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TMT M1 Segment Support Assembly (SSA) Preliminary Design Review (PDR) Volume-1: OVERVIEW

TMT M1 Segment Support Assembly (SSA) Preliminary Design Review (PDR) Volume-1: OVERVIEW. Pasadena, California October 24-25, 2007 Contributors to the development effort: from IMTEC RJ Ponchione, Eric Ponslet, Shahriar Setoodeh, Vince Stephens, Alan Tubb, Eric Williams from the TMT Project

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TMT M1 Segment Support Assembly (SSA) Preliminary Design Review (PDR) Volume-1: OVERVIEW

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  1. TMT M1 Segment Support Assembly (SSA) Preliminary Design Review (PDR)Volume-1: OVERVIEW Pasadena, California October 24-25, 2007 Contributors to the development effort: from IMTEC RJ Ponchione, Eric Ponslet, Shahriar Setoodeh, Vince Stephens, Alan Tubb, Eric Williams from the TMT Project George Angeli, Curt Baffes, Doug MacMynowski, Terry Mast, Jerry Nelson, Ben Platt, Lennon Rodgers, Mark Sirota, Gary Sanders, Larry Stepp, Kei Szeto TMT Confidential The Information herein contains Cost Estimates and Business Strategies Proprietary to the TMT Project and may be used by the recipient only for the purpose of performing a confidential internal review of the TMT Construction Proposal. Disclosure outside of the TMT Project and its External Advisory Panel is subject to the prior written approval of the TMT Project Manager. * Note: HYTEC, Inc. merged with IMTEC Inc. in March 2007.

  2. Outline • Volume-1: Overview • Thirty Meter Telescope Overview • SSA Project Overview • Key Design Requirements • Design Concept • SSA Preliminary Design • Key Subsystems • Axial Support • Lateral Support • Tower, Guide Flexure, Locks, Registration • Warping Harness • Subcell • Volume-2: System Level Calculations • M1 Segmentation • Segmentation Correction (for Variable Segment Geometry) • Budgets: • Installation & Alignment • Edge Gap • Actuator Stroke • Mass

  3. Outline • Volume-3: System-Level Finite Element Analysis • Model Description • Optical Performance • Stiffness and Modes • Buckling • Sensitivity Analyses • Stress Analysis • Backup Slides • Volume-4: Warping Harness Design and Analysis • Fundamental Approach & Architecture • Warping Harness Requirements • Opto-mechanical • Mechanical • Design Concept • Performance Analysis • Actuator arrangement • Surface correction • Derived Requirements for Components • Mechanical & Electrical Design • Quantization Error Estimate

  4. Outline • Volume-5: Flexure Design and Analysis • Design Load Combinations • Central Diaphragm • Rod-Type Flexures • Lateral Guide Flexure • Volume-6: Subcell Integration & Segment Handling • Subcell Integration & Alignment • Fixed Frame Installation • Dummy Mass • Subcell Alignment • Segment Lifting Jack & Lifting Talon • Jack design • Lifting Talon design • Volume-7: Summary and Future Plans • Prototype Testing • Test Plans • Component testing • Full Prototype testing • Schedule • Summary • Where we are and where we’re going • Technical Risks • Conclusions

  5. Thirty Meter Telescope BRIEF TELESCOPE OVERVIEW

  6. M1 Array • 30m Diameter • ~60m ROC • 492 Segments • 1.44m x 45mm1 PSA On Mirror Cell Note 1) 45mm for Glass-Ceramic, 50mm for Fused Silica

  7. Segment Size • Nominal Segment size is 1.44 m across vertices • Limited by blank size to maintain several competitive suppliers • Thickness: • 45 mm if glass ceramic • 50 mm if fused silica (ULE) • Aperture limits: • Outermost corners: 15.0 m radius • Innermost corners: 1.45 m radius 1.44 30m diameter 15.0 1.45

  8. YPSA YPSA Cell Truss XPSA ZPSA XPSA ZPSA SSA Base ZPSA 45 mm XPSA YPSA 1.44 m M1 Parameters • Fundamental M1 Parameters: • Constant-gap segmentation: • 82 different segment shapes • Six identical sectors • Nominal segment: • 1.44m regular hexagonal meniscus • Glass-Ceramic, 45mm thick • 60m paraxial radius of curvature • Neglect asphericity in support design activities • Average segment ROC ~62.5m • Assume worst case CTE = -0.05 ppm/°C in analyses • Alternate segment: • Fused Silica, 50mm thick meniscus • SSA can be re-tuned to accommodate

