PLATO Consortium Campi Bisenzio 12 Dec 2016 Optical Design Mechanical Design Optics Mass TradeOff Thermal Elastic Analysis Radiation Effects Glasses Procurement 2 PLATO Consortium ID: 612811
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Slide1
TOU Team
PLATO Consortium
Campi
Bisenzio
, 12 Dec 2016Slide2
Optical Design
Mechanical Design
Optics Mass Trade-OffThermal – Elastic AnalysisRadiation EffectsGlasses Procurement
2
PLATO Consortium
Campi Bisenzio, 12
December
2016Slide3
Optical Design
D. Magrin, M.
Munari, R. Ragazzoni, A. Brandeker, D. Greggio
PLATO Consortium
3
Campi Bisenzio, 12
December
2016Slide4
Reference ZEMAX File (cold environment):
PLATO-INAF-TOU-ML-001-i2.1-Baseline.zmx
24 N-TOUs2 F-TOUs
optical baseline
4
PLATO Consortium
Campi Bisenzio, 12
December
2016Slide5
Main Drivers: Performance + Mass Budget (cold environment)
optical baseline
5
PLATO Consortium
Campi Bisenzio, 12 December 2016Slide6
Optical elements parameters (cold environment)
optical baseline
6
PLATO Consortium
Campi Bisenzio, 12 December 2016Slide7
Lenses cut
optical baseline
7
PLATO Consortium
Campi Bisenzio, 12 December
2016
Mass before cut = 5578.5 g
Mass after cut = 5217.7 g
Mass cut = 360.8 g (6.5%)Slide8
Window
-
The main purposes of the entrance window are to shield the following lenses from possible damaging high energy radiation and to mitigate the thermal gradient that the first optical element will experience during the launch from ground to space environment. In contrast, the presence of the window increases the overall mass by a non-negligible quantity (586 g).optical baseline
8
PLATO Consortium
Campi Bisenzio, 12
December
2016Slide9
L1 aspheric surface (cold environment)
optical baseline
9
PLATO Consortium
Campi Bisenzio, 12 December 2016Slide10
Filters:
Deposited on window internal surface.
optical baseline10
PLATO Consortium
Campi Bisenzio, 12
December
2016
Environment
Surface Flatness
Wavelength cut off vs. FoV
Flat Field Uniformity
Cost/Risk
TOTAL
Window
surface 1
-
+
-
-
+
++/---
Window
surface 2
+
+
+
-
+
++++/-
L1
surface 1
+
+
+
-
--
+++/---
L3
surface 1/2
+
--
+
+
-
+++/---
L6
surface 2
-
+
-
--
-+/-----
N-TOUs: cut wavelengths below 500 nm.Slide11
Filters: F-TOUs transmissivity pass-band filters examples
optical baseline
11
PLATO Consortium
Campi Bisenzio, 12 December
2016
F-TOU
Blue
: 500-675 nm
F-TOU Red
: 675-1000 nm
The filter coating will consist of radiation resistant TiO2 and SiO2 layers that can
be combined
to produce a wide range of filter functions while being radiation resilient at
the same
time.Slide12
Image quality:
goal criteria is the 90% polychromatic enclosed energy in 2×2 pixels
2 with respect to centroid at nominal working temperature (-80°C) and pressure (0 atm) and a depth of focus of ± 20 µm on the FPA.
