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OWL TECHNOLOGIES Copenhagen, November 2004 Design overview Optics 6-mirror, f/7.5, ~6,900 m² collecting area, IAU Symposium 225 - Lausanne, July 2004 - - Slide 2 near-circular outer rim M1 Spherical dia. 100m, f/1.2 3048 segments M2 Flat, dia. 25.6 m 216 segments Corrector 4 elements, dia. 8, 8, 3.5, 2m FOV 6 focal stations (rotation of M6) 10 arc min. seeing-limited; > 2 arc min.diffraction-limited (vis.) Stability Very low sensitivity to external disturbances (gravity, thermal, wind) IAU Symposium 225 - Lausanne, July 2004 - - Slide 3 Optical design Adaptive, conjugated to pupil; First generation Adaptive, conjugated to 8km; Second generation Why a spherical primary / flat secondary ? System Performance Risk & cost Larger corrected field of view than equivalent Ritchey-Chretien Low sensitivity to M2 decenters IAU Symposium 225 - Lausanne, July 2004 - - Slide 4 Corrector excellent baffling options Secondary mirror an issue with aspherical primary Small M2 (< 3-m) very high sensitivity to disturbances Large M2 (> 3-m) severe fabrication issue if convex added tube length if concave (Gregorian) All wavefront control functions with 6 surfaces Multi-conjugate AO (2 mirrors 2- and 4-m, conjugated to 0, 8 km) Moderately large FOV (0.5 – 2 arc min) an essential mode Needs re-imaging; OWL provides dual conjugate with 6 surfaces only ! Maintainability: 3,000 segments, all identical & interchangeable. Why a spherical primary / flat secondary ? System Performance Risk & cost Use of planetary polishers or large stiff figuring tools IAU Symposium 225 - Lausanne, July 2004 - - Slide 5 Lower segment edge misfigure Stable reference, repeatability of radius of curvature No warping harness Structured blanks possible (SiC a serious option) Less stringent requirements on blanks internal stresses Segment size up to ~2.3-m possible Limited by cost-effective transport in standard container No aspherization weak size-dependence Performance losses Lower throughput than a Ritchey-Chretien (option: enhanced coatings ?) Higher emissivity (option: single surface corrector for very small field of view ?) Why a spherical primary / flat secondary ? System Performance Spherical polishing IAU Symposium 225 - Lausanne, July 2004 - - Slide 6 Simple and predictable processes, stable and predictable yield Stable reference (rigid tools) Fast process, high efficiency; OWL polishing tool area = 36 largest GTC tool area ! Simple test set-up Unique matrix no segments matching risk TBC: No edge cutting, polished hexagonal Risk & cost Segment assembly Segment unit Metrology Position sensors IAU Symposium 225 - Lausanne, July 2004 - - Slide 7 LCU Spacers Segment assembly Segment Optical surface Segment active support system Slave actuator for lateral support Position actuators Segment blank Support structure Interface pads Axial interface pads Lateral interface pads Reference targets Whiffle-tree Total quantity: 3048 + 216 + TBD spares Actuators - Outline of specifications Load cases (nominal, tension and compression) Glass segments: Lightweight SiC segments: 0 to 170 kg / actuator 0 to 40 kg / actuator IAU Symposium 225 - Lausanne, July 2004 - - Slide 8 Accuracy 2 stages Position Actuator Concept Coarse stage ± 0.05 mm. Fine stage ± 5 nm - Goal ± 2 nm Extractor ± 1 mm Stroke Coarse stage Fine Stage Extractor 20 mm 0.5 mm - Goal 1mm 150 mm TBC Closed Loop Bandwidth Fine stage Coarse stage 5Hz - Goal 10 Hz. 0.1 Hz. Max. cost (unit cost for a production of 10,000 units) Glass segments: SiC segments < € 3,500.< € 2,500,- Goal < € 2,500.Goal < € 2,000.