nirspec ifu eric prieto final presentation definition phase may, 11th – estec
TRANSCRIPT
NIRSpec IFUNIRSpec IFU
Eric PrietoEric Prieto
Final Presentation Definition PhaseFinal Presentation Definition PhaseMay, 11th – ESTECMay, 11th – ESTEC
May, 11th 2004May, 11th 2004 Nirspec Definition phase Final PresentationNirspec Definition phase Final PresentationESTECESTEC
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IntroductionIntroduction
Requirements overviewRequirements overview ImplementationImplementation PerformancePerformance BudgetsBudgets ComplianceCompliance StatusStatus
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Slicer PrincipleSlicer 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
Field beforeslicing
Pseudo-slit
Slicing mirror (S1)
Spectrogram
Pupil mirrors(S2)
To spectrograph
Field optics (slit mirrors S3)
From telescopeand fore-optics
1
2
3
4
How to rearrange 2D field to enter spectrograph slit:
Courtesy: JR Allington-Smith
May, 11th 2004May, 11th 2004 Nirspec Definition phase Final PresentationNirspec Definition phase Final PresentationESTECESTEC
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Requirement overviewRequirement overview
FOV: 3”x3” @ 0.075” FOV: 3”x3” @ 0.075” (40 slices of 40 pixels)(40 slices of 40 pixels) R~3000 R~3000 (Slit mode gratings)(Slit mode gratings) Optical throughput > 50%Optical throughput > 50% Mass < 1kgMass < 1kg
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ImplementationImplementation
No dedicated selection mechanismNo dedicated selection mechanism A 3mm aperture in the MSA frameA 3mm aperture in the MSA frame MSA magnet hides the IFU aperture during MOS operationMSA magnet hides the IFU aperture during MOS operation
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ImplementationImplementation
Slicer Stack(40 slices)
IFU aperturePupil mirror Line(40 elements)
Slit mirror Line(40 elements)
Relay optics
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Slicer stack subassemblySlicer stack subassembly
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Lines subassembliesLines subassemblies
Opto-mecha mount: clamps on stiff Opto-mecha mount: clamps on stiff
Zerodur barZerodur bar
Titanium clampsTitanium clamps
Positioning reference: thrustPositioning reference: thrust
Each individual mirrors optically Each individual mirrors optically bonded on the barbonded on the bar
Bonding strength: see slide 14Bonding strength: see slide 14
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Optical performance and budgetOptical performance and budget
Item Design Manufacturing Assembly Quad sum
Fore optics (2 mirrors) 65 nm 30 nm 10 nm 72 nm
Slicer (3 mirrors) 26 nm 35 nm 10 nm 45 nm
Folding mirrors (4 mirrors) 0 nm 40 nm 0 nm 40 nm
Spectrograph coupling 1mm of defocus in MSA plane: 20 nm 20 nm
Total WFE 96 nm
System Margin 49 nm
Overall Budget WFE 108 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)
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Mass BudgetMass Budget
Item Current design mass System margin Mass
Mechanics 510 300 810
Baffling 150 100 250
Optics 70 70 140
Thermal sensor 4 x 3g= 12g 0 12
Total 1212 g
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ComplianceCompliance
No major issue to be compliantNo major issue to be compliant Only vibration compliance to be demonstrated (in July 2004)Only vibration compliance to be demonstrated (in July 2004) Compliance to optical interfaceCompliance to optical interface Compliance with allocated volumeCompliance with allocated volume To Be Finalized: Mechanical interface with structureTo Be Finalized: Mechanical interface with structure
ItemItem RequirementRequirement PerformancePerformance MarginMargin
FOVFOV 3”x3”3”x3” 3”x3”3”x3” by designby design
SamplingSampling 0.075 +/-2.5%0.075 +/-2.5% 0.0750.075 by designby design
WFEWFE 108 nm108 nm 96 nm96 nm 49 nm49 nm
ThroughputThroughput 60%60% 83%83% 25%25%
MassMass 1kg1kg 1.212kg1.212kg470g of margin470g of margin
--212g212g
In the system marginIn the system margin
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DDV plansDDV plans
Item Deliverable Date
Structural Thermal Model 19/04/06
EQM 01/08/06
FM 21/09/07
SM 31/12/07
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Status: Prototype performancesStatus: Prototype performances
Thermal straps
Thermometers
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Status: Optical bonding strengthStatus: Optical bonding strength
Bonding surface: 47mm²Bonding surface: 47mm² Load increase speed: 4 N/minuteLoad increase speed: 4 N/minute 3 tests @ 18N3 tests @ 18N Mass: 0.36g Mass: 0.36g Equivalent acceleration: Equivalent acceleration: 5000 G Factor 100 of margin5000 G Factor 100 of margin
Lessons Learned:
Perpendicular Bonding
TO BE AVOIDED
Optical bonding
Optical bonding
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Conclusion: MaturityConclusion: Maturity Manufacturing maturity:Manufacturing maturity:
Slicer: okSlicer: ok Pupil/slit line: okPupil/slit line: ok Structure/opto-mechanical mount: okStructure/opto-mechanical mount: ok
Cryo maturity:Cryo maturity: Slicer: okSlicer: ok Pupil/slit line: okPupil/slit line: ok Structure/opto-mechanical mount: okStructure/opto-mechanical mount: ok
Vibration maturity: July 2004Vibration maturity: July 2004
Optical performance maturity:Optical performance maturity: Slicer: okSlicer: ok Pupil/slit : okPupil/slit : ok Overall system: ok (@30-40°K and RT)Overall system: ok (@30-40°K and RT)
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Conclusion: Conclusion:
Very close to be a mature technologyVery close to be a mature technology It is an unique opportunityIt is an unique opportunity It is very efficient It is very efficient (No slit losses)(No slit losses)
Most of ground instruments for 2010 in the European Most of ground instruments for 2010 in the European (the World?) community have IFU capabilities in the (the World?) community have IFU capabilities in the VIS/NIR Domain: VIS/NIR Domain:
(as GNIRS/GEMINI, KMOS/VLT, MUSE/VLT, Planet Finder/VLT, …)(as GNIRS/GEMINI, KMOS/VLT, MUSE/VLT, Planet Finder/VLT, …)
NIRSpec?NIRSpec?