demetrio magrin inaf – astronomical observatory of padova [email protected] optical...
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Demetrio MagrinINAF – Astronomical Observatory of [email protected]
Optical DesignCatania, 11/06/2014
Outlines Design parameters (Definition phase)
Nominal Baseline (Definition phase)
Nominal Performances (EE, spot diagram, PSFs, vignetting factor)
Sensitivity and thermal analysis
Breadboard – Prototype
New (Last…) Baseline
Open Issues
Spectral range 500 – 1000 nm
Entrance Pupil Diameter 120 mm
Working F/# 2.06 @ 700 nm
Field of View 1151.5 degree2
Image quality 90% Enclosed energy < 2×2 pixel2 over 1108.3 degree2
Maximum Field Distortion 5.043%
Plate scale 15 arcsec/pixel
Pixel size 18 micron
CCD format 4510×4510 (×4) pixel2
FPA size 164.36 mm (2 mm CCDs gap)
Optical elements weight 5 Kg (<6 Kg)
Working Temperature -80°C
Working Pressure 0 atm
Design parameters
Nominal DesignDefinition phase (18/03/2011)
X
Y
Z
BK7 (G18)S-FPL51
N-KZFS11CaF2
S-FPL53 KZFSN5
BK7
368 mm
196.
2 m
m
R Thickness Glass K a4 a6 Shape Diameter(mm) (mm) (mm)
windowS1 infinity 6.000
BK7G18 circular190
S2 infinity 2.000 190
Lens 1S3 177.857 23.000
S-FPL51-3.681 3.605E-8 -4.020E-12
circular178
S4 infinity 27.351 178
Lens 2S5 795.855 7.000 N-
KZFS11circular
142S6 135.943 56.975 130
Lens 3S7 151.697 23.000
CAF2 circular114
S8 -225.536 59.886 116
Lens 4S9 -742.200 17.000
S-FPL53 circular130
S10 -139.241 16.240 131
Lens 5S11 -101.194 5.000
KZFSN5 circular129.6
S12 -144.005 115.547 135.4
Lens 6S13 -103.083 5.000 N-BK7
(G18)circular
154S14 infinity 4.000 184
FPA S15 infinity square
Nominal DesignDefinition phase (18/03/2011)
Aspheric surface S-FPL51
0
5
10
15
20
25
0,0 10,0 20,0 30,0 40,0 50,0 60,0 70,0 80,0
mm
mm Surface Sag
BFS Sag
0
0,2
0,4
0,6
0,8
1
1,2
0,0 10,0 20,0 30,0 40,0 50,0 60,0 70,0 80,0
mm
mm Deviation
Maximum deviation from BFS 1.050 mm
See R.Ragazzoni presentation
Enclosed Energy
2x2 pixels
G0V + detector QE
-40 micron +40 micron
Enclosed Energy (through focus)
Spot diagrams and FoV
13.6 deg, 13.6 deg
14.3 deg, 14.3 deg
4x4 pixels
About vignetting
Natural vignetting
7.5% at the edge of the ‘in spec’ FoV
9.0% at the edge of the full FoV
About vignetting
Mechanical vignetting
4.2% at the edge of the ‘in spec’ FoV
6.4% at the edge of the full FoV
About vignetting
Natural + Mechanical vignetting
11.7% at the edge of the ‘in spec’ FoV
15.4% at the edge of the full FoV
Polychromatic PSFs
PLATOSim
Element Decentering (+/- in micron)
Tilt (+/- in degrees)
L1 80 0.07L2 100 0.05L3 30 0.03L4 60 0.03L5 60 0.05L6 100 0.10
Sensitivity Analysis
Optical elements defocus 30-50 micron
Merit Function: 80%EE< 2×2 pixel2 over the corrected FoV
Thermal Analysis
• In the case of the of a uniform change of the temperature the optical system has 2 C of tolerances without the need of refocusing. With a temperature change of 10 C the nominal performances are still recoverable by applying a defocus through the three resistors.
• In the case of temperature gradient around the nominal temperature, the optical system maintain the nominal performance with a T=5 C without the need of refocusing. While the performances are recoverable by applying a defocus in the case of a T=10 C.
BreadBoard/Prototype Design
X
Y
Z
L1* L2* L3
L4 L5
L6
X
Y
Z
L1 L2
L3 L4 L5
L6 Window
The baseline design has been modified to allow the SESO tools adaptation (surfaces curvatures) and to facilitate and to speed up the manufacturing and mounting processes (some thicknesses and apertures have been increased). For procurement reasons, the glass of L5, KZFSN5, has been substituted by N-KZFS5.
(J.Farinato / V.Viotto / M.Bergomi presentations)
1) A physical stop in front of L3 (at about 2.84 mm edge to edge).
2) New weights for the wavelengths used in the Zemax merit function provided by P. Levacher - P. Bernardi.
3) Change the glass of L5 from KZFSN5 to N-KZFS5 (almost no optical impact and facilitate the procurement).
4) Change the thicknesses of L5 and L6 from 5mm to 7mm (all the industries suggested to increase these numbers).
5) Change on all lenses apertures from 1mm to 2mm with respect to the clear aperture. It should help to minimize the mechanical vignetting.
My last ‘New Baseline’… 21/05/2011
Data mining… (about 3 years to resurrect). Converge on a well-identified design to use
as baseline. Optimize the design for new/modified
requirements.Plate scale, PSF size, window material and thickness, 2 F-TOUs dedicated design.
Perform a detailed manufacturing/alignment tolerances and consolidate sensitivity/thermal analysis.RUAG warnings: the design is tight/ de-spacing tolerances are sub-micron.
Double-check performances in terms of EE/Simulator
Contact SESO and discuss the upgrade from breadboard to prototype with the related implications.
Open Issues