performances
12
PLATO Consortium
Campi Bisenzio, 12
December
2016Slide13
performances
13
PLATO Consortium
Campi Bisenzio, 12 December 2016
Field of View:
about 1037 degrees
2
for N-TOUs,
about 619 degrees
2
for F-TOUs
F-TOUs
N-TOUsSlide14
performances
14
PLATO Consortium
Campi Bisenzio, 12 December 2016
Field distortion:
about 3.84%
on the FoV edge Slide15
performances
15
PLATO Consortium
Campi Bisenzio, 12 December 2016
Vignetting:
Mechanical 3.63%, Natural (View factor, Pupil distortion) 10.48%,
Total about 14.1%Slide16
performances
16
PLATO Consortium
Campi Bisenzio, 12 December 2016
Transmissivity:
internal transmissivity + AR coatings
BOL-EOL Transmissivity (coating 0.98)
BOL-EOL Transmissivity (coating 0.985)
ADOPTION
BOL-EOL Transmissivity (coating 0.985+window 0.97)
ADOPTION
BOL-EOL Transmissivity (coating 0.99)
BOL-EOL Transmissivity (coating 0.987)
BOL-EOL Internal TransmissivitySlide17
performances
17
PLATO Consortium
Campi Bisenzio, 12 December 2016
PSFs:
HR
and LRSlide18
Ghost and Straylight Analysis
18
PLATO Consortium
Campi Bisenzio, 12 December
2016
Ghosts
Straylight
Analysis
STEP model TOU+FPA imported in ASAPSlide19
Optical tolerances
19
PLATO Consortium
Campi Bisenzio, 12 December 2016
Manufacturing and alignment tolerances:
Mimic the current
foreseen optical alignment procedure. Analysis on cold environment model.Slide20
Optical tolerances
20
PLATO Consortium
Campi Bisenzio, 12 December 2016
Manufacturing and alignment tolerances:
MF is RMS spot radiusSlide21
Optical tolerances
21
PLATO Consortium
Campi Bisenzio, 12 December 2016
Manufacturing and alignment tolerances:
90% Enclosed EnergySlide22
Optical tolerances
22
PLATO Consortium
Campi Bisenzio, 12 December 2016
Manufacturing and alignment tolerances:
90% Enclosed Energy through
focusSlide23
Optical tolerances
23
PLATO Consortium
Campi Bisenzio, 12
December
2016
Manufacturing and alignment tolerances:
90% Enclosed Energy through
focus full FoV
90% of the detected energy from a star shall fall within the following areas:
- 30 x 30 arcsec
2
(2x2px) for 50% of the nominal FOV;
- 37.5 x 37.5 arcsec
2
(2.5x2.5px) for 95% of the nominal FOV;
- 45 x 45 arcsec
2
(3x3px) for 99.8% of the nominal FOV.Slide24
Mechanical Design
D. Piazza and UBE team
PLATO Consortium24
Campi Bisenzio, 12
December 2016Slide25
Mechanical Design
25
PLATO Consortium
Campi Bisenzio, 12 December 2016Slide26
Mechanical Design
26
PLATO Consortium
Campi Bisenzio, 12 December 2016Slide27
Mechanical Design
27
PLATO Consortium
Campi Bisenzio, 12 December 2016Slide28
Mechanical Design
28
PLATO Consortium
Campi Bisenzio, 12 December 2016Slide29
Mechanical Design
29
PLATO Consortium
Campi Bisenzio, 12 December 2016Slide30
Optics Mass Trade Off
PLATO Consortium
30
Campi Bisenzio, 12 December
2016Slide31
31
PLATO Consortium
Campi Bisenzio, 12 December 2016
Optics Mass Trade Off
Item
N-TOU #1/#4
N-TOU #2/#3
F-TOU
All TOU's on S/C
CBE
[g]
Nominal
[g]
CBE
[g]
Nominal
[g]
CBE
[g]
Nominal
[g]
CBE
[g]
Nominal
[g]
Lenses
4,632
5,558
4,632
5,558
4,632
5,558
Structure
4,382
5,040
4,382
5,040
4,382
5,040
Baffles
1,265
1,518
1,350
1,620
1,155
1,386
Thermal HW
240
288
240
288
240288Tot. per TOU10,51912,40410,60412,50610,40912,272Quantity per S/C14
14
14
14
2
2
Tot. per S/C
147,266
173,657
148,456
175,085
20,818
24,544
316,540
373,286
Baffles
weight
estimation
baseline
is
the
one
presented
at
the SRR. At the moment
it
shall
be
considered
an
upper
limit
.
