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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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Nirspec ifu

NIRSpec IFU

Eric Prieto

Final Presentation Definition Phase

May, 11th – ESTEC


Introduction

Introduction

  • Requirements overview

  • Implementation

  • Performance

  • Budgets

  • Compliance

  • Status

Nirspec Definition phase Final Presentation

ESTEC


Slicer principle

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

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Requirement overview

Requirement overview

  • FOV: 3”x3” @ 0.075” (40 slices of 40 pixels)

  • R~3000 (Slit mode gratings)

  • Optical throughput > 50%

  • Mass < 1kg

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Implementation

Implementation

  • No dedicated selection mechanism

  • A 3mm aperture in the MSA frame

  • MSA magnet hides the IFU aperture during MOS operation

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Implementation1

Implementation

Relay optics

Slicer Stack

(40 slices)

Slit mirror Line

(40 elements)

Pupil mirror Line

(40 elements)

IFU aperture

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Slicer stack subassembly

Slicer stack subassembly

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Lines subassemblies

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

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Optical performance and budget

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)

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Mass budget

Mass Budget

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Compliance

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

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Ddv plans

DDV plans

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Status prototype performances

Thermometers

Thermal straps

Status: Prototype performances

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Status optical bonding strength

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

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Conclusion maturity

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)

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    Conclusion

    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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