Integral Field Spectrograph Integral Field Spectrograph
Eric PRIETO
CNRS,INSU,France,Project Manager
11 November 2003
2
Spectrograph characteristicsSpectrograph characteristics
Property Visible IR
Wavelength coverage (m) 0.35-0.98 0.98-1.70
Field of view 3.0" 6.0" 3.0" 6.0"
Spectral resolution, 70-200 70-100
Spatial resolution element (arc sec) 0.15 0.15
detectorsLBL CCD
10 mHgCdTe
18 m
Efficiency with OTA and QE >40% >30%
3
Spectrograph: Functional OverviewSpectrograph: Functional Overview
RelayOptics
SlicerUnit
Collimator
PrismsDichroics
NIRCAM
VISCAM
NIRFocal plane
VisibleFocal plane
Shutter
Dithering
Thermal control
Interface Electronics
Science Software
Calibration lamps
OCU
4
• optics with 7 mirrors • two arms configuration• Two prisms
Pre optical design
Visible detector
IRdetector
slicerprisms
entrance
5
Entrance beam
IR detector
Visible detector
Floppy interface
Fix point
180 mm
dL=180 x (300-140) x 1,3.10-6 = 0,038 mm
420 mm
dL= 0,02 mm
dL = 0,09
6
Optical bench(Invar)weight =2,3Kg
Structural support
(Molibdenum)
weight =2,7Kg
Floppy interface
Fix point (nearest of the entrance beam point)
Structural support
fix on the cold plate
Displacement is amplify
7
Instrument road mapInstrument road map
Primary SNAP specifications
Concept definition
Pre conceptual
design
Detailed simulation
New requirements
Conceptual
design
Define system
requirements
Prove the feasibility
Verify performances
Budget errors
2002
2003
2004
First requirements
Interface control
document
11
Focal plan developmentFocal plan development
No ‘single point failure’
=> Only detectors are to be duplicate:
two detectors and their electronic:•Field of view of 3’’X6‘’ instead of 3’’X3’’ Field of view of 3’’X6‘’ instead of 3’’X3’’
•Need 40 slicesNeed 40 slices
•No effect on opticNo effect on optic
12
Performance: efficiencyPerformance: efficiency
# elementsEfficiency/elements
Cumulative efficiency
Telescope 4 0.98 0.92
Relay optic 1 0.98 0.90
Slicer(mirrors + straylight +
diffraction)0.82 0.71
SpectrographMirrors 2
PrismDichroic
0.980.810.95
0.57
Visible Detector 1 0.9 0.52
IR Detector 1 0.8 0.42
13
PerformancesPerformances
Spectral resolution for the visible detector
7595
115135155175195215235255275295
0,4 0,5 0,6 0,7 0,8 0,9 1
lambda Spectral resolution for the IR detector
70
75
80
85
90
95
100
105
110
1 1,1 1,2 1,3 1,4 1,5 1,6 1,7
lambdaZeemax optimisation
Simulation result
Integral Field Spectrograph:Integral Field Spectrograph:
R&T Slicer R&T Slicer
Eric PRIETO
CNRS,INSU,France,Project Manager
11 November 2003
(on behalf: ESA Slicer Prototype Team: LAM/CRAL/Durham
More specifically: Charles Maccaire and Florence Laurent)
15
SCOPESCOPE
• ESA Funded prototyping work
• JWST/NIRSPEC development• Previously MEMS back-up• Currently IFU option
• Collaboration LAM/CRAL/DURHAM
• Aim: Technical Readiness Level 6
16
Slicer PrincipleSlicer Principle
1. Field divided by
slicing mirrors in
subfields (40 for
SNAP)
2. Telescope pupil on
the pupil mirrors
3. Aligned pupil
mirrors
4. Sub-Field 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:
18
Design OverviewDesign Overview
Active Stack
Heel
Stack support
Steering mirror
Pupil mirror array
Slit mirror array
Main structure
Substructure
Thrust cylinders
Dummy Stack
20
Reality: Image Slicer (uncoated)Reality: Image Slicer (uncoated)
Support
18 “Flat” Slices (Dummies)
10 “Curved” Slices (Actives)
2 “Flat” Slices (Dummies)
21
Slicing-mirror stack measurementsSlicing-mirror stack measurements
