Intermediate review - ERC – February 9, 2009 – L. Pinard 1 Mirrors Sub-System Overview  Introduction  Scope of the subsystem, main tasks  Job done since 1st Review of November 2008  Substrates Procurement  Blank Material (fused silica) : material choice, specifications, planning, cost  Substrates Polishing  Polishing : strategy, choice of the company, planning, cost  Coating : planning, cost  Optical Metrology Upgrade

Intermediate review - ERC – February 9, 2009 – L. Pinard 2 Introduction Mir Sub-system  Procurement and preparation of the AdV test masses and spares Input and End mirrors, Beam Splitter, mirrors for non-degenerate Power and Signal Recycling cavities, Compensation Plates Silica blanks, polishing (Robot – Corrective coating)  Mirrors with larger dimensions (thicker) Modification in the coating process (cleaning, handling) Coatings  Mirrors with RMS flatness better than 1 nm More accurate metrology Metrology modifications Description

Intermediate review - ERC – February 9, 2009 – L. Pinard 3 Since the November Review  Mirror Construction Task form Description of all the tasks, of all the deliverables Time planning, Budget spending profile, Manpower  Mirror Finalization Task form Collecting the informations on all the open design questions Design question : the following decisions needs to be taken depending on open design issues 1) Physical dimensions of some main optics - Beam Splitter (diameter, Thickness) - Signal and power recycling mirrors in the Non Degenerate cavity configuration - Compensation plates 2) Lateral Support for the monolithic suspension New design or classical support (flats+ears silicate bonded) 3) Polishing strategy for the AdV mirrors

Intermediate review - ERC – February 9, 2009 – L. Pinard 4 Substrates Fabrication : 1,5 year o Planning for 4 IM- 4 EM- 3 BS – 4 CP – 6 ndg cavities solution : spares included Serial production of the silica blanks. Possibility to produce in parallel o Heraeus production : first bulk substrate produced after 4 month, then one bulk/2 weeks o Compensation plates included : same silica as IM o Optimization of the planning with Heraeus (include production constraints) Possibility to reduce the silica Blanks budget by 15% Substrates Procurement

Intermediate review - ERC – February 9, 2009 – L. Pinard 5 Substrates Procurement Motivations for Fused silica choice  Manufacturer = HERAEUS (like in VIRGO)  For IM, BS, CP : New fused silica (Suprasil 3001/3002) same optical performances Better bulk absorption (0.2 ppm/cm measured): better for thermal lensing Comparable price  For EM : Suprasil 312 Good optical (0.6 ppm/cm) and mechanical properties Cheaper  Non degenerate PR and SR cavities (3 mirrors 5-15 cm): Herasil 102 : cheap Properties satisfactory for this particular type of mirrors

Intermediate review - ERC – February 9, 2009 – L. Pinard 6 Substrates Procurement What remains to do (design questions): - Final dimensions for BS, CP and ndg cavities : OSD and PAY subsystem Dedicated internal meetings - For ndg cavities : small mirrors – production time not long not a problem for the planning if dimensions not yet decided

Intermediate review - ERC – February 9, 2009 – L. Pinard 7 Substrates Polishing : # 2,5 years (for all spares)  Real Time estimation with General Optics production time for the Virgo + mirrors (2007) (6 months for the first substrate, after 1 parts/month) P olishing starts as soon as first bulk substrate received (nov 2009)  CP polishing included (planning optimized)  Coating starts as soon as possible (after characterization) Substrates Polishing  Polishing company able to polish the large BS Only one found – long delay taken into account

Intermediate review - ERC – February 9, 2009 – L. Pinard 8  New geometry of the mirrors (monolithic lateral supports) - TCS - Checked with polishers if feasible (2 possible positive answers) - First comments : - silica bulk cost for IM and EM : + 15% - Lateral support machining : long (+2-3 months for each part) - Expensive : first approx. +30% for IM and EM - Dedicated meeting  Critical point: flatness requirements (# 0.5 nm RMS) Simulations necessary to evaluate the crucial spatial frequency domain Substrates Polishing Design Questions

Intermediate review - ERC – February 9, 2009 – L. Pinard 9 Substrates Polishing Design Questions  Polishing Strategy  Reference solution : Corrective coating technique (wavefront improvement by adding silica where it is necessary) – Convincing Results (<1 nm RMS) New robot (sample-holder) : present system not reliable Study quite finished with LAPP team, cost estimation in progress : ready in June 2009 for construction (LAPP – LMA projects manager) Advantage : can be used for future mirror upgrades  Alternative solution : Company able to reach flatness < 1 nm RMS on large area (Ion Beam Polishing) Contact established Cost estimation in progress with preliminary specifications

Intermediate review - ERC – February 9, 2009 – L. Pinard 10 Substrates Polishing Design Questions  Contact polishing companies : General Optics, CSIRO, SESO, ZYGO, L-3 communications (Tinsley)  Find the best compromise between the price and the performances

Intermediate review - ERC – February 9, 2009 – L. Pinard 11 Mirrors Coating phase : # 2 years Mirrors Coating  Global coating Task includes all the toolings necessary (cleaning, handling, Q factor Improvement, boxes…)  Coating start : as soon as 2 IM ready (polished, characterized) Coated at the same time (ITF arm symmetry) In the planning, a corrective coating phase included in the IM and EM coating  Coatings having the best available optical and mechanical features  CP coatings taken into account

Intermediate review - ERC – February 9, 2009 – L. Pinard 12 Metrology Upgrades Metrology mountings (IM/EM/BS) New motorized sample holder coupled with stitching interferometry software for wavefront measurement (0°- 45°) Better accuracy and reproducibility New motorized sample holder for the scattering and transmission measurement (BS)