Thermal H/W
weight
from TOU URD
Total made for 24+2 TOU
unitsSlide32
Mass Trade off:
32
PLATO Consortium
Campi Bisenzio, 12
December 2016
MASS
D
MASS
D
MASS
[g]
[g]
[%]
BASELINE
5217.7
N/A
N/A
UPPER LIMIT
5946.8
729.1
14.0
%
EDGE VIGNETTING ×2
5103.6
-
114.1
-
2.2
%
EDGE VIGNETTING ×3
4999.1
-
218.6
-
4.2
%
PUPIL 5%
5188.8
-
28.9
-
0.6
%
PUPIL 10%
5139.6
-
78.1
-
1.5
%FOV (13.00. 13.00)4960.3-257.4-4.9%FOV (12.71, 12.71)
4851.9
-
365.8
-
7.0
%
FOV (
12.71,
12.71) + VIGNETTING
4772.8
-
444.9
-
8.5
%
L6 SUPRASIL
5312.5
94.8
1.8
%
Optics Mass Trade OffSlide33
Mass Trade off:
The assumptions
taken on the modified optical design were studied in details, with the aim to consolidate the mass saving estimate of glasses and supplement it with a mass saving estimate of the TOU mechanical structure. From this study, it turned out that the mass saving of glasses had been overestimated and was
quantified to about 266 g. For the mechanical structure, a mass saving of about 40-50 g was estimated.In conclusion, at this working level, for the studied case the overall mass saving was estimated to be around 300 g per TOU.
33
PLATO Consortium
Campi Bisenzio, 12
December
2016
Optics Mass Trade OffSlide34
Mass Trade off: Relaxing manufacturability, coating, mounting and gluing
Mass Trade Off
34
PLATO Consortium
Campi Bisenzio, 12 December
2016
Physical Aperture w.r.t. Clear Aperture > 3mm (radius)
Central thickness > 8 mm
Edge thickness > 5 mm
Mass before cut = 6372.2 g
Mass after cut = 5946.8 g
Mass cut = 425.4 g (6.7%)
w.r.t. baseline
+ 729.1 g
+ 14.0% (<20%)Slide35
Thermal-Elastic Analysis
S.
Rockstein, S. Becker, D. MagrinPLATO Consortium
35
Campi Bisenzio, 12 December 2016Slide36
Thermal-Elastic Analysis
36
PLATO Consortium
Campi Bisenzio, 12 December 2016
Thermal
-Elastic analysis with:
Simplified model (thermal maps)
(materials CTEs, refractive indexes, curvature radii)
MultiPAS
model (-80
C steady state, ongoing)
(Thermal model, Structural model, Optical model)Slide37
Thermal-Elastic Analysis
37
PLATO Consortium
Campi Bisenzio, 12 December 2016
AA7075
CTE 23.60
53.9324
16.5440
13.5074
22.9690
22.9827
23.5181
ATi6AI4V
CTE 8.37
13.9908
10.4630
5.2951
ATi6AI4V
CTE 8.37
25.6013
5.2921
RSA 905
CTE 19.00
61.8805
8.9417
34.2537
RSA 443
CTE 13.50
40.4214
22.9786
9.9910
96.3410
ATi6AI4V
CTE 8.37
42.4605
ATi6AI4V
CTE 8.37
21.9746
T = -80°C
P = 0 atm
70.9407
2.3847
11.9952
0.6148
Invar 36
CTE 1.30
SiC
CTE 1.60
Si
CTE 4.00
STOP
FPA
WINDOW
L1
L2
L3
L4
L5
L6
Suprasil
CTE 0.51
S-FPL51
CTE 13.10
S-FPL51
CTE 13.10
N/KZFS11
CTE 6.56
Lithotec
CAF2
CTE 18.41
S-FTM16
CTE 9.00
BK7 G18
CTE 7.00
9.0000
23.0000
2.0000
26.3282
7.0000
55.1982
23.6000
66.3131
