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What is Nirvana?

What is Nirvana?. I don’t know, But I know it is for ever!. Final Nirvana. Visual arm. Multiple WFS. Multiple WFS. MCAO WFS. DM’s. DM’s. NIR arm. Instrum. 1. Instrum. 2. Instrum. 3. Instrum. 3. Instrum. 2. Instrum. 1. NIR Iterferometer first. Single WFS. Single WFS. NIR arm.

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What is Nirvana?

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  1. What is Nirvana? I don’t know, But I know it is for ever! What is Nirvana?

  2. Final Nirvana Visual arm Multiple WFS Multiple WFS MCAO WFS DM’s DM’s NIR arm Instrum. 1 Instrum. 2 Instrum. 3 Instrum. 3 Instrum. 2 Instrum. 1 What is Nirvana?

  3. NIR Iterferometer first Single WFS Single WFS NIR arm Step 1: Linc=narrow field NIR interf. 3M$?? What is Nirvana?

  4. Add to Link “one arm MCAO” Visual arm Multiple WFS MCAO WFS DM’s + 2 M$?? What is Nirvana?

  5. MCAO test Visual arm Multiple WFS MCAO WFS DM’s Single WFS Single WFS NIR arm Step 2: Single pupil MCAO What is Nirvana?

  6. Initial Nirvana Visual arm Multiple WFS Multiple WFS MCAO WFS DM’s DM’s NIR arm Step 3: Nirvana (imaging) +2 +2 M$?? ~ 10 M$ to this stage Instrum. 1 What is Nirvana?

  7. Blue arm: Interferometric focal stationwith “transmission” MCAO WFS WFDLIS MCAO MOS IFU Ifu unit Transmission MCAO Cameras ? MOS unit ~2 m ~3 m What is Nirvana?

  8. Two concepts for transmission MCAO Tubetto concept WFS WFS X stage X stage Y stage Y stage Mutiple WFS concept What is Nirvana?

  9. Field Up to 16 XY stages What is Nirvana? Focal Plane

  10. Transmission MCAO obstruction What is Nirvana?

  11. Instrument 0: High Resolution CameraHRC • Needed to setup narrow field Interferometry • Needed for setup of MCAO • Must be able to evolve in much more powerful HR imager: • Make it mobile! • Bands V to I • Many filters • 4000x4000 class detector What is Nirvana?

  12. HRC: what type of camera? ccd filter Direct? Problem with filters and with space near focal plane What is Nirvana?

  13. HRC: What type of camera? ~60 mm Dp ~f/30 ~2f dp ~f/80 pupil pupil ~ 700 mm ~2f Focal plane Re-imaged ~1/1 f = 150 mm Dp= 5 mm <30 mm What is Nirvana?

  14. 8 cameras (4000^2 pix) on top of MCAO Just to show that, with an 8 star MCAO There is a lot of choice for Placing 8 cameras (The two patterns are the same, but one is rotated by 180 deg, The red one is the shadow Of the MCAO) What is Nirvana?

  15. Instrument 1: Wide Field Diffraction Limited Imager/Spectrograph WFDLIS = “efoscone” • Features: • Necessary for Wide Field Interferometry setup!! • Necessary for LBC follow-up and source selection!! • ~Complete sky coverage with Ground Layer correction only • (Partial correction from V to I ) • ~ Complete sky coverage in Pointed AO mode (~λ/D) • Undersampled in interferometry • Modes: • Direct imaging (with filters) • Objective Prism ? • Multi-slit MOS!! What is Nirvana?

  16. WFDLIS Detector Camera Pupil Collimator Focal plane Field ~120 arcsec Detector ~ 92Mpix Sampling 12 mas/pix Pix size ~13.5 m Scale ~1.1 mm/arcsec Image F/N F/8 (F/3) Collim. F ~ 1000 mm Collim D ~400 mm Pupil D ~25 mm Pupil b ~67 mm Camera f ~330 mm Camera D ~100 mm Total length ~2.5 m from focal plane 1.5 m What is Nirvana?

  17. WFDLIS: a big detector array! 10 chips EEV 42-90 9,200x10,000 pix ~ 600 k$ λI/2D ~ 60 nrad ~ 12 mas (~10000 pix over 2’) Platescale ~ 0.9 arcsec/mm, ~F/8 Binned scales: 2x2=24mas 3x3=36 mas 4x4= 48 mas 5x5=60 mas What is Nirvana?

  18. WFDLIS: Limit sensitivity in Direct Imaging Revise! .012 arcsac! What is Nirvana?

  19. WFDLIS: Objective Prism mode Not as sensitive as spectroscopy, but good diagnostics over the field For instance, dispersing over 100 pixel: One can see strong lines, spectral slope for all compact objects in the field. Not really a priority,sensitivity is not that high What is Nirvana?

