open-loop, voltage-controlled operation, thedisplacement curves of piezo actuators show
a strong hysteresis (fig. 24) that usually rises
with an increasing voltage or field strength.

P I E Z O D R I V E S | W W W. P I . W S

Fig. 25: Displacement of a piezo actuator when driven
with a sudden voltage change (step function). The creep
causes approx. 1% of the displacement change perlogarithmic decadeFig. 26: Elimination of hysteresis and creep in a piezo
actuator through position control

Creep

Position Control

Creep describes the change in the displacement over time with an unchanged drive voltage. The creep speed decreases logarithmicallyover time. The same material properties thatare responsible for the hysteresis also cause
the creep behavior:

Hysteresis and creep of piezo actuators can beeliminated the most effectively through position control in a closed servo loop. To build
position-controlled systems, the PI Ceramicpiezo actuators of the PICA Stack and PICA
Power product line can be optionally offeredwith applied strain gauges.

ΔL(t) ≈ ΔLt = 0.1s 1 + γ lg (t
ΔL(t)ΔLt=0.1s
γ

t )
0.1s

(Equation 12)

In applications with a purely dynamic control,
the hysteresis can be effectively reduced tovalues of 1 to 2% even with open-loop control
by using a charge-control amplifier (p. 155).

Time [s]Displacement as a function of time [m]Displacement at 0.1 seconds after theend of the voltage change [m]Creep factor, depends on the material
properties (approx. 0.01 to 0.02, corresponds to 1% to 2% per decade)

139

PIEZO

NANO

POSITIONING

Temperature-Dependent Behavior
Properties of Piezoelectric Actuators

S

S

Srem

S

Srem

Srem
Ec

E

Ec

E

Ec

E

Fig. 27: Bipolar electromechanical large-signal curve of piezo actuators at different
temperatures. From left: behavior at low temperatures, at room temperature, at hightemperatures

Relative displacement

Below the Curie temperature, the temperaturedependence of the remnant strain andthe coercive field strength is decisive for thetemperature behavior. Both the attainabledisplacement with electric operation andthe dimensions of the piezoceramic elementchange depending on the temperature.

100%
unipolar 0 ... 120 V
80%

60%

The cooler the piezo actuator, the greater theremnant strain S rem and the coercive fieldstrength E rem (fig. 27). The curves become
increasingly flatter with decreasing temperatures. This causes the strain induced by aunipolar control to become smaller andsmaller even though the total amplitude of
the bipolar strain curve hardly changes overwide temperature ranges. The lower the temperature, the greater the remnant strain. All inall, the piezo ceramic has a negative thermal
expansion coefficient, i.e., the piezo ceramic
becomes longer when it cools down. In comparison: A technical ceramic contracts with a relatively low thermal expansion coefficient uponcooling. This surprising effect is stronger, themore completely the piezo ceramic is polarized.

bipolar -120 ... 120 V

Displacement as a
Function of the Temperature

40%

20%

0%
1

10

100

1000
Temperature [K]Fig. 28: Relative decrease in the displacement using theexample of a PICMA® Stack actuator in the cryogenic
temperature range with different piezo voltages inrelation to nominal displacement at room temperature

How much a key parameter of the piezo actuator changes with the temperature depends
on the distance from the Curie temperature.
PICMA® actuators have a relatively high Curie
temperature of 350°C. At high operating temperatures, their displacement only changes by
the factor of 0.05%/K.

140

P I E Z O D R I V E S | W W W. P I . W S

At cryogenic temperatures, the displacement
decreases. When driven unipolarly in theliquid-helium temperature range, piezo actuators only achieve 10 to 15% of the displacement at room temperature. Considerably higher displacements at lower temperatures can beachieved with a bipolar drive. Since the coercive field strength increases with cooling (fig.
27), it is possible to operate the actuator withhigher voltages, even against its polarization
direction.

Temperature Operating Range
The standard temperature operating range ofglued actuators is -20 to 85°C. Selecting piezo
ceramics with high Curie temperatures andsuitable adhesives can increase this range.
Most PICMA® multilayer products are specified
for the extended range of -40 to 150°C. With
special solders, the temperature range can beincreased so that special models of PICMA®
actuators can be used between -271°C and
200°C i.e. over a range of almost 500 K.

The temperature expansion coefficient of an
all-ceramic PICMA® Stack actuator is approximately -2.5 ppm/K. In contrast, the additional
metal contact plates as well as the adhesive
layers in a PICA Stack actuator lead to a nonlinear characteristic with a positive total coefficient (fig. 29).

Thermal strain [%]Dimension as a Function of the Temperature

0.06

0.04

If a nanopositioning system is operated in aclosed servo loop, this will eliminate temperature drift in addition to the nonlinearity, hysteresis, and creep. The control reserve to be kept
for this purpose, however, reduces the usabledisplacement.
For this reason, the temperature drift is often
passively compensated for by a suitable selection of the involved materials, the actuatortypes, and the system design. For example, allceramic PICMA® Bender actuators show only aminimal temperature drift in the displacement
direction due to their symmetrical structure.

0.08

0.02
PICMA® Stack
0
PICA Stack / PICA Power-0.02
E = 1 kV/mm
no preload-0.04
Measuring sequence
-0.06
-100

-80

-60

-40

-20

0

20

40

60

80

100
Temp. [°C]Fig. 29: Temperature expansion behavior of PICMA® andPICA actuators with electric large-signal control

141

PIEZO

NANO

POSITIONINGForces and Stiffnesses
Properties of Piezoelectric Actuators

E*

A
l
kA
ΔL0
Fmax
kL
Feff

Effective elasticity
module:Linear increaseof a stress-strain
curve of a sample
body or actuator
made of the corresponding piezoceramic material(fig. 30)
Actuator crosssectional area
Actuator length
Actuator stiffness
Nominal displacement
Blocking force
Load stiffness
Effective force

Preload and Load Capacity
The tensile strengths of brittle piezoceramicand single-crystal actuators are relatively low,with values in the range of 5 to 10 MPa. It istherefore recommended to mechanically preload the actuators in the installation. The preload should be selected as low as possible.
According to experience, 15 MPa is sufficient
to compensate for dynamic forces (p. 146); inthe case of a constant load, 30 MPa should not
be exceeded.
Lateral forces primarily cause shearing stresses in short actuators. In longer actuators witha larger aspect ratio, bending stresses arealso generated. The sum of both loads yield
the maximum lateral load capacities that are
given for the PICA shear actuators in the data
sheet. However, it is normally recommended
to protect the actuators against lateral forcesby using guidings.

Bending actuators, however, have stiffnesses of a few Newtons per millimeter, lower by
several orders of magnitude. In addition to thegeometry, the actuator stiffness also depends
on the effective elasticity module E*. Becauseof the mechanical depolarization processes,
the shape of the stress-strain curves (fig. 30)
is similarly nonlinear and subject to hysteresis
as are the electromechanical curves (fig. 21).
In addition, the shape of the curve depends on
the respective electrical control conditions, thedrive frequency, and the mechanical preload
so that values in a range from 25 to 60 GPa canbe measured. As a consequence, it is difficult
to define a generally valid stiffness value.

Stiffness

For specifying piezo actuators, the quasistatic large-signal stiffness is determined withsimultaneous control with a high field strength
or voltage and low mechanical preload. As aresult, an unfavorable operating case is considered, i.e. the actual actuator stiffness in an
application is often higher.

The actuator stiffness kA is an important parameter for calculating force generation, resonant
frequency, and system behavior. Piezoceramic
stack actuators are characterized by very highstiffness values of up to several hundred newtons per micrometer. The following equation isused for calculation:

The adhesive layers in the PICA actuators only
reduce the stiffness slightly. By using optimized technologies, the adhesive gaps are only
a few micrometers high so that the large-signal
stiffness is only approx. 10 to 20% lower thanthat of multilayer actuators without adhesive
layers.

kA Stack = E* A (Equation 13)l

The actuator design has a much stronger influence on the total stiffness, e.g. spherical end
piece with a relatively flexible point contact tothe opposite face.

Limitations of the Preload
The actuator begins to mechanically depolarize at only a few tens of MPa. A large-signal
control repolarizes the actuator; on the one hand, this causes the induced displacement toincrease but on the other hand, the effective capacity and loss values increase as well, which
is detrimental to the lifetime of the component.

142

A pressure preload also partially generates tensile stress (p. 156). For this reason, when very
high preloads are used, the tensile strength can locally be exceeded, resulting in a possible
reduction of lifetime or damage to the actuator. The amount of the possible preload is notdetermined by the strength of the ceramic material. Piezo actuators attain compressive
strengths of more than 250 MPa.

P I E Z O D R I V E S | W W W. P I . W SForce Generation and Displacement

Typical Load Cases

The generation of force or displacement in
the piezo actuator can best be understoodfrom the working graph (fig. 32). Each curveis determined by two values, the nominal displacement and the blocking force.

The actuator stiffness kA can be taken from theworking graph (fig. 32):

0
12
V
V
V
60
V

If the piezo actuator works against a springforce, its induced displacement decreases
because a counterforce builds up when thespring compresses. In most applications ofpiezo actuators, the effective stiffness of theload kL is considerably lower than the stiffness
kA of the actuator. The resulting displacement
ΔL is thus closer to the nominal displacement
ΔL0:
kA
kA + kL

80
Fmax

Displacement without Preload,
Load with Low Stiffness∆L ≈ ∆L0

V

Since such a stiffness does not exist in reality,
the blocking force is measured as follows: The
actuator length before operation is recorded.
The actuator is displaced without a load to thenominal displacement and then pushed backto the initial position with an increasing external force. The force required for this purpose
amounts to the blocking force.

V

The blocking force F max is the maximum
force produced by the actuator. This force isachieved when the displacement of the actuator is completely blocked, i.e. it works against
a load with an infinitely high stiffness.

It corresponds to the inverted slope of the curve.
The actuator makes it possible to attain any
displacement/force point on and below thenominal voltage curve, with a corresponding
load and drive.

20

Blocking Force(Equation 14)

40

The nominal displacement ΔL0 is specified in
the technical data of an actuator. To determine
this value, the actuator is operated freely, i.e.
without a spring preload, so that no force has
to be produced during displacement. After thecorresponding voltage has been applied, thedisplacement is measured.

ΔL0

0
10

Nominal Displacement

kA = Fmax
∆L0

Δl

F

Fig. 32: Working graph of a
PICMA® stack actuator withunipolar operation at different
voltage levels(Equation 15)

The displacement/force curve in fig. 31 on theright is called the working curve of the actuator/spring system. The slope of the working
curve Feff /ΔL corresponds to the load stiffness
k L.

S

Δl

ΔT

Δl

T
nal
sig
all
sm

ΔL0

la
rg
e

sig

na
l

A
ΔL

ΔS

V0

ΔL
B
kL

kL

V0

kA

Fig. 30: Stress-strain curve of a piezoceramic stackactuator when driven with a high field strength, inorder to prevent mechanical depolarizations. The linear
increase ΔT/ΔS defines the effective large-signal
elasticity module E*(GS). Small-signal values of theelasticity modules are always greater than large-signal
values

PIEZO

V

0V

Feff

Fmax

F

kA

Fig. 31: Load case with low
spring stiffness without preload:
Drawing, displacement/voltage
graph, working graph withworking curve

143

NANO

POSITIONINGForce Generation Without Preload, Load withHigh StiffnessΔlΔlWhen large forces are to be generated, theload stiffness kL must be greater than that of
the actuator kA (fig. 33):

ΔL0

ΔL0
A

kL

B

ΔL

0V
V0

kA

A

Feff ≈ Fmax

V0

ΔL
kL

V

Feff

F

Fmax

Nonlinear Load Without Preload, Opening
and Closing of a Valve

B

Δl

Δl

ΔL0

ΔL0
A
ΔL

V0

ΔL
B

V0

0V

V

Feff

Fmax

F

If a mass is applied to the actuator, the weightforce FV causes a compression of the actuator.
The zero position at the beginning of the subsequent drive signal shifts along the stiffness
curve of the actuator. No additional force
occurs during the subsequent drive signal
change so that the working curve approximately corresponds to the course without preload.

B
Δl

Δl

ΔL0
A

As an example of a load case in which a nonlinear working curve arises, a valve control issketched in fig. 34. The beginning of the displacement corresponds to operation without
a load. A stronger opposing force acts near
the valve closure as a result of the fluid flow.
When the valve seat is reached, the displacement is almost completely blocked so that only
the force increases.
Large Constant Load

Fig. 34: Nonlinear load without preload: Drawing,
displacement/voltage graph, working graph withworking curveA(Equation 16)

The careful introduction of force is especially
important in this load case, since large mechanical loads arise in the actuator. In order toachieve long lifetime, it is imperative to avoid
local pull forces (p. 142).

Fig. 33: The actuator works without a preload against aload with a high stiffness. From left: Drawing, displacement/voltage graph, working graph with working curvekA

kL
kA + kL

V0

An example of such an application is damping
the oscillations of a machine with a great mass.

ΔL’0
B
~ΔL0
m

V0

V

F

Fv
0V
F’max

F’

Fig. 35: Load case with large mass: Drawing, displacement/voltage graph, working graph with working curve
A

B

Example: The stiffness considerably increases when the actuator is electrically operated with a high impedance, as is thecase with charge-control amplifiers (p. 155). When a mechanical load is applied, a charge is generated that cannot flow
off due to the high impedance and therefore generates a strong opposing field which increases the stiffness.
144

P I E Z O D R I V E S | W W W. P I . W SSpring PreloadΔl

If the mechanical preload is applied by a relatively soft spring inside a case, the same shift
takes place on the stiffness curve as when amass is applied (fig. 36). With a control voltage applied, however, the actuator generates
a small additional force and the displacement decreases somewhat in relation to thecase without load due to the preload spring(Equation 15). The stiffness of the preload
spring should therefore be at least one orderof magnitude lower than that of the actuator.

ΔL0

ΔL’0
V0
KL

The energy amount Emech, that is converted
from electrical to mechanical energy whenan actuator is operated, corresponds to thearea underneath the curve in fig. 37. However, only a fraction Eout of this total amount
can be transferred to the mechanical load. The
mechanical system is energetically optimized
when the area reaches its maximum. This caseoccurs when the load stiffness and the actuator

Δl

Fv
B

V0

V
FV

F

kL

0 V F’eff

F’max

F’

Fig. 36: Load case with spring preload: Drawing,
displacement/voltage graph, working graph withworking curveA

The actuator volume is thus the determining
parameter for the attainable mechanical energy Emech=(ΔL0 Fmax)/2.

ΔL0
A

Actuator Dimensioning and Energy
Consideration
In the case of longitudinal stack actuators, theactuator length is the determining variable forthe displacement ΔL0. In the case of nominal
field strengths of 2 kV/mm, displacements of
0.10 to 0.15% of the length are achievable. The
cross-sectional area determines the blocking
force Fmax. Approximately 30 N/mm² can beachieved here.

ΔlB

stiffness are equal. The light blue area in theworking graph corresponds to this amount.
A longitudinal piezo actuator can perform
approx. 2 to 5 mJ/cm³ of mechanical work anda bending actuator achieves around 10 times
lower values.
Efficiency and Energy Balance of a Piezo
Actuator System
The calculation and optimization of the total
efficiency of a piezo actuator system depends
on the efficiency of the amplifier electronics, the electromechanical conversion, themechanical energy transfer, and the possibleenergy recovery. The majority of electricaland mechanical energies are basically reactive energies that can be recovered minus thelosses, e.g. from heat generation. This makes
it possible to construct very efficient piezo
systems, especially for dynamic applications.

Fig. 37: Mechanical energy amounts
in the working graph of a piezo actuator with spring load: Emech converted
mechanical energy and Eout output
mechanical energy

ΔLo

ΔL
Eout
Emech

Feff

Fmax

F

145

PIEZO

NANO

POSITIONING

Dynamic Operation
Properties of Piezoelectric Actuators

This behavior is desired especially in dynamic
applications, such as scanning microscopy,
image stabilization, valve controls, generating shockwaves, or active vibration damping.
When the control voltage suddenly increases,
a piezo actuator can reach its nominal displacement in approximately one third of the periodof its resonant frequency f0 (fig. 38).
Fig. 38: Displacement of an undamped piezo system after a voltage jump. The nominal
displacement is attained after around one third of the period length

m
M
φ
f0

f0'
Fdyn
meff

meff'

ΔL
f

Mass of the piezo
actuator
Additional load
Phase angle[degree]Resonant frequency without load
[Hz]
Resonant frequency with load [Hz]Dynamic force [N]Effective mass ofthe piezo stackactuator [kg]Effective mass ofthe piezo stackactuator with load[kg]
Displacement(peak-peak) [m]Control frequency[Hz]

Resonant frequency
The resonant frequencies specified for longitudinal stack actuators apply to operation when
not clamped on both sides. In an arrangementwith unilateral clamping, the value has to be
divided in half.
The reducing influence of an additional load on
the resonant frequency can be estimated withthe following equation:
meff

√m‘

f0‘ = f0

In positioning applications, piezo actuators
are operated considerably below the resonant
frequency in order to keep the phase shift
between the control signal and the displacement low. The phase response of a piezo
system can be approximated by a second
order system:φ ≈ 2 arctan

M

146

m

m

meff ≈ m/3

meff' ≈ m/3 + M(Equation 17)

eff

f
f0

(Equation 18)

Tmin ≈

1
3f0(Equation 19)

In this case, a strong overshoot occurs which
can be partially compensated for with corresponding control technology.
Example: A unilaterally clamped piezo actuatorwith a resonant frequency of f0 = 10 kHz canreach its nominal displacement in 30 μs.
Dynamic Forces
With suitable drive electronics, piezo actuators
can generate high accelerations of several ten
thousand m/s². As a result of the inertia of possible coupled masses as well as of the actuators themselves, dynamic pull forces occur thathave to be compensated for with mechanicalpreloads (p. 142 ff).
In sinusoidal operation, the maximum forces
can be estimated as follows:
Fdyn ≈ ±4π2 meffʻ ΔL f 2 (Equation 20)
2
Example: The dynamic forces at 1 000 Hz,
2 μm displacement (peak-to-peak) and 1 kg
mass are approximately ±40 N.

How Fast Can a Piezo Actuator Expand?
Fast response behavior is a characteristicfeature of piezo actuators. A fast change inthe operating voltage causes a fast positionchange.

Fig. 39: Calculation of theeffective masses meff and meff’of a unilaterally clamped
piezo stack actuator without
and with load

P I E Z O D R I V E S | W W W. P I . W SElectrical Operation
Properties of Piezoelectric Actuatorslarge-signal conditions, it is often sufficient to add
a safety factor of 70% of the small-signal capacitance (fig. 40).

The capacitance of the actuator depends on
the area and thickness of the ceramic as well as
the material properties. In the case of actuatorsthat are constructed of several ceramic layers
electrically connected in parallel, the capacitance also depends on the number of layers.
In the actuators there are leakage current
losses in the μA range or below due to the highinternal resistance.
Electrical Capacitance Values
The actuator capacitance values indicatedin the technical data tables are small-signal
values, i.e. measured at 1 V, 1 000 Hz, 20°C,
unloaded. The capacitance of piezoceramics
changes with the voltage amplitude, the temperature and the mechanical load, to up to
200% of the unloaded, small-signal, roomtemperature value. For calculations under

T
33

A

A

(Equation 21)

hL

l
hL

With a fixed actuator length l the following
holds true with n ≈ l/hL:

I
Q
V

T A
C = l ε 33
(Equation 22)
hL2

Accordingly, a PICMA® stack actuator with alayer thickness of 60 μm has an approx. 70
times higher capacitance than a PICA stackactuator with the same volume and a layer
thickness of 500 μm. The electric power consumption P of both types is roughly the same
due to the relationship P ~ C V2 since the operating voltage changes proportionally to thelayer thickness.
Positioning Operation, Static and with Low
Dynamics
When electrically charged, the amount ofenergy stored in a piezo actuator is aroundE = 12 CV 2. Every change in the charge (andtherefore in displacement) is connected witha charge transport that requires the following
current I:tCapacitance [C]Number of ceramiclayers in the actuator
Permittivity =ε33 /ε0 (cf. tablep. 128) [As/Vm]
Actuator crosssectional area [m²]Actuator length [m]Layer thickness in theactuator [m]Current [A]Charge [C, As]
Voltage on the piezo
actuator [V]Time [s]ΔLAt operating frequencies well below the resonant frequency, a piezo actuator behaves likea capacitor. The actuator displacement is proportional to the stored electrical charge, as afirst order estimate.

