Pythonic Mathematics Kirby Urner EuroPython 2005 Göteborg, Sweden.
Stabilization of Focus at ATF2 David Urner University of Oxford.
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Transcript of Stabilization of Focus at ATF2 David Urner University of Oxford.
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Stabilization of Focus at ATF2
David Urner
University of Oxford
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ATF2 Meeting May 2006 2
StaFF→MonALiSA
Dr. David Urner Dr. Paul Cole Dr. Armin Reichold
Stephanie Yang(mechanical engineering)
Tony Handford(workshop)
Roy Wastie(electrical engineering)
StaFF Stabilization of theFinal Focus
→
MonALiSAMonitoring of Alignment
and Stabilization with high Accuracy
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ATF2 Meeting May 2006 3
Interferometric Monitoring
• Develop 2 instruments:– Distance meter with nm resolution over 10m– Straightness monitor with nm resolution over
10m
Michelson mode: 1nm resolution relative distances
FSI mode: 1m resolution absolute distances
Distance meter:0.3 0.4 0.5
0
5
10
15
Am
plitu
de /
Arb
uni
ts
Length / m
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ATF2 Meeting May 2006 4
= 7m
FSI Performance
=4m
• Using 5m conventional Michelson interferometer in air as reference.
• Running at small tuning speed• Tuning over small fraction of tuning range
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ATF2 Meeting May 2006 5
Attaching Vacuum System Force-Free
Here attach vacuum tube for interferometerAttached to BPM.
Holds retro reflector.
Firmconnection
Strain Gauge• Needs bellow to allow motion of BPM– Vacuum causes a force
order of 100N!
• Develop small force vacuum mount using double bellow system.
• Allows small motion (~1 mm) of BPM-system
• Test stand to measure remaining (perpendicular) force on BPM frame. -1mm-3mm 1mm 3mm
1N
2N
-1N
0N
-2N
-3N
-3N
Force exerted on carbon frame (BPM)±1mm: < 0.5N/mm±3mm: < 0.8N/mm
Force exerted by perpendicular motion
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ATF2 Meeting May 2006 6
A Straightness Monitor Made from Distance Meters
• Red lines: Distance meter. • Multilateration measure 6D coord. of A with respect to B.
A
B
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ATF2 Meeting May 2006 7
A Straightness Monitor Made from Distance Meters
• Information related via central triangle
Floor node
A
B
Ceiling node 1Ceiling node 1
~2.5m
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ATF2 Meeting May 2006 8
Compact Straightness Monitor
• Too big in perpendicular direction!• Develop compact version
– Need 2 devices to separate rotation from vertical translation. + length measurement
– Next step: Test different ideas
Pointsource
Retro
Mirror
Collimator
Fibre launchand readout
Long arm
Use reflection from fibreend as short arm
Distancemeter
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ATF2 Meeting May 2006 9
Compact Straightness Monitor
• Too big in perpendicular direction!• Develop compact version
– Test different ideas
• Aspect ratio A/B is relevant• A 5m: B somewhere at 20cm – 50cm for 1nm
resolutions
BA
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ATF2 Meeting May 2006 10
ATF2: Stabilization
• General strategy:– Use one active feedback system only, which can combine inputs
from several measurements• Difficult if active feedback system compete!
– Test of a system with several input measurements using StaFF setup that will be installed at ATF.
– Big question is where to locate the actuators to get best response
• Should consider a system moving beam with kicker rather than move Shintake monitor.– This is a feed forward system, which is easier to control than an
active feedback system.– Additional cost?– Do we introduce jitter by such a kicker, and how much?
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ATF2 Meeting May 2006 11
Placement of MonALiSA monitoring system at ATF2
• Easiest if we have direct line of sight between FF quadrupole and Shintake monitor.– Which is the crucial element of Shintake monitor do
we have to monitor. • Are there several parts to monitor • Can we get optical access to the crucial element(s)
• We need room (30-50cm) above either the Shintake monitor or above the FF magnet– Probably easier to get above magnet.
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ATF2 Meeting May 2006 12
Funding and Timeline
• We are currently preparing bids to get funding in the framework of LC-ABD – 1 postdoc 2007-2010– ½ DAQ expert– Resources in electronics engineering and
construction, mechanical design and workshop– Funds to develop prototype and final system for ATF2
• We expect to have a first system ready early 2009.– Any reason why we urgently should be ready earlier?
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ATF2 Meeting May 2006 13
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ATF2 Meeting May 2006 14
Distance meter simulation
• Simulation done with Zemax
• Use non-sequential mode– Take into account
polarisation → correct interference pattern
– Allows stray light analysis
• Allow analysis of chromatic aberrations
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ATF2 Meeting May 2006 15
Simulated Interference Patters
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ATF2 Meeting May 2006 16
Piezzo Driven Monitor
Detector
Detector
PZT
MovingMirror
Mirror
Mirror
Mirror
Splitter
Splitter
Splitter
Tuning laser
SinglePointmeasurement
980 1000 1020 1040 1060 1080
-4
-3
-2
-1
0
1
2
3
4
Phase stepping cycle
Laser is tuning continuously
Pha
se
/rad
ian
s
(Derive phases modulo 2from intensity data)
Moving mirror: Measure Intensity pattern
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ATF2 Meeting May 2006 17
3–D mechanical model, detector side removed for clarity
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ATF2 Meeting May 2006 180 10 20 30 40
-5
0
5
10
15
0 10 20 30 40-2
0
2
Te
mp
era
ture
ch
an
ge
/ m
K
Time / s
Re
f V
/ m
V
Time / s
Reference channels Thermometer channels
First Temperature Measurements