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

2. May, 11th 2004Nirspec Definition phase Final Presentation ESTEC 2 Introduction  Requirements overview  Implementation  Performance  Budgets  Compliance  Status

3. May, 11th 2004Nirspec Definition phase Final Presentation ESTEC 3 Slicer Principle 1.Field divided by slicing mirrors in subfields 2.Telescope pupil on the pupil mirrors 3.Aligned pupil mirrors 4.Subfields imaged along an entrance slit 1 2 3 4 How to rearrange 2D field to enter spectrograph slit: Courtesy: JR Allington-Smith

4. May, 11th 2004Nirspec 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

5. May, 11th 2004Nirspec 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

6. May, 11th 2004Nirspec Definition phase Final Presentation ESTEC 6 Implementation Slicer Stack (40 slices) IFU aperturePupil mirror Line (40 elements) Slit mirror Line (40 elements) Relay optics

7. May, 11th 2004Nirspec Definition phase Final Presentation ESTEC 7 Slicer stack subassembly

8. May, 11th 2004Nirspec 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

9. May, 11th 2004Nirspec Definition phase Final Presentation ESTEC 9 Optical performance and budget ItemDesignManufacturingAssemblyQuad sum Fore optics (2 mirrors)65 nm30 nm10 nm72 nm Slicer (3 mirrors)26 nm35 nm10 nm45 nm Folding mirrors (4 mirrors)0 nm40 nm0 nm40 nm Spectrograph coupling1mm of defocus in MSA plane: 20 nm20 nm Total WFE96 nm System Margin49 nm Overall Budget WFE108 nm 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)

10. May, 11th 2004Nirspec Definition phase Final Presentation ESTEC 10 Mass Budget ItemCurrent design massSystem marginMass Mechanics510300810 Baffling150100250 Optics70 140 Thermal sensor4 x 3g= 12g012 Total1212 g

11. May, 11th 2004Nirspec 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 ItemRequirementPerformanceMargin FOV3”x3”3”x3” by design Sampling 0.075 +/-2.5% 0.075 by design WFE 108 nm 96 nm 49 nm Throughput60%83%25% Mass1kg1.212kg 470g of margin - 212g In the system margin

12. May, 11th 2004Nirspec Definition phase Final Presentation ESTEC 12 DDV plans ItemDeliverable Date Structural Thermal Model19/04/06 EQM01/08/06 FM21/09/07 SM31/12/07

13. May, 11th 2004Nirspec Definition phase Final Presentation ESTEC 13 Status: Prototype performances Thermal straps Thermometers

14. May, 11th 2004Nirspec Definition phase Final Presentation ESTEC 14 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 Lessons Learned: Perpendicular Bonding TO BE AVOIDED Optical bonding

15. May, 11th 2004Nirspec Definition phase Final Presentation ESTEC 15 Conclusion: Maturity  Manufacturing maturity: Slicer: ok Slicer: ok Pupil/slit line: ok Pupil/slit line: ok Structure/opto-mechanical mount: ok Structure/opto-mechanical mount: ok  Cryo maturity: Slicer: ok Slicer: ok Pupil/slit line: ok Pupil/slit line: ok Structure/opto-mechanical mount: ok Structure/opto-mechanical mount: ok  Vibration maturity: July 2004  Optical performance maturity: Slicer: ok Slicer: ok Pupil/slit : ok Pupil/slit : ok Overall system: ok (@30-40°K and RT) Overall system: ok (@30-40°K and RT)

16. May, 11th 2004Nirspec 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?