ε33T

The small-signal capacitance C of a stackactuator can be estimated as for a capacitor:
C=nElectrical Behavior

CnPolarisation
axis

+
o

PI Ceramic offers various types of piezo actuators with different layer thicknesses. This
results in nominal operating voltages from60 V for PICMA ® Bender actuators to up to
1 000 V for actuators of the PICA series.

L

Operating Voltage

I = dQ = C · dV (Equation 23)
dt
dt
Slow position changes only require a low current. To hold the position, it is only necessary
to compensate for the very low leakage currents, even in the case of very high loads. The
power consumption is correspondingly low.
Even when suddenly disconnected from theelectrical source, the charged actuator will notmake a sudden move. The discharge and thus
the return to zero position will happen continuously and very slowly.

Fig. 40: Relative change of capacitance of a PICMA®
Stack actuator measured at 1 kHz unipolar sine signal.
The electrical capacitance increases along with theoperating voltage and temperature

PIEZO

Fig. 41: Structure and contacting of a stacked piezotranslator

147

NANO

POSITIONINGOperation with Position Control
In closed-loop operation, the maximum safe
operating frequency is also limited by thephase and amplitude response of the system.
Rule of thumb: The higher the resonant frequency of the mechanical system, the higher
the control bandwidth can be set. The sensor
bandwidth and performance of the servo (digital or analog, filter and controller type, bandwidth) also limit the operating bandwidth ofthe positioning system.
Power Consumption of the Piezo Actuator
In dynamic applications, the power consumption of the actuator increases linearly withthe frequency and actuator capacitance. A
compact piezo translator with a load capacity of approx. 100 N requires less than 10 Wattof reactive power with 1 000 Hz and 10 μm
stroke, whereas a high-load actuator (>10 kNload) requires several 100 Watt under the same
conditions.
Heat Generation in a Piezo Element in
Dynamic Operation
Since piezo actuators behave like capacitive
loads, their charge and discharge currents
increase with the operating frequency. The
thermal active power P generated in the actuator can be estimated as follows:P ≈ π · tanδ · ƒ · C · V 2 (Equation 24)
pp4
For actuator piezo ceramics under small-signal
conditions, the loss factor is on the order of
0.01 to 0.02. This means that up to 2% of theelectrical power flowing through the actuatoris converted into heat. In the case of largesignal conditions, this can increase to considerably higher values (fig. 42). Therefore, themaximum operating frequency also depends
on the permissible operating temperature.
At high frequencies and voltage amplitudes,

cooling measures may be necessary. For
these applications, PI Ceramic also offers piezo
actuators with integrated temperature sensors
to monitor the ceramic temperature.
Continuous Dynamic Operation
To be able to operate a piezo actuator at thedesired dynamics, the piezo amplifier mustmeet certain minimal requirements. To assess
these requirements, the relationship between
amplifier output current, operating voltage ofthe piezo actuator, and operating frequency
has to be considered.
Driving with Sine Functions
The effective or average current Ia of the amplifier specified in the data sheets is the crucial
parameter for continuous operation with a sine
wave. Under the defined ambient conditions,the average current values are guaranteed
without a time limit.
Ia ≈ ƒ · C · Vpp (Equation 25)
Equation 26 can be used for sinusoidal single
pulses that are delivered for a short time only.
The equation yields the required peak current
for a half-wave. The amplifier must be capableof delivering this peak current at least for halfof a period. For repeated single pulses, thetime average of the peak currents must notexceed the permitted average current.
Imax ≈ ƒ · π · C · Vpptan δThe average current, peakcurrent and small-signal
bandwidth for each piezo
amplifier from PI can befound in the technicaldata.
PPower that isconverted into
heat [W]tan δDielectric loss
factor (ratio ofactive power toreactive power)fOperatingfrequency [Hz]C
Actuator
capacitance [F]VppDriving voltage(peak-to-peak) [V](Equation 26)

0,30
PIC255 Scher bipolar
PIC255 longitudinal bipolar

0,25

PIC151 longitudinal unipolar
PIC252/255 longitudinal unipolar
0,20

148

Fig. 42: Dielectric loss factors tan δ for different
materials and control modes at room temperature
and with quasistatic control. The conversion between
voltage and field strength for specific actuators is donewith the layer thicknesses that are given starting on p.
134. The actual loss factor in the component depends
on further factors such as the mechanical preload, thetemperature, the control frequency, and the amount ofpassive material.

0,15

0,10

0,05

0,00

P I E Z O D R I V E S | W W W. P I . W S

0,0

0,5

1,0

1,5

2,0

2,5

EPP [kV/mm]

Driving with Triangular Waveform
Both the average current and the peak currentof the amplifier are relevant for driving a piezo
actuator with a symmetrical triangular waveform. The maximum operating frequency of anamplifier can be estimated as follows:1
Ia
fmax ≈·(Equation 27)
CVpp
A secondary constraint that applies here is thatthe amplifier must be capable of delivering atleast Imax = 2 Ia for the charging time, i.e. for halfof the period. If this is not feasible, an appropriately lower maximum operating frequency
should be selected. For amplifiers which cannot deliver a higher peak current or not for a
sufficient period of time, the following equation should be used for calculation instead:f max≈

1
2·C

·

Ia
Vpp

(Equation 28)

Signal Shape and Bandwidth
In addition to estimating the power of thepiezo amplifier, assessing the small-signal
bandwidth is important with all signal shapesthat deviate from the sinusoidal shape.
The less the harmonics of the control signal
are transferred, the more the resulting shape
returns to the shape of the dominant wave, i.e.
the sinusoidal shape. The bandwidth should
therefore be at least ten-fold higher than thebasic frequency in order to prevent signal bias
resulting from the nontransferred harmonics.
In practice, the limit of usable frequency portions to which the mechanical piezo system
can respond is the mechanical resonant frequency. For this reason, the electrical control
signal does not need to include clearly higher
frequency portions.

Switching Applications, Pulse-Mode
Operation
The fastest displacement of a piezo actuator
can occur in 1/3 of the period of its resonant
frequency (p. 146). Response times in the
microsecond range and accelerations of morethan 10 000 g are feasible, but require particularly high peak current from the piezo amplifier.
This makes fast switching applications such as
injection valves, hydraulic valves, switching
relays, optical switches, and adaptive optics
possible.
For charging processes with constant current,
the minimal rise time in pulse-mode operation
can be determined using the following equation:
Vpp
t≈C·(Equation 29)
Imax

Ia

Average currentof the amplifier(source / sink) [A]Imax
Peak current of theamplifier (source /sink) [A]f
Operating frequency[Hz]
Maximum operating
fmax
frequency [Hz]C
Actuator capacitance, large signal[Farad (As/V)]
Vpp
Driving voltage(peak-to-peak) [V]tTime to charge piezo
actuator to Vpp [s]The average current andpeak current for each piezo amplifier from PI canbe found in the technicaldata.

As before, the small-signal bandwidth of theamplifier is crucial. The rise time of the amplifier must be clearly shorter than the piezo
response time in order not to have the amplifier limit the displacement. In practice, as arule-of-thumb, the bandwidth of the amplifiershould be two- to three-fold larger than theresonant frequency.
Advantages and Disadvantages of Position
Control
A closed-loop controller always operates in thelinear range of voltages and currents. Since thepeak current is limited in time and is therefore
nonlinear, it cannot be used for a stable selection of control parameters. As a result, position control limits the bandwidth and does notallow for pulse-mode operation as described.
In switching applications, it may not be possible to attain the necessary positional stability
and linearity with position control. Linearization can be attained e.g. by means of chargecontrolled amplifiers (p. 155) or by numericalcorrection methods.

Fig. 43: PICMA® actuatorswith patented, meandershaped external electrodes for
up to 20 A charging current

149

PIEZO

NANO

POSITIONING

Ambient Conditions
Properties of Piezoelectric Actuators

In case of questions
regarding use in special environments,
please contact
info@pi.ws or
info@piceramic.com

Piezo actuators are suitable for operation invery different, sometimes extreme ambientconditions. Information on use at high temperatures of up to 200°C as well as in cryogenic environments is found starting on p. 140.
Vacuum Environment
Dielectric Stability
According to Paschen's Law, the breakdown
voltage of a gas depends on the product ofthe pressure p and the electrode gap s. Air hasvery good insulation values at atmosphericpressure and at very low pressures. The minimum breakdown voltage of 300 V corresponds
to a ps product of 1000 Pa mm. PICMA® Stackactuators with nominal voltages of considerably less than 300 V can therefore be operated
at any intermediate pressure. In order to prevent breakdowns, PICA piezo actuators withnominal voltages of more than 300 V, however,should not be operated or only be driven atstrongly reduced voltages when air is in thepressure range of 100 to 50 000 Pa.
Outgassing
The outgassing behavior depends on thedesign and construction of the piezo actuators.
PICMA® actuators are excellently suited to use
in ultrahigh vacuums, since they are manufactured without polymer components and canbe baked out at up to 150°C. UHV options withminimum outgassing rates are also offered for
different PICA actuators.
Inert Gases
Piezo actuators are suitable for use in inert
gases such as helium, argon, or neon. However, the pressure-dependent flashover
resistances of the Paschen curves must also
be observed here as well. The ceramic-insulated PICMA® actuators are recommended forthis use, since their nominal voltage is below
the minimum breakdown voltages of all inert
gases. For PICA actuators with higher nominal voltages, the operating voltage should bedecreased in particular pressure ranges toreduce the flashover risk.

Magnetic Fields
Piezo actuators are excellently suited to be
used in very high magnetic fields, e.g. at cryogenic temperatures as well. PICMA® actuators
are manufactured completely without ferromagnetic materials. PICA stack actuators are
optionally available without ferromagnetic
components. Residual magnetisms in therange of a few nanotesla have been measured
for these products.
Gamma Radiation
PICMA® actuators can also be operated in highenergy, short-wave radiation, which occurs, forexample, with electron accelerators. In longterm tests, problem-free use with total dosesof 2 megagray has been proven.
Environments with High Humidity
When piezo actuators are operated in dry environments, their lifetime is always higher thanin high humidity. When the actuators are operated with high-frequency alternating voltages,
they self-heat, thus keeping the local moisturevery low.
Continuous operation at high DC voltages in adamp environment can damage piezo actuators (p. 151). This especially holds true for theactuators of the PICA series, since their active
electrodes are only protected by a polymer
coating that can be penetrated by humidity.
The actuators of the PICMA® series have an
all-ceramic insulation, which considerably
improves their lifetime in damp ambient conditions compared to polymer-coated actuators(p. 151).
Liquids
Encapsulated PICMA ® or specially encased
PICA actuators are available for use in liquids.
For all other actuator types, direct contact withliquids should be avoided. Highly insulating
liquids can be exceptions to this rule. Normally, however, the compatibility of the actuatorswith these liquids must be checked in lifetime
tests.

150

P I E Z O D R I V E S | W W W. P I . W SReliability of PICMA® Multilayer Actuators
Properties of Piezoelectric Actuators

Lifetime when Exposed to DC Voltage
In nanopositioning applications, constantvoltages are usually applied to the piezo
actuator for extended periods of time. In the
DC operating mode, the lifetime is influenced
mainly by atmospheric humidity.
If the humidity and voltage values are very
high, chemical reactions can occur and releasehydrogen molecules which then destroy theceramic composite by embrittling it.
All-Ceramic Protective Layer
The patented PICMA ® design suppresses
these reactions effectively. In contrast to coating made just of polymer, the inorganic ceramic protective layer (p. 134) prevents the internal
electrodes from being exposed to water molecules and thus increases the lifetime by several orders of magnitude (fig. 44).
Quasi-static Conditions: Accelerated Lifetime
Test
Due to their high reliability, it is virtually impossible to experimentally determine thelife time of PICMA ® actuators under realapplication conditions. Therefore, tests under
extreme load conditions are used to estimate
the lifetime: Elevated atmospheric humidity
and simultaneously high ambient temperatures and control voltages.
Fig. 44 shows the results of a test that was
conducted at a much increased atmospherichumidity of 90% RH at 100 V DC and 22°C. The
extrapolated mean lifetime (MTTF, mean time
to failure) of PICMA® actuators amounts tomore than 400000 h (approx. 47 years) while
comparative actuators with polymer coating
have an MTTF of only approx. one monthunder these conditions.

Fig. 44: Results of an accelerated lifetime test with increased humidity (test conditions:
PICMA® Stack and polymer-coated actuators, dimensions: 5 x 5 x 18 mm³, 100 V DC, 22 °C,
90% RH)

Calculation of the Lifetime when Exposed to
DC Voltage
Elaborate investigations have been done todevelop a model for calculation of the lifetimeof PICMA® Stack actuators. The following factors need to be taken into account under actual
application conditions: Ambient temperature,
relative atmospheric humidity, and applied
voltage.
The simple formula
MTTF = AU · AT · AF (Equation 30)
allows the quick estimation of the average
lifetime in hours. The factors AU as a functionof the operating voltage, AT for the ambient
temperature and A F for the relative atmospheric humidity can be read from the diagram(fig. 45).

Tests under near-realistic conditions confirm oreven surpass these results.

Important:
Decreasing voltage
values are associatedwith exponential
increases of the lifetime.
The expected lifetime at
80 V DC, for example, is
10 times higher than at
100 V DC.
This calculation can also
be used to optimize a
new application withregard to lifetime as
early as in the designphase. A decrease in thedriving voltage or control of temperature andatmospheric humidity byprotective air or encapsulation of the actuatorcan be very important inthis regard.

151

PIEZO

NANO

POSITIONING

Fig. 45: Diagram for calculating the lifetime of PICMA®
stack actuators when exposed
to DC voltage. For continuous
operation at 100 V DC and
75% atmospheric humidity(RH) and an ambient temperature of 45°C, the following
values can be read from thediagram: AF=14 (humidity,
blue curve), AT=100 (temperature, red curve), and AU=75(operating voltage, black
curve). The product results ina mean lifetime of 105 000 h,
more than 11 years

Lifetime in Dynamic Continuous Operation

Fig. 46: The patented PICMA®
actuator design with its
defined slots preventing
uncontrolled cracking due
to stretching upon dynamic
control is clearly visible

Cyclic loads with a rapidly alternating electricalfield and high control voltages (typically > 50
Hz; > 50 V) are common conditions for applications such as valves or pumps. Piezo actuators can reach extremely high cycles-to-failure
under these conditions.
The most important factors affecting the lifetime of piezo actuators in this context are theelectrical voltage and the shape of the signal.
The impact of the humidity, on the other hand,is negligible because it is reduced locally by
the warming-up of the piezo ceramic.
Ready for Industrial Application:
1010 Operating Cycles

152

Tests with very high control frequencies
demonstrate the robustness of PICMA® piezo
actuators. Preloaded PICMA® actuators withdimensions of 5 x 5 x 36 mm3 were loaded atroom temperature and compressed air coolingwith a sinusoidal signal of 120 V unipolar voltage at 1157 Hz, which corresponds to 108 cycles
daily. Even after more than 1010 cycles, there
was not a single failure and the actuators
showed no significant changes in displace-ment. In recent performance and lifetime tests
carried out by NASA, PICMA® actuators still
produced 96% of their original performanceafter 100 billion (1011) cycles. Therefore, they
were chosen among a number of different
piezo actuators for the science lab in the Marsrover "Curiosity". (Source: Piezoelectric multilayer actuator life test. IEEE Trans Ultrason
Ferroelectr Freq Control. 2011 Apr; Sherrit et al.
Jet Propulsion Laboratory, California Instituteof Technology, Pasadena, CA, USA)
Patented Design Reduces the MechanicalStressPICMA® actuators utilize a special patented
design. Slots on the sides effectively prevent
excessive increases of mechanical tensilestresses in the passive regions of the stackand the formation of un-controlled cracks (fig.
46) that may lead to electrical breakdowns andthus damage to the actuator. Furthermore, thepatented meander-shaped design of the external contact strips (fig. 43) ensures all internal
electrodes have a stable electrical contact evenat extreme dynamic loads.

P I E Z O D R I V E S | W W W. P I . W S

Piezo Electronics forOperating Piezo Actuators
Characteristic Behavior of Piezo Amplifiers

Fast step-and-settle or slow velocity with highconstancy, high positional stability and resolution as well as high dynamics – the requirements placed on piezo systems vary greatly
and need drivers and controllers with a highdegree of flexibility.
The control electronics play a key role in theperformance of piezoelectric actuators andnanopositioning systems. Ultra-low-noise,high-stability linear amplifiers are essential
for precise positioning, because piezo actuators respond to the smallest changes in thecontrol voltage with a displacement. Noiseor drifting must be avoided as much as possible. The prerequisite for the high-dynamics
displacement of the actuator is for the voltage
source to provide sufficient current to charge
the capacitance.
Power Requirements for Piezo Operation
The operating limit of an amplifier with a given
piezo actuator depends on the amplifier power,
the amplifier design and the capacitance ofthe piezo ceramics (cf. p. 148 – 149). In highdynamics applications, piezo actuators require
high charge and discharge currents. The peakcurrent is of special importance, particularly forsinusoidal operation or pulse operation. Piezo
amplifiers from PI are therefore designed sothat they can output and sink high peak currents. If an amplifier is operated with a capacitive load and frequency at which it can nolonger produce the required current, the output signal will be distorted. As a result, the full
displacement can no longer be attained.
Amplifier Frequency Response Curve
The operating limits of each amplifier model
are measured with different piezo loads
depending on the frequency and output voltage and are graphically displayed as amplifier
response curves to make the selection easier.
The measurements are performed after 15
minutes of continuous operation (piezo andamplifier) at room temperature. In cold condition after power up, more power can be briefly
available.

amplifier does not overheat, which could cause distortions of the sine wave. The amplifiercontinuously provides the output voltage evenover a long time. This amplifier response curve
cannot be used for peak values that are only
available for a short period.

Fig. 47: Amplifier frequency
response curve, determinedwith different piezo loads,
capacitance values in μF.
Control signal sine, operation
period >15 min, 20°C

The curves refer to open-loop operation; inclosed-loop operation, other factors limit the
dynamics.
Setting the Operating Voltage
After the operating limit of the amplifier has
been reached, the amplitude of the control
voltage must be reduced by the same proportion as the output voltage falls, if the frequencies continue to increase. This is importantbecause the current requirement continuously
increases along with the frequency. Otherwise,
the output signal will be distorted.
Example: The E-503 (E-663) amplifier can drivea 23 μF piezo capacitance with a voltage
swing of 100 V and a maximum frequency ofapproximately 15 Hz (with sine wave excitation). At higher frequencies the operating limit
decreases, e.g. to 80 V at 20 Hz. In order toobtain a distortion-free output signal at thisfrequency, the control input voltage must be
reduced to 8 V (voltage gain = 10).

The power amplifier operates linearly within
its operating limits so that the control signal
is amplified without distortion. In particular, no thermal limitation takes place, i.e. the

PIEZO

153

NANO

POSITIONING

Solutions for High-Dynamics Operation
Piezo Electronics for Operating Piezo Actuators

Switching Amplifiers with Energy Recovery
Piezo actuators are often used for an especiallyprecise materials processing, for example inmechanical engineering for fine positioning inmilling and turning machines. These require
high forces as well as dynamics. The piezo
actuators are correspondingly dimensioned for high forces; i.e. piezo actuators with ahigh capacity are used here. Particularly highcurrents are required to charge and discharge
them with the necessary dynamics. The controlof valves also requires similar properties.
Energy Recovery Minimizes the Energy Consumption in Continuous Operation

Unlike conventional class D switching amplifiers, PI switching amplifiers for piezo elements
are current- and voltage-controlled. Productexamples are the E-617 for PICMA® actuatorsand E-481 for the PICA actuator series.
Protection of the Piezo Actuator throughOvertemperature Protection
In continuous operation, the heat developmentin the piezo actuator is not negligible (p. 148).
Corresponding electronics can therefore evaluate the signals of a temperature sensor on thepiezo. This protects the ceramic from overheating and depolarization.
Valid patents
German patent no. 19825210C2International patent no. 1080502B1
US patent no. 6617754B1

100

25,00

80

20,00
Power consumption in W

Fig. 48: Piezo
actuator in a casewith connections
for temperature
sensor and cooling air

Efficiency in %Since these applications frequently run aroundthe clock, seven days a week, the energy consumption of the amplifier is particularly important. For this purpose, PI offers switching
amplifier electronics with which the pulse
width of the control signal is modulated (PWM)
and the piezo voltage is thereby controlled.
This results in an especially high efficiency.
In addition, a patented circuitry for energy
recovery is integrated: this stores part of the
returning energy in a capacitive store whena piezo is discharged and makes the energy
available again for the next charging operation.
This permits energy savings of up to 80% to berealized. Furthermore, the amplifier does notheat up as much and thus influences the actual
application less.