- IAU Symposium 225 - Lausanne, July 2004 - - Slide 9 Position sensors Capacitive, inductive or optical Mounted at segments edges Measurement range Differential accuracy over full range Maximum measurement frequency Re-calibration frequency Maximum heat dissipassion Maximum unit cost (20,000 units) Cross-section through glass / glass-ceramic segments Variable 2 to 14 mm 0.5 mm (TBC) 5 nm Goal 2 nm 20 Hz Goal 50 Hz once per week TBD (minimize) € 1,250.Goal € 750.Cross-section through SiC segments Variable 2 to 14 mm Max. 10 mm 70 to 90 mm, depending on segment size Min. 70 mm Max 10 mm Max. 10 mm Sliding enclosure M2 Handling tool M1 Covers Maintenance facility Azimuth tracks Altitude bearing Azimuth structure & bogies Altitude tracks Corrector & instrumentation Structure ribs (6-fold symmetry) Altitude cradles & bogies IAU Symposium 225 - Lausanne, July 2004 - - Slide 14 All dimensions as multiple of segment size Standardization Ease of integration Ease of maintenance Optimal loads transfers Optomechanics Fractal design - Low-cost, Eigenfrequency (Hz) IAU Symposium 225 - Lausanne, July 2004 - - Slide 15 lightweight steel structure 14,800 tons moving mass (60 times “lighter” than VLT) Mass reduced to ~8,500 tons with SiC Ample safety margins (stresses, buckling) 2.6 Hz locked rotor eigenfrequency Low thermal inertia (developed surface, natural internal air circulation inside structural elements) Differential M1-M2 decenters under gravity Piston Lateral Tilt 3.4 mm 17.6 mm 3.4 arc secs (rigid body motion) Moving mass (t) • Innocuous lateral M1-M2 decenters • Parallelogram-shaped structural modules favour lateral over angular decenters • Lose centring tolerances • Corrector favourably located (stiffness) • Ample design space 20305 IAU Symposium 225 - Lausanne, July 2004 - - Slide 16 Reducing sensitivity by design IAU Symposium 225 - Lausanne, July 2004 - - Slide 17 Instrument racks 6 focal stations; switch by rotating M6 about telescope axis. Max. instrument mass 15 tons each. Local insulation & air conditioning Issue: needs rigid connection with corrector (TBC). Controlled optical system Kinematics pointing, compensation for sky rotation encoders, on-sky guide probe bring optical system into linear regime internal, tolerances ~ 1-2 mm, ~5 arc secs re-position Corrector, M3 / M4 / M5 keep M1 and M2 phased within tolerances Edge sensors, Phasing WFS Segments actuators cancel “fast” image motion Guide probe M6 tip-tilt (flat, exit pupil, 2.35-m) finish off alignment / collimation relax tolerances, control performance & prescription Wavefront sensor(s) Rotation & piston M5; M3 & M4 active deformations atmospheric turbulence, residuals Wavefront sensor(s) M5, M6, … Metrology: Pre-setting Metrology: Correction: IAU Symposium 225 - Lausanne, July 2004 - - Slide 18 Phasing Metrology: Correction: Field Stabilization Metrology: Correction: Active optics Metrology: Correction: Adaptive optics Metrology: Correction: Controlled opto-mechanical system I – Pre-setting IAU Symposium 225 - Lausanne, July 2004 - - Slide 19 Corrector re-centering + 2 (TBC) surfaces within the corrector Internal metrology (e.g. fiber extensometer) Typical accuracy: 10 ppm goal 1 ppm Bandwidth << 1 Hz High operational reliability Controlled opto-mechanical system II – Kinematics IAU Symposium 225 - Lausanne, July 2004 - - Slide 20 Friction drives Azimuth: 246 units Elevation: 154 units Bandwidth ~0.5 Hz Fast steering mirror M6, dia. 2.35m Guide probes at technical focus accessible FOV 10’ IAU Symposium 225 - Lausanne, July 2004 - - Slide 21 M6 adaptive & tip-tilt unit Controlled opto-mechanical system III – Active optics IAU Symposium 225 - Lausanne, July 2004 - - Slide 22 Dual conjugate active optics Deformable M3 & M4 VLT-type mirrors Refocus & fine centering 5 Wavefront Sensors at each technical focus (FOV 10’) + feedback AO Controlled opto-mechanical system IV – Phasing Two segmented mirrors Bandwidth ~5 Hz TBC Edge sensors (capacitive, Inductive or optical) Reference channel Telescope focus Beamsplitter Mach-Zehnder phasing sensor Pinhole IAU Symposium 225 - Lausanne, July 2004 - - Slide 23 Beamsplitter Interferogram Interferogram On-sky calibration off-axis Mach-Zehnder calibration sensor IAU Symposium 225 - Lausanne, July 