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1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 1
Advanced VirgoAdvanced VirgoMirrors Sub-SystemMirrors Sub-System
Overview
Introduction Scope of the subsystem, main tasks
Substrates Procurement
Blank Material (fused silica) : material choice, specifications, planning, cost
Polishing : strategy, choice of the company,planning, cost
Coating : planning, cost
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 2
Advanced VirgoAdvanced VirgoIntroduction 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
Mirrors with larger dimensions (thicker) Modification in the coating process
Mirrors with RMS flatness better than 1 nm Polishing and Coating strategy More accurate metrology
Description
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 3
Advanced VirgoAdvanced VirgoIntroduction Mir Sub-systemIntroduction Mir Sub-system
Main Tasks Substrates: Blank materials procurement (fused silica), Choice of the best material (Company),
Order preparation
Polishing: Definition of the specifications, Geometry (ROC, monolithic suspension..) Flatness requirements, Definition of the polishing strategy (Corrective Coating) Call for tender for the micropolishing, Order preparation. Control of the different substrates delivered (Defects, roughness, ROC, flatness, bulk absorption, Birefringence) - Characterization report
Coatings: Coating process modification linked to the mirror weight increase (mirror handling tools, new sample-holder (robot) for Corrective Coating)
Design optimization, use of the best high index material (thermal noise), annealing
Metrology : Modification of the sample holder on optical metrology benches (Abs./Scat. bench) New ITF bench to measure the wavefront at 0° and 45° of 0.5 nm RMS (TBC) on the AdV test masses
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 4
Advanced VirgoAdvanced VirgoIntroduction Mir Sub-systemIntroduction Mir Sub-system
AdV Mirrors : Reference SolutionGeometry and performances
Input MirrorIM
End Mirror EM
Beam SplitterBS
Compensation Plate
CP
Non degenerate Power and Signal recycling Cavities
PRM3/SRM3 PRM2/SRM2 PRM1/SRM1
Number of parts 4 4 2 2 3 3 3
Fused Silica Nature Suprasil 3002 Suprasil 312 Suprasil 3001 Herasil 102 Herasil 102 Herasil 102 Herasil 102
Diameter 350 mm 350 mm<550 mm
(TBC)280 mm(TBC)
150 mm (TBC)
50 mm(TBC)
50 mm(TBC)
Thickness 200 mm 200 mm 65 mm100 mm(TBC)
50 mm 50 mm 50 mm
RoughnessReflective side <1 Å RMS <1 Å RMS <1 Å RMS <1 Å RMS <1 Å RMS <1 Å RMS <1 Å RMS
RMS Flatness Reflective side
0.5 nm RMS (TBC)
150 mm
0.5 nm RMS (TBC)
200 mm
3 nm RMS (TBC)
150 mm
3 nm RMS (TBC)
150 mm
3 nm RMS (TBC)
100 mm
3 nm RMS (TBC)
20 mm
3 nm RMS (TBC)
20 mm
TransmissionReflective side
0.7 % (TBC)
# 10 ppm(TBC)
50 % #100 %# 10 ppm
(TBC)# 10 ppm
(TBC)TBD
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 5
Advanced VirgoAdvanced Virgo
Detailed revised DRAFT Planning if starting on 01/07/2009Estimation based on real delay for the manufacturing of the silica and on the real timenecessary for the VIRGO + substrates polishing - Mirrors Delivery : beginning of 2012
Mirrors production PlanMirrors production Plan
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 6
Advanced VirgoAdvanced Virgo
Substrates Fabrication : 1,5 year
Planning for 4 IM-4 EM-2 BS solution (one spare for each mirror) Serial production of the silica blanks. Possibility to produce in parallel
but limitation = polishing phase
Heraeus production : first bulk substrate produced after 4 month, then one bulk/2 weeks
Choose the best material for each type of component Compromise between optical/mechanical performances and price
Substrates ProcurementSubstrates Procurement
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 7
Advanced VirgoAdvanced VirgoFused Silica properties comparisonFused Silica properties comparison
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 8
Advanced VirgoAdvanced VirgoSubstrates ProcurementSubstrates Procurement
Motivations for Fused silica choice No real advantages to choose Corning (performances, cost), limitation in size Manufacturer = HERAEUS (like in VIRGO)
For IM, BS :
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 and mechanical properties
Cheaper
Non degenerate PR and SR cavities (3 mirrors 5-15 cm) and CP:
Herasil 102 : cheap
Properties satisfactory for this particular type of mirrors