60

40

20

15,00

10,00

5,00

0

0

20

40
60
Output power, relative to max. in %Switching amplifier

80

0,00

100

0

500

1000

1500

2000

Frequency in Hz

Linear amplifier

Switching amplifier
Linear amplifierFig. 49: Thanks to their patented energy recovery
system, PI amplifiers only consume approx. 20% of
the power required by a corresponding linear amplifier
with the same output power

154

Fig. 50: Power consumption of a piezo amplifier withlinear and switched-mode amplifier at the piezo output, capacitive load 1 μF. The measured values clearlyshow that the pulse width modulated amplifier allows
significantly higher dynamics than the classic linear
amplifier. The linear amplifier reaches the upper limit of
its power consumption at frequencies of up to approx.
700 Hz, the switching amplifier does not reach the limit
until far beyond 2 kHz

P I E Z O D R I V E S | W W W. P I . W S

Linearized Ampliﬁers for Piezo
Displacement Without Hysteresis
Piezo Electronics for Operating Piezo Actuators

Charge Control

Charge and Displacement

A typical application for piezo actuators or
nanopositioning systems is dynamic scanning.
This involves two different methods: step-andsettle operation with precise and repeatable
position control on the one hand, and ramp
operation with especially linear piezo displacement on the other. The first method requires aclosed servo loop which ensures that positions
can be approached precisely and repeatedly
with constant step sizes.

Charge control is based on the principle thatthe displacement of piezo actuators is much
more linear when an electrical charge isapplied instead of a voltage. The hysteresis is
only 2% with electrical charges, whereas it isbetween 10 and 15% with open-loop control
voltages (fig. 51). Therefore, charge control canoften be used to reach the required precisioneven without servo loop. This enhances the
dynamics and reduces the costs. Charge control is not only of advantage as regards highly
dynamic applications but also when it comesto operation at very low frequencies. However,charge control is not suitable for applications
where positions need to be maintained for alonger period of time.

Of course, ramp operation with linear piezo
displacement is also possible using position
feedback sensors and a servo loop. However,in this case, the servo loop will determine thedynamics of the entire system which sometimes significantly limits the number of cycles
per time unit. This can be avoided by means ofan alternative method of amplification: charge
control.

For dynamic
applications:
Active vibration
damping
Adaptronics
High-speed
mechanicalswitches
Valve control(e.g. pneumatics)
Dispensing

The charge-controlled E-506.10 power
amplifier offers highly linear, dynamic
control for PICMA® piezo actuators

Δl

Δl

Q

ΔV

Fig. 51: Typical expansion of piezo actuators in relation to the applied voltage (left) and the charge (right). Controlling the applied charge significantly reduces the hysteresis

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Handling of Piezo Actuators

Piezo actuators are subject to high mechanical and electrical loads. Moreover, the brittle
ceramic or crystalline materials require carefulhandling.
Avoid mechanical shocks to the actuator,
which can occur if you drop the actuator,
for example.
Do not use metal tools during installation.

Fig. 52: Avoiding lateral forces
and torques

Avoid scratching the ceramic or polymer
coating and the end surfaces during installation and use.

Unbenannt-2
Unbenannt-2
1
1

Prevent the ceramic or polymer insulationfrom coming into contact with conductive
liquids (such as sweat) or metal dust.
If the actuator is operated in a vacuum:
Observe the information on the permissible
piezo voltages for specific pressure ranges(p. 150).

Fig. 53: Prevention of torques

If theactuator could come into contact with
30.03.12 16:56
insulating liquids such as silicone or
hydraulic oils: Contact info@piceramic.com.
If the actuator has accidently become dirty,
carefully clean the actuator with isopropanol or ethanol. Next, completely dry it in adrying cabinet. Never use acetone forcleaning. When cleaning in an ultrasonicbath, reduce the energy input to the necessary minimum.

Fig. 54: Avoiding tensilestresses by means of amechanical preload

Recommendation: Wear gloves and protective glasses during installation and startup.
DuraAct patch actuators and encapsulated
PICMA® piezo actuators have a particularlyrobust construction. They are partially exempt
from this general handling information.
30.03.12 16:56

Mechanical Installation (fig. 52, 53, 54)
Avoid torques and lateral forces when
mounting and operating the actuator byusing suitable structures or guides.
When the actuator is operated dynamically:
Install the actuator so that the center ofmass of the moving system coincides withthe actuator axis, and use a guiding forvery large masses.
Establish contact over as large an area as
possible on the end surfaces of a stackactuator.
30.03.12 30.03.12
16:56 16:56

Select opposing surfaces with an evennessof only a few micrometers.
GluingIf the mounting surface is not even, use
epoxy resin glue for gluing the actuators.
Cold-hardening, two-component adhesives
are well suited for reducing thermomechanical stresses.
Maintain the operating temperature range
specified for the actuator during hardening
and observe the temperature expansion
coefficients of the involved materials.
Uneven mounting surfaces are found, forexample, with PICMA® Bender and PICMA®
Chip actuators, since these surfaces are notground after sintering (fig. 55).
Applying a Preload (fig. 54)
Create the preload either externally in themechanical structure or internally in a case.
Apply the preload near the axis within thecore cross-section of the actuator.
If the actuator is dynamically operated andthe preload is created with a spring: Use aspring whose total stiffness is approximately one order of magnitude less thanthat of the actuator.

Fig. 55: Mounting of a onesidedly clamped bending
actuator by gluing

30.03.12 16:56

156

P I E Z O D R I V E S | W W W. P I . W SIntroducing the Load Evenly (fig. 56)
The parallelism tolerances of the mechanicalsystem and the actuator result in an irregularload distribution. Here, compressive stresses may cause tensile stresses in the actuator. Regarding the even application of a load,
there are diverse design solutions that differ
from each other in axial stiffness, separabilityof the connection and rotatability in operation,e.g. in the case of lever amplification.

TensilestressesFig. 56: Avoiding an irregular load application

Gluing the actuator (cf. gluing section)

Electrically insulate the actuator against the
peripheral mechanics. At the same time,observe the legal regulations for therespective application.

Hardened spherical end piece with point
contact to even opposing surface
Hardened spherical end piece with ring
contact to a spherical cap

Observe the polarity of the actuator forconnection.

Connection via a flexure joint

Only mount the actuator when it is shortcircuited.

If the actuator is coupled in a milling
pocket, make sure that there is full-area
contact on the end surface of the actuator.
For this purpose, select the dimensions of
the milling pocket correspondingly or makefree cuts in the milling pocket (fig. 57).
If a point load is applied to the end pieceof the actuator: Dimension the end pieceso that its thickness corresponds to half
Unbenannt-2
the cross-sectional dimension
in1order toprevent tensile stresses on the actuator(fig. 58).

When the actuator is charged: Discharge
the actuator in a controlled manner with a
10 kΩ resistance. Avoid directly short-circuiting the terminals of the actuator.

Fig. 57: Full-area contact of
the actuator

Do not pull out the connecting cable of theamplifier when voltage is present.
Safe Operation

Electrical Connection (fig. 59)
From an electrical point of view, piezo actuators are capacitors that can store a greatamount of energy. Their high internal resistances lead to very slow discharges with time
constants in the range of hours. Mechanical orthermal loads electrically charge the actuator.
Connect the case or the surrounding
mechanics to a protective earth conductorin accordance with the standards.

Unbenannt-2 1

TensilestressesUnbenannt-2
Unbenannt-2
1
1

Reduce the DC voltage as far as possible
during actuator operation (p. 151). You candecrease offset voltages with semi-bipolar
operation.
Always power off the actuator when it is
not needed.

Fig. 58: Proper dimensioningof the end pieces in the caseof point contact

Avoid steep rising edges in the piezo voltage, since they can trigger strong dynamic
forces when the actuator does not have a
preload. Steep rising edges can occur, forexample, when digital wave generators are
switched on.
30.03.12 16:56

Fig. 59: Mechanical loads
electrically charge the actuator. Mounting only whenshort-circuited

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H E X A P O D A N D S PA C E F A B | W W W. P I . W SHexapod and SpaceFAB

Products

Page 160 – 179

Technology of Parallel-Kinematic Precision Positioning Systems

Page 180 – 189

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Hexapod and SpaceFAB
Parallel Kinematics with 6 Motion Axes

In the ALMA project (Atacama desert, Chile), up to 64 antennas are combined to form a virtual single giant radio telescope. PI Hexapod systems areused to position the secondary reflectors of the antennas. The systems, which are specially designed for extreme ambient conditions, can positionloads of up to 75 kg (Photo: ALMA (ESO/NAOJ/NRAO))160

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Page 162

Controller for Hexapod Positioning Systems

Page 176

6D Vector Motion Control, Comprehensive Functions

Accessories

Page 178

For Hexapod Systems

Parallel Kinematics

Nanopositioning

UP TO 6 DEGREES OF FREEDOMSUB-NANOMETER RESOLUTION

Technology of Parallel-Kinematic Precision Positioning Systems

Page 180

Motion Control Software

Page 186

Effective and Comfortable SolutionsGCS
MOTION CONTROL

Drive Technology

Micropositioning

DC, STEPPER, PIEZO, MAGNETIC

LONG TRAVEL RANGES

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Compact, High-Precision,
Parallel-Kinematic Hexapods

H-811

Highlights■ Six-axis positioning system with excellent precision■ System with powerful controller with vector algorithms, virtual pivot point■ Comprehensive software package with integrated scan algorithms for fiber optic alignment■ Optional interface for PLC control

Applications
Automated 6D alignment systems assume important tasks for testing and manufacturing MEMS and photonics accessories. This includes positioning and aligning collimated fibers and assemblies.

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H-206

H-810

H-206

H-811

H-810

Ideal for ﬁber
positioning

Vacuum-compatible
version up to 10-6 hPa

Dimensions in mm

228 × 220 × 158

Ø 136 × 115

Ø 100 × 116

Travel range X, Y, Z
in mm

12 × 11 × 13

34 × 32 × 13

40 × 40 × 13

Travel range θX, θY, θZ in °11 × 13 × 11

13 × 13 × 42

20 × 20 × 60

Load capacity withhorizontal/any mounting
in kg

2

5 / 2.5

5 / 2.5

Repeatability
X, Y, Z in μm±0.3±0.3, ±0.3, ±0.1

±1, ±1, ±0.1

Min. incremental motion
X, Y, Z in μm

0.10.5, 0.5, 0.2

1, 1, 0.5

Max. velocity
in mm/s

10

10

2.5

All product details can be found at www.pi.ws

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163

Cost-Effective Hexapod Systems
For Medium Loads

H-840

Highlights■ Six-axis positioning system with high precision■ System with powerful controller with vector algorithms, virtual pivot point■ Comprehensive software package■ Optional interface for PLC control

Applications
These cost-efficient all-purpose 6-axis systems can be used for positioning and scanning in all degrees of freedom.

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H-824

H-820

H-824

H-840

H-820

Precision Hexapod,
vacuum-compatible
versions up to 10-6 hPa

Precision Hexapod

Standard Hexapod forautomation tasks inbiotechnology and life
sciences

Dimensions in mm

Ø 280 × 190

Ø 350 × 330

Ø 350 × 330

Travel ranges X, Y, Z
in mm

50 × 50 × 25

100 × 100 × 50

100 × 100 × 50

Travel ranges θX, θY, θZ
in °15 × 15 × 25

30 × 30 × 60

30 × 30 × 60

Load capacity in kg

5 to 1010 to 30

20

Repeatability in μm

to ±0.1

to ±0.4

to ±1

Min. incremental motion
in μm

0.3 to 1

0.5 to 3

10

1, 25

2.5, 50

20, with full load

Max. velocity
X, Y, Z in mm/s

All product details can be found at www.pi.ws

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165

SpaceFAB Precision Micro Robot
6 Degrees of Freedom in Low-Profile Design

SF-450 PS

Highlights■ Long travel ranges in X and Y with low-profile design■ Load of up to 3 kg
■ Vacuum-compatible versions to 10-9 hPa on request■ Modular structure for flexible travel ranges■ System with powerful controller with vector algorithms, virtual pivot point

Applications
SpaceFAB designs can be adapted in a fast and uncomplicated way to meet customer requirements with regard to
installation space or travel ranges. Therefore, the 6-axis systems are ideal for almost any precision application, from minipositioners for UHV chambers to integration in production processes.

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SF-3000

SF-6500 PS

SF-3000

SF-6500
PS

SF-450PS

Dimensions in mm

600 × 444 × 209

276 × 210 × 57

200 × 170 × 77

Travel range X, Y, Z
in mm

50 × 50 × 12.7

13 × 13 × 10

12 × 12 × 6

Travel range θX, θY, θZ in °10

12 × 12 × 12

13 × 13 × 10

Load capacity in kg

3

2

0.4

Repeatability in μm±0.5±0.008±0.25

Min. incremental motion
in μm

0.2

0.005

0.025

Max. velocity in mm/s

30102-phase stepper
motor

NEXACT piezo
stepping drive

Motor type

10®

PIShift piezo inertia
drive

All product details can be found at www.pimicos.com

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167

Precision Hexapods
For Loads of up to 50 kg

HP-550Highlights■ Six-axis positioning system with excellent precision■ System with powerful controller with vector algorithms, virtual pivot point■ Comprehensive software package

Applications
HP Hexapod systems include a powerful Delta Tau controller frequently used for automation in all fields of application.
This includes positioning antennas in telescopes or production line control in semiconductor manufacturing.

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HP-430

HP-300HP-550HP-430HP-300Ø 550 × 360

Ø 430 × 250

Ø 300 × 176

Ø 130

Ø 90

Ø 60

100 × 100 × 100

50 × 50 × 30

44 × 44 × 30

Travel range θX, θY, θZ in °40 × 40 × 60

20 × 20 × 40

18 × 18 × 25

Load capacity with horizontal mounting in kg

50

50

10

up to ±3

up to ±2

up to ±1Min. incremental motion
in μm

0.5

0.5

0.5

Max. velocity in mm/s

2

1

3

Dimensions in mm
Clear aperture in mm
Travel range X, Y, Z
in mm

Repeatability in μm

All product details can be found at www.pimicos.com

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Precision Hexapods
For Loads from 50 kg to 250 kg

H-850

Highlights■ Six-axis positioning system with excellent precision■ System with powerful controller with vector algorithms, virtual pivot point■ Comprehensive software package■ Optional interface for PLC control

Applications
Positioning mirrors in large telescope arrangements is a frequent application of 6-axis positioning systems. Inspection
systems, e.g. for large LCD screens, have similar requirements with regard to precision.

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M-850KWAH

M-850KPAH

H-850

M-850K
WAH

M-850K
PAH

High-precision,
vacuum-compatible
versions up to 10-6 hPa

Customized model
for positioning thesecondary mirror
in large telescopearrangements

Customized model for
positioning patients inmedical technology

Ø 350 × 330

Ø 580 × 360

1200 × 530 × 184

Ø 80

Ø 420

–

100 × 100 × 50

20 × 22 × 32

100 × 100 × 50

Travel range θX, θY, θZ in °

±15

±3

±5

Load capacity with horizontal mounting in kg

50 to 250
20 to 50 with any
mounting orientation

75

200

±0.2 to ±1

±5

±100

Min. incremental motion
in μm

0.5 to 1

2

100

Typ. velocity
in mm/s

0.3 to 5516

Dimensions in mm
Clear aperture in mm
Travel range X, Y, Z
in mm

Repeatability in μm

All product details can be found at www.pi.ws

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171

Precision Hexapods
For High Loads of More than 1 Ton

H-845

Highlights■ Six-axis positioning system with excellent precision■ System with powerful controller with vector algorithms, virtual pivot point■ Comprehensive software package■ Optional interface for PLC control

Applications
Astronomy and other fields of research, but also industrial production and testing facilities, use parallel kinematics
to position in 6 axes with a space-saving system. The mechanical coupling is always adapted to customer-specificrequirements.

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M-850KHTH

H-850KHLC

M-850KHLH

H-845.
D11

M-850K
HTH

H-850K
HLC

M-850K
HLH

Load capacity of
up to 400 kg in any
orientation

Customized model fora load of 1 ton

Customized model
for a load of 1.5 tons,
even in any mounting
orientation

Customized model for
vacuum up to 10-6 hPa

Dimensions in mm

Ø 790 × 660

Ø 900 × 710

Ø 1 200 × 600

Ø 1 000 × 500

Travel ranges X, Y, Z
in mm

220 × 220 × 100

400 × 400 × 200

340 × 340 × 220

24 × 24 × 24

40 × 40 × 60

40 × 40 × 10

40 × 40 × 60

6×6×8

Load capacity in kg

1 000

1 000

1 500

1 000

Repeatability in μm

±2

±1

±1

±2

Min. incremental motion
in μm

2

1

1

2

Typ. velocity
in mm/s

20

1

0.3

0.1

Motor typebrushless DC motors
with integrated brakes

brushless motors withintegrated brakes

brushless DC motors
with gearhead

brushless DC motors
with gearhead, integrated brakes

Travel range θX, θY, θZ in °All product details can be found at www.pi.ws

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173

Nanometer-Precision Parallel Kinematics
Driven by Piezomotors

P-911KNMV
P-

Highlights■ Customized models for applications with very high precision requirements■ Non-magnetic drives■ System with powerful digital controller and integrated drivers for piezo stepping drives

Applications
Semiconductor inspection, in particular, requires high-precision multi-axis positioners with high stiffness. Parallel
kinematics with PiezoWalk® piezo stepping drives guarantee accuracies down to nanometers, which is required foraligning wafers.

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N-515KNPH

N-510

P-911KNMV

N-515K
NPH

N-510

Customized model.
UHV-compatible to10-9 hPa, UV-resistantCustomized model withexcellent resolution

Powerful Z / tip/tilt
platform

Dimensions in mm

Ø 100 × 90

Ø 380 × 140
Aperture Ø 202

Ø 300 × 60
Aperture Ø 250

Travel ranges X, Y, Z
in mm

1.5

10

Z: 1.3

Travel range θX, θY, θZ in °2

6

θX, θY: 0.6

Load capacity in kg

5

50

20

Design resolution in nm
Motor type

100

5

PiezoWalk
piezo stepping drive®

5

PiezoWalk
piezo stepping drive®

PiezoWalk®
piezo stepping drive

All product details can be found at www.pi.ws

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175

Controller for Hexapod Positioning Systems
6D Vector Motion Control, Comprehensive Functions

C-887.11

Highlights■ Powerful controller with vector algorithms■ Virtual pivot point, freely programmable■ Data recorder■ Macro programming■ Stand-alone operation possible or control with TCP/IP and RS-232■ Extensive software package■ Included in the delivery of all PI standard Hexapod systems

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D E. P I . W SCustomized model for PiezoWalk®
piezo stepping drives

C-887.21

Digital Controller for 6-Axis Parallel Kinematics

Versions

C-887.11 19" controller, comprises the control for two additional single axes with servo motors, the functionality
can be enhanced with many additional options
C-887.21 compact bench-top controller for a lower system price

Functions

Position control using Cartesian coordinates, vectorized motion. Stable, virtual pivot point can be deﬁned freely
in the work space. Real-time data recorder for recording operating parameters such as motor control, velocity,
position or position error. Macro command language. Stand-alone operation possible with Autostart macro orconnection of keyboard and monitor. Optional: Manual control unit
TCP/IP Ethernet, can also be used for remote control and service. RS-232 for up to 25 m cable length.

Interfaces

Standard monitor and keyboard interface.
Optional: Analog input. Interface for PLC control. On request: RS-422 for up to 1.4 km cable length.
GPIB with measurement equipment
PIMikroMove® user software. Common command set for all PI positioning systems (GCS).