15.6000
14.9094
7.0000
110.0511
7.0000
4.0000
23.6036
12.2921
3.4415
23.7373
ATi6AI4V
CTE 8.37
RSA 443
CTE 13.50
RSA 905
CTE 19.00
ATi6AI4V
CTE 8.37
AlBeMet
CTE 12.68
Invar 36 -
Polyacetal
CTE 0.00
(Preloaded)
ATi6AI4V
CTE 8.37
ZrO
2
CTE 9.30
0.9991
11.4940
Model:
PLATO-INAF-TOU-ML-001-i2.1-Baseline-ThermalModel-i2.0Slide38
Thermal-Elastic Analysis
38
PLATO Consortium
Campi Bisenzio, 12 December 2016
AA7075
CTE 23.60
54.0597
16.5649
13.5187
23.000
ATi6AI4V
CTE 8.37
RSA 443
CTE 13.50
23.0119
23.5378
ATi6AI4V
CTE 8.37
14.0000
10.4763
5.2995
ATi6AI4V
CTE 8.37
25.6499
5.3021
RSA 905
CTE 19.00
RSA 905
CTE 19.00
61.9589
8.9492
34.2999
ATi6AI4V
CTE 8.37
RSA 443
CTE 13.50
40.4726
22.9978
10.0000
96.4631
ATi6AI4V
CTE 8.37
42.4960
21.9900
T = 20°C
P = 1 atm
71.0000
2.3850
11.9971
0.6150
Invar 36
CTE 1.30
SiC
CTE 1.60
Si
CTE 4.00
STOP
FPA
WINDOW
L1
L2
L3
L4
L5
L6
Suprasil
CTE 0.51
S-FPL51
CTE 13.10
S-FPL51
CTE 13.10
N/KZFS11
CTE 6.56
Lithotec
CAF2
CTE 18.41
S-FTM16
CTE 9.00
BK7 G18
CTE 7.00
9.0005
23.0301
2.0754
26.3737
7.0046
55.2633
23.6434
66.3759
15.6204
14.9136
7.0063
110.1814
7.0049
4.0069
23.6191
12.3147
3.4460
23.7587
AlBeMet
CTE 12.68
Invar 36 -
Polyacetal
CTE 0.00
(Preloaded)
ATi6AI4V
CTE 8.37
ZrO
2
CTE 9.30
1.0000
11.4940
ATi6AI4V
CTE 8.37
Model:
PLATO-INAF-TOU-ML-001-i2.1-Baseline-ThermalModel-i2.0Slide39
Thermal-Elastic Analysis
39
PLATO Consortium
Campi Bisenzio, 12 December 2016
A
B
C
D
CCD
Node
T [°C] at t = 0 hrs
T [°C] at t = 14 hrs
T [°C] at t = 3 mths
+Y B
TUBE
2000010
-79,9796
-79,9706
-79,9550
+Y C
2000020
-79,7792
-79,7685
-79,7579
+Y D
2000030
-79,6565
-79,6430
-79,6208
+X B
2000100
-80,1509
-80,1310
-80,0966
+X C
2000110
-79,8690
-79,8510
-79,8272
+X D
2000120
-79,7112
-79,6928
-79,6620
-Y B
2000190
-80,0454
-80,0308
-80,0057
-Y C
2000200
-79,8276
-79,8138
-79,7984
-Y D
2000210
-79,6788
-79,6629
-79,6366
-X B
2000280
-79,8900
-79,8863
-79,8801
-X C
2000290
-79,7375
-79,7304
-79,7266
-X D
2000300
-79,6240
-79,6128
-79,5950
+Y A
2000600
-81,3489
-81,3085
-81,2510
+X A
2000630
-81,8754
-81,7991
-81,6813
-Y A
2000660
-81,4589
-81,4013
-81,3160
-X A
2000690
-80,7189
-80,7035
-80,6905
-Y
CCDs
2001510
-78,4645
-78,4259
-78,3533
+X
2001520
-78,4713
-78,4336
-78,3624
+Y
2001530
-78,4315
-78,4001
-78,3405
-X
2001540
-78,4291
-78,3971
-78,3365
Thermal mapsSlide40
Thermal-Elastic Analysis
40
PLATO Consortium
Campi Bisenzio, 12 December 2016
Nominal
t = 0
hrs
t = 14
hrs
t = 3
mthsSlide41
Thermal-Elastic Analysis
41
PLATO Consortium
Campi Bisenzio, 12 December 2016Slide42
Thermal-Elastic Analysis
42
PLATO Consortium
Campi Bisenzio, 12 December 2016
Nominal
-80
C
-80
C, -16 µm refocusedSlide43
Radiation effects
F.
