1 / 19

Alignment status & plans

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).

said
Download Presentation

Alignment status & plans

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Alignment status & plans

  2. 2nd modulation frequency 2nd modulation frequency: absolute (demodulated) reference for common end alignment (not available with one fmod) Previously aligned with ITF reflection Q21_DC 2nd mod. (8.35 MHz) IMC mod. (22.4 MHz) Virgo mod. (6.26 MHz) 2nd mod. on the same EOM => line forest => difficult Solution: 2nd EOM => Much less problems but modulation must be weak (m=0.01 instead of 0.17) for avoiding perturbations => to be investigated

  3. 2nd fmod layout WSR10 alignment layout 6.26 MHz 8.35 MHz

  4. 2nd fmod: results • 8 MHz modulation is working • Low modulation index => Q22 signal noisy => use at LF • Common end loop adapted • Error signal remains Q21_DC • Absolute 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_DC Q22_8 MHz

  5. End mirror beam centering - before B8_q1 B8_q2 B8 WE B7_q1 WI NE B7_q2 NI PR BS B7 Before DSP Drift control QD error signal B8_q1_DC B8_q2_DC B7_q1_DC B7_q2_DC

  6. End mirror beam centering - now B8_q1 B8_q2 B8 WE 10 Hz B7_q1 before after WI NE B7_q2 NI PR (high ISYS noise!) BS B7 Now Alp Drift control Alp error signal 7...8 Hz line on NE/WE tx/ty Locking correction in z => control input mirrors Noise reduction but: upconversion 10-15 Hz ?!

  7. Alignment noise in dark fringe Automated alignment noise projections (10 min.) G. Vajente Coherence Differential end mirror tx mode almost limiting => more power on Q1p diode + whitening filter => alternative: improve correctorcut-off (but: need all margin for high LF gain)

  8. Recent Gc-Ali upgrades • Sensing – Filtering – Driving available • Driving switch needed during thermal transient • (switch NE-WE => Common-Differential) • Noise injection • For measurement of open loop transfer functions • Filtering gain change on-fly • For migrating all gain changes from DSP to Gc Noise Sensing Filtering Driving DSP Global control

  9. Alignment OL transfer function measurements Differential 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)

  10. Other improvements • Thermal transient robustness • Improved by switching on 1. differential 2. common end alignment • Driving matrix NE/WE => NE+WE/NE-WE after thermal transient • PR 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 Histogram Diff end tx error signal

  11. Plans up to scientific run I • Improve alignment stability (filter work) • Sometimes oscillations during thermal transient • Check stability in bad weather conditions • Reduce alignment noise • 10-50 Hz: alignment noise starts becoming important • Error signal improvement (B1p: more light + preshaping) • Filter tuning (LF gain / HF cutoff trade-off) • Continue transfer function measurements • Line injections for better coherence • Understand model deviations • Measure resonance frequencies: rad. pressureeffects? • Update sensing matrix • Continue alignment globalization • More logical system: all gain adjustments in Gc, …

  12. Plans up to scientific run II • Common mode error signal improvement • Create composite error signal (mix Q22_ACLF + Q21_DCHF) • Observe beam centering loops • Improve if needed (up-conversion, better centering, …) • Centering of input mirrors? • TBC

  13. To be done if needed • Switch BS/ISYS <-> NI/WI control • LA on NI/WI mirrors • BS/ISYS steer beams in arms • Globalize other LA degrees of freedom • PR, BS • PR alignment • Keep LC on marionette on? • Optimize IMC alignment filters • Reduce LF beam jitter (higher gain) • Increase 8 MHz modulation index • First understand where locking signal perturbation comes from

  14. End

  15. Alignment configurations • C7 14/09 – 19/09/2005 • tx IB PR BS NI NE WIWE • ty IB PR BS NI NE WIWE • 10 d.o.f. fast alignment • WSR1 08/09 – 11/09/2006 • tx BM PR BS NINEWIWE • ty BM PRBSNINEWIWE • 6 d.o.f. fast alignment; input beam and BS control • WSR10 09/03 – 12/03/2007 • tx BMPR BS NINEWIWE • ty BMPRBSNINE WIWE • 7 d.o.f. fast alignment; input beam and BS control XXLinear alignment XXLA (ref. mass) XX Drift control XXLocal control XX DC error signal XX DC + AC err.sig.

  16. WSR10 sensing matrix BMS PR BS NI NE WI WE ThetaX 0.5 B1p_q1_ACq 4 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_ACq 4 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

  17. WSR10 alignment control overview

  18. WSR10 alignment filtering Driving Sensing Filtering DSP Global control

  19. WSR10 alignment driving Driving Sensing Filtering DSP Global control

More Related