SoftwareShared libraries for Windows and Linux. Complete set of LabVIEW virtual instruments.
Graphical user interfaces (GUI), conﬁguration software and graphically displayed scan routine.
Optional: PIVeriMove software for checking a restricted operating space

Custom designs

For use at high altitudes, e.g. for astronomical telescope applications. Processing of absolute position sensors.
Control of motor brakes. Processing of additional (redundant) position sensors for increased safety requirements,
e.g. in medical technology

All product details can be found at www.pi.ws

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177

Accessories
For Hexapod Systems

C-887.MC■ Manual operation

Control unit for Hexapods, USB connection, 3 m cable■ Free step size definition

F-206.NCU■ Consists of P-611.3SF NanoCube® XYZ

Fast 3-axis piezo nanopositioning system
for use in combination with Hexapod
systems■ Display for position values

nanopositioning system with SGS sensors,
100 x 100 x 100 μm3, integrated fiber holder
and E-760.3S0 NanoCube® piezo controllercard, ISA bus

F-206.VVU
2-channel photometer card, visible range■ Optical inputs for 480 to 1 040 nm

F-206.iiU
2-channel photometer card, IR range■ Optical inputs for 850 to 1 680 nm■ Analog inputs 0 – 10 V

■ Analog inputs 0 – 10 V

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C-887.A20
Hexapod cable set, 20 m

■ With 2 signal amplifier boxes for differential

F-206.TMU■ For fast replacement of different assemblies

Additional mounting platform■ Magnetic coupling

data transfer

for H-206 Hexapods

F-311.LV■ Multi-channel image processing for 3D

PIMotion&Vision LabVIEW driver set

examination or various resolutions

for intelligent automation processes■ Functions such as autofocus, edge

F-603

■ Quick fasteners for easy set-up

Fiber, objective and waveguide holders■ Precision-machined, made of high-strengthfor H-206 and P-611 NanoCube®

alignment, distance measurements
and complex 6D alignment routines

aluminum/brass

More information at www.pi.ws

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179

Technology of Parallel-Kinematic Precision
Positioning Systems

Six Axes of Motion with Hexapods and SpaceFAB

Page 181

Compact Positioning System – Advantages over Serial Kinematics Design – Components – Work Space
Hexapods in Automation

Page 184

Precise Trajectory Control Using G-Code – User-Defined Coordinate Systems – Standardized Automation
Interfaces
Motion Control Software from PI

Page 186

Universal Command Set – PIMikroMove Host Software for Fast Start-Up – Fast Integration of PI Controllers
in Third-Party Programming Languages and Software Environments
Hexapod-Specific Software

Page 189

Determining the Work Space – Checking the Permissible Load – PIVeriMove: Preventing Collisions with
Restricted Work Space – Emulation: The Hexapod System as a Virtual Machine – HexaApp: PI Hexapod Control
via iPhone, iPad or iPod180

H E X A P O D A N D S PA C E F A B | W W W. P I . W SParallel-Kinematic Precision
Positioning Systems
Six Axes of Motion with Hexapods and SpaceFAB

Compact Positioning Systemwith Six Degrees of Freedom

Advantages over Serial-Kinematic Design

Hexapod platforms are used for moving andprecision positioning, aligning and displacing
loads in all six degrees of freedom, i.e. threelinear and three rotational axes.
Hexapods have a parallel-kinematic structure, i.e. the six drives act together on a single moving platform. The length of the single
drives can be changed so that the systemmoves in all six degrees of freedom in space.
This special Hexapod design optimizes theoverall system stiffness and allows for a large
central aperture.
Precise Positioning Even of Heavy Loads
Depending on their design, Hexapods canposition loads from several kg up to several
tons in any spatial orientation, in other words
independently of the mounting orientation andwith submicrometer precision.

Hexapods can be designed considerably morecompact than serially stacked multi-axis positioning systems. Since only a single platform,
most often provided with a large aperture, is
actuated, the moving mass of the Hexapod issignificantly smaller. This results in improved
dynamics with considerably faster response.
Furthermore, cabling is no issue, so that no
additional forces and torques reduce the accuracy.
In case of stacked systems, the lower axes
not only move the mass of the payload but
also the mass all other following drives. This
reduces the dynamic properties and the total
system stiffness. Moreover, the runouts of theindividual axes add up to a lower accuracy andrepeatability.

181

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Cardanic joints of the H-840
Hexapod model

Matching Components for High Precision

JointsThe basis is a zero-backlash structure and carefully selected and matching components. This
includes first of all the right material selection,
when e.g. thermal effects are to be expected
at the place of operation. The motor, if necessary with gearhead, an integrated guiding, theleadscrew/nut unit, as well as the joints forthe required load range up to high-resolution
position detection in every strut – all these elements determine the achievable precision.

Hexapods for precision positioning often have
Cardanic joints with two orthogonally arranged
axes. This is the optimum combination of two
degrees of freedom and the stiffness of thestructure.

Motors and Drives

Ball-and-socket joints

PI Hexapods are based on electromechanicaldrives and are much more accurate than thehydraulic Hexapods known from flight or driving simulators. Precision leadscrew drives or
piezo linear motors are used. Most systems
are self-locking. Direct-drive Hexapods ensure
higher velocities; for industrial use, brushless
motors (BLDC) are particularly suitable.

Ball-and-socket joints offer more degrees of
freedom in a relatively simple design. However, the overall stiffness and precision incase of external loads and torque can suffer.
A compensating preload is recommended but
requires drives with high output forces such as
the NEXLINE® piezomotor drives.
If the highest precision and few linear bending
displacements and angles are required, flexurejoints are recommended. They exhibit neither
friction nor backlash and do not require lubricants.

The application determines the drive technologies: Hexapods with piezoelectric PiezoWalk®
stepping drives are suitable for ultrahigh vacuum applications and can also be operated invery strong magnetic fields.

The positioning accuracy of a precision H-824 Hexapod in Z direction over the complete travel range of 25 mm is a
few micrometers, and the repeatability is considerably below ±0.1 μm

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The entirety of all combinations of translations androtations that a Hexapod canapproach from any given
position is called the work
space; it is given in reference
to the origin of the coordinate
system used. The work spacecan be limited by external
factors such as obstacles or
the position and size of theload

The Work or Motion Space

Advanced Motion Control

Due to actuator travel and joint angles, theHexapod platform can carry out any combination of tilting and rotation around a freely
selectable pivot point in addition to the linear
motion. The cables do not produce friction
nor limit the work space in contrast to a serial
arrangement with cabling for each individualaxis.

The individual drives of a Hexapod do notnecessarily point in the direction of motion,
which is why a powerful controller that canhandle the required coordinate transformations in real time is needed.

Hexapods with Passive Struts
Instead of variable, active struts, Hexapods
can be designed with passive struts that show
constant strut length. In this case the coupling
points or joints are usually moved along alinear path. This design is advantageous when
the drive unit is to be separated from the platform, e.g. outside of cleanrooms or vacuum
chambers.

Constant strut-length Hexapod design. The drive units
move the joint position up and down affecting the linear and rotary position of the platform

PI uses advanced digital controllers along withuser-friendly software. All motion commands
are specified in Cartesian coordinates, and alltransformations to the individual actuators
take place inside the controller.
An important Hexapod property is the freely
definable pivot point. The possibility to rotate
around any point in space opens up new application possibilities, and the Hexapod platform
can be integrated in the overall process.

In this 3-strut design, additional degrees of freedom are produced because a passive
strut can be moved in two or more axes. Example: In SpaceFAB, the individual struts are
driven by one XY translation stage each

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Hexapods in Automation
Control and Interfaces for Easy Integration

Precise Trajectory Control Using G-Code
The Hexapod controller may also control
the trajectory based on G-Code according to
DIN 66025/ISO 6983. The G-Code commandlanguage is directly implemented in the controller.
With G-Code, moving along complex trajectories with defined velocity and acceleration ispossible. The Hexapod system can, for example, move a workpiece or tool jerk-controlled
and with high precision during machining
with out the mechanical system starting tovibrate.

Any coordinate system used as a reference for target
values of the Hexapod may be definedUser-Defined Coordinate Systems
To adapt the trajectory perfectly to the requirements of the application, it is possible to define
various coordinate systems which refer, forexample, to the position of workpiece or tool.
This offers great advantages for applications inindustrial automation, but also for fiber alignment.

184

Standardized Automation Interfaces
Standardized fieldbus interfaces guarantee aneasy connection to parent PLC or CNC controls
so that Hexapods can work synchronously withother components in one automation line.

Standardized fieldbus interfaces make integration easier: Hexapods in automation technology

H E X A P O D A N D S PA C E F A B | W W W. P I . W S

The PLC acts as master and defines the target position in Cartesian coordinates andthe trajectories; in return, it gets the actual
positions also over the fieldbus interface. Allother calculations required to command theparallel-kinematic six-axis system are done by
the Hexapod controller, i.e. transforming thenominal positions from Cartesian coordinates
into drive commands for the individual drives.
In this case, the controller acts just like an intelligent drive.

PLC/CNC(Fieldbus
Master)Cartesian
NominalPosition

Cartesian
ActualPosition

The cycle times for determining new positions, evaluating signals and synchronizing
are between 1 and 3 ms. Fieldbus interfaces
are currently available for Profibus, EtherCAT,
Profinet, CANopen and SERCOS.

PI
Hexapod

PI Hexapod Controller
Calculation of
Inverse Kinematics
Fieldbus Slave
Interface

Fine Interpolation
Motor
Controller with
Speed/Rotation
Angle Control

Transformationof Encoder Values
to Cartesian
Coordinates

Block diagram: The Hexapod controller acts just like an intelligent drive. The fieldbus interface can be exchanged toallow communication with numerous types of PLC or CNC control

185

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Motion Control Software
Effective and Comfortable Solutions

Parallel Kinematics

Nanopositioning

UP TO 6 DEGREES OF FREEDOMSUB-NANOMETER RESOLUTIONGCS
MOTION CONTROL

Drive Technology

Micropositioning

DC, STEPPER, PIEZO, MAGNETIC

LONG TRAVEL RANGESSupported Operating
Systems■ Windows XP (SP3)■ Windows VISTA■ Windows 7 32/64 bit■ Linux 32/64 bit■ Windows 8 32/64 bit

All digital controllers made by PI are accompanied by a comprehensive software package. PI
supports users as well as programmers withdetailed online help and manuals which easeinitiation of the inexperienced but still answer
the detailed questions of the professional.
Updated software and drivers are always
available to PI customers free of charge via
the Internet.
PI software covers all aspects of the applicationfrom the easy start-up to convenient system
operation via a graphical interface and quick
and comprehensive integration in customer
written application programs.

Universal Command Set Simplifies Commissioning and Programming
PI’s General Command Set (GCS) structure isconsistent for all controllers regardless of theircomplexity and purpose. GCS with its many
preprogrammed functions accelerates theorientation phase and the application development process significantly while reducing
the chance of errors, because the commands
for all supported devices are identical in syntax and function. Further advantages are thatdifferent PI controllers can be added and integrated more easily and system upgrades canbe introduced with a minimum of programming effort.

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H E X A P O D A N D S PA C E F A B | W W W. P I . W S

PIMikroMove Software Ensures Rapid
Start-Up
PIMikroMove is PI’s convenient graphical userinterface for any type of digital controller andpositioning system, regardless of whether
piezoelectric, linear motors, or classical electrical motor drives are used and independent of
the configuration and number of axes.
All connected controllers and axes are displayed and controlled consistently with thesame graphical interface. Two or more independent axes can be moved in the position pad
using the mouse or a joystick, including vectorially; Hexapods are displayed graphically.
Macro programs simplify repetitive tasks forexample in automated processes. The macros
are created as GCS command sets that can be
executed directly on the controller, e.g. as astart-up macro that allows stand-alone operation; they can also be processed by the host PC.

Scan algorithms can record analog values asa function of position or find the global maximum of an analog value fully automatically.
Depending on the specific controller, PIMikroMove supports a number of additional functions. A data recorder can record system parameters and other variables during motion forlater analysis.
Optimizing System Behavior
When the mechanical properties of a positioning system are changed, e.g., by applying a
different load, motion control parameters often
need to be adapted. PI software provides tools
for optimization of the system response andstability. Different parameter sets can be saved
for later recall, also accessible from custom
application programs.

187

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Motion Control Software
Fast Integration of PI Controllers in Third-Party Programming Languages
and Software Environments

In measuring and control technology andautomation engineering, many applications
are produced in LabVIEW. PI provides complete LabVIEW drivers sets to facilitate programming. A controller-specific Configuration_Setup VI is integrated at the start of the
LabVIEW application and includes all system
information and initiation steps required forstart-up. The application itself is implemented
with controller-independent VIs.
In case of a controller change or upgrade, it isusually only necessary to exchange the Configuration_Setup VI , whereas the applicationspecific code remains identical due to the consistent GCS command set structure.
The driver set includes many specific programming examples, e.g. comprehensive scan andalign routines that can be used as template forcustomer-specific programs. Moreover, thesource code of many VIs being open allows
for rapid adaptation to the user needs.
Flexible Integration in Text-Based Programming Languages
The integration of PI positioning systems intext-based programming languages under
Microsoft Windows or Linux is simplified byprogram libraries and exemplary codes.

These libraries support all common programming languages and all PI positioning systems,
allowing the PI GCS command set functions to
be integrated seamlessly in external programs.
Third-Party Software Packages
Drivers for the PI GCS commands have now
been integrated in many third-party software
packages. This allows for the seamless integration of PI positioning systems in software
suites such as MetaMorph, μManager, MATLAB and ScanImage. Moreover, EPICS andTANGO drivers are available for integration
into experiments of large-scale research facilities. The drivers for μManager, MATLAB and alarge part of the EPICS drivers are being developed and serviced in-house by PI.

Supported Languages and Software
Environments■ C, C++, Python, Visual C++, Visual

Basic, Delphi■ LabVIEW, MATLAB, μManager, EPICS,TANGO, MetaMorph■ and all programming environmentsthat support the loading of DLLs188

H E X A P O D A N D S PA C E F A B | W W W. P I . W SHexapod-Speciﬁc Software

Due to their parallel kinematic structure, Hexapods necessitate a particularly complex control
system. The position coordinates, for example,
are given in virtual Cartesian axes which arethen converted into positioning commands forthe individual actuators by the controller. PI
supplies special software that allow the 6-axes
positioners to be more convenient in operationand easier to integrate.
Determining the Work SpaceThe limits of the work space vary dependingon the current position of the Hexapod (translation and rotation coordinates) and the current coordinates of the pivot point. A special
software tool included with each PI Hexapod
calculates these limits and displays themgraphically.
Checking the Permissible LoadAs with any multi-axis positioning system, theload limit of the Hexapod varies as a functionof a number of factors such as orientation of
the Hexapod, size and position of the payload,
current position (translation and rotation coordinates) of the Hexapod platform, and forces
and moments acting on the platform.
The Hexapod software package includes a PI
simulation tool that calculates all forces andmoments and compares them individually
against the specified load limits of the corresponding Hexapod mechanics.

PIVeriMove: Preventing Collisions with
Restricted Work Space
Another proprietary PI simulation softwaretool enables offline graphical configurationand simulation of the Hexapod motion in theapplication environment. CAD data of objects
can be imported or approximated with simple
shapes such as cylinders and cuboids.
PIVeriMove then checks restrictions in thework space. Implemented in the controller
firmware or the application software, this prevents the Hexapod from approaching positions where
the platform, struts, or the mounted load
would collide with the surroundings.

The simulation softwaregraphically displays the position and the available work
space of the Hexapod model

Emulation: The Hexapod System as a Virtual
MachineA virtual machine that can be installed on thecustomer’s host PC is available to emulate acomplete Hexapod systems (mechanics, controller and even peripherals). PI supplies asuitable software that can be used to realize acomplete hexapod system (hexapod mechanics and controller, possibly including peripherals) as a virtual machine on the host-PC.
Application programs can then be developed
and pre-tested, different load scenarios can be
simulated and the work space can be determined before the system arrives, saving significant cost and development time. And everything is ready for use at the time of delivery!
PITouch: PI Hexapod Control via iPhone, iPador iPod
The Hexapod system can also be controlledwirelessly from mobile Apple iOS devices. A
corresponding app enables command control
of touchscreen, motion sensors or via a command input window.

189

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Motorized Positioning Systems

Products

Page 192–251

Basics of Motorized Positioning Systems

Page 252–265

191

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Precision Linear Positioning Stages

System with high-precision PI miCos linear and rotational ax
xes
for the positioning of wafers in chip production

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Linear Positioning Stages with Piezomotors

Page 194

Small Precision Linear Positioning Stages

Page 198

Linear Positioning Stages for Travel Ranges up to 1 m

Page 202

Nanometer Precision over Long Travel Ranges

Page 208

Fast Scans at Constant Velocity

High-Speed Stages of Excellent Precision

Page 210

Electromagnetic Linear Motor Combined with High-Resolution Encoder

Precision Z Stages

Page 212

For manual positioning stages, see www.pi.ws and www.pimicos.com

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193

Miniature Stages with Piezomotors
and Direct Position Measurement
Piezomotors Replace Electric Motor-Spindle Drives in Miniature Positioning Stages

LPS-45Highlights■ Linear encoder with resolution down to a few nanometers■ Very compact XY combinations■ Vacuum versions up to 10-9 hPa available■ Nonmagnetic designs available on request

Applications
Piezoelectric linear motors allow production of stages with smallest dimensions. The direct drive avoids mechanicalcomponents such as gears and spindles, making for reliable and high-resolution drives down to a few nanometers. Piezomotors are in general vacuum-compatible and do not generate any magnetic interferences. Accordingly, they open up
areas of application in which electric motors cannot be used. In combination with a directly measuring optical encoder,for example stages with PIShift inertia drives allow high-precision and repeatable positioning. Depending on the drive
principle, high velocity, high forces and/or high resolution are achieved.

194

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LPS-24LPS-23

LPS-24

M-663

LPS-45

Smallest closed-loop
positioning system

Best force/installation
space ratio

High-speed linear
motor of up to
250 mm/s

High guiding accuracy

Travel range in mm

13, 2615

19

13, 26

Dimensions in mm

23 to 35 × 23 × 10

33 to 60 × 24 × 20

35 × 35 × 15

48 to 63 × 45 × 15

Design resolution in μm

0.001

0.002

0.1, 0.6

0.001

Min. incremental motion
in μm

0.01

sensor-dependent
0.3 to 0.04

sensor-dependent
0.3 to 3

0.006

Unidirectional
repeatability in μm

0.02

sensor-dependent
0.3 to <0.01

sensor-dependent
0.3 to 0.2

0.018

Angular crosstalk(pitch / yaw) in μrad

±80 to ±110

±100

±300

±50, ±80

Velocity in mm/s

10

10

250

10

Load capacity in N

2

10

5

10

Push / pull force in N

2

5

2

8

Holding force in N

2

7

2

8

PIShift piezo inertia
drive

NEXACT®
piezo stepping drive

PILine® ultrasonicpiezomotor

PIShift piezo inertia
drive

48

55

120

48

E-871 single-axis

E-861 single-axis

C-867 single- or
double-axis

E-871 single-axis

Motor typeOperating voltage
peak-to-peak in V
Recommended controller

M-663

All product details can be found at www.pi.ws and www.pimicos.com

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195

Linear Positioning Stages with Piezomotors
and Direct Position Measurement
Piezo Direct Drive Allows Very Low Profile

LPS-65Highlights■ Direct position measurement with high-resolution optical encoder■ Self-locking when at rest, no heat generation■ Very compact XY combinations■ Vacuum versions available

Applications
Test equipment for industrial production or quality assurance benefits from the low space requirement of the piezomotors. The large dynamic range of PILine® ultrasonic drives makes them suitable for life science applications or research
institutions in biotechnology, where quick switchover from scanning mode to precise positioning is required.