Images of the two scans• common reference surface• one slicing mirror is present in both scans and can be used to check results
22
Slicing-mirror stack measurementsSlicing-mirror stack measurements
Results• positioning accuracy includes both assembly and manufacturing errors
•Xc within +/- 22 µm from nominal
• Yc within +/-22 µm (except n°6) from nominal (measurement errors contribute to probably ~10 µm) to be compared to the +/-20 µm requirement
Slices mirrors curvature center DX default measured w ith the STIL machine
-0,025-0,020-0,015-0,010-0,0050,0000,0050,0100,0150,0200,025
1 2 3 4 5 6 7 8 9 10
slice number (1: sclice 28; 10: slice19)
DX
c (m
m)
Slices mirrors curvature center DY default measured with the STIL machine
-0,030
-0,020
-0,010
0,000
0,010
0,020
0,030
0,040
0,050
1 2 3 4 5 6 7 8 9 10
slice number (1: sclice 28; 10: slice19)
DX
c (m
m)
23
Pupil/slit mirrors linesPupil/slit mirrors lines
Opto-Mech. Mount
5 Pupil Mirrors
1 Broken Mirror
Glass Bar
•Optical contact released during manipulation
•New assembly will be produced compatible with vibration specifications
•Back-up solution from monolithic solution
24
Pupil-mirror line measurementsPupil-mirror line measurements
• damaged mirror to the right• scratches on the left-mirror are outside the usefull area (pupil size)
25
Pupil-mirror line measurementsPupil-mirror line measurements
Comparing the curvature center locations• remove a slope• compare with expected positions
MP_regresse
-0,005
0
0,005
0,01
1 2 3 4 5
x
y
Results• positioning accuracy includes both assembly and manufacturing errors • both Xc and Yc are within +/- 5-6 µm from their nominal positions (probably need to add a few µm of measurement accuracy)• to be compared to the +/- 20 µm requirement
the pupil mirror line meets the relative alignment requirements
26
Slit-mirror line measurementsSlit-mirror line measurements
• 5 identical mirrors• overall slope (will be removed during analysis)
27
Slit-mirror line measurementsSlit-mirror line measurements
Comparing the curvature center locations• remove a slope• compare with expected positions
Results• positioning accuracy includes both assembly and manufacturing errors • both Xc and Yc are within +/- 8 and even 1 µm from their nominal positions (probably need to add a few µm of measurement accuracy)• to be compared to the +/- 20 µm requirement
the pupil mirror line meets the relative alignment requirements
MF_RégressionLinéaire
-0,008
-0,006
-0,004
-0,002
0
0,002
0,004
0,006
1 2 3 4 5x
y
28
First Results: Pupil planeFirst Results: Pupil plane
• Impressive alignment of the pupils on the pupil mirrors
• Positioning alignment within 50µm (pitch: 2.75mm)
• Surface defect and edges are due to manipulation accident (assembly weakness)
• New line will be produced (stronger)
29
First PSF resultsFirst PSF results
• Preliminary results
• PSF Size in agreement with simulation
• Astigmitism & coma (as theory)
• Rotation along the slice
• TBD: deconvolve with instrumental PSF
30
First Results: Slit planeFirst Results: Slit plane
• Impressive alignment of the virtual slits on the slit mirrors
• Positioning alignment within 20µm (pitch: 2.75mm)
31
Thermal / Structural testsThermal / Structural tests
• Low level vibration tests performed: first mode 185hz
• Sinusoidal tests will be performed 20g (40g if possible)
• Random tests will be performed 15g (30 if possible)
• First test of optical mount at 77°K performed
• Full prototype will be tested @ 30-40°K (dec 03)
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