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System Overview

System Overview. Brent Ellerbroek. Presentation Outline. Primary subsystems and their characteristics Laser System (LS) Beam Transfer Optics (BTO) and Laser Launch Telescope (LLT) Adaptive Optics Module (AOM) MCAO Control System (MCAO CS)

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System Overview

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  1. System Overview Brent Ellerbroek

  2. Presentation Outline • Primary subsystems and their characteristics • Laser System (LS) • Beam Transfer Optics (BTO) and Laser Launch Telescope (LLT) • Adaptive Optics Module (AOM) • MCAO Control System (MCAO CS) • Safe Aircraft Localization and Satellite Acquisition System (SALSA) • System performance summary • Strehl • Strehl variability • Transmittance and Emissivity • Availability and Reliabilty MCAO Preliminary Design Review

  3. System Block Diagram (Boresight Calibration) DM/TTM commands MCAO CS LLT AOM Real-Time Control Fast tip/tilt WFS data BTO Beam alignment Close/open loops OI WFS Science Inst. Emergency halt Functional Control Diagnostics Calibration functions Status LS Commands M2/M1 offloads Data logging Telescope pointing Observing sequences SALSA Safety status TCS/SCS/OCS/DHS NGS Laser/LGS Science field MCAO Preliminary Design Review

  4. Laser and LGS Parameters MCAO Preliminary Design Review

  5. BTO andLLT Schematic Near- and far-field beam profiles Beam position & tilt MCAOCS BDS Miscellaneous Features Closed-loop Alignment Control Boresight Calibration PA, CA Periscope Pre Alignment Centering mirror (CM) X-Shaping Mirrors Beam Dump Mirror BS l/4 Plate PS KM PA, CA Shutter CC Pointing mirror (PM) Top-End Ring Mirror LLT cover PAC LGS WFS Top End Fast Steering Array MCAOCS PAC Offload to KM, PM, CM PAC Center Section PA, CA Relay Centering Array (CA) Pointing Array (PA) LLT l/4 Plate PM, CM Safety Shutter(SALSA) MCAO Preliminary Design Review

  6. Adaptive Optics Module Science Path NGS WFS Path LGS WFS Path Other Stuff DM9 DM0 ADC SCIBS Source Simulators • f/33.4 output • Focal- and pupil plane locations preserved • Standard optical bench design with space frame support • In-plane packaging with adequate room for electronics OAP2 OAP1 WFSBS Diagnostic WFS and Imaging Camera TTM DM4.5 LGS WFS Zoom Focus Lens OAP3 ADC WFS MCAO Preliminary Design Review

  7. Baseline AO Component Parameters MCAO Preliminary Design Review

  8. Real Time Control Block Diagram Integrator OIWFS Focus M1/M2 Offload Focus adjustment Higher- order wave front control OIWFS Tip/tilt Integrator Tip/tilt (tt) and tilt aniso- Planatism (ta) control Boresight adjustment Tip/tilt M2 Offload Higher order BTO tip/tilt DM’s LGS WFS’s + Null uncon- trolled modes ta TTM NGS WFS’s tt MCAO Preliminary Design Review

  9. MCAO Control System TCS pointing seeing M2 data TCS pointing CR angle Observing data M1 data Oiwfs data (CR angle Offset) OCS command OCS command status DWFS Detector Controller 7 Instrument Sequencer 1 Controller commands/status Pupil Alignment BTO/LLT Component Controller 4 SALSA Controller 5 AOM Component Controller 2 Laser Controller 6 Real Time Controller 3 BTO Fast TT NGS probe offset commands/status commands/status commands/status commands/status WFS data/DM commands AOM devices AOM WFS/DM/TTM BTO/LLT devices SALSA hardware Laser hardware MCAO Preliminary Design Review

  10. SALSA Elements • Boresighted IR aircraft camera • All-sky aircraft cameras • Laser traffic control arbitration with local observatories • Available radar feeds from air traffic control agencies (TBD) • US Laser Clearinghouse interface (TBD) MCAO Preliminary Design Review

  11. Strehl Ratio Summary • Median Cerro Pachon seeing • Mean Strehls over 1 arc minute square field • Delivered Strehls at the detector • Bright NGS • Detailed error budgets in system modeling presentation MCAO Preliminary Design Review

  12. Performance with an Interim Laser Complement • Initial MCAO laser configuration may be reduced for reasons of schedule or cost • Growth path to the full laser system should be maintained • One possible interim laser configuration: • 60% nominal laser power, split into • 1 full power and 4 half power laser guide stars • Expends Margin • Sodium column density • Laser power and beam quality MCAO Preliminary Design Review

  13. RMS Relative Strehl Nonuniformity • 1 square arc min field, median Cerro Pachon seeing, bright NGS • CoDR results • Linear modeling • Neglect effects of diffraction, 3-d LGS, DM-to-WFS misregisration, and other implementation error sources • Initial simulation results including these effects see no significant change MCAO Preliminary Design Review

  14. Science Path Transmittance and Emissivity MCAO Preliminary Design Review

  15. System Availability • Astrometry adds extra setup time for plate scale determination • CW laser penalty is due to LGS interference with thin cirrus • Conventional LGS AO still feasible • Includes system downtime of 10% • Met with laser MTBF of 48 hours MCAO Preliminary Design Review

  16. Summary • Overall system architecture equivalent to conventional LGS AO • Significant subsystem design progress since CoDR • Delivered H-band Strehl of 0.398 • Median CP seeing, zenith, bright NGS, average for a square 1 arc min field • Useful performance for an interim laser system with 60% power • Strehl ratio reduction factors of 0.888 to 0.985 • RMS relative Strehl nonuniformity of 0.04 in H • Science path throughput of 0.80-0.85 in H band, emissivity of 0.14-0.18 in K • System availability of 62-73% with queue scheduling MCAO Preliminary Design Review

  17. Thursday, 5/24 0800 Welcome 0805 Project overview 0830 Science case 0930 Break 0945 System overview System modeling 1100 AO Module optics 1145 Lunch 1245 AO Module mechanics 1340 AO Module electronics 1400 Break 1415 Beam Transfer Optics 1510 Laser Launch Telescope Closed committee session 1800 Adjourn PDR Agenda MCAO Preliminary Design Review

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