  9. M1 Parameters • Segmentation Pattern: Sector Boundary - Note Fixed Frame Clocking 60◦ View from Sky

  10. Thirty Meter Telescope SSA PROJECT OVERVIEW

  11. SSA Project Scope • IMTEC Design/Development Responsibilities Include: • Segment Support Assembly (SSA) • Segment Lifting Jack • Segment Lifting Talon • Attaches Mounted Segment Assembly (MSA) to Segment Handling Crane • Subcell Integration Hardware: • Mass Simulator • Surveying Target Holders • Subcell Alignment Tooling • Release Prototype Drawings • Build, Test and Deliver Prototypes • Refine design for production • Propagate design to 82 versions (segmentation effects)

  12. SSA Overview PRIMARY SEGMENT ASSEMBLY (PSA) Actuator1 Subcell Mounted Segment Assembly (MSA) Produced at Optics Shop IMTEC Responsibility Optical Coating Polished Mirror Assembly (PMA) Fixed Frame Assembly (1 ea) Adjustable Alignment Positioners (AAPs, 3 ea) Actuator Flexure (3 ea) IMTEC Responsibility Edge Sensors1 (6-drive, 6-sense) Polished Mirror Segment Segment Support Central Diaphragm (1 ea.) Moving Assembly (1 ea.) Cables & Connectors for Sensor1 & WH --Whiffletrees (3 ea) --Moving Frame Assembly (1 ea) --Warping Harness Actuators (21 ea) --Lateral Guide Flexure (1 ea) --Tower Assembly (1 ea) --Lock Assemblies (3 ea) --Sheet Flexures (6 ea) Electrical Bulkhead Panel Assembly Comprises the SSA Removed for Re-coating 1) In WBS, Actuator is part of the M1CS not M1Optics

  13. SSA Overview PSA ATTACHED TO MIRROR CELL Polished Mirror Segment Include Subcell + Actuators Add Segment Support Polished Mirror Assembly (PMA) Primary Segment Assembly (PSA) Add Optical Coating, Edge Sensors, Sensor & WH Cabling & Connectors Mounted Segment Assembly (MSA)

  14. SSA Overview SEGMENT SUPPORT ASSEMBLY (SSA)

  15. Requirements KEY DESIGN REQUIREMENTS

  16. Key Requirements (1/4) • SSA-Induced Surface Errors: • Goal: Minimize gravity and thermal distortion while controlling cost • Optical performance of SSA evaluated by system level PSS analysis • Performed by Project and JPL using IMTEC unit case predictions as inputs • When complete, analysis to consider all SSA distortion effects: • Gravity, Thermal Distortion, Thermal Clocking, Polishing, Mfg, + … • Assumptions: • Observing segment-zenith angle: -15° to +80° → max Δς = 80° • 0° to 65° telescope Zenith ± 15° from M1 curvature • Observing temperature: 9°C (TSITE) ± 4°C • Based on Armazones site testing data (80% of observing time within +/-4C) • Alignment & Phasing System (APS) + Warping Harness used regularly to null DC errors - Seasonal mean temperature offset, Tmean - Difference between optics shop figuring temp and Tref • Single Support-System design, customized for each segment type: • Accommodate shape variations from M1 segmentation (up to 0.5%) • No backlash or stick-slip: • Flexure-based mechanisms

  17. Key Requirements (2/4) • Accommodate ± 2.5mm actuator stroke: • SSA hard stops nominally at ±3.0mm • Survive full differential tip/tilt • Remote-controlled warping harness: • Control 2nd and 3rd order Zernikes: • Correction capability: 200 to 2100 nm P-V (38 to 410 nm RMS) • Improvement ratio (RMS before correction / RMS after correction) • > 15 on 2nd order terms: focus & astigmatism • > 5 on 3rd order terms: coma & trefoil • Periodic Adjustment: • Capability to readjust up to 10 times per night (~1/hour), if necessary • Power dissipation <2 Watts/segment • Includes all segment heat sources (Actuators, sensors, electronics, etc.) • 50 years lifetime; high reliability: • Only significant wear items are warping harness moment actuators • 6-DOF adjustable Subcell & repeatable registration system: • Correct for Mirror Cell tolerances ( ± 5 mm adjustment range, set-and-forget) • Removal/replacement of SSA with ± 50 μm repeatability

