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AICON 3D Systems GmbH

AICON 3D Systems GmbHBiberweg 30CD-38114 BraunschweigGermanyhttp://www.aicon3d.com

LaserTracer – A new type of self tracking laser interferometer

Carl-Thomas Schneider, Michael Engelhardt

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LaserTracer

ContentContent

1.1. Motivation : Motivation : Accuracy Improvement Accuracy Improvement of of CoordinateCoordinate MeasurementMeasurement Machines (CMM)Machines (CMM)

2.2. Technology : Technology : Self Tracking Self Tracking Laser Laser InterferometerInterferometer

3.3. Application Application : : Gear Wheel MeasurementGear Wheel Measurement

4.4. Application Application : CMM : CMM CalibrationCalibration

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Accuracy Improvement of CMM

Coordinate Measurement MachineCoordinate Measurement Machine

x

y

z+ universal

+ flexible

+ 3D-Metrology

ApplicationApplicationGear wheel measurement

ProblemProblemThe measurement accuracy

is not sufficient for

every application.

⇒ new concept for

accuracy improvement

PKMG = f (x, y, z)

P

rotation table

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LaserTracer

ContentContent

1.1. Motivation : Motivation : Accuracy Improvement Accuracy Improvement of of CoordinateCoordinate MeasurementMeasurement Machines (CMM)Machines (CMM)

2.2. Technology : Technology : Self Tracking Self Tracking Laser Laser InterferometerInterferometer

3.3. Application Application : : Gear Wheel MeasurementGear Wheel Measurement

4.4. Application Application : CMM : CMM CalibrationCalibration

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Commercial LaserTracker

Angleencoder

Reflector

ADM

Tripod

Rotation Axis

Sensor

Interferometer

[Leica]

• Position detection of movable reflector

• Resulting in spherical coordinates:Interferometric and absolute distance measurement+ two angles via encoder

• Laser beam follows reflector

DisadvantageDisadvantageinsufficient length accuracy

unnecessary angle measurement

size

price

⇒⇒ self tracking laser interferometerself tracking laser interferometer

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Self Tracking Interferometer

SteelSphere

•• DifferencesDifferencesTilt and Rotate of the complete Interferometer

•• PrinciplePrincipleRotation Centre of Interferometer = Origin for all Measurements

•• RealisationRealisationPrecision Sphere as Reference⇒ Centre in Intersection of

both Axis⇒ Reflection of Laser Beam

at Sphere‘s Surface

All measurements are referencing in one stable point in space !Tr

acki

ng U

nit

Inte

rfer

omet

er

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Laser Interferometer

Laser viaFibre Optics

Detector

Reflector

ReflectorInterferometer

Reference Sphere(Steel)

Shape Deviation≤ 30nm

4-QuadrantDiode

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Complete System

•• Tracking Tracking UnitUnit• Steel Sphere on Invar Pillar• Belt Drives for both Axis

•• AdvantagesAdvantages• high accuracy• small size• low weight (< 7kg)

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LaserTracer

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LaserTracer

ContentContent

1.1. Motivation : Motivation : Accuracy Improvement Accuracy Improvement of of CoordinateCoordinate MeasurementMeasurement Machines (CMM)Machines (CMM)

2.2. Technology : Technology : Self Tracking Self Tracking Laser Laser InterferometerInterferometer

3.3. Application Application : : Gear Wheel MeasurementGear Wheel Measurement

4.4. Application Application : CMM : CMM CalibrationCalibration

M E

A S

U R

E

T

H E

A D

V A

N T

A G

E

Application CMM Improvement

Coordinate Measurement MachineCoordinate Measurement Machine

x

y

z+ universal

+ flexible

+ 3D-Metrology

ApplicationApplicationGear wheel measurement

ProblemProblemThe measurement accuracy

is not sufficient for

every application.

⇒ new concept for

accuracy improvement