Advanced Virgo design finalization form by pptfiles

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									Advanced Virgo construction outline form

Subsystem INJ
Eric Genin January 2009 v3 0. Documents
Authors The Virgo collabora tion The Virgo collabora tion LIGO Science Collabor ation Marque, Genin, La Penna Date 10/2007 Title Advanced Virgo Conceptual design Link https://pub3.egogw.it/codifier/includes/showTmpFile. php?doc=1900&calledFile=VIR042A-07.pdf https://pub3.egogw.it/codifier/includes/showTmpFile. php?doc=2110&calledFile=VIR089A-08.pdf LIGO G-07011700-00-R

10/2008

Advanced Virgo Preliminary Design

08/2007

Input Optics Subsystem Preliminary Design Document

12/2008

Advanced Virgo: INJ subsystem Design study.

1. Description The INJ subsystem of Advanced Virgo takes care of the optics downstream of the high power laser, and of the interface of these optics and the laser itself. The whole system must deliver a beam with the required power, geometrical shape, frequency and angular stability. Given the 180-200 W power delivered by the High Power Advanced Virgo laser all the components will have to be compliant with this high power. An EOM system will provide the needed RF modulations (for control and sensing purposes). A power adjustment system will be used in order to tune ITF input power (important for ITF lock acquisition). A matching and steering system in air will be used to couple the beam into an in-vacuum suspended input mode cleaner (IMC) cavity. The IMC will geometrically clean the beam and reduce its amplitude and lateral fluctuation. The resonant IMC of which the length is locked on the reference cavity (RFC) will also serve as a first stage of frequency pre-stabilization. After the IMC an intensity stabilization section will provide the signal for stabilizing the laser RIN and reach the requirements (this should be provided by PSL subsystem). An in-vacuum Faraday isolator will prevent interaction of the ITF (interferometer) rejected light with the IMC and laser system. Finally, an ITF mode matching telescope will give to the beam the correct dimension for matching with the interferometer. A block diagram of INJ subsystem is given in figure 1.

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IMC Reflection Sensing

Figure 1 : INJ subsystem block diagram.

2. Project issues

Project table
No. Task 1 Electro-optical modulation system Phase Constr Duration 6 months Predecessor Possible start Mid 2010 Cost 40 kE (with a spare) Manpower Depends on the solution chosen (see INJ Design finalization form) 0.25 opt. P or E

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3 4 5

Constr Input Power Control Beam Pointing Constr Control Input Beam Jitter Constr Monitoring Constr Input beam spatial characterization Constr Input modecleaner (mirrors production: ordering, polishing and coating)

1 month

Possible start End 2010 Possible start End 2010 Possible start End 2010 Possible start Mid 2010

3 months 2 months 6 months

11 kE (with a spare) 20 kE 5 kE

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7 months

Possible start Jan 2010

Depends on the chosen configuration

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6 Input modecleaner (mirrors mechanics) Input Mode Cleaner

Constr

4 months

Possible start Mid 2010

Depends on the chosen configuration Depends on the solution chosen (see INJ Design finalization form) External production 2 optical P or E 40 kE

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Inst

2 months

Possible start Jan 2012

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7

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UHV Faraday isolator production UHV Faraday Isolator installation Other Faraday Isolators order/delivery Other Faraday Isolators installation

Constr

6 months

Mid 2010

80kE (with one spare)

Inst

0.5 month

Constr

3 months

New SIB ready for assembling Possible start End 2010 FI compliant with high power ordering and delivery Possible start Jan 2011 Vacuum pieces purchased and ready to be installed AdV Laser beam available and IMC cavity mirrors installed New SIB ready for assembling Design choice made

Inst

0.25 month

2 opt. P or E 1 electr. E

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9

RFC vacuum pieces order/delivery Reference Cavity installation

Constr

2 months

20 kE

Inst

1.5 month

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IMC Mode Matching Telescope

Inst

0.5 month

20 kE

Depends on the solution chosen (see INJ Design finalization form) 2 opt. P or E

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Optical 6 months and mechanical Design + Purchase Legend: P=physicist, E=engineer, T=technician, ...

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ITF Mode Matching Telescope Assembling of the various subsystems together