2004 - - Slide 24 Interferogram (ideal conditions) Complex geometry, But fully predictable Localized signal 2k x 2k camera sufficient for adequate sampling Piston, Tip, and Tilt: Examples Y – tilts opposite signs Signal X – tilts opposite signs Features IAU Symposium 225 - Lausanne, July 2004 - - Slide 25 Phase Piston only X – tilts same signs Antisymmetry axis Y Antisymmetry axis Y Antisymmetry axis X Symmetry axis Y AO Simulations on OWL. IAU Symposium 225 - Lausanne, July 2004 - - Slide 26 125 sub-apertures across pupil, 11198 actuators on M6 Bright NGS on-axis, 1 kHz frame-rate, ~1 sec of real-life PSF 4 ms coherence time, 0.5’’ seeing (at 0.5 mm) OWL pupil + cophasing M1 & M2: 35 nm WFE RMS each K band, Strehl ~70% Atmosheric Wavefront Illumination on the pyramid WFS MCAO simulation 2 arc minutes field, l=2.5 mm 2 adaptive mirrors, 8000 actuators each 3 guide stars Sqrt stretch Adaptive mirrors IAU Symposium 225 - Lausanne, July 2004 - - Slide 32 LBT – 911 mm diameter, 672 actuators MMT – 642 mm diameter, 336 actuators Adaptive mirrors IAU Symposium 225 - Lausanne, July 2004 - - Slide 33 Capacitive sensors (ref.plate) (MMT336) aspherical shell 642mm dia. 2mm thick Magnets (12mm diam.) IAU Symposium 225 - Lausanne, July 2004 - - Slide 34 Extreme AO High performance adaptive optics at visible wavelength Need for 105-106 actuators MOEMs Time scale : beyond 2015 Some effort going on but need to ramp up Positive factor: limited stroke necessary, large deformable mirrors act as first stage Technology review, design, production & testing of demonstrators foreseen in OWL Phase B Adaptive Optics IR Deformable Mirrors IAU Symposium 225 - Lausanne, July 2004 - - Slide 35 Diameter Actuator spacing Today 2008 2015 2019 LBT (JWST) Prototype OWL 1st Gen. 2nd Gen. 1-m (2-m) 30 mm 0.3-m 15 mm 2-m 15-25 mm 3.2-m 20-25 mm XAO corrector Detector Moems/Pzt 256x256 ? AO real time control Reference stars 512x512 1kx1k Almost OK NGS (LGS) NGS High sky coverage in the near-IR (better filling of metapupil) LGS needed ~2018; lower number of LGS, Cone effect requires novel approaches e.g. PIGS (Ragazzoni et al) NGS / LGS Telescope performance (wind) Tracking : low concern IAU Symposium 225 - Lausanne, July 2004 - - Slide 36 M2 flat ! Design insensitive to M2 lateral decenters Structural design privileges M2 lateral decenter over M2 tilt Corrector at very stiff location (Pupil shape outdated) DYNAMIC ANALYSIS Worst caseS combined (orientation), 10 m/s, conservative drag coefficients Maximum mean displacements out of worst load cases Mirror M1 M2 Piston (uz) [mm] -0.216 -0.336 Tilt (rotx) [arcsec] 0.420 1.680 Decenter (uy) [mm] -0.129 -1.132 Wind MODELLING & TESTING Limited confidence in CFD (Results suspiciously good !) Wind measurements at Jodrell Bank (2004) Wind tunnel testing (2004) Analysis & modelling Courtesy PSP Wind (pressure distributions) IAU Symposium 225 - Lausanne, July 2004 - - Slide 38 ACCELERATED - ACTUAL ELAPSED TIME 150 SECONDS M1 Corrector M2 Wind – design options 1. 2. IAU Symposium 225 - Lausanne, July 2004 - - Slide 39 3. 4. 5. 6. 7. Higher local stiffness (substructure supporting segments) increases resistance to high spatial frequencies Use of SiC segments higher M1 & M2 bandwidth Embedded variable wind screens (up to z~30o) Increase M4 (active mirror) bandwidth ~2-5 Hz (VLT M1 support dimensioned for 1 Hz) Increase range of M6 adaptive correction Operational constraints Site selection … required for AO anyway Variable wind screen embedded in the azimuth structure (notional design); M2 wind screen not shown Cost estimate (capital investment, 2002 M€) SUMMARY OPTICS 406 Primary & secondary mirror units 355.2 M3 unit 14.4 M4 unit 21.4 M5 temporary unit M6 temporary unit 5.3 10.1 ADAPTIVE OPTICS IAU Symposium 225 - Lausanne, July 2004 - - Slide 40 MECHANICS MEuros 110 M5/M6 design & prototypes 10 M6 AO unit 25 M5 AO unit XAO units LGS 35 20 20 Diffraction-limited