196

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M-664

M-683

M-664K

LPS-65

M-664

M-683

M-664K
CEP

Customized model
Travel range in mm

13, 26, 52

25

50

50

Dimensions in mm

80 to 160 × 65 × 20

90 × 50 × 16

130 × 95 × 21

120 × 40 × 9

Design resolution in μm

0.0005

0.1

0.02

0.5

Min. incremental motion
in μm

0.001

0.6

0.1

3

Unidirectional
repeatability in μm

0.001

0.2

0.1

1

Angular crosstalk(pitch / yaw) in μrad

±40 to ±60±75 / ±50±150 / ±50±150

Velocity in mm/s

10

400

350

100

Load capacity in N

20

25

50

–

Push / pull force in N

10

2.5

6

2

Holding force in N

10

2.5

6

2

NEXACT®
piezo stepping drive

PILine® ultrasonicpiezomotor

PILine® ultrasonicpiezomotor

PILine® ultrasonicpiezomotor

55

200

200

200

E-861 single-axis

C-867 single- or
double-axis

C-867 single- or
double-axis

C-867 OEM version,
networkable

Motor typeOperating voltage
peak-to-peak in V
Recommended controller

All product details can be found at www.pi.ws and www.pimicos.com

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197

Small Precision Micropositioning Stages
Equipped with Electric Motors
Travel Ranges of up to 52 mm (2"), Loads of up to 50 N

M-110

Highlights■ For loads of up to 5 kg
■ Very compact XY and XYZ combinations■ Travel ranges of up to 52 mm (2")

Applications
Compact drive solutions are indispensable for automated sequences in many areas ranging from micro-processing in precision mechanical engineering to photonics production. These small positioning stage series are highly suitable both for test
systems and for use in the production process. Different motorizations, positioning accuracy and travel ranges offer a wide
range of possible fields of application.

198

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M-122

LS-40

LS-40

M-110
M-111
M-112

M-122

Travel range in mm

13, 26, 52

5 to 25

25

Dimensions in mm

62.5 to 101.5 × 40 × 20
plus motor 77 × 40 × 26

60 to 80 × 62 × 20.5

86 × 60 × 20.5

Design resolution in μm

to 0.01

to 0.007

0.1

Min. incremental motion
in μm

0.1

0.05 to 0.2

0.2

Unidirectional
repeatability in μm

0.1

0.1 to 0.5

0.15

Angular crosstalk(pitch / yaw) in μrad±150 to ±190

±50 to ±150

±150

5

1 to 220

0.5, 1

0.4, 0.5

0.5

Load capacity in N

30

20 to 30

50

Push / pull force in N

20

10

20

DC gear motor / 2-phase
stepper motor with andwithout gearhead

DC gear motor / 2-phase
stepper motor

DC motor

SMC controller

C-863 single-axis
C-663 single-axis

C-863 single-axis

Velocity in mm/s
Drive screw pitch in mm

Motor type

Recommended controller

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws and www.pimicos.com

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199

Compact Precision Linear Positioning
Stages Equipped with Electric Motor
Travel Ranges of up to 100 mm, Loads of up to 300 N

MTS-65Highlights■ Large selection of models with different drive screws■ Compact XY combinations■ Large number of motor variants

Applications
These compact linear positioning stages offer travel ranges of up to 100 mm (4“) and can be used over a wide range.
Typically they are required for inspection systems with little available space. Their tasks range from micromanipulation, for example of optical components, to high-precision positioning of loads of up to 30 kg in testing and inspection
systems.

200

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M-126

LS-65

M-605

MTS-65

M-126

LS-65

M-605

Travel range in mm

13 to 52

20 to 25

26 to 10225, 50Dimensions in mm

38.5 to 62 × 65 × 31

101.5 x 83 x 26
plus motor 115 × 40 × 34

93 to 171 x 65 × 30
plus motor 90 × 40 × 40

194 × 113 × 33.5

Design resolution in μm

to 0.05

to 0.0035

to 0.50.1

Min. incremental motion
in μm

to 0.05

0.1 to 1

0.2 to 0.5

0.3

Unidirectional
repeatability in μm

0.1

0.1 to 0.2

0.3 to 0.5

0.1

Angular crosstalk(pitch / yaw) in μrad

±40 to ±80±50±70 to ±130±30Velocity in mm/s

80.7 to 50

13 to 20

50

Drive screw pitch in mm

1

0.5 to 1

1

1

Load capacity in N

10

200

60

300

Push / pull force in N

3

40/40 to 50/50

25

202-phase stepper motor

DC gear motor, DC
motor with integrated
ActiveDrive amplifiers

DC gear motor, 2-phase
stepper motor

DC motor withintegrated ActiveDrive
amplifiers

SMC controller

C-863 single-axis
C-663 single-axis

SMC controller

C-863 single-axis

Motor type

Recommended controller

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws and www.pimicos.com

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201

Linear Positioning Stages for Travel Rangesof up to 600 mm and Loads of up to 200 N
Large Range of Motorization Variants

M-404

Highlights■ Preloaded precision leadscrews or ball screws for high velocity and large number of cycles■ Variable travel ranges from 25 to 600 mm■ XY and XYZ combinations■ For cost-efficient system solutions■ Vacuum versions available

Applications
Possible applications range from process automation to industrial testing systems and quality assurance tasks. Thesestage series reliably position medium loads from 50 to 200 N. The large number of variants can be selected to perfectly
suit the particular situation.

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M-413

VT-80

VT-75

M-403
M-404

M-413
M-414

VT-80

VT-75

Travel range in mm

25 to 200

100 to 300

25 to 300

50 to 600

Dimensions in mm

141 to 316 x 80 x 40.5

255 to 455 × 120 × 57

100 to 375 × 80 × 25
plus motor 70 × 40 × 40

181 to 781 × 75 × 30
plus motor 110 × 43 × 70

Design resolution in μm

to 0.012

to 0.018

to 0.5

to 2

Min. incremental motion
in μm

0.1 to 0.25

0.1 to 0.5

0.2 to 0.5

0.4 to 2

Unidirectional
repeatability in μm

0.5 to 1

0.5 to 1

0.4 to 0.8

0.4 to 2

Angular crosstalk(pitch / yaw) in μrad

±75 to ± 200
per 100 mm±100 to ± 300
per 100 mm±100 to ±210

±40 to ±110Max. velocity
in mm/s

50

100

20

150

Drive screw pitch in mm

1, 2

1, 2

1

4

Load capacity in N

200

500

50

50

50, 100

50, 20030

18 to 88

DC gear motor, DC
motor with integrated
ActiveDrive amplifiers,2-phase stepper motor

DC gear motor, DC
motor with integrated
ActiveDrive amplifiers,2-phase stepper motor

DC gear motor,
2-phase stepper motor

DC motor, 2-phase
stepper motor

C-863 single-axis
C-663 single-axis

C-863 single-axis
C-663 single-axis

SMC controller

SMC controller

Push / pull force in N

Motor type

Recommended controller

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws and www.pimicos.com

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203

Linear Positioning Stages for Travel Rangesof up to 500 mm
Precision Micropositioning Stages for Loads of up to 1000 N

LS-110Highlights■ Covered mechanics as dust and dirt protection■ Combinations of different motorizations and variable travel ranges■ High stiffness and mechanical stability

Applications
Industrial applications in the production process such as laser processing benefit from the precise positioning of these
positioning stages. Their low profile makes the variable stage series suitable for universal use, ranging from testing
systems to production lines in precision automation.

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M-410

M-505

M-405
M-410
M-415

LS-180M-505

LS-110LS-180Dimensions in mm

207 to 307 × 106.5 × 40
plus motor 125 × 60 × 36

245 to 370 × 108 × 43

225 to 480 × 110 × 45

470 to 920 × 180 × 55

Travel range in mm

50 to 150

25 to 150

26 to 305

155 to 508

Design resolution in μm

to 0.0035

to 0.017

to 0.05 withlinear encoder

to 0.05 withlinear encoder

Min. incremental motion
in μm

0.1 to 0.25

0.05 to 0.25

0.05 to 1

0.05 to 0.5

Unidirectional
repeatability in μm

0.2

0.1 to 0.25

0.05 to 1

0.05 to 0.5

Angular crosstalk(pitch / yaw) in μrad

±25 to ±75±25±30 to ±100

±40 to ±100

0.7 to 15

3 to 50

45 to 90

75 to 200

Drive screw pitch in mm

0.5

1

2

5

Load capacity in N

200

1000

100

1000

40 to 50

50

80

200

DC gear motor, DC
motor with integrated
ActiveDrive ampliﬁers,
2-phase stepper motor

DC gear motor, DC
motor with integrated
ActiveDrive amplifiers,2-phase stepper motor

DC motor, 2-phase
stepper motor

DC motor, 2-phase
stepper motor

C-863 single-axis
C-663 single-axis

C-863 single-axis
C-663 single-axis

SMC controller

SMC controller

Velocity in mm/s

Push / pull force in N

Motor type

Recommended controller

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws and www.pimicos.com

PIEZO

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205

Linear Positioning Stages for Travel Rangesof up to 1 m
High-Precision Positioning with Step Sizes of down to a few 10 nm

M-511

Highlights■ Reference-class positioning■ Excellent long-term stability through high-stiffness basic profiles■ High-precision components such as crossed roller guides and zero-backlash ball screws■ XY combinations; matching Z stages available■ Optionally direct position measurement with linear encoder

Applications
The areas of application of these stage series are among the most demanding in precision positioning. They include
inspection of wafers in semiconductor technology, alignment and integration of testing devices in photonics production
or even measuring and inspection tasks in quality assurance.

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HPS-170

PLS-85

HPS-170

M-511
M-521
M-531

LS-270Travel range in mm

26 to 155

52 to 305

102 to 306

155 to 1016

Dimensions in mm

119.5 to 257.5 × 85 × 35
plus motor 100 × 43 × 70

261 to 556 × 170 × 50
plus motor 100 × 75 × 50

400 to 600 × 140 × 55

550 to 1 400 × 270 × 100

Design resolution in μm

0.05

to 0.05

to 0.02

to 0.05

Min. incremental motion
in μm

0.05 to 1

0.05 to 0.2

0.1 to 0.5

0.05 to 0.5

Unidirectional
repeatability in μm

0.05 to 1

0.05 to 0.2±0.1 to ±0.5

0.05 to 0.5

Angular crosstalk(pitch / yaw) in μrad

±60 to ±150

±20 to ±40±25 to ±50±20 to ±120

20 to 90

35 to 90

6 to 125

50 to 150

Drive screw pitch in mm

1, 2

2

2

5

Load capacity in N

100

350

1 000

1 500

Push / pull force in N

50

up to 150

80/80

up to 260

DC motor, 2-phase
stepper motor

DC motor, 2-phase stepper motor

Brushless DC motor(BLDC), DC gear motor,
DC ActiveDrive, 2-phase
stepper motor

DC motor, 2-phase
stepper motor

SMC controller

SMC controller

C-863 single-axis
C-663 single-axis

SMC controller

Velocity in mm/s

Motor type

Recommended controller

LS-270

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws and www.pimicos.com

PIEZO

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207

Nanometer Precision over Long Travel Ranges
Fast Scans at Constant Velocity

N-664

Highlights■ Nanometer step sizes■ Direct position measurement■ Control within a few milliseconds

Applications
In surface inspection, e.g. for white light interferometry, uniform feed at constant velocity and nanometer-precision
positioning are essential. Fast scans also benefit from this.

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M-511.HD

M-511.HD

M-714

UPM-160

M-714

N-664

UPM-160

Travel range in mm

100

7

30

55 to 205

Dimensions in mm

400 × 140 × 51.5

140 × 120 × 55

120 × 65 × 20

210 to 360 × 160 × 55
plus motor 120 × 60 × 55

Design resolution in nm

2

2

0.5

to 0.001

Min. incremental motion
in μm

0.004

0.004

0.002

0.035 to 0.05

Unidirectional
repeatability in μm

0.01

0.01

0.00050.035 to 0.05

Angular crosstalk(pitch / yaw) in μrad

±25

±10

±20

±15 to ±30

Velocity in mm/s

50

0.2

10

18 to 100

Drive screw pitch in mm

2

1

no spindle

2.5, 5

Load capacity in N

200

–

20

350

Push / pull force in N

80/80

100/100

10

Hybrid: DC motor with
piezo direct drive

Hybrid: DC gear motorwith piezo direct drive

NEXACT piezo
stepping drive

DC motor, 2-phase
stepper motor

C-702 double-axis

C-702 double-axis

E-861 single-axis

SMC controller

Motor type
Recommended controller

100®

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws and www.pimicos.com

PIEZO

NANO

POSITIONING

209

High-Speed Stages of Excellent Precision
Electromagnetic Linear Motor Combined with High-Resolution Encoder

UPS-150

Highlights■ Direct drive without any additional mechanical components, thus fewer wear parts■ High velocities of several 100 mm/s
■ Precision depends only on encoder and guides■ Combinable with highly dynamic direct-drive rotation stages■ Limit switches to protect the mechanical system

Applications
Especially industrial applications use the reliability and excellent precision of these direct-drive stages. Their highdynamics ensures high throughputs of automated tasks in the area of testing systems for example in the semiconductor
industry. They also increase efficiency, for example in electronics production lines or laser processing.

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LMS-60

LMS-180

LMS-60

UPS-150

LMS-180V-106

15-nm linear encoder
integrated

1-nm or 15-nm linear
encoder integrated

15-nm linear encoder
integrated

Voice-coil drive forhigh-speed scanningand positioning

Travel range in mm

25, 6552 to 305

155 to 508

6, 20

Dimensions in mm

145 to 185 × 60 × 14

198 to 454 × 150 × 55

470 to 820 × 180 × 55

120 × 120 × 44

Design resolution in μm

0.015

0.001 to 0.015

0.015

0.1

Min. incremental motion
in μm

0.1

0.015 to 0.02

0.04

0.2

Unidirectional
repeatability in μm

0.10.015 to 0.025

0.05

0.2

Angular crosstalk(pitch / yaw) in μrad

±80 to ±100

±15 to ±40±40 to ±80±25Velocity in mm/s

500

600

500

270

Load capacity in N

30

150

450

36, 817 (typ.), 31 (max.)

22 (typ.), 88 (max.)

50 (typ.), 170 (max.)

5, 3.3

SMC controller

SMC controller

SMC controller

C-863 single-axis

Push / pull force in N
Recommended controller

V-106

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws and www.pimicos.com

PIEZO

NANO

POSITIONING211

Precision Z Stages
High-Accuracy Positioning of High Loads

UPL-120

Highlights■ For high loads■ Travel ranges of up to 13 mm■ With integrated limit switches

Applications
Lithographic methods, wafer inspection or photonics have very high requirements in terms of the precision of positioning
systems. These Z stages are designed especially for loads of up to 300 N, so that they can also carry additional axes, if
necessary.

212

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NPE-200

UPL-120

M-451

NPE-200

M-451

Excellent straightness /ﬂatness

Compatible with piezo
positioning stages

Dimensions in mm

170 × 110 × 55

238 × 200 × 85

154 × 150 × 95 plus
motor 110 × 60 × 40

Travel range in mm

13

13

12.5

Design resolution in μm

to 0.013

0.001

to 0.0028

Min. incremental motion
in μm

0.1 to 0.5

0.005

0.2

Unidirectional
repeatability in μm

0.05 to 0.5

0.04

0.3

Angular crosstalk(pitch / yaw) in μrad

±100

±20

±75

6

0.2

0.8 to 3

0.268

2

0.5

up to 200

300

120

DC motor, 2-phase
stepper motor

DC motor, gearhead

DC gear motor, DC
ActiveDrive, 2-phase
stepper motor

SMC controller

SMC controller

C-863 single-axis
C-663 single-axis

Velocity in mm/s
Drive screw pitch in mm
Load capacity in N

Motor type

Recommended controller

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws and www.pimicos.com

PIEZO

NANO

POSITIONING213

Precision Z Stages
Combination with Linear and Rotation Stages

M-501

Highlights■ Different load classes■ Travel ranges of up to 25 mm■ With integrated limit switches

Applications
For motions in Z, elevation stages are available, which can be combined with linear positioning stages or rotation stages
as compactly as possible. As an alternative to Z stages, linear positioning stages can be used for Z motions by means ofadapter brackets, thus allowing also longer travel ranges to be achieved.

214

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ES-82

ES-100ES-82

ES-100M-501

For combination with
PLS-85, LS-65 andMTS-65For combination with
LS-110 and PRS-110

For direct mounting on
M-511, M-521, M-531

Dimensions in mm

92 × 82 × 45

140 × 100 × 90 to 105

130 × 130 × 95

Travel range in mm

13

13 and 26

12.5

Design resolution in μm

up to 0.05

up to 0.05

up to 0.005

Min. incremental motion
in μm

0.1 to 0.3

0.05 to 0.5<0.1

Unidirectional
repeatability in μm

0.1 to 0.3

0.05 to 0.5

0.1

Angular crosstalk(pitch / yaw) in μrad±75±100 to ±150

±150.08 to 0.1

15 to 20

1 to 3

Drive screw pitch in mm

7

1

1

Load capacity in N

20

up to 55

50, 100

DC motor, 2-phase
stepper motor

DC motor, 2-phase
stepper motor

DC gear motor,
DC ActiveDrive

SMC controller

SMC controller

C-863 single-axis

Velocity in mm/s

Motor type
Recommended controller

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws and www.pimicos.com

PIEZO

NANO

POSITIONING215

Precision XY Stages
For Microscopy and Inspection Tasks

Endothelial cells as seen under the microscope (Source: Lemke Group, EMBL Heidelberg)

216

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Microscopy Stages

Page 218

XY Stages with Clear Aperture

Precision XY Stages

Page 220

Scanners for Inspection and Microscopy Tasks

Z Piezo Scanners for Microscopy

Page 44

Fast and Precise Positioning of Objective and Sample

217

PIEZO

NANO

POSITIONING

Microscopy Stages
XY Stages with Clear Aperture

M-687

Highlights■ Fit on common microscopes from known manufacturers such as Nikon, Zeiss, Leica and Olympus■ Stable positioning■ Low profile for easy integration■ Compact and flat design allows free access to sample■ High constant velocity even at velocities around 10 μm/s
■ Suitable piezo scanning stages for XYZ and Z sample positioning available

Applications
For superresolution microscopy, tiling, automated scanning microscopy

218

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M-545

M-686

M-545

M-686

M-687

Manual drive via
micrometer screws,
optional motorization

Dynamic through directdrive equipped withultrasonic piezomotor

Dynamic through directdrive equipped withultrasonic piezomotor

Suitablepiezo scanning stages

P-545 PInano®

P-563 PIMars, P-541

P-736 PInano®

Clear aperture in mm

140 × 100for object slides andPetri dishes

78 × 78

160 × 100for multititer plates

Dimensions in mm

230 × 240 × 30

170 × 170 × 32

400 × 297 × 48
(for Nikon Eclipse Ti)
400 × 237 × 36
(for Olympus IX2)

Travel range in mm

25 × 25

25 × 25

135 × 85(for Nikon Eclipse Ti)
100 × 75
(for Olympus IX2)

Design resolution in μm

0.046 (motorized)

0.1

0.1

Min. incremental motion
in μm

1 (motorized)

0.3

0.3

2

0.3

0.3

Max. velocity in mm/s

1.5

100

120

Load capacity in N

50

50

50

motorized system
including controller andjoystickC-867 PILine® motion
controller double-axis

system including
controller and joystick

Unidirectional
repeatability in μm

Recommended controller

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

219

Precision XY Stages
Scanners for Inspection and Microscopy Tasks

MCS

Highlights■ Stable platforms equipped with electric motors■ With clear aperture suitable for transmitted light and incident light microscopy■ Optionally with linear encoder■ Minimum flatness error

Applications
The guiding and position accuracy of these microscopy XY stages is required in particular in industrial metrology. Its
areas of applications include industrial surface measurement technologies such as topology measurements on workpieces and optics or structural measurements on semiconductor wafers. Their high loads allow further axes, e.g. thoseof rotary stages, Z modules and tilt stages to be mounted on the platform.

