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NIRSpec IFU

NIRSpec IFU. Eric Prieto Final Presentation Definition Phase May, 11th – ESTEC. Introduction. Requirements overview Implementation Performance Budgets Compliance Status. 4. 1. 3. 2. Slicer Principle. How to rearrange 2D field to enter spectrograph slit:.

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NIRSpec IFU

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  1. NIRSpec IFU Eric Prieto Final Presentation Definition Phase May, 11th – ESTEC

  2. Introduction • Requirements overview • Implementation • Performance • Budgets • Compliance • Status Nirspec Definition phase Final Presentation ESTEC

  3. 4 1 3 2 Slicer Principle How to rearrange 2D field to enter spectrograph slit: • Field divided by slicing mirrors in subfields • Telescope pupil on the pupil mirrors • Aligned pupil mirrors • Subfields imaged along an entrance slit Courtesy: JR Allington-Smith Nirspec Definition phase Final Presentation ESTEC

  4. Requirement overview • FOV: 3”x3” @ 0.075” (40 slices of 40 pixels) • R~3000 (Slit mode gratings) • Optical throughput > 50% • Mass < 1kg Nirspec Definition phase Final Presentation ESTEC

  5. Implementation • No dedicated selection mechanism • A 3mm aperture in the MSA frame • MSA magnet hides the IFU aperture during MOS operation Nirspec Definition phase Final Presentation ESTEC

  6. Implementation Relay optics Slicer Stack (40 slices) Slit mirror Line (40 elements) Pupil mirror Line (40 elements) IFU aperture Nirspec Definition phase Final Presentation ESTEC

  7. Slicer stack subassembly Nirspec Definition phase Final Presentation ESTEC

  8. Lines subassemblies • Opto-mecha mount: clamps on stiff Zerodur bar • Titanium clamps • Positioning reference: thrust • Each individual mirrors optically bonded on the bar • Bonding strength: see slide 14 Nirspec Definition phase Final Presentation ESTEC

  9. Optical performance and budget Relay optics Slicer Unit Prototype Throughput reflectivity: > 83% (R123: with 25% of margin) Throughput diffraction: > 90% (equivalent to R76) Overall IFU: 75% Overall NIRSPEC+IFU: 30% (diffraction included) Nirspec Definition phase Final Presentation ESTEC

  10. Mass Budget Nirspec Definition phase Final Presentation ESTEC

  11. Compliance • No major issue to be compliant • Only vibration compliance to be demonstrated (in July 2004) • Compliance to optical interface • Compliance with allocated volume • To Be Finalized: Mechanical interface with structure Nirspec Definition phase Final Presentation ESTEC

  12. DDV plans Nirspec Definition phase Final Presentation ESTEC

  13. Thermometers Thermal straps Status: Prototype performances Nirspec Definition phase Final Presentation ESTEC

  14. Optical bonding Lessons Learned: Perpendicular Bonding TO BE AVOIDED Optical bonding Status: Optical bonding strength • Bonding surface: 47mm² • Load increase speed: 4 N/minute • 3 tests @ 18N • Mass: 0.36g • Equivalent acceleration: 5000 G Factor 100 of margin Nirspec Definition phase Final Presentation ESTEC

  15. Conclusion: Maturity • Manufacturing maturity: • Slicer: ok • Pupil/slit line: ok • Structure/opto-mechanical mount: ok • Cryo maturity: • Slicer: ok • Pupil/slit line: ok • Structure/opto-mechanical mount: ok • Vibration maturity: July 2004 • Optical performance maturity: • Slicer: ok • Pupil/slit : ok • Overall system: ok (@30-40°K and RT) Nirspec Definition phase Final Presentation ESTEC

  16. Conclusion: • Very close to be a mature technology • It is an unique opportunity • It is very efficient (No slit losses) • Most of ground instruments for 2010 in the European (the World?) community have IFU capabilities in the VIS/NIR Domain: (as GNIRS/GEMINI, KMOS/VLT, MUSE/VLT, Planet Finder/VLT, …) NIRSpec? Nirspec Definition phase Final Presentation ESTEC

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