alignment status & plans
DESCRIPTION
Alignment status & plans. 2 nd modulation frequency. 2 nd modulation frequency: absolute (demodulated) reference for common end alignment (not available with one f mod ) Previously aligned with ITF reflection Q21_DC. 2 nd mod. (8.35 MHz). IMC mod. (22.4 MHz). Virgo mod. (6.26 MHz). - PowerPoint PPT PresentationTRANSCRIPT
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1 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Alignment status & plansAlignment status & plans
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2 Commissioning meeting, Cascina 02.04.2007H. Heit mann
22ndnd modulation frequency modulation frequency
Virgo mod. (6.26 MHz)
2nd mod. (8.35 MHz)
2nd modulation frequency:absolute (demodulated) reference for common end alignment
(not available with one fmod)
Previously aligned with ITF reflection Q21_DC
IMC mod. (22.4 MHz)
2nd mod. on the same EOM => line forest => difficult
Solution: 2nd EOM=> Much less problemsbut modulation must be weak (m=0.01 instead of 0.17)for avoiding perturbations => to be investigated
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3 Commissioning meeting, Cascina 02.04.2007H. Heit mann
22ndnd f fmodmod layout layout
6.26 MHz8.35 MHz
WSR10 alignment layout
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4 Commissioning meeting, Cascina 02.04.2007H. Heit mann
22ndnd f fmodmod: results: results
8 MHz modulation is working Low modulation index => Q22 signal noisy => use at LF
Common end loop adaptedError signal remains Q21_DCAbsolute Q21 position set by shifting until Q22_AC = 0
(Alp loop; stopped in science mode)
Alternative possibility“Mix” Q22_AC (LF) <=> Q21_DC (HF)
One error signal; filters in sensing matrix
Advantage: absolute DC reference is kept during science mode
Q21_DCQ22_8 MHz
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5 Commissioning meeting, Cascina 02.04.2007H. Heit mann
B7_q1
B7_q2
B7
B8_q2
B8
B8_q1
WE
WI
NI NE
BS
PR
End mirror beam centering - beforeEnd mirror beam centering - before
BeforeDSP Drift controlQD error signalB8_q1_DC B8_q2_DCB7_q1_DCB7_q2_DC
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6 Commissioning meeting, Cascina 02.04.2007H. Heit mann
B7_q1
B7_q2
B7
B8_q2
B8
B8_q1
WE
WI
NI NE
BS
PR
End mirror beam centering - nowEnd mirror beam centering - now
NowAlp Drift controlAlp error signal7...8 Hz line on NE/WE tx/tyLocking correction in z=> control input mirrorsNoise reductionbut: upconversion 10-15 Hz ?!
10 Hz
beforeafter
(high ISYS noise!)
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7 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Alignment noise in dark fringeAlignment noise in dark fringe
Differential end mirror tx mode almost limiting=> more power on Q1p diode + whitening filter=> alternative: improve corrector cut-off (but: need all margin for high LF gain)
G. Vajente Automated alignment noise projections (10 min.)
Coherence
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8 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Recent Gc-Ali upgradesRecent Gc-Ali upgrades
Sensing – Filtering – Driving availableDriving switch needed during thermal transient(switch NE-WE => Common-Differential)
Noise injection For measurement of open loop transfer functions
Filtering gain change on-flyFor migrating all gain changes from DSP to Gc
Sensing Filtering DSP
Global control
Driving
Noise
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9 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Alignment OL transfer function measurementsAlignment OL transfer function measurementsDifferential end tx
Excellent fit with Matlab model
Gain adjustment => matrix calibration
Differential end ty
? Less excellent fit
But still good in the important region (a few Hz)
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10 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Other improvementsOther improvements
Thermal transient robustnessImproved by switching on 1. differential 2. common end alignmentDriving matrix NE/WE => NE+WE/NE-WE after thermal transientPR alignment acts on reference mass
Local control on marionette remains on
High gain filters (end mirror control)Further tuning needed Sometimes more gain than needed
=> Rather invest in HF cut-off
HistogramDiff end tx error signal
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11 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Plans up to scientific run IPlans up to scientific run I
Improve alignment stability (filter work)Sometimes oscillations during thermal transientCheck stability in bad weather conditions
Reduce alignment noise10-50 Hz: alignment noise starts becoming important
Error signal improvement (B1p: more light + preshaping)
Filter tuning (LF gain / HF cutoff trade-off)
Continue transfer function measurementsLine injections for better coherence
Understand model deviationsMeasure resonance frequencies: rad. pressure effects?
