24.09.07

ATF2 meeting LAPP; David Urner

1

David Urner

Paul Coe

MatthewWarden

Armin Reichold

GeoffreyRayner

MPhys

alumnus

MONALISA

Monitoring, Alignment & Stabilisation with high Accuracy

24.09.07

ATF2 meeting LAPP; David Urner

2

Compact Straightness Monitor CSM

2-dim sketch (3d requires second lateral measurement ) Use mechanical stability of small platforms A&B. Use multiple lines to cancel systematic effects Resolution scales aproximately with H/L

H=

~10

cm

L = as needed

AA B

24.09.07

ATF2 meeting LAPP; David Urner

3

FSI: Frequency Scanning Interferometry

24.09.07

ATF2 meeting LAPP; David Urner

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Progress in 06 / 07

Hardware Built novel Interferometer designs Pioneered new phase measurement techniques Still making vacuum vessel to demonstrate nm

precision Tested compact launch optics

Software Developed novel phase analysis technique Collaborated with LiCAS on OO analysis package Developed binary file format for data handling

users MonAliSA, LiCAS and ATLAS (FSI)... Available in Java, C and LabVIEW

24.09.07

ATF2 meeting LAPP; David Urner

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Reference Interferometer

Both interferometers have same mirror sweep

Interferometers cross check step size and other systematics

If one is very short and one quite long, uneven laser tuning can be more easily followed

Parallels

PiezoSweptmirror

24.09.07

ATF2 meeting LAPP; David Urner

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• Parallel Michelson interferometers built and tested

• Installed continuous thermometer readout system

• Calibration studies this autumn

Parallel Reference Interferometer

24.09.07

ATF2 meeting LAPP; David Urner

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0 200 4000.2

0.4

0.6

0.8

1.0

Pho

todi

ode

sign

al /

a.u.

time / ms

Multi-fibre read out (compact launch)

0 200 400

-4

-2

0

Dis

pla

cem

en

t /

m

Time / ms

• Fixed frequency laser (FFI)• Same interferometer can be used for FSI• Test shown here with moving mirror• First stationary mirror test :

- resolution 5 nm demonstrated - to be improved with vaccuum- and laser frequency stabilisation- temperature and pressure dependence look reasonable

FFI: Fixed Frequency Interferometry (OPD 400mm)

24.09.07

ATF2 meeting LAPP; David Urner

8

Multi-fibre read out (compact launch)

• Fixed frequency laser (FFI)• Same interferometer can be used for FSI• Test shown here with moving mirror• First stationary mirror test :

- resolution 5 nm demonstrated - to be improved with vaccuum- and laser frequency stabilisation- temperature and pressure dependence look reasonable

Time (hours)

Dis

pla

cem

ent

/ m

Dis

pla

cem

ent

/ nm =4.5nm

FFI: Fixed Frequency Interferometry (OPD 400mm)

24.09.07

ATF2 meeting LAPP; David Urner

9

Multi-fibre read out (compact launch)

• Fixed frequency laser (FFI)• Same interferometer can be used for FSI• Test shown here with moving mirror• First stationary mirror test :

- resolution 5 nm demonstrated - to be improved with vaccuum- and laser frequency stabilisation- temperature and pressure dependence look reasonable

Time (hours)

Dis

pla

cem

ent

/ m

Time (hours)

Dis

pla

cem

ent

/ m

Dis

pla

cem

ent

/ nm =4.5nm

FFI: Fixed Frequency Interferometry (OPD 400mm)

24.09.07

ATF2 meeting LAPP; David Urner

10

=750nm

Multi-fibre read out (compact launch)

• Fixed frequency laser (FFI)• Same interferometer can be used for FSI• Test shown here with moving mirror• First stationary mirror test :

- resolution 5 nm demonstrated - to be improved with vaccuum- and laser frequency stabilisation- temperature and pressure dependence look reasonable

=750nm=70nm

Add box to reduce air turbulence

FSI:Frequency Scanning Interferometry (OPD 400mm)

24.09.07

ATF2 meeting LAPP; David Urner

11

Ellipse fitting phase extraction

Novel technique for multi-fibre phase readout

Signals from 2 fibres Normalise onto unit circle

Phase angle

24.09.07

ATF2 meeting LAPP; David Urner

12

Setup at ATF2

Shintake monitor table

QD0

ATF2 Beamline

Goal: Prove we don’t induce vibrations onto Shintake monitor

Problem: No room for wings that arerequired to get necessary stiffness

Possible solutions:-Attach to QD0 support table-Cross brace between Shintake table and QD0 support table

79 Hz mode

What is the gap between QD0 support table and Shintake Monitor?

24.09.07

ATF2 meeting LAPP; David Urner

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Vertical table for mounting interferometer(made of non-magnetic SUS honeycomb core)

Beam

Horizontal table for mounting vertical table(made of steel honeycomb core)

Cover for preventing LASAR

(Base plate forEnsure flatness)

Table for F.F.magnets

Horizontal position

adjustment

Rigid mount for optical table-top view outline

24.09.07

ATF2 meeting LAPP; David Urner

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CSM mount at magnet end

Survey holes

What is sizeof cutouts required to mount surveynests

CSM mountedon this platform

Observe motionof pole tips with respect to platformon upstream end of magnet

24.09.07

ATF2 meeting LAPP; David Urner

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CSM mount at Shintake monitor end

Shintake monitor table

Shintake monitor vacuumvessel

IP BPMBeam line

CSM vacuumchamber

Position monitor to measureIP-BPM position with respectto platform

Platform used to mount CSM

24.09.07

ATF2 meeting LAPP; David Urner

16

Next steps

Develop mounting structure compatible with ATF2 layout Is there space for a cross brace between

Shintake monitor and magnet table Can we attach our system to magnet table

Develop real designs for platforms on magnet and Shintake monitor side.

Make conceptual design for CSM vacuum vessel.

24.09.07

ATF2 meeting LAPP; David Urner

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Plans

Develop CSM Monitor ATF2 IP Laser frequency stabilisation with 87Rb

standard Required for stable FFI

Demonstrate nm resolution in vacuo Install interferometers into vacuum drum

Continue analysis software collaboration with LiCAS Analysis framework Adapt LiCAS readout hardware / software

24.09.07

ATF2 meeting LAPP; David Urner

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Simplified Schematic:

40 MHz

Laser 1560 nm

Correctionto laser

frequencyAO

modulator(dithering

about line centre)

Stabilised frequency at 1560 nmEDFAC-band

SHG produces780 nm

PPLN

87RbCell

VCOf

3f

PD

Lock - in

Frequency stabilisationFrequency standard: 87Rb D2 line at 780 nm

24.09.07

ATF2 meeting LAPP; David Urner

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Frequency standard : 87Rb D2 line at 780 nm

Take ultra – narrow line-width laser at 1560 nm Amplify with EDFA (erbium doped fibre) Frequency double in PPLN to produce 780 nm Use saturated absorption spectroscopy 87Rb to

pick out hyperfine structure Lock source laser to peak providing stability of

a few kHz (compared to 1 MHz without Rb) At 10 m range, 1 MHz limits resolution to 5 nm

locked laser (theoretically 20 pm) other errors will take over