Mirrors SubSystem Overview q Introduction q Scope of

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

Introduction Mir Sub-system Description q Procurement and preparation of the Ad. V 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) q Mirrors with larger dimensions (thicker) Modification in the coating process (cleaning, handling) Coatings q Mirrors with RMS flatness better than 1 nm More accurate metrology Metrology modifications Intermediate review - ERC – February 9, 2009 – L. Pinard 2

Since the November Review q Mirror Construction Task form Description of all the tasks, of all the deliverables Time planning, Budget spending profile, Manpower q 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 Ad. V mirrors Intermediate review - ERC – February 9, 2009 – L. Pinard 3

Substrates Procurement 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% Intermediate review - ERC – February 9, 2009 – L. Pinard 4

Substrates Procurement Motivations for Fused silica choice q Manufacturer = HERAEUS (like in VIRGO) q 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 q For EM : Suprasil 312 Good optical (0. 6 ppm/cm) and mechanical properties Cheaper q 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 5

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 6

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

Substrates Polishing Design Questions q 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 q Critical point: flatness requirements (# 0. 5 nm RMS) Simulations necessary to evaluate the crucial spatial frequency domain Intermediate review - ERC – February 9, 2009 – L. Pinard 8

Substrates Polishing Design Questions q Polishing Strategy q 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 q 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 9

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

Mirrors Coating phase : # 2 years q Global coating Task includes all the toolings necessary (cleaning, handling, Q factor Improvement, boxes…) q 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 q Coatings having the best available optical and mechanical features q CP coatings taken into account Intermediate review - ERC – February 9, 2009 – L. Pinard 11

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