1 / 19

Outline

candy
Télécharger la présentation

Outline

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. IRIS OIWFS Concept StudyD. Loop1, M. Fletcher1, V. Reshetov1, R. Wooff1, J. Dunn1, G. Herriot1A. Moore2, R. Dekany2, A. Delacroix2, R. Smith2, D. Hale2,J. Larkin3, L. Simard4, D. Crampton4, B. Ellerbroek4, C. Boyer4, L. Wang41NRC-Herzberg Institute of Astrophysics2California Institute of Technology3University of California Los Angeles4TMT Observatory CorporationAO4ELT 2009 ConferenceJune 25, 2009 TMT.IAO.PRE.09.036.DRF01

  2. Outline We report on the concept study of the On-Instrument low order natural guide star WaveFront Sensors (OIWFS) for the TMT IRIS science instrument, a collaborative effort by NRC-HIA, Caltech, UCLA, TMT AO team, and TMT Instrument team. This includes work on sky coverage modeling, patrol geometry, detector alternatives, acquisition, guiding, and dithering scenarios, probe optics & mechanics, control architecture, and interfaces with NFIRAOS, IRIS, and TMT observatory. TMT.IAO.PRE.09.036.DRF01

  3. IRIS on TMT NFIRAOS  IRIS TMT.IAO.PRE.09.036.DRF01

  4. Key OIWFS Requirements • Instrument rotator & services wrap - alignment between NFIRAOS delivered beam and IRIS science instrument • Critical to IRIS image quality • 2 tip/tilt and 1 tip/tilt/focus wavefront sensors • Fast guiding, focus and tilt anisoplanatism • 2 mas positioning accuracy > 4.4 µm at focal plane • OIWFS are the positional reference for astrometric performance • High sky coverage - < 2 mas tip/tilt jitter at galactic pole • Near infrared, 1.0 to 1.7 µm, sensing on ‘sharpened’ guide stars • High acquisition probability = low acquisition time TMT.IAO.PRE.09.036.DRF01

  5. Work Breakdown Structure TMT.IAO.PRE.09.036.DRF01

  6. Sky Coverage(Lianqi Wang, Brent Ellerbroek, 2008) 1 TTF + 2TT probes TMT.IAO.PRE.09.036.DRF01

  7. Object Selection Mechanism • Object Select Mechanisms considered • Robot placed pickoff & pathlength mirrors (EAGLE concept) • Tip/tilt mirror tiling of focal plane (Caltech TIPI concept) • Theta-Phi, 2 rotation stages (Flamingos-2 OIWFS, etc) • Theta-R, 1 rotation + 1 linear stages (IRMOS, KMOS, etc) • Requirements for positioning accuracy, dithering, non-sidereal tracking • Theta-R concept chosen for initial sky coverage analysis • TT and TTF function change – versus - 2 probe planes TMT.IAO.PRE.09.036.DRF01

  8. Patrol Geometry(Lianqi Wang, Brent Ellerbroek, 2008) 3 identical ‘theta-R’ probes at 120 degree spacing Each probe capable of TT or TTF (key for sky coverage) Only need to reach 50% across 2’ field TMT.IAO.PRE.09.036.DRF01

  9. Theta-R Patrol Geometry The Information Herein is Subject to the Restrictions Contained on the Cover Page of this Document TMT.IAO.PRE.09.036.DRF01

  10. Converter lens and fold mirror TTF TT Field stop Collimator Fold mirrors Fold mirrors ADC ADC Imager Lenslet array ‘Trombone’ mirrors Detector Dewar ‘face’ Theta-R Probe Optics Detector TMT.IAO.PRE.09.036.DRF01

  11. Theta-R Probe Mechanics TMT.IAO.PRE.09.036.DRF01

  12. Macro Mechanics The Information Herein is Subject to the Restrictions Contained on the Cover Page of this Document TMT.IAO.PRE.09.036.DRF01

  13. Exploded View The Information Herein is Subject to the Restrictions Contained on the Cover Page of this Document TMT.IAO.PRE.09.036.DRF01

  14. OIWFS Probe Platform OIWFS platform assembly (with pickoff arms integrated) G10 or titanium flexures Thermal insulation (bottom part) Dewar interface frame (aluminum) The Information Herein is Subject to the Restrictions Contained on the Cover Page of this Document TMT.IAO.PRE.09.036.DRF01

  15. OIWFS Cameras • TT pixel scale = lH/2D = 5.67 mas/pixel • TTF pixel scale = lH/D = 11.34 mas/pixel • Same detectors can be used for TT and TTF functions • Analysis of tip/tilt jitter & image wander during acquisition shows worst case of ~250 mas • at 4 sigma and 5.67 mas/pixel > minimum of ~180x180 pixels • Acquisition probability > larger probe FoV > more pixels • Hawaii HxRG 1024x1024 HgCdTe detector w/new MBE material testing underway – read noise, dynamics • Speedster 128x128 HgCdTe detector testing soon • HgCdTe e-APDs and InGaAs emerging technologies TMT.IAO.PRE.09.036.DRF01

  16. Acquisition Probability(Corinne Boyer, Luc Simard, 2008) 1024x1024 pixels 5.8’ probe FoV 1’ Telescope pointing σθ (worse at 1st light) provide on-chip small dithering capability (2-3’) TMT.IAO.PRE.09.036.DRF01

  17. Sky Coverage Update(Lianqi Wang, Brent Ellerbroek, Jean-Pierre Veran, 2009) • NGS mode errors combined with LGS mode errors of 178 nm RMS • Overall on-axis budget of 187 nm RMS met at 45% sky coverage • Shortfall (in quadrature) of ~28 nm RMS at 50% • System optimization still underway • Detector performance • “Fitting field” for LGS modes • Optimal choice of NGS modes and reconstructor TMT.IAO.PRE.09.036.DRF01

  18. Shared Memory Control Architecture NFIRAOS RTC Engineering GUI Time Service Position Service AO Sequencer Logging & Status Service TCS Command Service IRIS IS Environ- mental Service House- keeping Service Motion Control Service Engineering Data System TMT.IAO.PRE.09.036.DRF01

  19. Acknowledgements • The authors gratefully acknowledge the support of the TMT partner institutions • They are • the Association of Canadian Universities for Research in Astronomy (ACURA) • the California Institute of Technology • and the University of California • This work was supported as well by • the Gordon and Betty Moore Foundation • the Canada Foundation for Innovation • the Ontario Ministry of Research and Innovation • the National Research Council of Canada • the Natural Sciences and Engineering Research Council of Canada • the British Columbia Knowledge Development Fund • the Association of Universities for Research in Astronomy (AURA) • and the U.S. National Science Foundation. TMT.IAO.PRE.09.036.DRF01

More Related