220

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CS-430

MCS

M-880

CS-430M-880

380 × 380 × 80

430 × 430 × 100

600 × 600 × 105

150 × 150

–

Ø 160

102 × 102
205 × 205 / 305 × 305
on request

350 × 300

20 × 20
θZ: 8°

Design resolution in μm

0.005 to 0.2

to 0.05–

Min. incremental motion
in μm

to 0.005

0.1 to 0.5–

0.2

0.1 to 0.5

0.5

Crosstalk in μrad

±40 / ±20±80–Max. velocity
in mm/s

35 to 300

100

20

200

300

1500 (holding force)

80 to 200

110

200

2-phase stepper motor,
DC motor, linear motor

2-phase stepper motor

DC-motor ActiveDrive

SMC controller

SMC controller

system including
controller

Dimensions in mm
Clear aperture in mm

Travel range in mm

Unidirectional
repeatability in μm

Load capacity in N
Push / pull force in N
Motor type

Recommended controller

All product details can be found at www.pi.ws and www.pimicos.com

PIEZO

NANO

POSITIONING221

Precision Rotary Stages

Two rotation stages are connected via a bracket and form a2-circle goniometer: a Cardanic joint with a common pivot point222

M O T O R I Z E D P O S I T I O N I N G S Y S T E M S | W W W. P I . W SSmall Rotation Stages Equipped with Piezomotors

Page 224

Dynamic Direct Drive

Small Rotation Stages Equipped with Electric Motors

Page 226

For Compact Stacked Multi-Axis Positioning Systems

Precision Rotation Stages

Page 228

Ultraprecise Rotation Stages

Page 230

Reference-Class Rotation Stages for the Most Demanding Requirements

Goniometers and Tip/Tilt Stages

Page 232

1- or 2-Axis Motion

223

PIEZO

NANO

POSITIONING

Small Rotation Stages Equippedwith Piezomotors
Dynamic Direct Drive

M-660

Highlights■ Excellent start/stop dynamics■ Compact combinations with linear positioning stages possible■ Direct metrology: Integrated optical encoders for direct position measurement■ Self-locking when at rest, no heat generation, no servo jitter■ Excellent guiding accuracy■ Vacuum versions available

Applications
These miniature stages can be used in a wide range of applications, for example in materials testing or for equipment
of beamlines on accelerator rings. Their piezo drive is in general vacuum-compatible and nonmagnetic, while the stages
themselves are very compact.

224

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U-624

M-660

U-628

U-624

U-628

Preliminary data

Preliminary data

Dimensions in mm

116 × 116 × 14

30 × 30 × 12

50 × 50 × 16

Rotation range in °no limit

no limit

no limit

Design resolution in
μrad (°)

4 / 34 (0.0002 / 0.002)

10 (0.0006)

3 (0.0002)

Min. incremental motion
in μrad (°)

12 / 34 (0.0007 / 0.002)

70 (0.004)

10 (0.0006)

Max. velocity in °/s

720

> 360

> 720

Load capacity (axial
force) in N

20

2

20

Torque in Nm

0.3

0.02

0.05

Drive

ultrasonic piezomotor

ultrasonic piezomotor

ultrasonic piezomotor

Recommended controller

C-867 PILine® motion
controller

C-867 PILine® motion
controller

C-867 PILine® motion
controller

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING225

Small Rotation Stages Equippedwith Electric Motors
For Compact Stacked Multi-Axis Positioning Systems

RS-40

Highlights■ Unlimited rotation range with contactless reference point switch■ Precision stages for minimized backlash

Applications
Many applications in microscopy require free light passage. These compact rotation stages can also be used in optics
applications, where they position, for example, filters, reliably and with excellent repeatability.

226

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DT-34

M-116

DT-34

M-116

RS-40

DT-65 N

Preloadedbelt drive

Backlash-compensatedworm drive

Backlash-compensatedworm drive

Backlash-compensatedworm drive, preloaded
double-row ball bearings for minimal tilt

10

19

20

25

Dimensions in mm

34 × 58 × 18.5

66 × 70 × 23.5

56 × 64 × 20

70 × 92.5 × 25

Design resolution in
μrad (°)

to 0.7 (0.00004)

2.5 (0.00015)

to 0.5 (0.00003)

to 17 (0.001)

700 (0.04)

10 to 12(0.0006 to 0.0007)

90 (0.005)

35 (0.002)

Max. velocity in °/s

675

20

7

60

Load capacity in N

15

15

20

30

up to 0.9

up to 1.5

0.2

0.8

2-phase gear stepper
motor, DC gear motor

DC gear motor, 2-phase
stepper motor

2-phase gear stepper
motor, DC gear motor

2-phase stepper motor,
DC motor

SMC controller

C-863 single-axis
C-663 single-axis

SMC controller

SMC controller

Drive details

Clear aperture Ø in mm

Unidirectional
repeatability in μrad (°)

Torque in Nm
Motor type

Recommended controller

DT-65 N

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws and www.pimicos.com

PIEZO

NANO

POSITIONING227

Precision Rotation Stages

PRS-110Highlights■ Backlash-compensated worm drive■ Unlimited rotation range with contactless reference point switch

Applications
These high-precision rotation stages are used in many areas of application in industry and research. Test equipment
in materials testing or optical metrology in photonics production benefits from the excellent travel accuracy and theuniform feed.

228

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M-062

DT-80 R

M-060
M-061
M-062

DT-80
DT-80 R

PRS-110

PRS-200

Available withmanual drive

Belt transmission version for high velocity>3 revolutions/second

Preloaded and calibrated bearings forminimal tilt

Preloaded ball bearings
for minimal tilt

Clear aperture Ø in mm

20 to 45

40

35

120

Rotary plate Ø in mm

60 to 120

64

85

190

Dimensions in mm

90 × 70 × 29 to
150 × 130 × 38
plus motor

83 × 86 × 30
plus motor

125 × 110 × 55
plus motor

225 × 200 × 75
plus motor

Design resolution in
μrad (°)

to 0.96 (0.00006)

to 17 (0.001)

to 1.7 (0.0001)

to 1.3 (0.00008)

Min. incremental motion
in μrad (°)

to 5 (0.0003)

to 17 (0.001)

to 1.7 (0.0001)

to 1.3 (0.00008)

Unidirectional
repeatability in μrad (°)

to 50 (0.003)

170 (0.01)

to 3.5 (0.0002)

to 5.2 (0.0003)

Max. velocity in °/s

9040
high-speed version:
1170

200

150

Load capacity in N

500 to 650

20

100

500

4 to 80.1

3

4

DC motor, ActiveDrive,
DC gear motor, 2-phase
stepper motor

2-phase stepper motor,
DC motor

2-phase stepper motor,
DC motor

2-phase stepper motor,
DC motor

C-863 single-axis
C-663 single-axis

SMC controller

SMC controller

SMC controller

Special features

Torque in Nm

Motor type

Recommended controller

PRS-200

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws and www.pimicos.com

PIEZO

NANO

POSITIONING

229

Ultraprecise Rotation Stages
Reference-Class Rotation Stages for the Most Demanding Requirements

UPR-120

Highlights■ Optionally, all series are available with air bearings for motion without wobble and zero-backlash causedby friction effects■ Brushless torque motors for particularly smooth synchronous running even at low velocities■ Unlimited rotation range with contactless reference point switch■ Direct position measurement

Applications
These reference-class rotation stages are aimed at applications that require simultaneously high dynamics and highpositioning precision. Research areas such as beam lines or semiconductor technology with their high accuracy andthroughput requirements are the target markets.

230

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UPR-100

UPR-160

UPR-270

UPR-100

UPR-120

UPR-160

UPR-270<±0.2 μm<±0.1 μm<±0.1 μm<±0.1 μm

20

35

35

35

Dimensions in mm

100 × 100 × 50

155 × 129 × 90

178.4 × 165 × 90

281 × 270 × 135

Design resolution in
μrad (°)

0.17 (0.00001)

0.17 (0.00001)

0.17 (0.00001)

0.17 (0.00001)

Min. incremental motion
in μrad (°)

0.35 (0.00002)

0.35 (0.00002)

0.35 (0.00002)

0.17 (0.00001)

Unidirectional
repeatability in μrad (°)

1.4 (0.00008)

1.4 (0.00008)

1.4 (0.00008)

1.2 (0.00007)

Max. velocity in °/s

360

360

360

360

Load capacity in N

15 to 20

200

200

400

Max. torque in Nm

0.25 to 0.5

2

2

10

SMC controller

SMC controller

SMC controller

SMC controller

Out of plane andeccentricity with air
bearing
Clear aperture Ø in mm

Recommended controller

All product details can be found at www.pimicos.com

PIEZO

NANO

POSITIONING

231

Goniometers and Tip/Tilt Stages
1- or 2-Axis Motion

WT-90

Highlights■ Excellently smooth performance and uniform feed at constant angular velocity■ Rotational axis above platform in goniometers or at platform level in tilt stages■ Common pivot point possible for WT-85 on WT-100, WT-90 on WT-120■ Vacuum versions available on request

Applications
Goniometers can replace rotation stages in applications of restricted installation space. This is advantageous, for example, for laser technology and materials research, where optical elements have to be positioned in the beam guidance.
For scanning or tracking applications, the motorized tip/tilt stages can be equipped with a high-resolution piezo drive.
For particularly high dynamics piezo tip/tilt mirror systems are available, depending on the application.

232

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WT-85

WT-100

WT-120

M-044

WT-85

WT-100

WT-90
WT-120M-041 toM-044

Goniometer with clear
aperture Ø 30 mm

Goniometer with clear
aperture 60 × 25 mm²Goniometer for highloads with wide adjustment range

Tilt stage with 1 or 2
axes and large platform

optionally direct
position measurement

optionally direct
position measurement

optionally direct
position measurement

drive zero-backlashmagnetically coupled

10

10

90

14 to 18

Dimensions in mm

85 × 130.5 × 44
plus motor

132 × 158 × 37
plus motor

115 × 125 × 61 (WT-90)
150 × 235 × 106 (WT-120)
plus motor

60 × 60 × 27 to
100 × 100 × 47
plus motor

Design resolution in
μrad (°)

to 1.7 (0.0001)

to 1.6 (0.00009)

to 1.6 (0.00009)

to 0.23

Min. incremental motion
in μrad (°)

to 87 (0.005)

to 87 (0.005)

to 17 (0.001)

to 65 (0.004)
manually
15 (0.001) motorized

Unidirectional
repeatability in μrad (°)

to 87 (0.005)

to 87 (0.005)

to 17 (0.001)

to 15 (0.001)

Max. velocity in °/s

7 to 15

7 to 15

15 to 30

up to 4.5

Load capacity in N

20

2080, 200

4 to 50.75

0.75

2.5, 8up to 0.75

Special features
Rotation / tilt range in °Torque in Nm

Drive

Recommended controller2-phase stepper motor,
DC motor

2-phase stepper motor,
DC motor

2-phase stepper motor,
DC motor

DC motor, optionallysupplemented by piezo
drive.
For manual stages,
see www.pi.ws

SMC controller

SMC controller

SMC controller

C-863 single-axis

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws and www.pimicos.com

PIEZO

NANO

POSITIONING

233

Motorized Precision Linear Actuators

The E-ELT, the "largest eye" for looking into space, has a primary mirror of approx. 39 m in diameter consisting of nearly eight hundred hexagonal
mirror elements. Each mirror element is positioned by three linear actuators using high-precision drive technology. (Figure: European Southern
Observatory, ESO)234

M O T O R I Z E D P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

Precision Actuators

Page 236

Cost-Efficient Linear Actuators

Page 238

High-Load Actuators

Page 240

Compact Linear Actuators

Page 242

For Alignment of Optomechanical Components

235

PIEZO

NANO

POSITIONING

Precision Actuators

M-230

Highlights■ High-resolution drives combined with precision components■ Backlash-compensated design with nonrotating end piece■ Vacuum versions available

Applications
These positioners offer compact solutions for restricted installation space, for example in testing and inspection systems
in industry and research. Their nonrotating end piece with uniform motion prevents wobble, torque, and wear at the pointof contact. Especially the actuators with piezomotor are ideal for use as micro- and nano-manipulators, for example inbio- and nanotechnology.

236

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M-230MP-20

MP-20B

N-381

M-230

MP-20

MP-20B

N-381

High resolution

Flexible travel range

Highly compact
through folded drive

Nanometer precision
with piezomotor,
optionally nonmagnetic

Dimensions in mm

Ø 19 × 175 to 205

Ø 20 × 124.5 to 196.5

30 x 47.9 × 100 to 143

Ø 25 × 121.5

Travel range in mm

10 to 25

13 to 76

13 to 76

30

Axial force in N

up to 70

up to 125

up to 11010Permissible lateral force
in N

up to 301

1

10Max. velocity
in mm/s

1.2 to 2

0.8 to 12

0.6 to 10

10

Design resolution in nm

4.6 to 37

22

22

20, 0.03 open-loop

Min. incremental motion
in μm

0.05

0.1

0.1

0.02

2

2

2

0.2

0.1

0.3

0.3

0.1

Encoder typerotary encoder

rotary encoder

rotary encoder

linear encoder

Motor typeDC gear motor,
2-phase stepper
motor

2-phase stepper motor,
DC gear motor

2-phase stepper
motor, DC gear motor

NEXACT® piezo stepping drive

C-863 single-axis
C-884 up to 4 axes
C-663 single-axis

SMC controller

SMC controller

E-861 single-axis

Backlash in μm
Unidirectional
repeatability in μm

Recommended controller

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws and www.pimicos.com

PIEZO

NANO

POSITIONING

237

Cost-Efﬁcient Linear Actuators

M-229

Highlights■ Stepper motors with and without gearhead, DC servo motor or closed-loop piezomotor■ Nonrotating end piece for uniform linear motion prevents wobble, torque, and wear at the point of contact

Applications
Cost-sensitive applications benefit from the low system cost of the linear axes. They are also highly suitable for OEM
applications in several axes. As an alternative to motor-spindle combinations or electromagnetic linear motors, theceramic direct drive offers self-locking when at rest without generation of heat.

238

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M-228

M-227

M-272

M-228.11 M-228.10
M-229.26 M-229.25

M-227

M-272

Handwheel,
integrated positionindicator

Slim design, integrated
position indicator

High precisions,
optionally with piezo
drive

Minimizes backlash
through linear directdrive

39 × 39 × 100 to 120

Ø 21 × 100
Ø 30 × 135

Ø 19 × 125 to 187

26 × 40 × 130

50, 8020, 5040

8

up to 0.5

up to 0.5

0.1

10

10, 2510, 2510, 50

50

5

1.5

0.75

150

Design resolution in μm

0.078

0.046

0.0035

0.6
with direct metrology

Min. incremental motion
in μm

1

1

0.05

1.8

Backlash in μm

10

5 to 102

1

Unidirectional
repeatability in μm

2

2

0.1

2

Encoder type––rotary encoder

linear encoder

Motor type2-phase stepper
motor

2-phase stepper motorwith gearhead

DC gear motor,
stepper motor variant
M-168 online

U-164 PILine®
ultrasonic piezomotor

Recommended
controller

C-663 single-axis

C-663 single-axis

C-863 single-axis
C-884 up to 4 axes

C-867.OE

Dimensions in mm
Axial force in N
Permissible lateral force
in N
Travel range in mm
Max. velocity in mm/s

M-229

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

239

High-Load Actuators

MA-35

Highlights■ Lateral guiding of the pusher for lateral forces of up to 100 N■ Powerful drives equipped with precision components■ Backlash-compensated design■ Nonrotating end piece with uniform motion prevents wobble, torque, and wear at the point of contact

Applications
High load capacity combined with high dynamics is the distinguishing feature of these actuators. Loads of 100, 200 oreven 500 N are positioned with high precision, reliability and repeatability. PI offers the right solution both for testing andinspection systems and for use in production lines in precision mechanical engineering.

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M-235

M-238

M-235

MA-35

MA-35

M-238

Ø 27 × 166 to 196

Ø 40 × 249

Ø 40 × 275 to 300

Ø 42 × 247.2

up to 120500

up to 300

400

8

10

10

100

Travel range in mm

20 to 50

52

52

50

Max. velocity in mm/s

2.6 to 30

up to 5up to 90

30

Design resolution in μm

0.016 to 0.5

to 0.01

0.5

0.13 to 0.1

Min. incremental motion
in μm

0.1 to 0.5

to 0.1

to 0.1

0.5 to 0.3

1

2

2

3/1

0.1 to 0.5

0.2

to 0,2

1 to 0.3

DC gear motor, DC
motor, 2-phase stepper motor

DC gear motor

DC motor, 2-phase
stepper motor

DC motor, ActiveDrive

C-863 single-axis
C-884 up to 4 axes
C-663 single-axis

SMC controller

SMC controller

C-863 single-axis
C-884 up to 4 axes

Dimensions in mm
Axial force in N
Permissible lateral force
in N

Backlash in μm
Unidirectional
repeatability in μm

Motor type

Recommended
controller

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws and www.pimicos.com

PIEZO

NANO

POSITIONING

241

Compact Linear Actuators
For Alignment of Optomechanical Components

N-470 PiezoMike

Highlights■ Precision-class linear drives■ High-quality components■ Motorization of manual positioning stages

Applications
The compact micro pushers are ideally suitable for stable positioning of optical components. Classical motorized linear
axes fit directly on manual positioning stages and mirror stages. PIShift drives are suitable in particular for drift-freelong-term positioning.

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MP-15

M-231
M
-

MP-15

M-231
231

M
M-232
232

N
N-470
470

Vacuum variants up to
10-6 hPa available

Slim gear motor

Highly compact
through folded drive

PIShift piezomotor ofhigh holding force

Dimensions in mm

Ø 17 × 85 to 108

Ø 19 × 134

20 × 49 × 72

16 × 28 × 48

Travel range in mm

6, 12.7

17

17

7.4

Axial force in N

10

40

40

22 active,
holding force > 100 N

Max. velocity
in mm/s

0.3

1.5

1.5

0.06

Design resolution in μm

to 0.05

0.007

0.007

–

Min. incremental motion
in μm

0.2

0.1

0.1

0.03

Backlash in μm

10

2

2

–

Unidirectional
repeatability in μm

0.5

0.2

0.2

–

DC gear motor, 2-phase
stepper motor

DC gear motor, 2-phase
stepper motor

DC gear motor, 2-phase
stepper motor

PIShift piezo inertia
drive

SMC controller

C-863 single-axis
C-884 up to 4 axes

C-863 single-axis
C-884 up to 4 axes

E-870

Motor type

Recommended controller

M-232

Stepper motor resolution controller-dependent

All product details can be found at www.pi.ws and www.pimicos.com

PIEZO

NANO

POSITIONING243

Motion Controllers

target–control
voltageoffsetdisturbancesignal

DDL
signalControlalgorithm

controlvariableresultingcontrol
voltagecontrol
voltageAmp.

PI – stage
with sensor

Output Matrix

feedback

specialfiltered
sensorsignalaxis
feedback
signaltargetX

Sensorfilterchannel signal area

Input Matrix

axis signal arearaw
sensorsignallinearized
sensorphysicalsignallinearized
sensorsignalMechanics
linearization

Sensorelectronics
linearization

Customized Closed-Loop Control of a Mechanical System Featuring Integrated Active Vibration
Damping
A crucial factor for the precision can be the decoupling of low-frequency ambient vibrations, which excite resonances in themechanical system, thus interfering in high-precision positioning. Piezo actuators use a specifically developed 6D acceleration sensor and a suitable digital controller to suppress the excitations in the range up to approx. 50 Hz. Digital linearization
algorithms for the mechanical and electronic systems and filter functions for the sensor signals further enhance performanceby suppressing multidimensional vibrations with damping factors of more than 20.