Inst

0.5 month

5 kE

2 opt. P or E

245 kE

2 opt. P or E

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It is not possible for the moment to give an accurate estimation of time and cost required for each tasks since there are a lot of open points where an answer should come the design study that should be completed not before May 2009. A. Deliverables EOM: We should provide and EOM system able to modulate the laser beam as required by ISC subsystem (for ITF and IMC control and locking purpose). The modulation electronics will have to be properly designed and characterized to be compliant with AdV requirements. Input Power Control (IPC): With this system we should be able to remotely tune the laser power from low (a few watts) up to full power. This system will be based on Virgo+ IPC system. The laser power should be adjusted in two points of INJ subsystem. Before the IMC cavity and on the suspended injection bench after optical elements that are sensitive to laser beam heating in order to adjust the laser power at the interferometer input port. Beam Pointing Control: The aim of this control loop is to reduce angular beam jitter and shifts of the beam at low frequency before entering vacuum vessels. Dedicated sensors will have be developed starting from Virgo experience in this field. Input Beam Jitter Monitoring: We should provide a system that monitors beam shifts and tilts on the whole sensitivity curve bandwidth. The main concern is about the sensor choice and the proper design of the dedicated electronics to detect very low jitter noise on the 10 kHz bandwidth. Input Beam Spatial and Spectral Characterization system: It should provide some useful tools to characterize ITF input beam properties. This characterization should be done by different ways: - Beam imaging in order to extract geometrical properties of the beam - Beam quality (higher order modes content beam spectral characterization ). - Sidebands characterization before entering the ITF. Input Mode Cleaner cavity: The input mode cleaner should provide active frequency stabilization through feedback to the Laser, passive frequency noise suppression above its cavity pole frequency, and passive spatial stabilization at all frequencies. The input mode cleaner should also reduce higher order modal content of the laser beam entering the vacuum vessels. A locking electronics will have to be provided as well as an automatic aligment system (opto-electronic control loops will have to be designed and carried out). Faraday Isolators: High power compatible in-vacuum faraday isolator compensated in term of thermal lensing and depolarization. A remote adjustment of the isolation should also be provided. Reference cavity: A cavity used a reference to control and the IMC cavity length and lower the laser frequency noise in order to lock the Fabry-Perot cavities should be provided. According to preliminary calculations Virgo reference cavity should fulfil AdV requirements. IMC Mode Matching Telescope: A telescope to match the laser beam and maximize the coupling into the IMC cavity should be designed and carried out. It could be interesting to have this device remotely adjustable.

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ITF Mode Matching Telescope: The same kind of telescope has to be built to match the IMC output beam onto the interferometer (ITF). This telescope has to be vacuum compatible and should be remotely adjustable. Choosing a non-degenerate power recycling cavity will relax a lot the work on this telescope. Assembling of the various subsystems together: All the various subsystems of INJ have to be assembled. A general layout of in-air and invacuum benches has to be given. From the layout, optics, electronics and mechanics parts will be designed, selected and purchased (optics mounts, optical benches, actuators, sensors,…). These parts will have to fulfil AdV requirements. In particular, low scattering optics and mechanical mounts specially designed to avoid low frequency resonances should be used in order to reduce environmental noise coupling. B. Time planning

This time planning will be given later on. C. Subsystem interdependencies External predecessors For all the different parts of INJ system, we will need: - Infrastructures ready (Air conditioning, room) - INJ and MC tower super attenuators upgraded as required for AdV. EOM: - Modulation frequencies and modulation depth are need from ISC. - Prototype from HPIO R&D (crystal selection, modulation electronics). - Information on laser output beam size is required from LAS. Input Power Control (IPC): - AdV laser should be installed. Beam Pointing Control: - Requirements on beam jitter should be given before designing the system (sensors and actuators selection and optical design). Input Beam Jitter Monitoring: - Requirements on beam jitter monitoring should be given before designing the system (sensors selection and electronics realization). Input Beam Spatial Characterization system: - Characterization means have to be defined (scanning cavity, beam imaging and beam size measurement systems,…).

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Input Mode Cleaner cavity: - Requirements on laser frequency prestabilization, Intensity noise filtering and passive beam jitter filtering should be given to freeze IMC cavity parameters (Finesse, mirrors reflectivity,…). These requirements should be given by OSD and ISC subsystems. Faraday Isolators: - Requirements on Faraday isolator isolation should come from IMC cavity design study. - UHV compatible faraday isolator that is compensated for depolarization, thermal lensing and where the isolation is remotely tuneable (as done in Virgo+) should be studied by IAP group (Novgorod, Russia). - From the design study, a prototype should be built. - SIB optical design (faraday integration). Reference cavity: - Simulation (RFC FEM simulation). - Evaluation of EIB-SIB differential motion. - EIB optical design. - SIB optical design. - Requirement for locking (locking strategy) given by ISC subsystem. IMC Mode Matching Telescope: - IMC cavity parameters (waist size, waist location). - Optical simulations using an optical simulation software (Zemax, Code V,…). ITF Mode Matching Telescope: - ITF parameters (waist size, waist location). - Optical simulations using an optical simulation software (Zemax, Code V,…). Assembling of the various subsystems together: - Laser output beam and ITF input beam characteristics (waist size, waist location) are required from LAS and OSD. - Optical simulations using an optical simulation software (Zemax, Code V,…). External successors EOM: - IMC cavity and Interferometer locking and alignment activities will require the installation of the EOM system. Input Power Control (IPC): - IMC and ITF locking strategy at different laser power levels. Beam Pointing Control: - Required to commission the ITF and reach high sensitivity at low frequency. Input Mode Cleaner cavity: - Power stabilization and Laser frequency pre stabilization loops commissioning. - Interferometer installation (core optics installation and alignment) and commissioning.