  18. Key Requirements (3/4) • SSA mass < 90 kg (moving mass < 45 kg) • Not including actuators, segment, edge sensors & cables for edge sensors • Ref: Segment mass ~153 kg for glass ceramic • Static stiffness > 12 N/μm, piston: • Assuming rigid actuator & mirror cell • Natural frequencies of PSA > 35 Hz with 10N/mm actuator stiffness: • Avoid rotating machinery disturbances at ~25 and ~30 Hz • 50 or 60 Hz AC power grids possible • Permit higher actuator control bandwidth • EXCEPT: • Torsional modes permitted to be <35 Hz • Unlikely to be excited on telescope • fn >8 Hz required for static stiffness • Environments: • Operating conditions such as temperatures, g-levels, etc • summary slide to follow

  19. Key Requirements (4/4) • MSA shall be compatible with Coating Chamber requirements TBC: • Cleanliness, Outgassing and Coating process compatibility • SSA design shall be designed for manufacture • 492 units + Spares allows for economies of scale if the design is sound • Maintainability and Servicing considerations • Segment exchanges are frequent and must be straightforward • Recoating every 2 years implies 5 segment exchanges per week on average • Cost control is fundamental to the design • Cost of manufacture and test • Cost of ownership • Reliability • Maintainability

  20. Environments 1. About any axis in local x-ySSA plane 2. In local zSSA direction (piston) 3. SSA on telescope 4. Scaled up from 1.2m segment loads by a2 5. Scaled up from 1.2m segment loads by a3 6. All dynamic loads treated as quasi-static. 1g dead weight not additional

  21. SSA Design DESIGN CONCEPT

  22. Key Functions of SSA • Support segment with minimum distortion (observation mode): • Relative to reference state (as figured) ςSEG = 0°, TREF • Ability to position segment in 3 DOFs (piston, tip, tilt): • Continuous, active positioning by three linear actuators • Ability to alter surface shape to correct for figuring errors and other effects: • Occasional correction • Interface with Mirror Cell • Provide means to align SSA in 6 DOFs: • Compensate for mirror cell fabrication tolerances (+/- 5mm any direction TBC] • One-time adjustment during telescope integration • Ability to remove and replace MSA with specified repeatability: • Quick replacement of segments without re-alignment of Subcell • Accommodate irregular/variable size segments with single support design: • Uniform gaps lead to irregular and/or variable size hexagons • Provide means to extract segment out of M1 array for re-coating/maintenance: • Lifting jack • Segment Lifting Talon • Interface with segment removal crane

  23. Design Concept Final Figuring Polished Mirror Segment Cam Locks (3ea) 3 ea Whiffletree Diaphragm Axial Support Rod Flexures Guide Flexure Edge Sensors (12) Warping Harness Actuators, 21ea Moving Frame Tower Mounted Segment Assembly (MSA) Note: Does not represent assembly sequence

  24. Design Concept 3ea Adjustable Alignment Positioners (AAPs) Actuator flexure Actuator Output Shaft Mirror Cell Fixed Frame 3ea Actuators SUBCELL+ACTUATORS

  25. Design Concept Lifting Talon Segment Lifting Jack MSA Placed on Jack

  26. Design Concept Actuator Flexure Clamped to Moving Frame (3 places) MSA Attached to Subcell

  27. Design Concept Cam Locks Released Diaphragm Mirror Segment 3 ea Whiffletree Guide Flexure Axial Support Rod Flexures Warping Harness Actuators, 21ea Moving Frame Tower Fixed Frame Mirror Cell 3ea Adjustable Cell Interface MSA hold-down bolts 3ea Actuators PSA Operational Configuration

  28. SSA Design PRELIMINARY DESIGN

  29. Design Status • Segmentation scheme has been chosen: • Scaling rule selected to minimize blank diameter • We have a detailed 1.44m Preliminary Design: • 27-point mechanical whiffletree axial support • Central diaphragm lateral support • 21-actuator/segment, whiffletree-based warping harness • Correction for segment shape variations via custom WT joint locations • Repeatable interface, Subcell alignment, and actuator attachment • Extensive, coupled performance modeling has been performed: • Complete FEA revision to reflect Preliminary Design is complete • Design satisfies nearly all requirements • Completing final changes required for Prototype SSA fabrication • Hardware designs being detailed: • Detailed drawings for prototype in process