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DC Servo Motor Controllers

Page 246

Stepper Motor Controllers

Page 248

Digital Controllers for Piezomotors

Page 250

245

PIEZO

NANO

POSITIONINGDC Servo Motor Controllers

C-884

Highlights■ PID servo control, parameter change on the fly■ User-friendly PIMikroMove user software■ Motion control of PI positioning systems with DC motors: direct motor control, PWM control for PI positioning stages

with integrated ActiveDrive amplifiers or for stages with integrated block commutation (brushless motors). Supports
motor brakes■ Data recorder. Parameter change on the fly. Extensive software support, for example for LabVIEW, dynamic libraries for

Windows or Linux■ Linear vector motion in multi-axis controllers

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C-863

C-843

C-885

C-863

C-884

C-843

C-885

Motion controller for
1 axisMotion controller for
4 axes

PCI motor control cardfor 2 or 4 axes

Modular controller
design, modules
for different drive
technologies

1

4

2, 4

up to 40

Profile Generator

trapezoid
velocity proﬁletrapezoid
velocity profile

trapezoid or S-curve
velocity profile

trapezoid
velocity profile

Interface /Communication

USB, RS-232

TCP/IP, USB, RS-232

PCI-Bus

TCP/IP, USB

I/O ports

analog/digital inputs,
digital outputs

analog/digital inputs,
digital outputs

digital inputs andoutputs

digital inputs andoutputs

Software drivers

LabVIEW drivers,
dynamic libraries for
Windows and LinuxLabVIEW drivers,
dynamic libraries for
Windows and LinuxLabVIEW drivers,
GCS-DLLLabVIEW drivers,
dynamic libraries for
Windows and Linux

Supported functionality

point-to-point motion,
powerful macro programming language,
stand-alone operation

linear vector motion,
point-to-point motion, powerful macro
programming language,
stand-alone operation

trigger programming

point-to-point motion,
powerful macro programming language,
stand-alone operation

Manual control

pushbutton box, joystick

USB interface for HIDcompliant devices

only via PC–

Operating voltage

power supply includedin scope of delivery

power supply includedin scope of delivery

supply via PC

integrated power supply

130 × 76 × 40 mm³

320 × 150 × 80.5 mm³

PCI card

19-inch case

Channels

Dimensions

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING

247

Stepper Motor Controllers

SMC hydra

Highlights■ Sensor signal processing and PID servo control for 2-phase-stepper motor drives■ Data recorder. Parameter change on the fly■ Linear vector motion in multi-axis controllers■ SMC Controllers use a special technology with up to 300 000-fold microstepping. The effect is an extremely highprecision positioning. In combination with a position feedback sensor, a particularly smooth motion and excellent
tracking accuracy.

248

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SMC corvus

SMC pollux

C-663

C-663

SMC
corvusSMC
hydra CM

SMC
polluxAlso available as PCI
card or bench-top

Also available for othermotor types such as
DC motors, linear motors, etc.

Optionally with integrated motor–

70 × 240 × 305

48 × 56 × 150

48 × 56 × 77

130 × 76 × 40

2, 3

2

1

1

>60 000>60 000>60 000

16

RS-232, TCP/IP, GPIB

RS-232, TCP/IP

RS-232

USB, RS-232––

up to 16 units on single
interface

up to 16 units on single
interface

optionally digital inputs
and outputs

optionally digital inputs
and outputs–

analog/digital inputs,
digital outputs

Venus-1 ASCII

Venus-3 ASCII

Venus-2 ASCIIPI General CommandSet (GCS)LabVIEW drivers,
dynamic libraries for
Windows

LabVIEW drivers,
dynamic libraries for
Windows

LabVIEW drivers,
dynamic libraries for
Windows

LabVIEW drivers,
dynamic libraries for
Windows and Linux

position control, linear
vector motion, point-topoint motion

position control, linear
vector motion, point-topoint motion

position control, linear
vector motion, point-topoint motion, start-up
macro

start-up macro

joystick, 3-axis handwheel

joystick, 3-axis handwheel–

joystick, pushbutton box

Current limitation/
motor phase in A

3

3

1.2

1

Operating voltage

90 to 250 V

external power supply

external power supply

power supply includedin scope of delivery

Dimensions in mm
Channels
Microstepping
Interface /Communication
Controller network

I/O ports

Command set

Software drivers

Supported functionality

Manual control

All product details can be found at www.pi.ws and www.pimicos.com

PIEZO

NANO

POSITIONING

249

Digital Controllers for Piezomotors
System Optimization and Ease of Operation: Plug-and-Play

E-871

Highlights■ Extensive software support, e.g. for LabVIEW, shared libraries for Windows and Linux.

Data recorder, e.g. for position values■ Processing of incremental sensors■ Analog I/O, e.g. for connection to joystick, and digital I/O for automation applications■ Integrated drivers, optimized for the corresponding drive type, e.g. with auto-resonant ultrasonic frequencies

or concerted displacement of shear and longitudinal actuators■ Alternative: Driver electronics without integrated control for designing an external servo loop

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E-755

E-861

C-867

E-755

E-861

E-871

C-867

For NEXLINE®
piezo stepping drives

For NEXACT®
piezo stepping drives

For PIShiftpiezo inertia drives

For PILine®
ultrasonic drives

Special featureslinearization with polynomials for perfectlinearity of motion,
deviation approx.
0.001% over the entire
travel range of the
NEXLINE® nanopositioning stage

supports all motion
modes: Point-to-pointmotion, analog modefor nanometer-precise
positioning at target
position. Non-volatile
macro memory

supports all motion
modes: Point-to-pointmotion, analog modefor nanometer-precise
positioning at target
position. Non-volatile
macro memory

supports all motion
modes: Point-to-pointmotion, slow motion
at μm/s, precise stepand-settle. Non-volatile macro memory

Interfaces /Communication

RS-232

USB, RS-232

USB, RS-232

USB, RS-232

Multi-axis control

up to 16 units
via daisy chain.
E-712 modular multiaxis controller fordifferent drive modes
available

up to 16 units
via daisy chain.
E-712 multi-axis
controller

up to 16 units
via daisy chain

up to 16 units via
daisy chain. 2-axis
controller available

Open-loop designs /drive electronics

open-loop designs
available

E-862 OEM drive electronics available

E-870 OEM drive electronics available

OEM version in eurocard format or C-872
OEM driver electronics
available

All product details can be found at www.pi.ws

PIEZO

NANO

POSITIONING251

Basics of Motorized Positioning Systems

Motors and Drives

Page 253

Linear Drives – Piezo Drives – Rotating Electric Motors – Combinations of Piezo Actuator and Electric Motor
Drive Train Elements

Page 257

Gearheads – Types of Drive Screw
Metrology

Page 258

Indirect Metrology – Direct Metrology – Extended Metrology Concepts
Guidings and Bearings

Page 259

Linear Guides – Air Bearings – Flexure Guides
Use in Vacuum

Page 261

Decisive: Material Selection – Preferred Materials – Mounting in Cleanrooms – Important Factors for VacuumStages – Controllers, Amplifiers and Other Electronic Devices – Adapting Stages to Different Classes of Vacuum
SMC Controller Technology

Page 263

Precision Positioning with SMC Controller – Position Control, Velocity and Correction of Position Errors
in the Controller
Glossary

Page 266

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Motors and Drives

Linear Drives
Linear drives basically allow for unlimited travel ranges. They are direct-drive systems; they
do not use drive screws or gearheads and arebacklash-free. The positioning accuracy of theoverall system is only affected by the position
measurement and the guides.

millimeters. To maintain a stable position, thevoice-coil linear drive, just as any other linear drive, has to be operated in closed-loop, or
alternatively combined with brakes.

Electromagnetic Linear Drives
Linear servo motors are used both for very
high and for very low feed velocities. They
work precisely in a range from 0.1 μm/s tomore than 5 m/s. If combined with air bearings, a position resolution down to a few nanometers is possible.
Voice-Coil Linear Drives
These friction-free electromagnetic linear
drives are characterized by their good dynamics, albeit with relatively low holding force.
They are used primarily in scanning applications with travel ranges from several ten

Very compact designs are possible with voice-coil linear drives of the PIMag series

Piezo Drives
Piezo Actuators
Piezo actuators guarantee position resolutionsof less than one nanometer. Several micropositioning stage series can be supplied withadditional piezo drives. As an alternative tothis serial configuration, they are combined tohybrid drives, that use a common control loop
for both motor and piezo actuator.

force and velocity development, PI provides
a series of different piezomotor technologies,
each of which focuses on different features.

Piezo actuators can achieve extremely highaccelerations of many thousand g, are frictionless and backlash-free. Normally, theirtravel ranges are limited to less than one millimeter.

Piezomotor Properties■ Self-locking when powered off with

Piezomotors: PiezoWalk , PILine , PIShift®

®

Piezomotors do not generate magnetic fields
nor are they affected by them. They are used
for nanometer-precision-stages with long
travel ranges.
Piezomotors are optimally suited for using thespecific properties of piezo actuators to achieve
longer travel ranges. Adapted to the required

PIEZO

maximum holding force■ Scalable travel ranges■ Nanometer-precision resolution■ Easy mechanical integration■ Different technologies optimized forhigh velocities or for high forces
253

NANO

POSITIONINGPI Piezomotors Compared to Piezo Actuators
Piezo ﬂexure or stackactuatorsPiezoWalk® piezo stepping
drive

PILine® ultrasonic piezomotor

PIShift piezo inertia drive

Sub-nanometer resolution

Sub-nanometer resolution

Sub-micrometer resolution

Sub-nanometer resolution

Fast response within a few
microseconds

Velocity up to 10 mm/s
High-dynamics scan mode

Very high operating frequency
Noiseless driveHigh velocity of up to several
100 mm/s

Very high operating frequency
Noiseless drive
Velocity of more than 10 mm/s

Travel ranges of up to approx.
300 μm directly and 2 mmwith lever ampliﬁcation

Long travel ranges, only limitedby the runner lengthLong travel ranges, only limitedby the runner lengthLong travel ranges, only limitedby the runner length

High stiffness
Force generation of up to
100 kN

Very high forces of up to 800 N(NEXLINE®)
Self-locking at rest

Forces up to 40 N
Self-locking at rest

Forces up to 10 N
Self-locking at rest

Control via analog voltage
Voltage range 150 V (PICMA®
multilayer actuators),
1 100 V (PICA high-load
actuators)

Multi-actuator drive generates
stepping motion
Voltage range 55 V (NEXACT®),
500 V (NEXLINE®)

Single-actuator drive
Control via high-frequency alternating voltage (sinus)
Voltage range 120 V, 200 V. Minimotors substantially lower

Single-actuator drive
Control via high-frequency
alternating voltage (modiﬁed
sawtooth)
Voltage range <48 V■ Nanometer-precision■ Positioning with sub-μm■ Nanometer-precision position-accuracy■ Fast step-and-settle■ Scan mode with high velocities■ Operation at constant low, velocity

ing stable over a prolonged
period■ Quasi-static applications at low
to medium holding force

Ideal for:■ Nanometer-precise position-

ing with high dynamics■ Lever-amplified and guided
systems■ Piezo scanners■ Fine adjustment■ Force generation■ Active vibration insulation

positioning■ Quasi-static applications at highholding force■ Travel ranges of up to afew mm■ Coarse and fine adjustment■ Force generation■ Active vibration insulation■ Operation at constant, lowvelocity

Rotating Electric Motors
DC Motor / Servo Motor

254

A DC motor with position measurement iscalled servo motor. The typical characteristics
of DC servo motors are uniform, vibrationfree operation, a large velocity range and hightorques at low velocity. To benefit in a best possible way from these properties, a motor controller with proportional, integral and differential control (PID) and suitable filters is required.
The servo motor has numerous advantages,
such as good dynamics, fast addressing, hightorques at low velocities, reduced heat generation and low vibration.

DC servo motors require an operating voltage
of up to 12 VDC. The rotational velocity of the
motor is directly proportional to the voltage;
the sign determines the direction. Repeatable positioning requires an additional position
feedback system.
Brushless DC Motor
PI uses more and more electronically commuted, brushless DC motors. Optimized hollow
shaft or torque motors achieve high torques.
At the same time, the drive train can be shorterfor the same travel range because the drive
shaft is located inside the motor.

M O T O R I Z E D P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

ActiveDrive DC Motors

Stepper Motor Drives

Some of the advantages of DC motor drives
are good dynamic performance with a large
control range, high torque at low revolutions,
low heat dissipation and low vibration with ahigh position resolution. The cost of a highperformance linear amplifier, however, isgenerally higher than that for a stepper motor.

Contrary to DC motors, stepper motor drives
only take up discrete positions in a revolution.
As these steps have a constant distance, aposition may be commanded using the number of steps without any need of a position
sensor. Normally, there are 200 to 1 000 fullsteps in each revolution. The actually achievable step width is determined by the stepper
motor control, which electronically interpolates
up to several hundred thousand microsteps in
between the full steps depending on the version. PI uses smoothly running 2-phase stepper motors.

The ActiveDrive system reduces this cost considerably by integrating a PWM (pulse widthmodulation) driver-amplifier in the motor case.
The operating voltage of normally 24 V for
ActiveDrive motors is supplied by a separate
power supply included in the scope of delivery. The ActiveDrive concept provides several
advantages:■ Increased efficiency by eliminating power

losses between the amplifier and motor■ Reduced cost, more compact system, andimproved reliability, because no external
driver and cabling are required■ Elimination of PWM amplifier noise radia-

tion by mounting the amplifier and motor
together in a single shielded case

Stepper motors have very long lifetimes and,compared to DC motors, are especially suited
for applications with reduced dynamics and ina vacuum. A mechanical damper on the motor
shaft, which also works as handwheel, enhances running smoothness.
To maintain a position, stepper motors without
self-locking gearhead need to be energizedcontinually. This may cause a position jitter
between the steps and generate heat.

Combinations of Piezo Actuator and Electric Motor
In micropositioning, PI offers combinations ofpiezo-driven and motorized or manual stages.
The motorized drive screw provides long travel
ranges, and the additional piezo drive ensuresaccuracy to the nanometer and fast response
behavior. The closed-loop control of suchstacked systems works independently using
separate position sensors, and the piezo starts
to work when the motor stops. The positioning
accuracy (not the design resolution) of such astructure is limited by the motorized system.
Ideally, this combination is completed by an
external control loop.

This 3-axis fiber positioning system combines motorized stages for rough positioning
over 15 mm with a step width of 50 nm with a fast piezo scanner for fine adjustment overa travel range of 100 μm with 1 nm resolution. The intensity of the light in the fiber determines the optimum position and is used as external control variable

PIEZO

NANO

POSITIONING

255

Hybrid Concept with Single Higher-Level PosiMeasurement and Closed-Loop Control
tion Me

Schematic view of the hybrid drive. The common closed-loop control of the motor (blue)
and the piezo actuator (yellow) with a single high-resolution linear encoder (green)allows for extremely constant velocity and high positioning accuracy

hybrid drives, the moving platform is
In hybdecoupled from the motorized drive train bydecoupmeans of a highly stiff piezo actuator as wellbacklash-free and frictionless flexure joints.
as backmode, settling to a few nanomeIn positioning
posit
only takes a few milliseconds, and miniters onin the range of the encoder
mal increments
incresolution can be reliably executed. In dynamic
resolut
operation, the piezo actuators guarantee a very
operaticonstant velocity by compensating the irreguconsta
larities in the motion of the motorized drive.
Stick-slip effects when reaching the position or
backlash can so be compensated for.
The closed-loop control for both motion
systems use the same high-resolution position sensor. The result is a motion systemwith hundreds of millimeters travel but withthe precision of a piezo-based nanopositioner.
The resolution and the positioning accuracy
depend on the choice of the position sensor.
PI hybrid systems currently use optical linear
encoders with a resolution of 2 nm.

Feed over 1 mm with hybrid stage, velocity 100 μm/s. The deviation from thecommanded trajectory is less than 10 nm

Hybrid stages are particularly suited for
applica tions that need high accuracy formeasuring a position and returning to it, orfor surface inspection and metrology if you
want to reach a target position accurately tothe nanometer.

256

M O T O R I Z E D P O S I T I O N I N G S Y S T E M S | W W W. P I . W SDrive Train Elements

Gearhead

Recirculating Ball Screws

Gearheads are used between motor and drive
screw; they improve position resolution andtorque. Most models use preloaded gearheads
to eliminate backlash.

Recirculating ball screws have significantly
less friction than leadscrews because they
replace sliding friction with rolling friction.

Leadscrews
Leadscrews can provide very high resolutionsand very smooth motion. A leadscrew drive
consists of a motor-driven screw with a nut
coupled to the moving platform of the stage.
The nut can be spring-preloaded to reducebacklash. They have higher friction than recirculating ball screws so that they are self-locking;on the other hand, however, this has an effecton velocity, motor power and lifetime. Typical leadscrews have a pitch between 0.4 and
0.5 mm/revolution, up to 1 mm/revolution for
longer travel ranges.

A recirculating ball screw drive consists of a
motor-driven screw with a nut coupled to themoving platform of the stage. Balls in a closed
circuit are located between nut (ball case) anddrive screw. Backlash can be minimized by
selecting the proper ball-to-thread-diameter
ratio. Recirculating ball screws are not selflocking but very efficient and offer high velocities and long lifetime in continuous operation.
PI uses pitches of 0.5, 1 or 2 mm/revolution.

Threaded Spindle Drives
Threaded spindle drives use rolls instead ofballs as rolling bodies so that a higher load
rating, higher velocity and considerably longer
lifetime are achieved.

257

PIEZO

NANO

POSITIONING

Metrology

Either rotary or linear optical encoders areused as position feedback sensors.

Indirect Metrology
Position sensor configuration with indirect
measurement of the platform motion. Mostoften, the sensor is integrated in the drive
train, for example, by means of a rotary encoder on the motor shaft. The advantage is aneasier attachment of the sensor. Backlash andmechanical play, however, affect the measurement result.
Rotary Encoder
A rotary encoder is implemented at a rotating
point in the drive train, e.g. the motor shaft.
To determine the relative position, the controller counts the encoder signals (impulses). To
measure an absolute position, a limit switch
or reference point switch signal must be used
as reference. A typical step width of rotary
encoders is approx. 0.1 μm.

Direct Metrology
Noncontact linear optical encoders measure
the actual position with utmost accuracy
directly on the moving platform (direct metrology). Errors in the drive train, such as nonlinearity, mechanical play and elastic deformation, are not considered. With linear encoders
a resolution down to the nanometer range canbe achieved.

Extended Metrology Concepts
Absolute Encoders
Absolute encoders deliver additional information about the absolute position of the moving
platform.
Parallel Metrology
Position sensor configuration for multiaxis parallel-kinematic systems, in which all
sensors measure the position between baseplate and moving platform. It is essential that
all motions that differ from the defined trajectory are detected and controlled. This meansthat position crosstalk of individual axes of all
actuators can be compensated ("active trajectory control") which requires highly complex
control algorithms.
Serial Metrology
Position sensor configuration for multi-axis
systems, in which some sensors measure
the position between two moving platforms.
Advantages are an easy integration in a serialkinematics system and an easy control concept. Guiding errors with position crosstalk of
the platforms in between cannot be compensated.
Tachometer
Tachometers are used for measuring andcontrolling velocity. Alternatively to a direct
measurement, the time course of the position
data from the encoder can also be used forvelocity control.

258

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Guidings and Bearings

Linear Ball Bearing

Recirculating Ball Bearings

The balls run in a brass cage and are preloadedwith regard to the hardened precision guiding
shafts. Exact tolerances between guiding andbearing are necessary for zero backlash andlow friction. Load capacity is limited.

High-precision stages are equipped with precision double linear rails. Precision assembly
allows these bearings to yield excellent resultsin terms of load capacity, lifetime, low maintenance and guiding accuracy. The moving partof the stages is supported by a total of four
preloaded linear bearings with two rows ofrecirculating balls each. They are also immune
to the cage migration as occur with crossed
roller bearings (can be an issue where small
ranges are scanned repeatedly).

Crossed Roller Bearings
In crossed roller bearings, the point contact of
the balls in ball bearings is replaced by a line
contact of the hardened rollers. Consequently,
they are considerably stiffer and need less preload so that friction is reduced and a smooth
run is possible. Crossed roller bearings arealso characterized by high guiding accuracy
and high load capacity. Permanent guiding of
the rolling body cages avoids migration of thecrossed roller bearings.

Air Bearings
An air film of a few micrometers is used as
bearing. Therefore, air bearings are frictionfree and have a tenfold better guiding accuracy than mechanical bearings. PI miCos uses
air bearings in ultra-precion, and high-velocity
stages.

259

PIEZO

NANO

POSITIONING

Magnetic Bearings

Flexure Guides

Magnetic levitation ensures excellent guiding
accuracy in a plane, both linear and rotational:
The passive platform levitates on a magnetic
field and is actively guided by it. Sequenceerrors are measured and compensated by very
accurate noncontact sensors. Contrary to air
bearings, which are also very accurate, magnetic bearings can also be used in vacuum.

The motion of a flexure joint is based on theelastic deformation of a solid. Therefore, there is no static, rolling or sliding friction. Flexure elements have a high stiffness and load
capacity and are very insensitive to shocks
and vibrations. Flexure guides are free frommaintenance and wear. They are 100% vacuum compatible, function in a wide temperature
range and do not require any lubricants.
Flexure guides from PI have proven their worth
in nanopositioning. They guide the piezo
actuator and ensure a straight motion without
tilting or lateral offset. A solid is elastically
deformed by a device (flexure) free from staticand sliding friction – completely without rollingor sliding parts. This deformation is sufficientto guide the actuator over travel ranges fromseveral 10 to several 100 μm.

