1. TOU Team
PLATO Consortium
Campi Bisenzio, 12 Dec 2016

2. Thermal – Elastic Analysis Radiation Effects Glasses Procurement
Optical Design
Mechanical Design
Optics Mass Trade-Off
Thermal – Elastic Analysis
Radiation Effects
Glasses Procurement
Campi Bisenzio, 12 December 2016
PLATO Consortium

3. Optical Design D. Magrin, M. Munari, R. Ragazzoni, A. Brandeker, D
Optical Design D. Magrin, M. Munari, R. Ragazzoni, A. Brandeker, D. Greggio
Campi Bisenzio, 12 December 2016
PLATO Consortium

4. optical baseline PLATO-INAF-TOU-ML-001-i2.1-Baseline.zmx
Reference ZEMAX File (cold environment):
PLATO-INAF-TOU-ML-001-i2.1-Baseline.zmx
24 N-TOUs
2 F-TOUs
Campi Bisenzio, 12 December 2016
PLATO Consortium

5. optical baseline
Main Drivers: Performance + Mass Budget (cold environment)
Campi Bisenzio, 12 December 2016
PLATO Consortium

6. optical baseline Optical elements parameters (cold environment)
Campi Bisenzio, 12 December 2016
PLATO Consortium

7. optical baseline Lenses cut Mass before cut = 5578.5 g
Mass after cut = g
 Mass cut = g (6.5%)
Lenses cut
Campi Bisenzio, 12 December 2016
PLATO Consortium

8. optical baseline
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).
Campi Bisenzio, 12 December 2016
PLATO Consortium

9. optical baseline L1 aspheric surface (cold environment)
Campi Bisenzio, 12 December 2016
PLATO Consortium

10. Wavelength cut off vs. FoV
optical baseline
Filters: Deposited on window internal surface.
Environment
Surface Flatness
Wavelength cut off vs. FoV
Flat Field Uniformity
Cost/Risk
TOTAL
Window
surface 1 - +
++/---
surface 2
++++/- L1 --
+++/--- L3
surface 1/2 L6
+/-----
N-TOUs: cut wavelengths below 500 nm.
Campi Bisenzio, 12 December 2016
PLATO Consortium

11. optical baseline
Filters: F-TOUs transmissivity pass-band filters examples
F-TOU Blue: nm
F-TOU Red: 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.
Campi Bisenzio, 12 December 2016
PLATO Consortium

12. performances
Image quality: goal criteria is the 90% polychromatic enclosed energy in 2×2 pixels2 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.
Campi Bisenzio, 12 December 2016
PLATO Consortium

13. performances
Field of View: about 1037 degrees2 for N-TOUs, about 619 degrees2 for F-TOUs
N-TOUs
F-TOUs
Campi Bisenzio, 12 December 2016
PLATO Consortium

14. performances Field distortion: about 3.84% on the FoV edge
Campi Bisenzio, 12 December 2016
PLATO Consortium

15. performances
Vignetting: Mechanical 3.63%, Natural (View factor, Pupil distortion) 10.48%, Total about 14.1%
Campi Bisenzio, 12 December 2016
PLATO Consortium

16. performances Transmissivity: internal transmissivity + AR coatings
BOL-EOL Transmissivity (coating 0.98)
BOL-EOL Transmissivity (coating 0.985)
ADOPTION
BOL-EOL Transmissivity (coating window 0.97)
BOL-EOL Transmissivity (coating 0.99)
BOL-EOL Transmissivity (coating 0.987)
BOL-EOL Internal Transmissivity
Campi Bisenzio, 12 December 2016
PLATO Consortium

17. performances PSFs: HR and LR Campi Bisenzio, 12 December 2016
PLATO Consortium

18. Ghost and Straylight Analysis
Ghosts
Straylight Analysis
STEP model TOU+FPA imported in ASAP
Campi Bisenzio, 12 December 2016
PLATO Consortium

19. Optical tolerances
Manufacturing and alignment tolerances: Mimic the current foreseen optical alignment procedure. Analysis on cold environment model.
Campi Bisenzio, 12 December 2016
PLATO Consortium

20. Optical tolerances
Manufacturing and alignment tolerances: MF is RMS spot radius
Campi Bisenzio, 12 December 2016
PLATO Consortium

