WHITEPAPER – This is how PI Does Measuring - Part I-- Claus Mansmann --This is how PI Does Measuring - Part I
Measuring Environment / Measuring Equipment Portfolio / Data Evaluation

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

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WHITEPAPER – This is how PI Does Measuring - Part I-- Claus Mansmann --For PI, each individual measurement and qualification of apositioning and motion system is an instrument for quality
assurance. This makes sure that only those products leave thepremises that are within the guaranteed specifications. Highprecision measuring is necessary for qualifying as well as for
final inspection and approval checks of all motion andpositioning systems. Both the selection of the measuring
environment and setup of the measuring equipment areadapted to the requirements of the respective product line.
The desired resolution, measuring accuracy, tolerances, andsampling rate are the criteria for selection. In addition, thestability of the measuring setup over time plays a decisiverole and makes special demands on avoiding drift effects, e.g.,
by using adequate temperature and vibration isolation.

1 Measuring Environment
1.1

Measuring Laboratories

Number oflaboratoriesformeasuring

VC
classification*Air
conditionedand simple
seismicbase
isolation

Multipleseismic,
acoustic, andthermal baseisolation

VC-D, VC-E, VCF, VC-G

VC-G, VC-H, VC-I

5276 m282 m210481 m

2-Fig. 2 Laboratories available for measuring.
*The VC classification is different for each room. Simple seismicdecoupled rooms achieve classes VC-D to VC-G. That corresponds tomaximum vibration of <6.25 µm/s in a frequency range of 1 to 100
Hz. Multiple seismic-decoupled rooms achieve classes VC-F to VC-I.
That corresponds to a maximum vibration of <0.78 µm/s in afrequency range of 1 to 100 Hz.

Precision measuring is done on honeycomb tables that areisolated passively from vibration. The foundation of every
measuring room is in turn, isolated from the rest of thebuilding and therefore suppresses seismic influences. All
measuring laboratories are air-conditioned.
15 special measuring laboratories with an overall surface of
2
750 m are available at PI's headquarters in Karlsruhe. Fivemeasuring laboratories with upstream areas for preliminary
temperature regulation have special seismic, electromagnetic, and thermal isolation, which ensures temperaturestability better than 0.25 Kelvin over a period of 24 hours.
This makes accurate measuring possible down to thepicometer range. Long-term measuring of the positional
stability is only possible under such conditions.

Fig. 3 Temperature stability of a measuring room over several days

1.2

Measuring Technology in the ProductionEnvironment

In (large) series production, a large part of the measuring
takes place directly in the production environment. This
allows deviations in the process to be detected quickly, whichhelps to prevent rejects or costs for reworking.
For this purpose, PI develops fully and semiautomatic
measuring and test stations that are validated for theirsuitability with the help of a measuring system analysis before
they are used in production ("Gage Repeatability &Reproducibility").
Fig. 1 View into a nanometrology laboratory with six-fold isolation.
Measuring is done fully automatically under controlled ambientconditions.

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

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WHITEPAPER – This is how PI Does Measuring - Part I-- Claus Mansmann --1.4

Special Equipment

Lifting and tilting equipment with a load capacity of 5000 kg
allows qualifying of positioning systems at any angle withapplication-specific alignment and load.
Qualification of a two-ton hexapod assumes that masses up
to five tons can be safely attached for measuring. In theheavy-load hall, three gantry cranes span the working area,and lift and transport the components of the positioningsystems.
Fig. 4 View of semiautomatic test stations for large series production

1.3

Overview of Measuring Capabilities
under Specifically Designed
Environmental Conditions

In extensively equipped application laboratories, a large
number of measurements can be made under specificambient conditions.
-11

Vacuum chambers with a base pressure to 10 hPa allow
function tests and residual gas analysis. Depending on theapplication, not only the pressure area is decisive, but also
the permissible residual materials inside the vacuum chambersuch as for example, in the crystallography or the opticalcoating.
Cryogenic chambers for measuring to 77 °K (condensation
point of nitrogen) allow startup and function checking atextremely low temperatures.
Even long-term examinations and lifetime testing are possible
under these special conditions.

Fig. 5 At PI in Karlsruhe, lifting and tilting equipment specifically formeasuring or qualifying products according to application isavailable. In this picture, a hexapod with load is measured
interferometrically

2 Measuring equipment

Measuringequipment

Temperature
range

Humidity
range

Test
chamber
volumeClimatechamber-72 °C to+180 °C

10 ... 95 %rel.

190 / 275 l

All measuring equipment is subject to recalibration andtherefore, it is possible to perform suitable measuring withminimal uncertainty. This means that the resulting
measurement and the actual value correspond to each otherat all times, and can be reproduced with respect to national
and international standards. Interferometric measuringsystems are frequently used that are particularly
distinguished by high resolution, short measuring times, andnoncontact, wear-free measuring.

Cryogenicchamber

77 °K to300 °K-21.2 lNot all locations have measuring equipment for everyresolution.

