1. 1 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann Alignment: Virgo+ changes

2. 2 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann Fast quadrant centering system Fast quadrant centering system New Alignment electronics New Alignment electronics Anderson technique? Anderson technique?Topics

3. 3 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann Fast Quadrant Centering System

4. 4 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann Present centering system Translation stage centering < 0.3 Hz Q1p Q51 Q22 Q21 Q72 Q71 Q81 WSR10

5. 5 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann 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 Even with the best centering rate now possible (every 4-5 seconds) we can’t reach this precision. G. Vajente

6. 6 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann Test of GEO system on NE bench QD B7_q2

7. 7 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann Galvo feedback on NE bench (07/2006) Quadrant Electronics ADC DC Signals Asymmetry computing DAC Galvo Driver Filter Qr Server Tilting Mirrors DOL (DAQ) Digital feedback Used existing Qr server (slightly modified) 30 Hz bandwidth Commercial galvo driver tested at EGO: OK

8. 8 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann Galvo system performance I Centering is given in normalized asymmetry T-stage centering Galvo centering

9. 9 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann Galvo system performance II Error signals Correction signals Galvo on Beam position fluctuations become visible in the correction signal Galvo off Galvo on

10. 10 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann Fast galvo centering: cost Estimate; to be updated with recent information

11. 11 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann 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. 12 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann Possible planninng Implementation Plan M1M2M3 Tasks and DeliverablesW1W2W3 W4W4 W1W2W3W4W1W2W3W4 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. 13 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann New Alignment Electronics

14. 14 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann 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. 15 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann 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: 1.Produce some spares (for run?) 2.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. 16 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann Anderson technique

17. 17 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann Anderson: fundamental mode resonance Carrier Upper Sideband Lower Sideband TEM 00

18. 18 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann TEM 01 Anderson: 1 st order resonance Carrier Upper Sideband Lower Sideband L MC = 143.5722 m f mod = 6264287 Hz

19. 19 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann Anderson: optical scheme Get two more output ports for alignment (4 quadrant diodes)

20. 20 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann 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 2 nd 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

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22. 22 Ist Virgo+ review Cascina 03.04.2007 H. Heitmann Fast galvo centering: cost ITF quadrant diodes + MC quadrant diodes (caution: IMC QD’s have integrated demodulator!)