Borsa, M. GhigoPLATO Consortium
43
Campi Bisenzio, 12 December 2016Slide44
transmission loss estimates as of 21/01/2016
44
We agree in principle with CNES method,
weighting
krads
on the spectrum of the incident radiation
.
But cannot exclude completely losses >10% at low wavelengths
CNES method takes into account L2 radiation spectrum as incident on the lenses, which is not the real case: the lenses (beside window) are inside the “tube”
Radiation
& Glass
Darkening
Campi Bisenzio, 12
December
2016
PLATO ConsortiumSlide45
Update on Radiation Analysis from OHB - 08 Sep 2016
45
Radiation
for 5 different lens zones
Top+bottom
irradiation values (8 years)
Not possible to have incident proton spectrum,
but propagation inside lens
Radiation
& Glass
Darkening
Campi Bisenzio, 12
December
2016
PLATO ConsortiumSlide46
46
New darkening analysis using the new values
Considering a “mean” radiation on the lens:
Considering
worst case position of telescope
Always considered
a
2x margin
-mean value for each lens
-5 different EOL transmission values
Radiation
& Glass
Darkening
Campi Bisenzio, 12
December
2016
PLATO ConsortiumSlide47
47
EOL transmission
loss using L2 spectrum for darkening
Radiation
& Glass
Darkening
Campi Bisenzio, 12
December
2016
PLATO ConsortiumSlide48
48
Energy [
MeV
]
Fluence
How to make a more accurate analysis: estimating the radiation environment inside
the tube (still preliminary)
SPENVIS analysis, using ESA L2 radiation environment and 1mm Al shielding
SHIELDOSE2
+ inside-tube spectrum
L2 spectrum
Inside-tube spectrum
Local dose for SiO2
Mean dose for SiO2
Radiation
& Glass
Darkening
Campi Bisenzio, 12
December
2016
PLATO ConsortiumSlide49
49
With spectrum inside-tube, literature s-fpl51 data
WL (nm)
500
600
700
800
900
1000
Loss (%)
-14.0%
-6.7%
-1.9%
-0.5%
0.0%
0.0%
WL (nm)
500
600
700
800
900
1000
Loss (%)
-3.3%
-1.8%
-0.8%
-0.5%
0.0%
0.0%
Preliminary
: using ALWAYS a 2X radiation margin
With spectrum inside-tube, (confidential) new s-fpl51 data
Radiation
& Glass
Darkening
Campi Bisenzio, 12
December
2016
PLATO ConsortiumSlide50
50
Irradiation tests to be made:
N-KZSF11 - data on equivalent glass
S-FTM16 - no proper data in literature
S-FPL51 - most sensible glass, to be verified
AR
coatings
still not considered
Radiation
& Glass
Darkening
Campi Bisenzio, 12
December
2016
PLATO ConsortiumSlide51
Glasses Procurement
PLATO Consortium
51
Campi Bisenzio, 12 December 2016Slide52
52
Glasses Procurement
Campi Bisenzio, 12
December 2016
PLATO Consortium
Our experience
is based on THALES-SESO glasses procurement for the prototype
:
They had a delay on L1 glass procurement (S-FPL51) because at that time there was no blank of the required size available off-the-shelf. It was required to wait for a new melting.
No other particular problem was experienced BUT no radiation-hard version of the glasses are implemented in the prototype. For Flight Models, the current baseline foresee B-K7 G18 for L6 and Suprasil (
radiation
resilient) for the window.
Note: We required the measurement of the optical and mechanical constants (CTEs, refractive indexes in the nominal working conditions: T =-80
C and P=0
atm
).