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 9
Advanced VirgoAdvanced VirgoSubstrates ProcurementSubstrates Procurement
Real Fused Silica Cost (IM/EM thickness 20 cm)Solution 4 IM/ 4 EM/ 2 BS/ 6 PR-SR cavities/ 4 CP
If thickness 30 cm for IM and EM : extra cost # +30 %
Cost IM/EM/BS/SR+PR/CP Cost - Thickness 30 cm
Reference Solution
1 277 880,00 € 3002 / 312 / 3001 / Herasil 102 1 667 072,00 €
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 10
Advanced VirgoAdvanced Virgo
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) Different from one polisher to the other
Polishing starts as soon as first bulk substrate received (nov 2009)
Coating starts as soon as possible
Substrates PolishingSubstrates Polishing
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 11
Advanced VirgoAdvanced Virgo
New strategy for the Larger beam splitter (< 55 cm- TBC) Several polishers contacted to check feasibility(in progress)
New geometry of the mirrors (monolithic lateral supports) Check with polishers if feasible (in progress)
Critical point: flatness requirements (# 0.5 nm RMS) Simulations necessary to evaluate the crucial spatial frequency domainFlatness metrology improvement (better accuracy and reproducibility)New bench : stitching interferometry, stable sample holder,
measurement also at 45°
Substrates PolishingSubstrates Polishing
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 12
Advanced VirgoAdvanced VirgoSubstrates PolishingSubstrates Polishing
Two Paths
Corrective Coating (LMA)New opportunity
Flatness reached with Ion Beam polishing
Polisher not able to guaranteethe flatness specifications
(Best effort)
Polisher able to guaranteethe flatness specifications
Development of a new Robot
Refere
nce so
lutio
n
To be testedCost (?)Future AdV Mirrors upgrades
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 13
Advanced VirgoAdvanced VirgoSubstrates Polishing : Corrective coatingSubstrates Polishing : Corrective coating
Substrate
Interferometer
Ion source
Robot
mask
Silica target
Sputtered atoms
Substrate 156 mm VIRGO type
Before correction (120 mm)3.3 nm R.M.S. / 16 nm P.V.
After correction (120 mm)0.98 nm R.M.S. /10 nm P.V.
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 14
Advanced VirgoAdvanced VirgoSubstrates PolishingSubstrates Polishing
Polishing costSolution 4 IM/ 4 EM/ 2 BS/ 6 PR-SR cavities / 4 CP
Cost estimation obtained for VIRGO+ (2007)
Contact polishing companies : General Optics, CSIRO, SESO (?)
Find the best compromise between the price and the performances
1 300 k€
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 15
Advanced VirgoAdvanced Virgo
Mirrors Coating : # 2 years
Mirrors CoatingMirrors Coating
Coating start : as soon as 2 IM ready (polished, characterized) Coated at the same time (ITF arm symmetry)
Coatings having the best available optical and mechanical features
Reference path : flatness correction by “Corrective Coating” (IM, EM)
2 CP
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 16
Advanced VirgoAdvanced Virgo
For “Corrective Coating”: new robot in the Virgo large coater (ordered at the same time as the polishing, end 2009) – 300 k€
Study of the robot already started Help from LAPP (P. Mugnier, L. Giacobone) for the technical study of the robot Test on a real large substrate (old VEM ?) Simulation with a corrected wavefront (Nice group) : see if CC improves or not
CC : Quite no impact on the coating planning (limitation : polishing)
Alternative strategy : Advanced polishing company able to reach the 0.5 nm specification by Ion Beam Polishing (final step after a classical polishing). Coating test on this type of substrate
Mirrors CoatingMirrors Coating
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 17
Advanced VirgoAdvanced VirgoMirrors CoatingMirrors Coating
Coating cost
Cleaning Facility (real)
Tooling for cleaning
Tooling for coating
Handling Tools
Robot
Ion Assist source (Q improvement)
Under vacuum furnace
Coating (corrective coating)
Total (€) 1 050 k€
1st Advanced Virgo Review – November 3-4, 2008 – L. Pinard 18
Advanced VirgoAdvanced VirgoMirrors CoatingMirrors Coating
Metrology cost : 300 k€Lots of modifications to control heavier and thicker substrates
Metrology mountings (IM/EM/BS)
New motorized sample holder for the scattering and transmission measurement (BS)
New motorized sample holder coupled with stitching interferometry software for wavefront measurement (0°- 45°)