Vacuumchamber

20 °C toapprox. 70 °C-98 / 106 l

Glovebox-approx.
5 ppm

748 l

Special environmental conditions

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

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WHITEPAPER – This is how PI Does Measuring - Part I-- Claus Mansmann --2.1

Measuring Equipment According to MeasurandLength / Path
Measuring equipment

Measuring principle

Resolution/DPMI

Measuring range

Tactile measuring sensor

Inductive (incremental)

to 5 nm

to 50 mm

Laser interferometer

Optical (incremental)

to 0.151 nm

to 10 mVibrometer

Optical (Doppler effect)

2 nm

40 mm

Multi-sensor measuring machine

Optical and tactile

0.1 µm

300 mm × 300 mm ×160 mm

CNC coordinate measuringmachine

Incremental sensor with glass
scale

0.1 µm

900 mm × 1800 mm ×800 mm

PISecaCapacitive sensor

0.001 % of the travel range

to 100 µm

Angle
Measuring equipment

Measuring principle

Resolution/DPMI

Measuring range

Laser interferometer

Optical (incremental)

to 34 nrad

± 0.11°

Autocollimator (AKF)

Optical (autocollimation)

to 0.05 arcsec± 0.29° (up to ± 2.3°)

Angle measuring device /rotary encoder

Incremental

to 0.4 arcsec

360°

Measuring equipment

Measuring principle

Velocity resolution

Vmax

Laser interferometer

Optical (incremental)

to 10 nm/s

up to 4 mm/s

Vibrometer

Optical (Doppler effect)

to 0.005 µm/s

up to 10 mm/s

Measuring equipment

Measuring principle

Resolution/DPMIMeasuring range

White light interferometer

Optical (incremental)

λ/25

80 mm × 80 mm

White light interferometer

Optical (scanning white lightinterferometry)to 1 nm

Z=70 mm
X=38 mm
Y =28 mm

Velocity

Surface finish / surface flatness

Laser scanning microscopefor smooth surfaces

Optical

X=100 mm; Y=100 mm;
1× - 8× objective

Eccentricity / wobble
Measuring equipment

Measuring principle

Resolution/DPMI

Measuring range

Static spindle analyzer

Capacitive

80 µV/µm

Low ±125 µm
High ±6.5 µm

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

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WHITEPAPER – This is how PI Does Measuring - Part I-- Claus Mansmann --3 Evaluation of the Measured
Data
The DIN ISO 230-2 and VDI/DGQ 3441 standards are the basis
for qualification of PI products and evaluation of themeasurands.
The qualification data is always verifiable for each individualproduct. The measured data is compiled in a database andused for process control. Traceability at product level isparticularly interesting for large production runs.
The measurement log is provided with many systems such as
hexapods or piezo systems. It is therefore possible for thecustomer to verify the measured performance of the systembefore it was dispatched and also to see which systemcomponents belong together.

Fig. 7 Examples of visualizations from the database of measurement
results

3.2

Measuring Software

The software for controlling the fully or semiautomatic
measuring and test stations is developed in-house by PI. All
measuring equipment can be configured directly and readfrom the software, which means that there are nounnecessary sources of error for the measured values, storingin databases, and creating the log.
Software development makes use of current development
standards such as version control systems, bug tracking,automatic build systems, static code analysis, unit tests, andcode reviews. This ensures that the software is always
traceable and the quality standards are adhered to.

Fig. 6 Typical measurands in a measuring log showing the linearity andimpulse response of a piezo system

3.1

Acquiring Measuring Data and Statistical
Process Control

The measuring data is transmitted in real time automatically,
saved to a database, and then visualized on a web-based userinterface. Access to the control charts and the analysis tool isdone via a web browser. The technical experts have
immediate access to all process data and if required, canintervene immediately.
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Fig. 8 Standardized process control with full documentation of theindividual measuring logs

Automatic saving of the measured data after measuring
Real-time display of the measured values in the controlcharts
Multi-control charts for maximum process control
Dynamic calculation of warning and intervention limits
Download of raw data and customer log
Calculation of process capability Cpk level
Pareto chart for process analysis and optimization
Correlation chart to check the dependence of twomeasurands
Various export functions

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

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WHITEPAPER – This is how PI Does Measuring - Part I-- Claus Mansmann --Well known for the high quality of its products, PI (PhysikInstrumente) has been one of the leading players in the global
market for precision positioning technology for many years. PI
has been developing and manufacturing standard and OEM
products with piezo or motor drives for 40 years. Continuous
development of innovative drive concepts, products, andsystem solutions and more than 200 technology patents
distinguish the company history today. PI develops,
manufactures, and qualifies all core technology itself: Frompiezo components, -actuators, and motors as well as
magnetic direct drives through air bearings, magnetic andflexure guides to nanometrological sensors, control
technology, and software.
PI is therefore not dependent on components available on
the market to offer its customers the most advancedsolutions. The high vertical range of manufacturing allows
complete control over processes and this allows flexible
reaction to market developments and new requirements. By
acquiring the majority shares in ACS Motion Control, aworldwide leading developer and manufacturer of modular
motion controllers for multi-axis drive systems, PI can also
supply customized complete systems for industrialapplications that make the highest demand on precision anddynamics. In addition to four locations in Germany, the PI
Group is represented internationally by fifteen sales andservice subsidiaries.

WP4011E Measuring Environment 04/2018.0 Subject to changes. © Physik Instrumente (PI) GmbH & Co. KG 2018

About PI

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

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