21. Optical tolerances
Manufacturing and alignment tolerances: 90% Enclosed Energy
Campi Bisenzio, 12 December 2016
PLATO Consortium

22. Optical tolerances
Manufacturing and alignment tolerances: 90% Enclosed Energy through focus
Campi Bisenzio, 12 December 2016
PLATO Consortium

23. Optical tolerances
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 arcsec2 (2x2px) for 50%  of the nominal FOV;
-          37.5 x 37.5 arcsec2 (2.5x2.5px) for 95%  of the nominal FOV;
-          45 x 45 arcsec2 (3x3px) for 99.8%  of the nominal FOV.
Campi Bisenzio, 12 December 2016
PLATO Consortium

24. Mechanical Design D. Piazza and UBE team
Campi Bisenzio, 12 December 2016
PLATO Consortium

25. Mechanical Design
Campi Bisenzio, 12 December 2016
PLATO Consortium

26. Mechanical Design
Campi Bisenzio, 12 December 2016
PLATO Consortium

27. Mechanical Design
Campi Bisenzio, 12 December 2016
PLATO Consortium

28. Mechanical Design
Campi Bisenzio, 12 December 2016
PLATO Consortium

29. Mechanical Design
Campi Bisenzio, 12 December 2016
PLATO Consortium

30. Optics Mass Trade Off Campi Bisenzio, 12 December 2016
PLATO Consortium

31. 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]
Lenses
4,632
5,558
Structure
4,382
5,040
Baffles
1,265
1,518
1,350
1,620
1,155
1,386
Thermal HW
240
288
Tot. per TOU
10,519
12,404
10,604
12,506
10,409
12,272
Quantity per S/C 14 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 units
Campi Bisenzio, 12 December 2016
PLATO Consortium

32. Optics Mass Trade Off Mass Trade off: MASS D MASS [g] [%] BASELINE
5217.7
 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 ( )
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%
Campi Bisenzio, 12 December 2016
PLATO Consortium

33. Optics Mass Trade Off 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 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.
Campi Bisenzio, 12 December 2016
PLATO Consortium

34. Mass Trade Off
Mass Trade off: Relaxing manufacturability, coating, mounting and gluing
Physical Aperture w.r.t. Clear Aperture > 3mm (radius)
Central thickness > 8 mm
Edge thickness > 5 mm
Mass before cut = g
Mass after cut = g
 Mass cut = g (6.7%)
w.r.t. baseline g
+ 14.0% (<20%)
Campi Bisenzio, 12 December 2016
PLATO Consortium

35. Thermal-Elastic Analysis S. Rockstein, S. Becker, D. Magrin
Campi Bisenzio, 12 December 2016
PLATO Consortium

36. Thermal-Elastic Analysis
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)
Campi Bisenzio, 12 December 2016
PLATO Consortium

37. Thermal-Elastic Analysis
AA7075
CTE 23.60
ATi6AI4V
CTE 8.37
5.2951
5.2921
RSA 905
CTE 19.00
8.9417
RSA 443
CTE 13.50
9.9910
T = -80°C
P = 0 atm
2.3847
0.6148
Invar 36
CTE 1.30
CTE 1.60
SiC
CTE 4.00 Si
STOP
FPA
WINDOW L1 L2 L3 L4 L5 L6
Suprasil
CTE 0.51
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
2.0000
7.0000
4.0000
3.4415
AlBeMet
CTE 12.68
Invar 36 - Polyacetal
CTE 0.00
(Preloaded)
CTE 9.30
ZrO2
0.9991
Model: PLATO-INAF-TOU-ML-001-i2.1-Baseline-ThermalModel-i2.0
Campi Bisenzio, 12 December 2016
PLATO Consortium

38. Thermal-Elastic Analysis
AA7075
CTE 23.60
23.000
ATi6AI4V
CTE 8.37
RSA 443
CTE 13.50
5.2995
5.3021
RSA 905
CTE 19.00
8.9492
T = 20°C
P = 1 atm
2.3850
0.6150
Invar 36
CTE 1.30
CTE 1.60
SiC
CTE 4.00 Si
STOP
FPA
WINDOW L1 L2 L3 L4 L5 L6
Suprasil
CTE 0.51
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
2.0754
7.0046
7.0063
7.0049
4.0069
3.4460
AlBeMet
CTE 12.68
Invar 36 - Polyacetal
CTE 0.00
(Preloaded)
CTE 9.30
ZrO2
1.0000
Model: PLATO-INAF-TOU-ML-001-i2.1-Baseline-ThermalModel-i2.0
Campi Bisenzio, 12 December 2016
PLATO Consortium

