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Alignment: Virgo+ changes

Alignment: Virgo+ changes. Topics. Fast quadrant centering system New Alignment electronics Anderson technique?. Fast Quadrant Centering System. Present centering system. Q1p. Q21. Q71. Q81. WSR10. Q22. Q72. Q51. Translation stage centering < 0.3 Hz. Requirements for centering.

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Alignment: Virgo+ changes

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  1. Alignment: Virgo+ changes

  2. Topics • Fast quadrant centering system • New Alignment electronics • Anderson technique?

  3. Fast Quadrant Centering System

  4. Present centering system Q1p Q21 Q71 Q81 WSR10 Q22 Q72 Q51 Translation stage centering < 0.3 Hz

  5. Requirements for centering With the present centering configuration (activates every few minutes) RMS change of a factor of 4 Extrapolating from these measurements… Taking a reasonable range around the “minimum”, the maximum DC asymmetry must be less than 0.1 G. Vajente Even with the best centering rate now possible (every 4-5 seconds) we can’t reach this precision.

  6. Test of GEO system on NE bench B7_q2 QD

  7. Galvo feedback on NE bench (07/2006) • Digital feedback • Used existing Qr server (slightly modified) • 30 Hz bandwidth • Commercial galvo driver tested at EGO: OK Quadrant Electronics ADC Asymmetry computing Filter DAC DC Signals Qr Server DOL (DAQ) Galvo Driver Tilting Mirrors

  8. Galvo system performance I T-stage centering Centering is given in normalized asymmetry Galvo centering

  9. Galvo system performance II Galvo off Galvo on Error signals Galvo on Beam position fluctuations become visible in the correction signal Correction signals

  10. Fast galvo centering: cost Estimate; to be updated with recent information

  11. Possible work plan • Suggestion: we should start preparing the system now • Last tests finished successfully (galvo drivers) • Procurement of material (2 months) • Delivery time of galvos, drivers, mirrors, mirror holders • Realization of mechanics • Check space constraints on benches • Make new optics layout • Prepare new version of Gc • Reading galvo voltages instead of QD DC signals • Implementation (2 shifts per bench) • Rearrangement of mirrors • Cabling • Reconfiguration of Qr server, connection to Gc • Adaptations in Alp • => Could be implemented after science run, or for Virgo+

  12. Implementation Plan Possible planninng M1 M2 M3 Tasks and Deliverables W1 W2 W3 W4 W1 W2 W3 W4 W1 W2 W3 W4 Tasks 1: Order galvos, … 2: New bench designs 3: Modify mechanical drawings 4: Production of mechanics 5: Adapt global control 6: Install new centering system Deliverables 1: Mechanics 2: Galvo assemblies 3: New centering system From change request draft; to be confirmed

  13. New Alignment Electronics

  14. New alignment electronics • Demodulation board • Spares with slight improvements • Higher LF cut-off • 4 gain settings (instead of 2) • … • QD front-ends • Improved version, but fully compatible (mechanical, connectors,…) • Higher light power • Lower electronics noise • Lower offsets • Better geometrical configuration • Changeable gain • … • See Virgo CHRQ 008/2006

  15. LA electronics status • Demodulator • 2 prototype boards received and tested - OK • One of these boards is now used for Q22 (8 MHz) • 3 more (final) boards under production as spares • Front-end electronics • Large delay due to manpower problems • Tentative planning (CHRQ) was: delivery ~ Feb. 2007 • Present plans: • Produce some spares (for run?) • Produce enhanced version • Design review needed before production of final FE’s • CHRQ contains some big changes • Planning/status: See talk by Jo • => Wait for discussions with Nikhef before making planning • But possible scenario: • Spares for science run • Enhanced version for IInd commissioning period or Virgo+

  16. Anderson technique

  17. Anderson: fundamental mode resonance TEM00 Upper Sideband Carrier Lower Sideband

  18. Anderson: 1st order resonance TEM01 Upper Sideband Carrier Lower Sideband LMC = 143.5722 m fmod = 6264287 Hz

  19. Anderson: optical scheme Get two more output ports for alignment (4 quadrant diodes)

  20. What we should think about • Necessity of end quadrants not clear • Present Virgo might function without them • Virgo+ ? • Effects of Anderson frequency • Anderson offset (during CITF): made locking more difficult • Still an issue? • Stronger mixing of alignment error signals • Without Anderson frequency, maybe no need of 2nd modulation • Simulations to be done • Effort needed for abandoning Anderson frequency • Shift MC length (5 cm for 2 kHz freq. shift) • Other? • No investigations started yet • If you have an opinion, please give your arguments

  21. End

  22. Fast galvo centering: cost ITF quadrant diodes + MC quadrant diodes (caution: IMC QD’s have integrated demodulator!)

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