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'OHANA: Kilometric Infrared Arrays for Visions in InfraRed Astronomy

This poster presentation discusses the 'OHANA project, which aims to demonstrate the potential of fiber optics for beam propagation in kilometric arrays for infrared astronomy. The project focuses on combining large apertures, adaptive optics correction, and single-mode fibers to achieve high sensitivity and angular resolution in the near-infrared. The poster highlights the progress made in the development and testing of the 'OHANA instrument.

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'OHANA: Kilometric Infrared Arrays for Visions in InfraRed Astronomy

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  1. ‘OHANATowards kilometric infrared arrays Visions for InfraRed Astronomy Paris March 21, 2006 Guy Perrin (+ many others including Pierre)

  2. VLTI Very Large Telescope Interferometer: 4 x 8 m telescopes + 4 x 1.8 m telescopes Maximum baseline: 200 m

  3. (Poster by Poncelet et al.) Based on VISIR data in Burst Mode analyzed in the speckle way NGC 1068 at different spatial scales @ 12 µm

  4. First interferometric measurements of an AGN at VLTI (Jaffe et al. 2004) NGC 1068 @ 8-13 µm with MIDI

  5. (Poncelet, Perrin & Sol, 2006) The putative torus spatially and spectrally resolved

  6. Active Galactic Nuclei scenario AGN 2 like NGC 1068 AGN 1

  7. First interferometric measurements of an AGN at Keck NGC 4151 (Swain et al. 2003) NGC 4151 (Seyfert 1) @ 2.2 µm with Keck : the compact core is not resolved (résolution = 5 mas)

  8. 10 1 2 10 1 2 1pc @ 100 Mpc Angular resolution B = 200 m l (mm) 0.5 0.5 q (mas)

  9. Low cost VLTI proposal (1995) ‘OHANA(Optical Hawaiian Array for Nanoradian Astronomy) Link CAT and the 3.60 m in La Silla (2nd year of PhD program of V. Coudé du Foresto) • Link the 7 largest Mauna Kea telescopes with infrared single-mode fibers • 800 m synthesized pupil • No immediate competition

  10. Goals • Demonstrate the potential of fibers for beam propagation in kilometric arrays • Demonstrate the sensitivity of interferometers that combine large apertures, AO correction and single-mode fibers -> fibers transmit 60-95% of the light over a 1 km in the near-infrared • Go to a few 0.1 mas angular resolution in the near-infrared • Demonstrate the astrophysical potential of the instrument Build ‘OHANA and make it work

  11. Injection module OA OA Injection Injection Delay line Detector ‘O H A N A Single-mode fibers Beam combiner

  12. FLUOR(Fiber Linked Unit for Optical Recombination) Partnership with Le Verre Fluoré

  13. Cleaning beams with single-mode fibers core ~ 5 µm Trade phase (coherence) fluctuations against intensity fluctuations which can be easily measured Requirement: focus light in a tiny core  adaptive optics

  14. (Benson et al. 1993) (Perrin et al. 1998) The gain

  15. Injection module OA OA Injection Injection Delay line Detector ‘O H A N A Single-mode fibers Beam combiner

  16. Injection tests (2002-2003) Adaptive Optics Injection module Fibers Gemini North Cassegrain focus

  17. Injection tests • Injection tests at: • CFHT (July 2002) (K) (3 nights) • Keck (December 2002) (K) (2 half nights) • Gemini North (July 2003) (H) (2 half nights) • Results: • best injection efficiency CFHT: 20% (24% theoretical) • best injection efficiency Keck: 50% (60% theoretical) Green light to proceed with first baselines

  18. Chromatic differential dispersion Interferograms at different wavelengths form at Different zero optical path difference No differential dispersion With differential dispersion

  19. The starting point Coudé du Foresto, Perrin & Boccas (1995) Coupler (a few meters of fibers) 77 m long fibers

  20. ‘OHANA fibers: example in the K band 2x300 m fluoride glass fibers Kotani et al. (2005, K) Vergnole et al. (2005, J&H) No differential dispersion !!!

  21. First tests with the two Kecks

  22. Keck I - Keck II (85 m) Subaru - Keck II (214 m) VLTI Keck II - IRTF (251 m) Subaru - IRTF (454 m) CFHT - Gemini (159 m) Gemini - UKIRT (188 m) CFHT - UKIRT (338 m)

  23. 2 x 300 m cables Equivalent to a 500 m interferometer Set-up

  24. First fringes on 107 Herculis (June 2005) Perrin et al. (2006)

  25. First fringes on 107 Herculis (June 2005) Perrin et al. (2006)

  26. First (technical) results • Fringe contrast: • 25% on 107 Herculis because of dispersion in adaptive optics • 75% in autocollimation • Transmission : • 0.5% on 107 Herculis: cloudy night, 2 magnitudes of extinction @ V • potentially 4% with the current system and 10% if improved • to be compared to the 1% of Keck (the same order as VLTI) • We have been granted with a science night (NASA + Keck time) : May 8, 2006

  27. A difficulty: fibers are very efficient antennas for vibrations • Elasticity of fibers ~ 0.1-1%  1 µm amplitude every millimeter • Measured amplitude: 3 µm • Sources: motors, fans, oil and glycol hoses running in cable wraps … • Solutions: • damping (insulating fibers) • servoing of fiber lengths

  28. What’s next ?

  29. Keck I - Keck II (85 m) Subaru - Keck II (214 m) VLTI Keck II - IRTF (251 m) Subaru - IRTF (454 m) CFHT - Gemini (159 m) Gemini - UKIRT (188 m) CFHT - UKIRT (338 m)

  30. The Gemini - CFHT baseline (156 m)

  31. Set-up in the Coudé room at CFHT CFHT GEMINI

  32. The ‘OHANA stream

  33. Optical ALMA ´ Leap for Extraordinary Nanoradian Astronomy

  34. Some more technology requiredFibered incremental delay line opd modulator (±100 µm) Long stroke delay line (several 100 m) Hollow Photonic Crystal Fibers

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