CALIBRATIONErwin Pilch

Prevessin Site, F - 01631 CERN CEDEX, FrancUniversity of Technology Graz, Austria9th August 2001

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Positioning Metrology and Surveying Group

EST Engineering Support & Technology Division

European Organization for Nuclear Research

http://cern.web.cern.ch/CERN/Divisions/EST/SU/

http://www.cern.ch

http://cern.web.cern.ch/CERN/Divisions/EST/

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Building 926,Prevessin Site,F - 01631 CERN CEDEX, Franc

Office

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Calibration base

Calibration of lengths (interferometric bench) :

Reference : interferometer (s < 0.1 µm). Carriage : manual or automatic mode. Calibrated instruments : invar wires, Electro-optical distance-meters(for constant & cyclic errors), passive or active linear gauges, engraved tapes, scale bars, leveling staves.

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Emitter

Receiver Mirror

Phase lag

Electrooptical Distance Meter

Industrial Total StationsHigh precision motorized theodolite with integrated distance meter.

Characteristics of the Leica Total Stations:integrated infra-red distance meter measures on prisms and retro-reflective tapes of various sizes allows to set any addition constant high accuracy

Typical accuracy up to 120m0.5mm / 0.02"absolute

TDA 5005

)sin( tAyE

)(sin ttAyR

'2 tcd

)sin( A

)( ER ttc

sinA

'2

tc

d

Outgoing Signal

Incoming Signal

Distance

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Interferometer

LS

FR

BS MRPD

C

The laser interferometer is manufactured by Hewlett Packard and consists of a stabilized Helium Neon laser, (l = 632,8nm, output power 1mW), a remote interferometer prism with a fixed reflector, a mobile reflector, a receiver and a display unit.

The laser beam is split in two parts by the beam splitter, one part is reflected back by the fixed reflector and the other by the mobile reflector. The two beams are recombined and reach the receiver where the phase difference is proportional to the distance traveled by the mobile reflector.

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Trolley

Reflector

The motorized trolley can be moved manually or automatically. It supports two reflectors for the interferometer. This allows to calibrate many different systems.

During a calibration, the ground and the rail do not show any significant deformation. (weight around 280kg)

Microscope

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Parts of the installation

Temperature sensor Prism Mirror

Support No. 3 Support No. 1 (Zero) Support No. 2

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The whole calibration process is fully computer controlled for this instruments. The meteorological parameters are collected from digital sensors and automatically stored and used to correct distances throughout the operation.

Program at the base

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Program - Calibration 2001

Opens a selected file and sorts the data. Example 50m–1m 1m–50m

This function double the points in the area were there are fewer points.

Plots a comparison between Fourier series and the data.Calculates points and lines

with the parameters.

Linear Regression, …Fourier Series, ….

Connects two files with interpolation between the points.

based on Etalonnage.m by Sara Poncet11

Screenshots - Calibration 2001Input data

Ok!

Error!

Choose!

Results!

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Thanks...

Thanks to my colleges

Special Thanks to my supervisor

Jean-Pierre Quesnel,

and my collegeAndré Mathieu

Thank you for listening.

Thank you toSeamus Hegarty

Karine JoassetRicarda BetzingIngrid Schmid

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