Metrology toolbox for mechanical design & alignment

PACMAN, CERN, Geneva, 20-22 March 2017

Metrology toolbox

for

mechanical design & alignment

(Alain LESTRADE, Synchrotron SOLEIL)

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SOLEIL Project

Synchrotron source: 2.75 GeV SR: ø110m

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SOLEIL Project

Ex: phase contrast microtomography on PSICHE beamline

of a 320M y/o grasshopper hosting an acarid

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Magnet & magnetic bench Stages for scanning Opto-mechanical component


Frame of the lecture

Full SR alignment procedure from the rotating coil

to the beam based alignment

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Practical tools for Metrology & Mechanical engineering in the field of the instrumentation

Examples are oriented “Synchrotron facility”

Metrology toolbox


Nothing is specially new in this toolbox

It is just a formalization of well known rules of good use and good design,

a way to a global point of view, to reorganize.

Metrology toolbox: a “checklist” which allows a

Spatial layout analysis of dimensional measurement systems

- Mechanical units under beam

- Metrology setup for their qualification

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Dimensional Metrology

Measure Time

SpaceMechanics

Means: Point of view:

Stability Time Constant

Vibrations

Sensors & instruments:

Random & Bias Errors

Mechanical units:

Random & Bias Errors

Degrees of freedom

Metrology loop

Lever arms & effective length

Error Separation Layout

Affine & vector spaces

Sensitive direction

Differential measurements

Not exhaustive6


The main question

• How to link these notions from each other in order to analyze stability,

accuracy, etc, in a qualitative (& quantitative) way?

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Measure Time

SpaceMechanics


Metrology loop

Lever arms

Error Separation Layout

Not exhaustive

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Metrology loopMeasure Time

SpaceMechanics

CMM (Hennebelle, ENSAM)

Metrology loop

Sensor

𝑇𝑍

Object

𝑇𝑋

𝑇𝑌

Support

Wobble, straightness

& backlash

Encoders errors

Encoder errors

?

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• Any system dedicated to positioning or requiring a positioning operation, consists of a stack of mechanical parts and/or of sensors, the metrology loop.

𝑆𝑋

Support 𝑆𝑌

𝑆𝑍

Sensor

Measuring loop

Kinematic loop


Metrology loop: partial dissociationMeasure Time

SpaceMechanics

(Hennebelle, ENSAM)

h

W

𝑒𝑥=W.h

B

𝑇𝑌

h

Fixed

𝑇𝑌

W

B

Movable

Support

Sen

sor

B: backlash

W: wobble

h: lever arm

e: error

Encoder

Wobble

rotation axis

X

𝑇𝑋

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Each point of interest for the analysis

Quantitatively:

the corresponding transfer function:

sin-cos error, random error,

optics function, torsor, etc.

Qualitatively:

the sources of errors

Sources of errors Transfer function

….

….

….

Metrology loop

Measure Time

SpaceMechanics

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Lever arms & effective length


Measure Time

SpaceMechanics

The effective length (EL) is the smaller lever arm on the metrology loop

Lever arms applied to parasitic rotation (sine-cosine errors)

𝐸𝐿 ≈ 10𝑚𝑚

𝑀𝑒𝑐ℎ. 𝑐𝑜𝑛𝑡𝑎𝑐𝑡 ≈ 80𝑚𝑚

4-quad cellDiode

Support

Contact 80mm

Body

Sensor 10mm

𝑔

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W

(Hennebelle, ENSAM)

ℎ𝑧

ℎ𝑦

ℎ𝑖: Encoder / object (sample)

ℎ𝑥


Error Separation LayoutMeasure Time

SpaceMechanics

1st reversal

2nd reversal

Reversal of a

centring system

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Multiprobe method for

rotation stage SOC

n-points rotation of a coil

ESLCone

𝑇𝑟𝑖𝑏𝑎𝑐𝑘

Target

𝑃1

𝑃2

𝑃1

𝑃2

Monument𝑖 =𝑙1 ± 𝑙2

2

𝑒 =𝑙1 ∓ 𝑙2

2

ESL

Sphere

To collect both measurement & bias error:

offset, excentricity, SOC, cylinder circularity, etc.


Measure Time

SpaceMechanics



Not exhaustive

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• The stability of the set “Instrument-Object” should be better than the measurement accuracy target .

