Download Prieto-new-review-nov2003

Integral Field Spectrograph
Eric PRIETO
CNRS,INSU,France,Project Manager
11 November 2003
Spectrograph 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"
70-200
70-100
0.15
0.15
LBL CCD
10 m
HgCdTe
18 m
>40%
>30%
Spectral resolution, l/dl
Spatial resolution element (arc sec)
detectors
Efficiency with OTA and QE
2
Spectrograph: Functional Overview
Shutter
Slicer
Unit
Relay
Optics
Calibration
lamps
Collimator
Dithering
Science
Software
Thermal
control
OCU
Prisms
Dichroics
VIS
CAM
NIR
CAM
Visible
Focal
plane
NIR
Focal
plane
Interface
Electronics
3
Pre optical design
• optics with 7 mirrors
• two arms configuration
• Two prisms
IR
detector
Visible
detector
entrance
prisms
slicer
4
Entrance
beam
Floppy
interface
dL = 0,09
Fix point
Visible detector
dL=180 x (300-140) x 1,3.10-6 = 0,038
mm
IR detector
5
Fix point
(nearest of
the entrance
beam point)
Floppy
interface
Displacement is
amplify
Optical
bench
(Invar)
weight
=2,3Kg
Structural
support
fix on the
cold plate
Structural
support
(Molibdenu
m)
weight
=2,7Kg 6
Instrument road map
Primary SNAP specifications
First requirements
2002
Define system
Concept definition
requirements
Pre conceptual
design
2003
Prove the
feasibility
Detailed simulation
Interface control
document
New requirements
2004
Verify performances
Budget errors
Conceptual
design
7
Implementation:
IFS
Telescope
focal plane
Dark zone
Telescope
8
Optical design (option1)
9
Slicer Design:
Telescope
Focal Plane
Spectrograph
Slit mirrors :
Spectrograph
Slit
Folding
mirrors
Pupil mirrors
Slice mirrors
Fore- mirror
10
Focal 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’’
•Need 40 slices
•No effect on optic
11
Performance: efficiency
# elements
Efficiency
/elements
Cumulative
efficiency
Telescope
4
0.98
0.92
Relay optic
1
0.98
0.90
0.82
0.71
Spectrograph
Mirrors 2
Prism
Dichroic
0.98
0.81
0.95
0.57
Visible Detector
1
0.9
0.52
IR Detector
1
0.8
0.42
Slicer
(mirrors + straylight +
diffraction)
12
Performances
Spectral resolution for the visible detector
295
275
255
235
215
195
175
155
135
115
95
75
Simulation result
Spectral resolution for the IR detector
lambda
0,4
0,5
0,6
0,7
0,8
0,9
1
110
105
100
95
90
85
80
Zeemax optimisation
75
lambda
70
1
1,1
1,2
1,3
1,4
1,5
1,6
1,7
13
Integral Field Spectrograph:
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)
SCOPE
• ESA Funded prototyping work
• JWST/NIRSPEC development
• Previously MEMS back-up
• Currently IFU option
• Collaboration LAM/CRAL/DURHAM
• Aim: Technical Readiness Level 6
15
Slicer Principle
How to rearrange 2D field to enter spectrograph slit:
1. Field divided by
slicing mirrors in
subfields (40 for
4
SNAP)
2. Telescope pupil on
1
the pupil mirrors
3. Aligned pupil mirrors
3
4. Sub-Field imaged
2
along an entrance slit
16
Optical Design
Slit mirrors array
Slice mirrors
Pupil mirrors array
Steering mirror
17
Design Overview
Dummy Stack
Pupil mirror array
Slit mirror array
Active Stack
Heel
Stack support
Thrust
cylinders
Substructure
Main structure
Steering mirror
18
Reality
19
Reality: Image Slicer (uncoated)
Support
18 “Flat” Slices
(Dummies)
10 “Curved” Slices
(Actives)
2 “Flat” Slices
(Dummies)
20
Slicing-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
21
Slicing-mirror stack measurements
DXc (mm)
Slices m irrors curvature center DX default m easured w ith
the STIL m achine
0,025
0,020
0,015
0,010
0,005
0,000
-0,005
-0,010
-0,015
-0,020
-0,025
1
2
3
4
5
6
7
8
9
Results
• positioning accuracy includes both
assembly and manufacturing errors
10
•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
slice num ber (1: sclice 28; 10: slice19)
Slices m irrors curvature center DY default m easured
w ith the STIL m achine
0,050
0,040
DXc (mm)
0,030
0,020
0,010
0,000
-0,010
1
2
3
4
5
6
7
8
9
10
-0,020
-0,030
slice num ber (1: sclice 28; 10: slice19)
22
Pupil/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
23
Pupil-mirror line measurements
• damaged mirror to the right
• scratches on the left-mirror are
outside the usefull area (pupil size)
24
Pupil-mirror line measurements
MP_regresse
0,01
0,005
x
y
0
1
2
3
4
5
Comparing the curvature center
locations
• remove a slope
• compare with expected positions
-0,005
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
25
Slit-mirror line measurements
• 5 identical mirrors
• overall slope (will be removed
during analysis)
26
Slit-mirror line measurements
MF_RégressionLinéaire
0,006
0,004
0,002
0
-0,002
-0,004
x
1
2
3
4
5
y
Comparing the curvature center
locations
• remove a slope
• compare with expected positions
-0,006
-0,008
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
27
First 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)
28
First PSF results
•
Preliminary results
•
PSF Size in agreement with simulation
•
Astigmitism & coma (as theory)
•
Rotation along the slice
•
TBD: deconvolve with instrumental PSF
29
First Results: Slit plane
•
Impressive alignment of the virtual slits on the slit mirrors
•
Positioning alignment within 20µm (pitch: 2.75mm)
30
Thermal / 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)
Inside Liquid Nitrogen
•
31
Current output
• System expertise demonstrated
• Optical manufacturing demontrated
• Optical performance compliant
• To be done: thermal qualification (Dec 03)
• To be done: vibration qualification (Dec 03)
• Re-manufacture pupil line for vibration (April 04)
32