  20. WFDLIS: MOS mode 500 pix over 500 nm or ~1 nm/pix or d λ/ λ ~400 ~ 5” slits (!!!) ~ 24x20 slitlets without spectral overlap dispersion direction What is Nirvana?

  21. WFDLIS: MOS mode By inserting a multislit mask in the focal plane and a Grism at the pupil plane one can do spatially resolved (> λI/D, >24 mas) multi-object spectroscopy on many sources. Assuming that one disperses light on 400 pixels: One can make low resolution Spectroscopy to mag ~25 . (Detector noise limited) > 500 slitlets possible at low dispersion Per Hour? What is Nirvana?

  22. WFDLIS: : MCAO/Interferometry setup • Measures on field stars, to a fraction of a pixel • Field scale • Field rotation • Co-pointing of the two arms (shutters on both arms) • (And, on background, position of probes) • Provides astrometry of MCAO stars to a few mas • With narrow band I filter and pupil mask shows fringes • on ~21st mag stars over the entire field (omothetism) in <1 min • Using two narrow band filters, pupil mask and differential • fringe motion allows zeroing path difference over field What is Nirvana?

  23. WFDLIS: Interferometry setup with pupil mask b ~7m w~ 0.5 m h ~ 4 m λI ~ 1000 nm, b ~ 7 m λI /2b ~ 70 nrad ~ 14 mas (~8600 pix over 2’) λI/2D ~ 60 nrad ~ 12 mas (~10000 pix over 2’) λR/2D ~ 50 nrad ~ 10 mas (12000 pix over 2’) λI/w ~ 400 mas λI/h ~ 50 mas λI/2b ~ 14 mas Pixel ~12 mas What is Nirvana?

  24. More instruments • Multi-head fibre fed IFU(s) • 8 (multiple head ?) probes • 8 low resolution spectrographs (1000x1000 LLLCCD) • More specialized spectrographs for alternative IFU heads Low res. Spectrograph 1 Special Spectrgraph What is Nirvana?

  25. Organization of the army • The Nirvana project is nearly as complex as the entire LBT!!! • We need: • long term planning capability • flexible planning to allow different developments in parallel • and addition of further contributors (unpredictable extra-funding) • clear and achievable short term objectives (on “sure” funding) • I believe we may try to identify: • Initial funding • Composition of initial “steering committee” • Initial project “branches” or “phases”and respective PIs (+ co-PIs) • Initial composition of a “science group” • The next formal step can be some sort of MOU What is Nirvana?

  26. Initial Funding 2002-2005 MPIA (Humbolt) 2. 0 M€ Univ. Koln 0.5 M€ Arcetri 2.5 M€ (??) LBT 0 Total 5 M€ (??) Is it all real cash? Can we add more in labor? Can we ask LBT for “in kind” strategic contribution? (~ 1 M€ of mechanics?) (~ 1 M€ of optics) How far can we go with only 5 M€? What is Nirvana?

  27. cost Visual arm Multiple WFS MCAO WFS DM’s Single WFS Single WFS NIR arm Hardware only (??): LINK PHASE Full support mechanics 0.5 M€ Full Linc optics 0.5 M€ NIR arm 1.0 M€ 2 WFS 0.2 M€ Link TOTAL 2.2 M€ STEP 2 PHASE Blue arm optics 0.2 M€ 2 DM 0.7 M€ MCAO WFS 0.5 M€ 6 more WFS 0.5 M€ Single CCD camera 0.2 M€ Step 2 “Total” 2.1 M€ “Current funding” is too much for Link, may be enough for Step 2. WITHOUT LABOR We may need “in kind” tricks! What is Nirvana?

  28. Which AO modes? • The “double field” MCAO concept has in principle various modes of operation and different GOALS: • 0) Near axis correction only (standard AO), λ/D and λ/b • Ground Layer Only (reduced FWHM): • ~ 50% sky coverage at HGL in V (in good seeing) • 100% sky coverage at HGL in I, J, H, K • < 0.3 arcsec FWHM in median seeing • Pointed Correction λ /D: (STILL TO BE DEMONSTRATED) • Single Conjugate, < 10 arcsec isoplanatic field diameter • > 50% sky coverage at HGL in V (in good seeing and • using all possible tricks) • MCAO MERAVIGLIAO, λ / D and λ /b: • Wide field (2 arcmin) correction in V over >10% HGL sky What is Nirvana?

  29. Ground Layer WFS Photon Flux CHECK!! With these assumptions a V mag 18 K5 star gives ~1 Ph/m^2*ms in R+I What is Nirvana?

