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NFIRAOS Opto-mechanical Design

NFIRAOS Opto-mechanical Design. Preliminary Design Kickoff 23 August, 2007 Peter W.G. Byrnes, HIA - NRC. Outline. NFIRAOS Then and Now Design progress since CoDR Windage abatement LGS Zoom packaging Visible wavefront sensors and ADC layout Infrared acquisition camera layout

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NFIRAOS Opto-mechanical Design

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  1. NFIRAOSOpto-mechanical Design Preliminary Design Kickoff 23 August, 2007 Peter W.G. Byrnes, HIA - NRC TMT.AOS.PRE.07.024.DRF02

  2. Outline • NFIRAOS Then and Now • Design progress since CoDR • Windage abatement • LGS Zoom packaging • Visible wavefront sensors and ADC layout • Infrared acquisition camera layout • Optical bench support • Interface definition • NFIRAOS + IRIS assembly, integration and verification TMT.AOS.PRE.07.024.DRF02

  3. NFIRAOS Then and Now CONCEPTUAL DESIGN REVIEW Q2 2007 PRELIMINARY DESIGN KICKOFF Q3 2008 TMT.AOS.PRE.07.024.DRF02

  4. Opto-mechanical Concept Overview INPUT LIGHT • Assemblage of four horizontal optical benches support science optics • Visible path extends upward of science path and feeds into wavefront sensors on bench above • LGS path above science path; zoom optics folded vertically down TMT.AOS.PRE.07.024.DRF02

  5. Nasmyth Layout NFIRAOS mirrored to –X platform Electronics relocated to lower platform level Windage abatement Visible path fold, re-locating OAP2c LGS zoom packaging Optical design: new concept Visible wavefront sensors HOL, MOR (Truth); High-order ADC IR Acquisition Camera Design and packaging in progress Interface Definition (in progress) Optical bench support structure IRIS service access Assembly and Integration Plan IRIS Integration @HIA Design Progress since CoDR TMT.AOS.PRE.07.024.DRF02

  6. Nasmyth Layout (First Light) • M1 flushing concerns drove Nasmyth platform to 7m below elevation axis • NFIRAOS also assigned to −X platform • NFIRAOS model “mirrored” • to be accessed via lightweight deck • to be supported by intermediate structure, extending to Nasmyth platform Ref: OAD, Fig. 5 TMT.AOS.PRE.07.024.DRF02

  7. OAP2c 2m FOLD TTP Windage Abatement • CoDR NFIRAOS enclosure height was driven by position of OAP2c, part of the visible path relay optics • Introduction of a fold allows enclosure height to be truncated by 2m • Provisional fold dimensions 0.7 x 0.5m • Fold mirror may be smaller, once the final tip-tilt platform (TTP) volume is known TMT.AOS.PRE.07.024.DRF02

  8. ASPHERICAL LENSES WFS BARRELS PICKOFF MIRRORS LGS Zoom Optics at CoDR • CoDR LGS Zoom incorporated six off-axis aspherical lenses, four of which translated • Light from all six artificial stars corrected by these lenses • Supported from underside of visible WFS bench • Pickoff mirrors for individual WFS barrels • High vendor price quotations for aspherical lenses provided impetus for an alternative design TMT.AOS.PRE.07.024.DRF02

  9. WFS BARREL ZOOM LENS GROUP (1 STAR) FIXED LENSES LIGHT FROM OAP2b FOLD/FAST STEERING MIRROR (TBD) PERISCOPE LGS Zoom Optics – PD Concept • Current concept consists of four (fixed) off-axis spherical lenses which feed into separate trains of translating lenses for each guide star (total: 6 guide stars) • Prescription of each channel optimised specifically • Three linear stages required for each channel • Additionally, two channels include a cylindrical corrector with rotator • WFS barrels are fixed • Fold/fast steering mirror (provisional) • Periscopes spread beams of outer five guide stars in pentagonal asterism TMT.AOS.PRE.07.024.DRF02

  10. LGS Zoom from 85km to 235km TMT.AOS.PRE.07.024.DRF02

  11. 2.6m OUTER GUIDE STAR PERISCOPES CENTRE CHANNEL RAIL LGS Zoom System Assembly • Proposed embodiment has tapering framework supporting linear stages • Optics and motion systems carried within framework • Total number of motors (linear and rotary) = 20 • Need for steerable fold mirrors feeding WFSs: TBD TMT.AOS.PRE.07.024.DRF02

  12. COOLED ENCLOSURE (-30C) LGS Zoom Integration FOLD MIRROR • LGS path does not require cooling to mitigate emission • Dimensions of LGS assembly also encourage location outside the main NFIRAOS enclosure • Propose to fold LGS path vertically below NFIRAOS • Uses space created by lowering of the Nasmyth platform • Improved service access • Removes 20 out of 36 motors from cold environment • Two of the fixed lenses will serve as a dual-pane window into cooled enclosure • Fold dimensions 0.64 x 0.5m LGS ZOOM ENCLOSURE TMT.AOS.PRE.07.024.DRF02

  13. SCAN GIMBAL MIRRORS CoDR DESIGN (incl. VIS ACQ CAMERA) NGS WFS HOL TRUTH WFS MOR TRUTH WFS ADC DEPLOYABLE BEAMSPLITTER Visible WFS Bench Layout • System now consists of three wavefront sensors (additional Truth WFS) • Natural guide star selection via two gimbal mirrors • WFS barrel dimensions TBD pending choice of detectors and lenslet arrays • Two modes of operation • Necessitating deployable beamsplitter PD CONFIGURATION (incl. ADC) TMT.AOS.PRE.07.024.DRF02