instrumentation (acceptable étendue !) Assumes “friendly site” Average seismicity (0.2g) Moderate altitude Average wind speed Moderate investment in infrastructures 185 Azimuth 53.8 Elevation 34.9 Cable wraps Azimuth bogies (incl. motors) Altitude Bogies & bearings Mirror shields Adapters Erection CONTROL SYSTEMS (*) Telescope Control System M1 Control System M2 Control System Active optics Control System CIVIL WORKS 5.0 14.7 5.7 15.0 6.0 50.0 17 5.0 8.0 2.0 2.0 170 Enclosure 40.4 Technical facilities 35.0 Site infrastructure 25.0 Concrete 70.0 INSTRUMENTATION 50 INSTRUMENTATION Total without contingency 50 939 938.9 (*) High level cs only; local cs included in subsystems Cost estimates (industrial studies) Primary & secondary mirror segments; 1.8-m; polished, prices ex works. SiC (2 suppliers A and B) with overocatings (3 suppliers 1, 2, 3) Glass-Ceramics (2 suppliers C and D) Polishing: 2 suppliers, only one shown (both agree within 10%) 2002 ESO ESTIMATE Polishing Overcoating Blanks Total cost IAU Symposium 225 - Lausanne, July 2004 - - Slide 41 Blanks: SiC A + Overcoating SiC B + Overcoating SiC B + Overcoating 1 2 3 Glass-ceramics C Substrate & polishable overcoating Glass-ceramics D IAU Symposium 225 - Lausanne, July 2004 - - Slide 42 Optimized geometry (interface optics-mechanics) All parts fitting in 40-ft containers 1.6-m all-identical segments (~3000 units), single optical reference for polishing 12.8-m standard structural modules (integer multiple of segment size) Friction drive (bogies), hydraulic connection Cost vs quantity Industrial data Applies to conceptually simple items (e.g. segments, structural nodes) 1.00 VLT M1 polishing (4 units) COST FACTOR IAU Symposium 225 - Lausanne, July 2004 - - Slide 43 0.80 0.60 OWL segments (industrial studies) 0.40 0.20 0.00 1 10 100 Number of units 1000 10000 IAU Symposium 225 - Lausanne, July 2004 - - Slide 44 Polishing: factory implementation Size (area) comparable to VLT 8-m production facility IAU Symposium 225 - Lausanne, July 2004 - - Slide 45 Meanwhile … ECM BOOSTEC IAU Symposium 225 - Lausanne, July 2004 - - Slide 46 • Phase C/D approval 2010 • 8-m mirrors need 6 years First light early 2016 Start of science 2017, 60m BUT: long lead items highly standardized multiple supply lines possible faster integration possible ALTERNATIVE ALLOWING FIRST LIGHT IN 2014 (TBC) IS UNDER EVALUATION 2020 2015 2010 2005 2000 Timeframe Phase A IAU Symposium 225 - Lausanne, July 2004 - - Slide 47 Phase A review ELT Design Study APE on sky Phase B Site selection First light (50-m) Completion Phase C/D Start of science (60-m) Groundbreaking Driven by funding, not by technology IAU Symposium 225 - Lausanne, July 2004 - - Slide 48 Planned studies 2005 - OWL phase A Conceptual design of M6 adaptive subunit Storage and postprocessing of the Jodrell Bank data Feasibility study for wind tunnel measurements Wind tunnel measurements (Jodrell Bank model) Feasibility study for CFD simulations CFD simulations Dynamic Analysis of M1 / Corrector M3-M6 Control OWL Instruments Conceptual Design Studies Vibration dampers (local modes) Optimization runs of the mechanical structure I/F with concrete Feasibility study M4 figuring / CGH Conceptual Design ELT Design Study The R&D part of a phase B IAU Symposium 225 - Lausanne, July 2004 - - Slide 49 Objectives Technology development towards a European ELT Preparatory work for observatory design Top level requirements Academic & industrial synergy Design-independent Proposal to EC within FP6 - Approved 39 partners, 47 WPs / Tasks 42 M€ total, 22 M€ requested Timescale 2005-2008 IAU Symposium 225 - Lausanne, July 2004 Slide 50 ELT Design Study Proposal The R&D part of a phase B Objectives – – – – Technology development towards a European ELT Preparatory work for observatory design Top level requirements Academic & industrial synergy Design-independent Proposal to EC within FP6 - Approved – 39 partners, 