The platform levitates on a magnetic field generated byonly six planar coils in the stator

Flexure joints extend the travel range, can re-direct the
motion and offer excellent guiding accuracy without
friction. The lever mechanism shown above with flexure guides transforms the actuator travel range (vertical)
to an even, straight motion (horizontal)

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M O T O R I Z E D P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

Use in Vacuum

Almost all stages can be modified for being
used in different classes of vacuum. On request, outgassing tests are carried out using a
mass spectrometer.

Stage suitable for UHV andcryogenic environment at 77 K

Vacuum Classification at PI
Admissible temperature rangeof the motors

Pressure range

Fine vacuum

FV-20 to +150°C

up to 1 × 10-3 hPa

High vacuum*

HV-20 to +210°C

1 × 10-3 hPa to 1 × 10-7 hPa

Ultrahigh vacuum, no lubricants

UHV-20 to +210°C

1 × 10-7 hPa to 1 × 10-9 hPa

Ultrahigh vacuum, vacuum lubricant

UHV-G-20 to +210°C

1 × 10-7 hPa to 1 × 10-9 hPa

Ultrahigh vacuum, cryogenic range

UHV-C-269 to +40°C

up to 1 × 10-11 hPa

Extremely high vacuum

XHV-20 to +300°C

1 × 10-9 hPa to 1 × 10-11 hPa

1 hPa = 1 mbar
Design and manufacture for ranges beyond these limits are offered on request.
* A high-vacuum class up to 1 × 10-6 hPa is also usual.

Decisive: Material Selection
To determine the required vacuum class, it isnecessary to know the application well. Crystallography or optical coating, for example,
have different requirements not only withregard to the pressure range but also withregard to allowed residual elements in thevacuum chamber. Frequently, the partial pressure of carbon hydrides is decisive. They arepart of lubricants and plastics, are released
when pumping out the vacuum chamber andcan contaminate surfaces. Laser applications in
the UV range are particularly sensitive because
carbon hydrides are split up and precipitate on
the optical system.

For use in HV and UHV, special vacuum lubricants are used. On request, the lubricant may
be defined when placing the order. The useof plastics and adhesives is reduced as far as
possible.

Preferred Materials■ Stainless steel■ Aluminum■ Titanium■ Bronze■ FPM, e.g. Viton■ Ceramics■ Sapphire■ PTFE, e.g. Teflon■ PEEK■ Polyimide,e.g. Kapton■ Glass ceramics,

e.g. Macor
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Mounting in Cleanrooms
Vacuum stages are mounted under cleanroom
conditions. All components are cleaned inultrasound. They are dispatched in an antistaticand particle-free packaging.

Important Factors for Vacuum Stages■ Low velocity: Maximum 10 revolu-

tions per second■ Short operating time
■ Vacuum stages should only be

operated in vacuum
If not agreed otherwise, the following
applies:■ Bakeout temperature max. 80°C
■ Connectors mounted to the stage

Controllers, Amplifiers and Other
Electronic Devices
In general, the control electronics is not suitablefor being operated in the vacuum chamber. It
has to be mounted outside of the chamber.

262

when being delivered are not intended for use under vacuum conditions. Customers have to replacethese test connectors by vacuum
connectors■ The vacuum feedthroughs arenormally not included in the scopeof delivery and may be orderedseparately, if required

FV to 10-3 hPa

HV from 10-3 to 10-7 hPa

UHV from 10-7 to 10-9 hPa

Motor- (just as air)

vacuum motor

suitable vacuum motor

Encoder- (just as air)

modiﬁedmodiﬁedCables- (just as air)

1 m PTFE (Teﬂon) cable

1 m PI (Kapton) cable

Limit switches- (just as air)- (just as air)none
special UHV limit switches, onrequestSurfaceanodized (just as air)

not anodized*

not anodized

Screwsstainless steel

stainless steel

stainless steel with silver coating,gas emission bore

Lubrication (guidings, drive
train)

vacuum lubricant

vacuum lubricant

UHV: no lubricant
UHV-G: vacuum lubricant

Connector- (just as air)test connector, not suitable forvacuumtest connector, not suitable forvacuumHoles- (just as air)

only through-holes

only through-holes

Other materials- (just as air)no CuZn alloys

no CuZn alloys,
no plastic

Bakeout temperature

up to 50°C

up to 80°C

up to 120°C, on request up to
150°C*For use at up to 10-6 hPa vacuum stages with black anodized aluminum surface are offered.

M O T O R I Z E D P O S I T I O N I N G S Y S T E M S | W W W. P I . W S

SMC Controller Technology

The control technology of the SMC stepper
motor controllers guarantees a particularlysmooth running of the motors. The result is avery high position resolution, smooth feed anda large dynamical range of velocity and acceleration. The efficiency of the SMC controllers
is very high so that heating of the motors is
avoided.
SMC controllers are based on a 32-bit processor combined with high-resolution amplifiers
making possible a position resolution down
to nanometers. Driving high-precision mechanical systems, uniform feed velocities of lessthan 1 μm/s can be achieved.
Instead of a linear acceleration profile, you
may choose a sin2 profile so that smooth, jerkfree acceleration and deceleration phases are
possible.
If a stable long-term positioning is required,
SMC stepper motor controllers also evaluate
position feedback systems for closed-loop control. Processing of an analog 1 V-peak-to-peakvalue allows you to set the position very accurately and continuously without limitation by a
bit-depending digital transformation.

Fig. 1

PLS-85 with 2-phase stepper motor, without position control, 100 nm steps

Fig. 2

PLS-85 with 2-phase stepper motor, without position control, 25 nm steps

SMC controllers are available in different versions, from a one-channel compact unit to multiaxis control in 19 inch-case.

Precision Positioning with the SMC
Controller
Figure 1 shows 100 nm steps of a PLS-85 linear stage with 2-phase stepper motor without
additional position feedback. The stage carries
out these steps very accurately.
When commanding 25 nm steps (see fig. 2),
there are more variations in the individual
steps. On average, these deviations are ±5 nm
only.

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Position Control
The positioning behavior for small steps canbe further improved by using position feedback control, in particular, if the analog output
signal of a high-resolution sensor is used forprocessing.
SMC controllers can process sensor resolutions down to 2 nm so that the position resolution only depends on the sensor. However,environmental effects may not be neglected:
Variations of ambient temperature by only
0.01°C already cause an expansion of the stage
body by approx. 10 nm. If required, ultra-precision stages or specific developments, such asstages with granite base with high-resolution
linear encoders, are used.

Fig. 3LS-110 with 2-phase stepper motor in control, 1 V-peak-to-peak sensor
signal, 50 nm steps

Figure 3 shows the minimum incremental
motion of an LS-110 stage equipped with linear encoder. The 50 nm resolution can be clearly seen with precisely separated steps. Evenchanges in load do not affect this accuracy.

Velocity Control
One decisive parameter for selecting a position ing system is velocity. Frequently, themaximum achievable velocity is meant, butsome applications require a particularly slow
and smooth feed motion. This is a major challenge for both stepper motors and DC motors.
The velocity control of SMC controllers guarantees an excellent stability of the stage velocity of well below 1 μm/s. A higher encoder
resolution directly improves the results.

Fig. 4

PLS-85 with 2-phase stepper motor in control, velocity 100 nm/s

Figure 4 shows the measuring results of a
PLS-85 stage with integrated linear encoderwith 10 nm resolution. The velocity was set
to 100 nm/s, which is a feed of 360 μm per hour orapprox. 10 mm per day. The motion is verysmooth. The individual steps shown here are
due to the interferometer resolution of 5 nm.

264

M O T O R I Z E D P O S I T I O N I N G S Y S T E M S | W W W. P I . W SCorrecting the Position Error in theController
The quality of the guides and the drive train
normally limits the positioning accuracy thatcan be achieved. A nonlinearity of the spindle
pitch, for example, causes a deviation from thecommanded position.
In some applications, it is important to improve
the absolute accuracy while bidirectional
repeatability is less relevant. The error correction in the SMC controller saves the measured
deviation and then corrects the target position
correspondingly.
Figure 5 shows the deviation of 32 μm between
target and actual position of an LS-180 over
the travel range of 100 mm. The measurement
includes both directions of motion; the bidirectional repeatability is, on average, 1.78 μm.

Fig. 5LS-180 with 2-phase stepper motor, without position control, position
measurement

Fig. 6LS-180 with 2-phase stepper motor, without position control, position
measurement with correction

The result is shown in Fig. 6: The deviationis considerably smaller, only about ±1.5 μm.
Repeatability may be improved even more bymeans of position control.

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Glossary

Absolute accuracy

Eccentricity

Absolute accuracy is the maximum difference
between the target position and the actual position. Accuracy is limited by backlash, hysteresis,
drift, nonlinearity of drive or measurement
system, tilt, etc. The best absolute accuracy isachieved with direct metrology sensor systems.
In such systems, the position of the platform
itself is measured, with, for example, an interferometer or linear encoder so that mechanicalplay within the drive train does not affect theposition measurement. Indirect metrology
systems (e.g. rotary encoders on the motor
shaft) or open-loop stepper-motor-driven stages,
have significantly lower absolute accuracies.
Independent of this fact, they can still offer highresolutions and repeatabilities.

Backlasharound the Y axis and a yaw around the Z axis
with the motion being in X direction (orthogonal
coordinate system). The data table shows typicalmeasured values as +/- values.

The deviation between theoretical and actual
rotational axis of a rotary stage.

The straightness (in relation to Y) and flatness(in relation to Z) are specified in absolute μm
values.

The guiding error represents the deviation of thestage platform from the planned trajectory perpendicularly to the positioning direction and tilt
around the axes. For a single-axis linear stage,
it is unwanted motion in all five degrees of freedom. For a translation in X, linear runout occurs
in Y and Z, tip and tilt occur in X (θX, roll), Y (θY,
pitch) and Z (θZ, yaw). Guiding errors are causedby the guiding system itself, by the way thestage is mounted (warping) and the load conditions (e.g. torques).

Direction of the axes with linear stages, seealso "Guiding accuracy"

Holding force, de-energized

The position error that appears upon reversing
direction is called backlash. Backlash is causedby mechanical play in the drive train components, such as gearheads or bearings, or by friction in the guiding system. Unlike hysteresis, it
can lead to instability in closed-loop setups
because it causes a deadband in the control
loop. The backlash depends on temperature,acceleration, load, leadscrew position, direction,
wear, etc.

Hysteresis is a position error that occurs whenreversing direction. It is due to elastic deformation, such as friction-based tension and relaxation. Hysteresis of a positioning system varies
greatly with load, acceleration and velocity.

Lateral force

Term definition for rotary stages: Wobble,
flatness, eccentricity

Bidirectional repeatability

Maximum permissible force orthogonally to thepositioning direction. This value is valid whenapplied directly to the moving platform, and isreduced when the force applies above the platform.

Defining linear and rotational axes

Limit switches

X: Linear motion in positioning direction
Y: Linear motion perpendicularly to the X axis
Z: Linear motion perpendicularly to X and Y
θX: Rotation around X
θY: Rotation around Y
θZ: Rotation around Z

Each limit switch sends an overtravel signal on
a dedicated line to the controller. The controller
then interrupts the motion avoiding that thestage gets damaged when the hard travel stop
is reached. PI stages have mechanical, noncontact optical or Hall-effect limit switches.

A closed-loop operation requires processing theresults of a position feedback system. A control
algorithm then compares the target position
with the measured actual position. The closedloop control provides a better repeatability andpositional stability.

Degree of freedom

Load capacity

A degree of freedom corresponds to an active
axis of the positioning system. An XY positioning stage has two degrees of freedom, a Hexapod six.

Maximum load capacity vertically if the stage ismounted horizontally. The contact point of theload is in the center of the platform.

Cosine error

Design resolution

The cosine error is a cumulative position error
in linear systems that occurs when a drive
system is misaligned in regard to the driven
part. The error is calculated by multiplying thechange in position with the difference between
1 and the cosine of the angular error.

The theoretical minimum movement that can be
made. Design resolution must not be confusedwith minimum incremental motion.

Micropositioning stages are normally made ofanodized aluminum or stainless steel. Small
amounts of other materials may be used (forbearings, preload, coupling, mounting, etc.). On
request, other materials, such as nonmagnetic
steel or Invar, can be used.

The accuracy of returning to a position within
the travel range after any change in position.
Effects such as hysteresis and backlash affectbidirectional repeatability if the system does nothave direct metrology. See also "Unidirectional
repeatability".

Closed-loop operation

Crosstalk:
Pitch / yaw, straightness / flatness
266

Piezomotor linear drives are self-locking at rest,
they do not consume current and do not generate heat. If they are switched off for a longer
time, the holding force decreases. This is typicalfor piezomotors. The minimum holding force inlong-term operation is specified.

Hysteresis

Backlash is suppressed by the preload of thedrive train. A position measurement method,that can detect the position of the platform
directly, eliminates all errors in the drive train(direct metrology).
The data table shows typical measured values.
Data for vacuum versions can differ.

Guiding accuracy, guiding error

Deviation from the ideal straight motion measured along the entire travel range; it is a pitch

In indirect position measurement methods,
values for spindle pitch, gear ratio, motor or
sensor/encoder resolution, for example, areincluded in the calculation of the resolution; normally it is considerably below the minimum
incremental motion of a mechanical system. In
direct measurement methods, the resolution of
the sensor system is specified.

MaterialMax. push / pull force
Maximum force in direction of motion. Somestages may reach higher forces but with limited
lifetimes.

M O T O R I Z E D P O S I T I O N I N G S Y S T E M S | W W W. P I . W SMeasured values

Perpendicularity, orthogonality

Stick-slip effect, friction

Measured values, such as backlash and repeatability, are determined based on the VDI standard
3114.

Perpendicularity describes the deviation from an
ideal 90° angle of the X, Y and Z motion axes.

This effect limits the minimum incremental
motion. It is produced during the transition fromstatic to sliding friction and causes a motion.
Friction-free drives, such as piezo actuators with
flexure guides, are not affected by stick-slip
effects so that resolutions in the sub-nanometer
range are possible.

Min. incremental motion
The smallest motion that can be repeatedly executed is called minimum incremental motion, or
typical resolution, and is determined by measurements. The data table shows typical measured values.
The minimum incremental motion differs inmost cases strongly from the "design resolution", which can be considerably smaller innumerical values. Repeatable motions in nanometer and sub-nanometer range can be carriedout using piezo stage technology and frictionfree flexure guides.

MTBF“Mean Time Between Failure”. Measure for lifetime and reliability of the stage.

Open-loop operation
Operation without processing the position sensor and without control loop. Stages with stepper motors execute precise and repeatablesteps; therefore, they do not need any closedloop control. The closed-loop control provides abetter repeatability and positional stability.

Operating temperature range
Safe operation, no damage to the drive. All technical data specified in the data sheet refer toroom temperature (22 ±3°C).

Orthogonality

Pitch / yaw
See "Crosstalk".

Precision
Precision is a term not clearly defined and isused by different manufacturers in different
ways for repeatability, accuracy or resolution. PI
uses the term for a high, but not quantified,accuracy.

Pulse width modulation (PWM)
The PWM mode is a highly effective amplifiermode in which the duty cycle is varied rather
than the amplitude of the output signal. See"ActiveDrive DC Motors", p. 255

Reference point switch
Many stages are equipped with direction-sensing reference point switches, which are locatedat about the midpoint of the travel range. It is
recommended to approach the reference pointswitch always from the same direction to obtain
best position repeatability.

Resolution
See "Design resolution" and "Min. incremental
motion".

Sensor resolution

The maximum possible travel range is limitedby the length of the drive screw. The distance
between the limit switches, if any, determines
the travel range.

Unidirectional repeatability
The accuracy of returning to a given position
from the same direction. Because unidirectional
repeatability is almost unaffected by backlashand hysteresis, it is often considerably better
than "bidirectional repeatability".

Velocity, max.
This is the short-term peak value for horizontal
mounting, with no load, and not intended forcontinuous operation. Average and permanent
velocities are lower than the peak value anddepend on the external conditions of the application. Data for vacuum versions can differ.

WobbleWobble describes tilting of the rotary stages
around the rotational axis in each revolution.

Rotary encoder: Impulses per screw rotation
Linear encoder: Smallest motion still detectedby the sensor system used

See "Perpendicularity".

Serial kinematics

Parallel kinematics

Multi-axis system design in which each actuator
drives its own separate platform. Advantages
are simpler mechanical assembly and control
algorithms. Disadvantages compared to parallel
kinematics are poorer dynamic performance, nointegrated parallel metrology possible, cumulative guiding errors, less accuracy.

Multi-axis system, in which all actuators act
directly on the same moving platform. The
advantages if compared to serial kinematics area lower mass moment of inertia, no moved
cables, lower center of gravity, no cumulated
guiding errors, more compact structure.

Travel range

Comparison between parallel-kinematic andserial-kinematic structure of a 6-axis positioner

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Patents

PI holds the following product-related patents. They protect the technology and guarantee the technological advance.
We list the patents relevant for each product in product literature and on product labels. In some parts of the world,
this is mandatory to keep up patent protection.

PatentGranted on

Concerns products

German patent no. 10021919

2001-08-08

PICMA®, P-88x, all products that use PICMA®

German patent no. 10234787

2003-10-30

PICMA®, P-88x

German patent no. 10348836

2004-11-08

PICMA®, P-88x

US patent no. 7,449,077

2008-11-08

PICMA®, all P-5xx, P-6xx, P-7xx, P-8xx, P-9xx

German patent no. 29618149.8

1996-12-05

F-206, F-206.S, H-206

US patent no. 6,765,335

2004-04-20

PILine®, M-663, M-664, M-272, M-683, M-686, M-687, P-661, U-161, U-164, U-264,

German patent no. 10154526

2007-02-08

U-628

US patent no. 6,800,984

2004-10-05

German patent no. 10148267

2005-11-24

US patent no. 6,950,050

2005-09-27

German patent no. P4408618.0

2004-04-22

European patent 0 624 912 B1

1997-01-22

German patent no. 102004011724

2006-08-10

German patent no. 10051784

2002-08-14

US patent no. 6,930,439

2005-08-16

German patent no. 19825210C2

2003-09-25

International patent no. 1080502B1

2002-07-10

US patent no. 6617754B1

2003-09-09

NEXLINE®, P-911, N-111, N-216

HyperBit

NEXACT® N-310, N-381, N-664, LPS-24, LPS-65

P-712, P-713

P-876 DuraAct

E-481, E-482, E-504, E-617

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W W W. P I . W S

Imprint

Physik Instrumente (PI) GmbH & Co. KG

Auf der Roemerstrasse 176228 Karlsruhe
Germany
Tel.: +49 721 4846-0
Fax: +49 721 4846-1019
info@pi.ws
www.pi.ws
General Management: Dr. Karl Spanner (CEO), Norbert Ludwig, Dr. Peter Schittenhelm, Markus Spanner
Commercial Register: Reg.-Gericht Mannheim: HRA 104804
VAT ID Nr: DE 1431 828 03
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Partner liable to unlimited extend: Physik Instrumente (PI) Verwaltungs GmbH, Karlsruhe, Germany
Commercial Register: Reg.-Gericht Mannheim: HRB 109941
Although the information in this document has been compiled with the greatest care, errors cannot be ruled out completely. Therefore, we cannot guarantee for the information being complete, correct and up to date. Illustrations may differ
from the original and are not binding. PI reserves the right to supplement or change the information provided without
prior notice.

Trademarks

The following company names and brands are registered trademarks of Physik Instrumente (PI) GmbH & Co. KG:
PI®, PIC®, PICMA®, PILine®, PIFOC®, PiezoWalk®, NEXACT®, NEXLINE®, PInano®, NanoCube®, Picoactuator®, Nanoautomation®
The following company names or brands are the registered trademarks of their owners:
μManager, LabVIEW, Leica, Linux, MATLAB, MetaMorph, Microsoft, National Instruments, Nikon, Olympus, Windows, Zeiss

CAT130E R1 05/2013.10000 © Physik Instrumente (PI) GmbH & Co. KG 2013. Subject to change without notice.
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Any copying, modification or redistribution in whole or in parts is subject to a written permission of PI.

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