Transcript Diapositiva 1

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Preliminary Optical Design
Plato
Preliminary Optical Design
D.Magrin, M.Munari, R.Ragazzoni, M.Dima, J.Farinato
Padova, 28/08/2008
Requirements and Design Drivers
Payload definition document
ESA Preliminary Design
Spectral Range
> 500 m (350-900 m)
400-1000 m
Field of view
≥ 500 degree2 (~550 degree2)
<634 degree2 (high field distortion)
Image quality
90% en-squared energy  2×2 pixel2
PSF Flat-topped (defocused)
Yes
No
Collecting Area
~ 100 cm2
~83-105 cm2 (field dependent)
Plate scale
12.5 arcsec/pixel TBC
Detector format
3584×3584×4
Pixel size
18 mm
Padova, 28/08/2008
Refractive Design (one of …)
5 lens (maybe 4 or 6)
Schott glass catalogue
CaF2
SF15
LASF35
CaF2
CaF2
2 symmetric aspheric surfaces (K,a4,a6)
Spectral Range
Field of view
Collecting Area
Plate Scale
500-900 m (to be extended ?)
550 degree2 (field distortion)
100 cm2
11.78 arcsec/pixel (nominal)
Padova, 28/08/2008
En-squared Energy
ESA design
Refractive design
Flat spectrum
Padova, 28/08/2008
PSFs
ESA design
Refractive design
2×2 pixel2
(0,0)mm
(34,34)mm
(68,68)mm
Asymmetric
No Flat-topped
Symmetric
Padova, 28/08/2008
Field Distortion
ESA design
Projected field of view of the focal plane
Refractive design
Maximum distortion 4.52%
Padova, 28/08/2008
Size
ESA design
Refractive design
809 mm
809 mm
437 mm
192 mm
412 mm
Padova, 28/08/2008
Envelope
Optical elements mass (clear aperture)
ESA design
Mirror 1
Mirror 2
Lens 1
Lens 2
2.01 Kg
2.70 Kg
0.33 Kg
0.87 Kg
Total Mass: 5.91 Kg
Refractive design
Volume (cc)
Lens 1
414.5
Lens 2
121.0
Lens 3
169.4
Lens 4
335.7
Lens 5 (squared) 453.0
Density (g/cc)
3.18
4.06
5.41
3.18
3.18
Mass (Kg)
1.32
0.49
0.92
1.07
1.44
Total Mass: 5.24 Kg
Padova, 28/08/2008
To Do
•Extend spectral range ( 400 m ? 350 m ?)
•Investigate different designs (stop position, aspheric surfaces…)
•Investigate glasses proprieties – creation of custom catalog of glasses suitable
to space
Desiderata
•Accomodation study (PDD pag 17)
•Data about QE detectors, science drivers?
•Clarify defocused PSF requirement (4 pixels in extent?) , flat-topped PSF?
Padova, 28/08/2008
Glasses: Schott Lithotec CaF2
Max dimensions: 350mm dia, 80 mm thickness
Transmission: >0.95 500-1000 m (25mm thickness)
Optical data:
nd=1.43384 vd=95.23 (587.5618 nm)
Status: preferred
Data:Schott website
Glasses: Schott LASF35
Max dimensions: Transmission: >0.94 500-1000 m (25 mm thickness)
1.200
1.000
0.800
0.600
0.400
0.200
0.000
0
Optical data:
500
1000
1500
2000
2500
3000
nd=2.03035 vd=29.06 (587.5618 nm)
Status: obsolete (inquiry)
Data:Schott website
Glasses: Schott SF15
Max dimensions: Transmission: >0.99 500-1000 m (25 mm thickness)
1.2
1
0.8
0.6
0.4
0.2
0
0
Optical data:
500
1000
1500
2000
2500
3000
nd=1.699 vd=30.068 (587.5618 nm)
Status: obsolete
Data:Schott Zemax Catalog