47 WPs / Tasks – 42 M€ total, 22 M€ requested – 8 M€ granted – Timescale 2005-2008 ESO as coordinator Contract currently under negotiation with EC IAU Symposium 225 - Lausanne, July 2004 Slide 51 Matrix structure WP/Task (47) 1 Participants (39) A B C ... Z WP budget 2 3 4 5 … WP budget WP budget WP consol. tool 46 47 Part. budget Part. budget Part. budget Budget prep. tool IAU Symposium 225 - Lausanne, July 2004 Slide 52 Project Organization IAU Symposium 225 - Lausanne, July 2004 Slide 53 Shares, in % of total estimated budget International organization 38% Industry 22% Institute / university 40% UK Australia Belgium Sweden 5.9% 3.8% 4.5% CH 4.8% 1.4% Spain France 10.6% 16.4% NL 1.3% Germany 2.2% Italy 10.4% Israel 0.2% Ireland 0.5% ESO International 38.0% IAU Symposium 225 - Lausanne, July 2004 Slide 54 Engineering WP - overview No Title 01000 Project Management 04000 Wavefront Control 05000 06000 07000 08000 09000 10000 11000 12000 13000 Topics Breadboard / prototypes [includes overall system / project engineering] Phasing, actuators, metrology, APE, WEB (wind) PSF properties, high contrast imaging, error budgeting Optical fabrication SiC, opt. finishing, Al mirrors, coatings 8 x 1-m SiC segments Mechanics Composite materials, MagLev, Friction Drive breadboard Friction drives Control Support to other WPs (APE, WEB) Enclosure & infrastr. Enclosure concepts, renewable energies, infrastructures, wind tunnel Adaptive Optics WFE on 100-m scale, AO units DM prototypes designs, large DMs, novel concepts, algorithms, simulations Observ. & science ops. System operations (studies, requirements) Instrumentation Point designs, ADC Site characterization Site parameters, measurements, [site testing equipment] modeling, large scale atmo. properties System layout, Integrated modelling tools, support to analysis & modelling other WPs From concept to sky testing: APE Active Phasing Experiment IAU Symposium 225 - Lausanne, July 2004 - - Slide 55 Segmenting the VLT Laboratory & on-sky evaluation of up to 3 phasing techniques Integration of phasing into global wavefront control On-sky by 2007 IAU Symposium 225 - Lausanne, July 2004 Slide 56 WEB IAU Symposium 225 - Lausanne, July 2004 Slide 57 Silicon Carbide prototypes 1-m class, 8 pcs., different overcoatings 4 blanks already at ESO Explore overcoating & figuring processes, check for bimetallic effects Advantages – Stiffer, lighter, better thermo-mechanical properties (than glass) – Higher control bandwidth (position) – Hardness – Lighter, stiffer telescope structure – ~20 years of development, space-qualified – Potentially cost-effective if appropriate design BUT – Needs qualification for segmented apertures IAU Symposium 225 - Lausanne, July 2004 Slide 58 Friction drive breadboard Mandatory – Hydraulic pads / tracks not an option ! Alternative: magnetic levitation - TBD IAU Symposium 225 - Lausanne, July 2004 Slide 59 Overall schedule IAU Symposium 225 - Lausanne, July 2004 - - Slide 60 ELT Design Study – subcontracts (planned) Subject Contact email Design & testing of 18 segments position actuators E. Brunetto, ESO [email protected] Feasibility study for magnetic levitation (telescope kinematics) E. Brunetto, ESO [email protected] Conceptual design of opening enclosure for a 50- and a 100-m telescope G. Pescador, GRANTECAN [email protected] Wind studies – CFD L. Noethe, ESO M. Quattri, ESO [email protected] [email protected] Wind studies – wind tunnel Idem Idem Site characterization equipment J. Vernin, LUAN [email protected] Contacts @ ESO OWL IAU Symposium 225 - Lausanne, July 2004 - - Slide 61 J. Strasser, Telescope Systems Division, Project Controller P. Dierickx, Project Engineer / Manager R. Gilmozzi, Prime Investigator E. Brunetto Optomechanics [email protected] [email protected] [email protected] [email protected] ELT Design Study P. Dierickx Project Manager R. Gilmozzi Project Coordinator [email protected] [email protected]