  14. FOLD 1 COLLIMATOR PINHOLE FOLD 2 ADC Layout • The ADC is located at a pupil between a collimator – focusing lens pair • Fold mirrors included to afford space for ADC on visible WFS bench • Pinhole and collimator feed visible wavefront sensors • Beamsplitters omitted for clarity ADC COLLIMATOR - FOCUSING PAIR TMT.AOS.PRE.07.024.DRF02

  15. IR CAMERA LOCATION FOLD MIRRORS INSTRUMENT SELECTION MIRROR FIELD LENS Infrared Acquisition Camera • CoDR committee recommendation • Opto-mechanical layout concept feeds camera via instrument selection mirror • Packaging folds and field lens similar to CoDR visible camera • IR camera optics particulars: work-in-progress TMT.AOS.PRE.07.024.DRF02

  16. TYPE A: FOCUS, OAP1 TYPE A: DM0, OAP2 TYPE B Optical Bench Support Structure TABLE SUPPORT TRUSS Ref: Design and Construction of Large Optical Telescopes, Bely (ed.) Springer, 2003 3m PLAN VIEW FROM ABOVE • NFIRAOS Science path optics rest on four large optical benches • Initial concept consists of trusses supporting tables via kinematic connections • Connections likely will be implemented via flexures • Proposed locations of type A and type B connections shown; type C locations TBD • Interface to intermediate structure/Nasmyth platform TBD TMT.AOS.PRE.07.024.DRF02

  17. IRMS IRIS IRIS SERVICE CORRIDOR TURBULENCE SIMULATOR ENVELOPE NFIRAOS Interface Definition • Considerations include: • Providing access for IRIS servicing • Space allocation for turbulence simulator (near input window) • Consolidation of structural support for four main optical benches into a kinematic interface TMT.AOS.PRE.07.024.DRF02

  18. 750mm BFD 250mm SNOUT Interface Definition (2) • NFIRAOS provides 750mm BFD at all three ports • Plus up to 250mm snout • NFIRAOS Instrument Support Tower will bear vertical mass loads • Upper and lower instruments will need to provide rotator bearings • Lateral instrument mass will not be supported by NFIRAOS • Requires separate support structure • Thermal control of NFIRAOS will require refrigerant supply • Type, flow rate and temperature to be determined during PD phase TMT.AOS.PRE.07.024.DRF02

  19. NFIRAOS + IRIS AIV @ HIA • Large former optical shop at HIA can accommodate NFIRAOS plus IRIS • Crane height just sufficient to winch large components into position within NFIRAOS • Reinstatement of original pit required (currently floored off) • Pit area sufficient to install IRIS using crane + pallet lift • IRMS integration also potentially feasible TMT.AOS.PRE.07.024.DRF02

  20. Opto-mechanical PD Plan • Iterate and freeze opto-mechanics in accord with optical design • Incorporate IR acquisition camera details • Create ICDs for NFIRAOS/TEL.STR and NFIRAOS/INST interfaces • Develop NFIRAOS support structure concept • Packaging of turbulence simulator • Determine and specify requirements e.g. coolant particulars • Raise level of detail throughout NFIRAOS design model • Develop and elucidate assembly and integration procedures TMT.AOS.PRE.07.024.DRF02

  21. NFIRAOSOpto-mechanical Trade Studies, Risks, and Open Items Preliminary Design Kickoff 23 August, 2007 Peter W.G. Byrnes, HIA - NRC TMT.AOS.PRE.07.024.DRF02

  22. Outline • Visible path fold mirror size reduction • LGS Zoom opto-mechanics placement • Horizontal configuration • “Inverted” NFIRAOS • As alternative to folded visible path • Issues and potential solutions TMT.AOS.PRE.07.024.DRF02

  23. TTP ENVELOPE Visible Path Fold • Visible path fold mirror is large (0.7 x 0.5m) • Instrument selection fold: 0.6 x 0.4m $80k • Cost risk • TTP envelope drives fold angle and mirror position • TTP envelope is generous • Given TTP prototype actual dimensions • Move fold closer to BS • Reduce included angle TMT.AOS.PRE.07.024.DRF02

  24. Horizontal LGS Zoom • Fold LGS zoom assembly horizontally, protruding from side of NFIRAOS • Alleviates potential complications with IRIS access; NFIRAOS support structure • Disadvantages include greater risk of LGS zoom mechanics gravity deflection • This alternative is not currently preferred TMT.AOS.PRE.07.024.DRF02

  25. ORIGINAL TABLE PLACEMENT TTP INSTRUMENT SUPPORT STRUCTURE SPACE OAP2c IN “ORIGINAL” POSITION “Inverted” NFIRAOS • “Invert” NFIRAOS • Alternative approach to windage abatement • Avoids need for large visible path fold mirror • Visible path would extend into space under NFIRAOS • Optical bench placement awkward in this configuration • LGS path occupies natural bench location • Placement below LGS path encroaches on space needed for instrument support • Pylons required to support heavy optics (esp. TTP) TMT.AOS.PRE.07.024.DRF02

  26. “Inverted” NFIRAOS (2) • Rough concept in which optical benches are replaced by structural framework • Stiffness, stability, mass and cost trade vs. commercial optical benches with visible path fold mirror? TMT.AOS.PRE.07.024.DRF02

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