1 ist virgo+ review cascina 03.04.2007 h. heitmann alignment: virgo+ changes

1 Ist Virgo+ review Cascina 03.04.2007H. Heit mann

Alignment: Virgo+ changesAlignment: Virgo+ changes


• Fast quadrant centering systemFast quadrant centering system

• New Alignment electronicsNew Alignment electronics

• Anderson technique?Anderson technique?

TopicsTopics


Fast Quadrant Centering SystemFast Quadrant Centering System


Present centering systemPresent centering system

Translation stage centering < 0.3 Hz

Q1p

Q51 Q22

Q21

Q72

Q71 Q81

WSR10


Requirements for centeringRequirements 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


Test of GEO system on NE benchTest of GEO system on NE bench

QD

B7_q2


Galvo feedback on NE bench (07/2006)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


Galvo system performance IGalvo system performance I

Centering is given in normalized asymmetry

T-stage centering

Galvo centering


Galvo system performance IIGalvo system performance II

Error signals

Correction signals

Galvo on

Beam position fluctuations become visible in the correction signal

Galvo offGalvo on


Fast galvo centering: costFast galvo centering: cost

QD's to be equipped 10

pcs spares price totalGalvo G102 20 4 415 9960Driver A 102 20 4 227 5448Mechanics 10 2 50Mirror substrate 20 4 24 576Coating 1 0 1000 1000Mirror mount 10 2 200 2400

Total 19434

Estimate; to be updated with recent information


Possible work planPossible work plan

Suggestion: we should start preparing the system nowLast tests finished successfully (galvo drivers)

Procurement of material (2 months)Delivery time of galvos, drivers, mirrors, mirror holdersRealization of mechanics

Check space constraints on benchesMake new optics layout

Prepare new version of GcReading galvo voltages instead of QD DC signals

Implementation (2 shifts per bench)Rearrangement of mirrorsCablingReconfiguration of Qr server, connection to GcAdaptations in Alp

=> Could be implemented after science run, or for Virgo+


Possible planninngPossible planninng

Implementation Plan

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


New Alignment ElectronicsNew Alignment Electronics


New alignment electronicsNew alignment electronics

Demodulation boardSpares with slight improvements – Higher LF cut-off– 4 gain settings (instead of 2)– …

QD front-endsImproved version, but fully compatible (mechanical, connectors,…)– Higher light power– Lower electronics noise– Lower offsets– Better geometrical configuration– Changeable gain– …See Virgo CHRQ 008/2006


LA electronics statusLA electronics status

Demodulator2 prototype boards received and tested - OKOne of these boards is now used for Q22 (8 MHz)3 more (final) boards under production as spares

Front-end electronicsLarge 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’sCHRQ contains some big changes

Planning/status: See talk by Jo

=> Wait for discussions with Nikhef before making planningBut possible scenario:– Spares for science run– Enhanced version for IInd commissioning period or Virgo+


Anderson techniqueAnderson technique


Anderson: Anderson: fundamental mode fundamental mode resonanceresonance

Carrier

Upper Sideband

Lower Sideband

TEM00


TEM01

Anderson: Anderson: 11stst order order resonanceresonance

Carrier

Upper Sideband

Lower Sideband

LMC = 143.5722 mfmod = 6264287 Hz


Anderson: optical schemeAnderson: optical scheme

Get two more outputGet two more outputports for alignment ports for alignment (4 quadrant diodes)(4 quadrant diodes)


What we should think aboutWhat we should think about

Necessity of end quadrants not clearPresent Virgo might function without themVirgo+ ?

Effects of Anderson frequencyAnderson offset (during CITF): made locking more difficult

Still an issue?

Stronger mixing of alignment error signalsWithout Anderson frequency, maybe no need of 2nd modulation

Simulations to be done

Effort needed for abandoning Anderson frequencyShift MC length (5 cm for 2 kHz freq. shift)Other?

No investigations started yetIf you have an opinion, please give your arguments


Fast galvo centering: costFast galvo centering: cost

QD's to be equipped 12

pcs spares price totalGalvo G102 24 4 415 11620Driver A 102 24 4 227 6356Mechanics 12 2 50Mirror substrate 24 4 24 672Coating 1 0 1000 1000Mirror mount 12 2 200 2800

Total 22498

ITF quadrant diodes + MC quadrant diodes(caution: IMC QD’s have integrated demodulator!)

1 ist virgo+ review cascina 03.04.2007 h. heitmann alignment: virgo+ changes

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