39. Thermal-Elastic Analysis
Thermal maps 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
-79,9796
-79,9706
-79,9550
+Y C
-79,7792
-79,7685
-79,7579
+Y D
-79,6565
-79,6430
-79,6208
+X B
-80,1509
-80,1310
-80,0966
+X C
-79,8690
-79,8510
-79,8272
+X D
-79,7112
-79,6928
-79,6620
-Y B
-80,0454
-80,0308
-80,0057
-Y C
-79,8276
-79,8138
-79,7984
-Y D
-79,6788
-79,6629
-79,6366
-X B
-79,8900
-79,8863
-79,8801
-X C
-79,7375
-79,7304
-79,7266
-X D
-79,6240
-79,6128
-79,5950
+Y A
-81,3489
-81,3085
-81,2510
+X A
-81,8754
-81,7991
-81,6813
-Y A
-81,4589
-81,4013
-81,3160
-X A
-80,7189
-80,7035
-80,6905 -Y
CCDs
-78,4645
-78,4259
-78,3533 +X
-78,4713
-78,4336
-78,3624 +Y
-78,4315
-78,4001
-78,3405 -X
-78,4291
-78,3971
-78,3365
Campi Bisenzio, 12 December 2016
PLATO Consortium

40. Thermal-Elastic Analysis
Nominal
t = 0 hrs
t = 3 mths
t = 14 hrs
Campi Bisenzio, 12 December 2016
PLATO Consortium

41. Thermal-Elastic Analysis
Campi Bisenzio, 12 December 2016
PLATO Consortium

42. Thermal-Elastic Analysis
Nominal
-80C, -16 µm refocused
Campi Bisenzio, 12 December 2016
PLATO Consortium

43. Radiation effects F. Borsa, M. Ghigo
Campi Bisenzio, 12 December 2016
PLATO Consortium

44. transmission loss estimates as of 21/01/2016
Radiation & Glass Darkening
transmission loss estimates as of 21/01/2016
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”
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
Campi Bisenzio, 12 December 2016
PLATO Consortium

45. Update on Radiation Analysis from OHB - 08 Sep 2016
Radiation & Glass Darkening
Update on Radiation Analysis from OHB - 08 Sep 2016
Top+bottom irradiation values (8 years)
Radiation for 5 different lens zones
Not possible to have incident proton spectrum, but propagation inside lens
Campi Bisenzio, 12 December 2016
PLATO Consortium

46. Radiation & Glass Darkening
New darkening analysis using the new values
Considering worst case position of telescope
Considering a “mean” radiation on the lens:
-mean value for each lens
-5 different EOL transmission values
Always considered a 2x margin
Campi Bisenzio, 12 December 2016
PLATO Consortium

47. Radiation & Glass Darkening
EOL transmission loss using L2 spectrum for darkening
Campi Bisenzio, 12 December 2016
PLATO Consortium

48. Radiation & Glass Darkening
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
Fluence
Energy [MeV]
SHIELDOSE2 + inside-tube spectrum
Local dose for SiO2
L2 spectrum
Inside-tube spectrum
Mean dose for SiO2
Campi Bisenzio, 12 December 2016
PLATO Consortium

49. Radiation & Glass Darkening
Preliminary: using ALWAYS a 2X radiation margin
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%
With spectrum inside-tube, (confidential) new s-fpl51 data
WL (nm)
500
600
700
800
900
1000
Loss (%)
-3.3%
-1.8%
-0.8%
-0.5%
0.0%
Campi Bisenzio, 12 December 2016
PLATO Consortium

50. Radiation & Glass Darkening
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
Campi Bisenzio, 12 December 2016
PLATO Consortium

51. Glasses Procurement
Campi Bisenzio, 12 December 2016
PLATO Consortium

52. Glasses Procurement
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).
Campi Bisenzio, 12 December 2016
PLATO Consortium