1 / 20

Virgo – I njection SYS tem …Today and Tomorrow… Olivier FRAN Ç OIS

Virgo – I njection SYS tem …Today and Tomorrow… Olivier FRAN Ç OIS (European Gravitational Observatory). ISYS nowadays… Current problems/limitations Next upgrades. Introduction. ISYS today…situation wrt the interferometer. ISYS today…the Injection Bench. Mode Cleaner reflection.

erasto
Download Presentation

Virgo – I njection SYS tem …Today and Tomorrow… Olivier FRAN Ç OIS

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. Virgo – Injection SYStem …Today and Tomorrow… Olivier FRANÇOIS (European Gravitational Observatory)

  2. ISYS nowadays… Current problems/limitations Next upgrades Introduction

  3. ISYS today…situation wrt the interferometer

  4. ISYS today…the Injection Bench Mode Cleaner reflection Toward Mode Cleaner Mode Cleaner transmission M4 M6 O S M2 N E From the Laser Lab M1 Dps M3 M5 Toward the interferometer Beam going through M1 and entering the RC RC (reference cavity)

  5. Power Recycling back scattering and IMC instability Injection Bench resonances Mode Cleaner mirror defects Injection System alignment Monolithic Power Recycling mirror Current problems/limitations

  6. PR backscattering & IMC instability PR aligned PR misaligned IMC control loop for freq stab is perturbated

  7. PR backscattering & IMC instability Temporary solution: decrease to 10% the amount of light transmitted to the ITF (1% of the light is back-reflected by the PR into the MC) Definitive solution: Implement a Faraday isolator Not enough room on the current IB>redesign

  8. IB resonances IB internal modes Susp. wires Finite element model analyis

  9. IB resonances • Higher frequency modes (dihedron, reference cavity, …) are more difficult to be identify

  10. IB resonances 26/06 C4: control from the ground coils 07/09 DT: control from the marionetta • Many attempt to explain how IB resonance noise enters in the interferometer • Local control noise enters through coil drivers noise • Coherence between coil driver output and B2_ACq confirms this hypothesis • Controlling from the marionetta improves only partially the noise • On the 18-10-2004 it has been understood that the modulation frequency of the MC was about 70 Hz away the MC length matching frequency Before frequency tuning After frequency tuning

  11. MC mirror defects • The source of a large part of the light scattering we have in the ISYS is due to the MC mirror • That scattering is only partially due to dust contamination => The MC mirror will be changed

  12. Present Injection System alignment scheme -- lock servo -- alignment servo lock MC length on RFC MC auto- alignment LC picomotors piezos MC RFC auto- alignment ty tx Laser LC ABP Matrix Matrix MC lock frequ. prestab. NF NF FF h h v Ref. cav. h v FF M6 M3 M5 M2

  13. Injection system alignment • The stability and reproducibility of the IMC alignment is not completely reliable • Present Injection System is automatically aligned on the RC: RC transmission drifts less than the Mode Cleaner one • It would be better align separately IMC and RC

  14. Power recycling mirror • PR is a composite mirror • It shows internal modes at low frequency (about 100 and 400Hz) • These frequencies are changing in time • They are making the locking more complex and the final noise higher

  15. Next upgrades: IB redesign

  16. Next upgrades: IB redesign

  17. Next upgrades: IB redesign

  18. New automatic alignment system New hardware is needed Next upgrades: new alignment scheme -- alignment servo Beam pre- Alignment (Frederic Cleva) RFC auto- alignment Beam drift control IMC auto- alignment picomotors piezos MC Laser LC ABP ABP Matrix Matrix Matrix NF NF FF Ref. cav. FF M6 M3 M5 M2

  19. Next upgrades: new PR • In the last VSC it has been decided to make the PR flat and without wedge, like the Input Mirrors: • A substrate is ready. Only coating time needed • It allows thermal regulation of the PR cavity reflectivity • An off-axis parabolic mirrors for the telescope in the IB has to be assembled IMC: waist 4.9 mm Condensing telescope FI: waist 2.65 mm M5: f= 75 mm M6: f = 600 mm Ø  10 cm to PR: waist=20 mm d= 675 mm

  20. Thermal lensing effect [100m-10m] can be compensated (curved FI exit surface) Not necessary to implement a FK51 compensator Next upgrades: OAPM telescope

More Related