Post on 28-Dec-2015
Intermediate review - ERC – February 9, 2009 – L. Pinard 1
Mirrors Sub-SystemMirrors 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-systemIntroduction 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 ReviewSince 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 suspensionNew 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
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
Heraeus production : first bulk substrate produced after 4 month, then one bulk/2 weeks
Compensation plates included : same silica as IM
Optimization of the planning with Heraeus (include production constraints) Possibility to reduce the silica Blanks budget by 15%
Substrates ProcurementSubstrates Procurement
Intermediate review - ERC – February 9, 2009 – L. Pinard 5
Substrates ProcurementSubstrates 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 ProcurementSubstrates 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)
Polishing starts as soon as first bulk substrate received (nov 2009)
CP polishing included (planning optimized)
Coating starts as soon as possible (after characterization)
Substrates PolishingSubstrates 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 PolishingSubstrates Polishing
Design Questions
Intermediate review - ERC – February 9, 2009 – L. Pinard 9
Substrates PolishingSubstrates 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 reliableStudy 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 establishedCost estimation in progress with preliminary specifications
Intermediate review - ERC – February 9, 2009 – L. Pinard 10
Substrates PolishingSubstrates 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 CoatingMirrors 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 UpgradesMetrology 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)