  30. Ground Layer Stars and Photons A • To correct the ground layer @V with • >50% HGL sky coverage we need: • 4 arcmin field radius • 16 probes • Noise-free detectors • And good seeing! "handbook of space astronomy and astrophysics“ M. Zombek, Cambridge Univ. Press, 1990 What is Nirvana?

  31. Ground Layer Stars and Photons B • To correct the ground layer @V with •  80% HGL sky coverage we need: • >3 arcmin field radius • 8 to 16 probes • Noise-free detectors What is Nirvana?

  32. Pointed AO Correction There are conceptual problems to be solved for this mode, in particular concerning the partially “open loop” operation. In terms of star density the requirements differ from the “Ground layer only” mode essentially only for the need of acquiring slope information on the high metapupils. The binocular nature of LBT may help on metapupils above ~ 7 km if the Ground Layer field is ~ 4’, as there is the possibility of using a single large metapupil with stars seen by both LBT arms. See Fig. 1, 2, 3, and Table 1 for clarity I strongly believe we have to make it work! What is Nirvana?

  33. Pointed AO Fig. 1 2’ MCAO field H=14.4 km θ=3’ D”=D+2H/1000 D”=38m H=7 km D’=22m θ=3’ 6’ Ground Layer field What is Nirvana?

  34. Pointed AO Fig. 2 38 m metapupil of 6’ ground layer at 14.4 km 16.5 m metapupil of 2’ MCAO at 14.4 km 8.25 m pupil 14.4 m What is Nirvana?

  35. Pointed AO Fig. 3 13 stars Seen twice At 14.4 km What is Nirvana?

  36. Pointed AO Correction Table 1: Metapupil coverages Example of Coverage=1 Good coverage is ~1.5 The “second eye” trick allows PAOC to correct to ~ 12 km (Pupil coverage ~ 1,5) No overlap area What is Nirvana?

  37. Pointed AO Correction summary • If Pointed AO Correction is at all possible, the binocular • Ground Layer WFS numerically combined can be used to • construct “binocular” metapupils well filled with star footprints • up to ~ 12 km above the telescope (15 km above sea level) at HGL. • PROS: • Nearly total sky coverage • Better Strehl due to correction of higher layers • “Pointed Interferometry “ possible • CONS: • Narrow field correction only • Metapupils become large (large memory, fast communication!) • Binocular metapupil coverage evolve with time (who cares?) What is Nirvana?

  38. MCAO parameters and questions Optical Field 2 arcmin (Is it enough for HGL coverage?) Bands V,R,I (add B if at all possible!!) IR field 1 arcmin (what is limiting it, dewar apart?) Bands J.H.K’ Resolution /b HGL coverage >10% (???) Platescale 3.2 mm/arcsec (~ ok) Flat field VERY DESIRABLE!!! Vexata Questio Tubetti Versus Numerical What is Nirvana?

  39. MCAO: are there enough stars and photons at HGL? • Here we have assumed that • the extra optics has transmission of 60% • we can use stars with mV < 19 • we limit ourselves to the most favorable 5% of sky at HGL (3σ fluctuations) • we can use larger subapertures on high metapupils • We seem to NEED noiseless detectors even with 3 arcmin field • We have problems in filling the High Metapupil (with any field) • The solution could be in Taylor : Layer turbulence prediction. according to Bahcall model of NGP 2x above!! What is Nirvana?

  40. Details X axis Cable twist Counterweight Ferromagnetic rails Capacitive Super-resolver Pre-load magnets Driving Gears, Using torque Motors and Abs. Enc. Wheels What is Nirvana?

  41. Details Y axis Counterweight Of triangle What is Nirvana?

  42. Parts of Nirvana Visual arm Multiple WFS Multiple WFS MCAO WFS DM’s DM’s Single WFS Single WFS NIR arm What is Nirvana?

  43. IFU(s) A small array of 16x16 fibers. Core D=30 mu Cladd. D=40 mu Sampling~50% of field over 0.13x0.11 arcsec. Dcore=100 mu D cladd=110 mu Gives ~70% sampling Over 0,55x 0.45 arcsec What is Nirvana?

  44. What is Nirvana?

  45. Hexagonal Pattern Gives much Better Filling And lower Area, but At much Higher Cost. 16x16 hexagons What is Nirvana?

  46. Pupil geometry is lost! becomes • Output angular FWHM of beam becomes ~ 2.44 λ/d • λ = 0.8 mu, d= 30 mu • Angular FWHM =0.8/30 = 1.52 deg (F/18) • Design low res. spectrograph for • 23 m, F/10 telescope • input slit ~ 100 mu What is Nirvana?

  47. What is Nirvana?

  48. What is Nirvana?

  49. θ=2’ θ=3’ θ=4’ What is Nirvana?

  50. 30 mas pix 400 mas Airy disk 35 mas /b fringe What is Nirvana?

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