• STC is the acceptable duration t during which we do not want less than a parasitic displacement

quantity d :

• STC = (d, t)

• Whatever the origin of the disturbance of the system: mechanical, electronic, etc.



t (s)

Meas. Duration t

Meas. Accuracy δm

STC

Parasitic slow drift

Max. displ. d

d (µm)

Measure Time

SpaceMechanics

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• Differential DOF * has to be considered.

• Theodolite: 3.10-4deg accuracy t=4h measurement duration:

Measure Time

SpaceMechanics

* DOF: Degrees OF Freedom

Metrology loop

in 𝑅𝑧 stability

𝑅𝑧 object

𝑅𝑧 intrument

𝑺𝑻𝑪𝑹𝒛= (<3.10-4deg; 4h)

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Fixed

Floor

Tripod

Theodolite

Stand

4ℎ

4ℎ

4ℎ

4ℎ

Mirror

Ref. m

easur.

30′Ref.

meas.30′

Wall

Metrology loops in Storage Ring

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Physics (BBA): STC=(1µm;run)

Alignment: STC=(15µm;survey)

Mechanics Stability:

STC=(15µm;2 surveys)


Qpole

BPM

GirderStand

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Metrology loop and HLS at NANOSCOPIUM

18PACMAN, CERN, Geneva, 20-22 March 2017

BPM1NanoProbe

BPM2 M1Secondary Source

OH5 hutchhallSR tunnelInsertion

device

𝑀1 𝑆𝑆SP

𝑴𝒗(z)

HLS+water

BPMs+beam

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M1 transfer function

𝑴𝒗

𝑴𝒗

HLS+water

M1+beam

HLS+water

SS+beam


Case study: The Qpole Alignment at SOLEIL

• The following steps are applied:

– Magnetic axis detection

– Fiducialization

– Mechanical alignment on girder

– Checking survey per girder Fiducials

1 X Shims

4 Z Shims

e-

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ESL

ESL

Tool mag axis

Tool stand

Pin

Bench

Tool ext face

Coil rotation axis

Coil mag axis

Ball bearings

Coil stand

months

months

months

months

𝑚𝑛

𝑚𝑛

𝑝𝑒𝑟𝑖𝑜𝑑𝑖𝑐𝑖𝑡𝑦

𝐶𝑀𝑀Pin

Coil mag axis

• The bench for magnetic measurements, calibration tool:

– Link the coil axis to the bench in order to avoid STC = (few µm,months)

• A permanent Qpole tool with 8 faces

• The tool is accurately measured


Pin

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Case study: Qpole zero detection

– Each Qpole is measured by the bench: differential measurements

– A set of shims are chosen for having the zero on the axis of the coil

– STC = (few µm, months) for the whole metrology loop

– The weak point is the pin STC = (few µm, months):

– 200 times in contact with 300-500kg!

ESL

Pin

Bench

Coil rotation axis

Coil mag axis

Ball bearings

Coil stand

months

months

months

months

𝑚𝑛

Qpole mag axis

Shim

Pin

months

months

months

Qpole yoke

months

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• Fiducialization:

– Qpole Comparator: 4 electronic dial gages + 1 inclinometer

– Contact on the coil support in rotation

– Error Separation Layout: for X direction & tilt, not for Z!

– STC = (10µm,30mn) in X thanks to the ESL, STC = (10µm,∞) in Z

– The metrology loop does not include the bench!

Reversal

Qpole comparator

Hz ESLCoil rotation axis

Coil mag axis

Dial gauges zero 1

Inox structure

Dial gauges zero 2

Fiducials

𝑚𝑛

𝑚𝑛

𝑚𝑛

ESL

𝑚𝑜𝑛𝑡ℎ𝑠

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Laser ecartometry of Qpoles on a girder :

– Qpoles are mechanically aligned by the contact of their shims with the girder

references: X pin & Z surface

– ESL: reversal of the laser position WR to the girder

– Beam stability is easy: STC = (few µm,2mn)


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Ecart-type: XCM (µm) ZCM (µm) TiltCM (mm/m)

per girder: 15.2 10.6 0.053

for the orbit: 14 9 0.053

Global loop

Girder pins alignment

Zero detection

Fiducialization

Laser ecartometry

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Metrology toolbox for mechanical design & alignment

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