Update sensing matrix
Continue alignment globalizationMore logical system: all gain adjustments in Gc, …
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12 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Plans up to scientific run IIPlans up to scientific run II
Common mode error signal improvementCreate composite error signal (mix Q22_ACLF + Q21_DCHF)
Observe beam centering loopsImprove if needed (up-conversion, better centering, …)
Centering of input mirrors?TBC
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13 Commissioning meeting, Cascina 02.04.2007H. Heit mann
To be done if neededTo be done if needed
Switch BS/ISYS <-> NI/WI controlLA on NI/WI mirrorsBS/ISYS steer beams in arms
Globalize other LA degrees of freedomPR, BS
PR alignmentKeep LC on marionette on?
Optimize IMC alignment filtersReduce LF beam jitter (higher gain)
Increase 8 MHz modulation indexFirst understand where locking signal perturbation comes from
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End
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15 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Alignment configurationsAlignment configurations
C7 14/09 – 19/09/2005
tx IB PR BS NI NE WI WE ty IB PR BS NI NE WI WE
10 d.o.f. fast alignment
WSR1 08/09 – 11/09/2006
tx BM PR BS NI NE WI WE ty BM PR BS NI NE WI WE
6 d.o.f. fast alignment; input beam and BS control
WSR10 09/03 – 12/03/2007
tx BM PR BS NI NE WI WE ty BM PR BS NI NE WI WE
7 d.o.f. fast alignment; input beam and BS control
XX Linear alignmentXX LA (ref. mass)XX Drift controlXX Local controlXX DC error signalXX DC + AC err.sig.
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16 Commissioning meeting, Cascina 02.04.2007H. Heit mann
WSR10 sensing matrixWSR10 sensing matrix
BMS PR BS NI NE WI WE ThetaX 0.5 B1p_q1_ACq4 B2_q1_ACp 2 B5_q1_ACq -0.5 B8_q1_ACp -1.5 B2_q1_DC 1 B7_q1_DC -1.5 B7_q2_DC 1 B8_q1_DC -0.8 B8_q2_DC
BMS PR BS NI NE WI WE ThetaY -0.6 B1p_q1_ACq4 B2_q1_ACq 2 B5_q1_ACq 0.4 B8_q1_ACq 4 B2_q1_DC 1 B7_q1_DC -1 B7_q2_DC 1 B8_q1_DC -0.7 B8_q2_DC
* Filtered in Gc sensing
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17 Commissioning meeting, Cascina 02.04.2007H. Heit mann
WSR10 alignment control overviewWSR10 alignment control overview
Beam
Diode
Demod.
Loop
Arm diff.
B1p Q Fast
Arm common
B2 12 for
centering
- Fast
PR B5 1 Q Fast
BS B8 1 P (tx)Q
(ty)
Fast (tx)Drift (ty)
NI B7 1+2 - Drift
WI B8 1+2 - Drift
BMS B2 1 P (tx)Q
(ty)
Drift
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18 Commissioning meeting, Cascina 02.04.2007H. Heit mann
WSR10 alignment filteringWSR10 alignment filtering
Sensing Filtering DSP
Sensing Filtering 1DC
Filtering 2Initial
Filtering 3Boost
DSP
PR tx--- --- --- --- Ref.mass
+ mario LC
PR ty--- --- --- --- Ref.mass
+ mario LC
End tx--- --- INITIAL BOOST ---
End ty--- --- INITIAL BOOST ---
Global control
Driving
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19 Commissioning meeting, Cascina 02.04.2007H. Heit mann
WSR10 alignment drivingWSR10 alignment driving
Sensing Filtering DSP
Driving 1Initial_Driving
Driving 2Driving
CommonEnd => NE => NE+WE
Differ.End => WE => NE-WE
Global control
Driving