  30. Current PSA Design • PSA attached to mirror cell: Mirror Cell Actuator

  31. Flexures Bonded to Segment Central Diaphragm (bonded to segment) Segment Edge Sensor 12 ea. Alignment Arrow Points to center of M1 Axial flexure assemblies 27 ea. bonded to segment Note: Does not represent assembly sequence

  32. Small Whiffletree Triangles Attached Small whiffletree triangle - 3 inner - 6 outer Note: Does not represent assembly sequence

  33. Large Whiffletree Triangles Attached Large whiffletree triangle Note: Does not represent assembly sequence

  34. Sheet Flexures Added Sheet flexure, 6ea In-plane connection between Whiffletree Triangles and Moving Frame Note: Does not represent assembly sequence

  35. Moving Frame Attached V-Groove for lifting, 3 ea. Sheet flexure, 6ea In-plane connection between Whiffletree Triangles and Moving Frame Moving frame Note: Does not represent assembly sequence

  36. Warping Harness Added Warping harness leaf-spring Warping harness actuator Note: Does not represent assembly sequence

  37. Tower & Locks Installed Tower Assembly with Repeatable Interface Electrical Connector Bulkhead Panel Note: Does not represent assembly sequence

  38. Fixed Frame Included Fixed Frame Note: Does not represent assembly sequence

  39. Installed on Mirror Cell Actuator flexure Actuator Mirror Cell Adjustable Alignment Positioner (AAP) Note: Does not represent assembly sequence

  40. PSA’s Clocked 60 degrees between sectors Two fixed frame versions Sufficient clearance at boundary Sector Boundary Adjacent actuators 35mm nominal clearance Sector-A Sector-F

  41. View of Seven Adjacent Segments – Top View Group of Segments

  42. View of Seven Adjacent Segments – Bottom View Group of Segments

  43. SSA Design AXIAL SUPPORT SYSTEM

  44. Axial Support System • Two level, 27-point whiffletree system • All-Aluminum design (nearly) • Triangles and sheet flexures Aluminum • Rod Flexures Stainless Steel • Analysis shows high CTE of Aluminum to be acceptable • Lower machining costs and corrosion resistance a plus • Triangles nested for compactness Pivot Flexures at Moving Frame Connection Mirror Support Rod Flexures Rod Flexures at pivot locations

  45. Axial Support System • Whiffletrees Ride on Moving Frame • Moving Frame: 6061 Aluminum weldment Pivot Flexure Actuator Rod Flexure Clamp Handling Feature

  46. Axial Support System • Sheet Flexures: • Concept introduced by SALT • Stabilize whiffletrees in XYSSA plane • Pivots (Kz) + Sheet Flexures (Kx, Ky, Rz) provide 4 Degrees of Stiffness • Tip/Tilt (Rx & Ry) remain compliant • Whiffletree mass is nominally balanced about sheet flexure plane • Aluminum 7075-T651, 0.508mm (0.020”) thick Pivots 3 per WT Sheet Flexures 2 per WT Sheet Flexure Attachment to Moving Frame, Typical No further discussion of Sheet Flexures Questions?

  47. Axial Support System Bondline • 27-Mirror support rod flexures • Invar pucks bonded to mirror using 3M EA-2216 Epoxy • Well characterized adhesive • JPL heritage for Invar/Zerodur bonds (documented process ) • 0.250mm nominal bondline (0.010”) • Stainless Steel rods connect pucks to triangles • 304V Cold drawn 94% CW • 250 ksi yield strength • Threaded end connections: • Stiff, strong, adjustable & removable Mirror Vent Hole Invar Puck Flexure: 2.1mm OD x 143mm Long Vent Hole Small WT Triangle Detailed discussion: PDR Volume-5

  48. Axial Support System • 9-Small whiffletree triangles • Extruded Aluminum: 6061 T6 • Low cost • ~$12 per extruded blank, in production qty. • 3-Large load-spreader triangles • Cast Aluminum (A356 T51) • Lowest manufacturing cost • Complex shapes & large size ideal for casting No further discussion of Triangle design Questions?

  49. Axial Support System • Optical Performance • Whiffletree support points and pivot locations determined by optimization • Pivot locations unique for each of the 82 segment types • See PDR Volume-2 for details • Axial support gravity print-thru: • Figured out at ςseg=0 • Springs-back as [1-cos(ςseg)] • Surface error amplitude ~10 nm RMS (ςseg=90) • See PDR Volume-3 for details

  50. SSA Design LATERAL SUPPORT SYSTEM

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