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Faraday Isolators: - Required to lock the interferometer to avoid sending back the ITF reflection in the IMC cavity (can be uncontrollable) and in the laser (can be damaged). Reference cavity: - Laser frequency stabilization loop commissioning. - AdV Interferometer locking activities. IMC Mode Matching Telescope: - IMC cavity commissioning (locking and alignment system). ITF Mode Matching Telescope: - Interferometer commissioning (locking and alignment system). Assembling of the various subsystems together: - INJ subsystem installation and commissioning. - Interferometer alignment and commissioning. D. Cost A rough estimation of INJ subsystem cost is given in Table 1. Item Price (kE)

Ultra high vacuum Faraday isolator 80 EOM system 40 Input power control 11 Beam pointing control 20 Quadrant photodiodes 4 Actuators 12 Mechanics 3 Input beam jitter monitoring 5 Quadrant photodiodes 4 Mechanics 1 Input beam spatial and spectral characterization system 30 In-air high power compliant faraday isolators 40 RFC (vacuum pieces(pump,...)) 20 IMC mode matching telescope (optics, electronics, mechanical mounts,...) 20 ITF mode matching telescope (optics, electronics, mechanical Depends on Recycling cavity optical mounts,...) configuration (5 kE if NDRC) Assembling of the various INJ parts together 245 Polarizers 20 Low-scattering in-air optics 50 In-air mechanics 60 Suspended injection bench mechanics (excluded IMC and PR mirrors suspensions) 30 Other optics (waveplates, mirrors, lenses,...) 20 Vacuum compatible electronics 50 In-air electronics (photodiodes (single element and quadrant), locking electronics) 15 New resonant Input Mode-Cleaner (mirrors, mechanics, electronics,…) 150 TOTAL 666 Table 1 : Rough cost estimation of INJ subsystem by construction task.

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This estimation has been given without taking into account the taxes and the total cost is about 666 kEuros with spare parts. For the specific item of ITF mode matching telescope, a contingency of about 100 kEuros has to be considered if it is decided not to use the Non Denegerate Recycling Cavity configuration. In this case, the ITF mode matching telescope will have to be an off-axis parabolic telescope of the same kind that what is currently used in Virgo. Due to cavity geometry, the second mirror of this telescope will have to be at least 300 mm diameter to avoid clipping losses. A 10 % contingency for the rest should be foreseen since a lot of parts should be bought in the USA and are obviously depending on Euro/Dollar exchange rate. E. Manpower The manpower given in the project table is very rough and based on past experience in Virgo. This will be completed once we will know the technical solution chosen for each part of INJ subsystem. F. Construction/installation responsibilities EOM: EGO lab, who has an extensive experience on this item and that is the principal investigator of HPIO R&D program that aims to select and carry out a prototype compliant with AdV needs, is the best institute to take care of this system. Input Power Control (IPC): The responsibility should be assigned to EGO lab since this lab has already carried out Virgo+ IPC system. Beam Pointing Control & Input Beam Jitter Monitoring: Virgo Beam Monitoring System that aims to monitor and control the beam jitter is well known by EGO. EGO optics group can be responsible for this task. Input Beam Spatial Characterization system: EGO group has already installed some Beam characterization tools for Virgo Input Mode Cleaner cavity: Concerning the IMC mirrors, LMA that is already responsible for the selection and the purchase of ITF core optics could be responsible for AdV IMC mirrors selection and for the coating of these objects. IMC input mirrors assembling and IMC mirrors suspension lower part : Nikhef. For the mirrors alignment and AdV IMC installation and commissioning, EGO is the right group to be responsible for this activity. Faraday Isolators: A collaboration has started in September 2008 with the Institute of Applied Physics, Novgorod, Russia that is the specialist of High power faraday isolators. They should provide an UHV compliant faraday isolator under the supervision of EGO staff working on HPIO R&D. They could provide some other smaller faraday isolator to be used on the laser and external injection benches. Reference cavity: No particular work to be done. The only thing is to include this object in INJ subsystem optical layout. IMC Mode Matching Telescope: 8

EGO group has an extensive experience in this kind of telescope and could be responsible for this task.

ITF Mode Matching Telescope: APC lab has expressed the wish to work on the ITF Mode Matching Telescopes, one of these telescopes is on the suspended injection bench and could be of the responsibility of APC even if EGO has the required experience to deal with this task. Assembling of the various subsystems together: This task should be assigned to EGO group that has a lot of experience in designing Virgo and Virgo+ optical benches (Virgo+ Laser bench, Virgo and Virgo + EIB and SIB and Virgo+ end benches). 3. Risk Give a list of potential problems. List first the risks during construction/installation (delays of external firm ...) and then eventual risks during operation (failure ...). Problem 1 (C/O) C=Construction/installation risk, O=operation risk Describe the potential problem. Try to assess the probability that the problem occurs. Describe to consequences of the problem. In the following table, try to give quantitative estimates in terms of Euros, man-days of extra workforce needed, days of delay, reduced performance of the subsystem or part of it. Enter text here. Extra cost Extra needed manpower Delay Performance of subsystem/AdV Other Describe possible solutions. Enter text here. Problem 2 Copy from Problem 1...

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