Dirk Soltau
Kiepenheuer-Institut für Sonnenphysik
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Synoptic Network Workshop, Boulder 22.-24.4.2013

Basic assumptions and immediate conclusions
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Detector size: 4k x 4 k pixels, 5 µm pixel size
Field of view:  0.7°  2500 arcsec
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 pixelscale = 0.6 arcsec
 image scale = 120 arcsec/mm
 focal length = 1720 mm
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Synoptic Network Workshop, Boulder 22.-24.4.2013

  resolution according to sampling theorem: 1.2 arcsec =
5.8 µrad
  D = 1.22 λ / 5.8E-6
  minimum Diameter w.r.t resolution = 0.1 m
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Synoptic Network Workshop, Boulder 22.-24.4.2013

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Assumed bandwidth: 0.005 nm ( 50 mÅ)
Assumed Exposure time: 0.005 s
F Ret
PBS
Sun Telescope
Cam1
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Synoptic Network Workshop, Boulder 22.-24.4.2013
Cam2

Aperture wavelength
 λ = 5 pm
0.1 m
0.5 m
400 nm
400 nm
1.0 m
0.1 m
400 nm
630 nm
0.5 m
1.0 m
630 nm
630 nm
Heat load Photoelect rons
10 W
200W
4500
110000
1000 W
10 W
200W
1000 W
450000
9000
230000
900000
SNR
70
350
670
100
480
950
5
Diameter should exceed 0,5 m
 f/# < f/3.5
Synoptic Network Workshop, Boulder 22.-24.4.2013

Mounting (common instrument platform)
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May be we need different instruments for different SNR requirements (Polarimetry vs. imaging)
 Several instruments on one platform may be a solution
6
Synoptic Network Workshop, Boulder 22.-24.4.2013

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2 pixel
1 pixel
0.1 m
0.1 m
1 m
1 m
Sun = 10 4 isoplanatic patches  Average seeing induced image motion of the whole disk will be around 0.01 pixel

1 m
0.1 m
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Synoptic Network Workshop, Boulder 22.-24.4.2013

Image motion: Effect on image subtraction
= Example: shift by 0.1 pixel  10 -2 noise
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 Image stabilization needed, dual beam polarimetry desirable
Synoptic Network Workshop, Boulder 22.-24.4.2013

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Main cause probably instrumental:
 spatial dimensions: 1m  1 arcsec corresp. 5 µm
Limb sensor vs. Correlation tracker
Tiptilt mirror
 relay optics?
 Solar Orbiter (PHI) concept?
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Synoptic Network Workshop, Boulder 22.-24.4.2013

 Design driving parameters:
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Detector
SNR @ typical exposure time
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Synoptic Network Workshop, Boulder 22.-24.4.2013

 Good performance, limited diameter
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Example: Chrotel (KIS)
Synoptic Network Workshop, Boulder 22.-24.4.2013

D = 200 mm, FOV = 0.5 deg
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X Z
Y
M A K S U T O V , D = 2 0 0 m m , f / 1 0
2 1 .
0 4 .
2 0 1 3
3 D L a y o u t
D . S o l t a u
KIS
M a k s u t o v .
Z M X
C o n f i g u r a t i o n 1 o f 1
-
+ Potential for evacuation
Synoptic Network Workshop, Boulder 22.-24.4.2013
0 . 0 0 0 0 ( d e g )
0 . 2 5 0 0 ( d e g )
0 . 8
0 . 7
0 . 6
0 . 5
1 . 0
0 . 9
0 . 2
0 . 1
0 . 4
0 . 3
0 . 0
0 2 4 6 8
R a d i u s F r o m C e n t r o i d i n µ m
G e o m e t r i c E n c i r c l e d E n e r g y
M A K S U T O V , D = 2 0 0 m m , f / 1 0
2 1 .
0 4 .
2 0 1 3
W a v e l e n g t h : P o l y c h r o m a t i c
D a t a h a s b e e n s c a l e d b y d i f f r a c t i o n l i m i t .
S u r f a c e : I m a g e
C o
D . S o l t a u
KIS
M a k s u t o v .
Z M X n f i g u r a t i o n 1 o f 1
10 µm

Example: Ritchey-Chretien Cassegrain
D = 600 mm, FOV = 0.5 deg
Y
X Z
3 D L a y o u t
R i t c h e y C h r e t i e n w i t h f = 1 9 0 0 m m , D = 6 0 0 m m
2 1 .
0 4 .
2 0 1 3
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- 0 . 2 0 0 0 , 0 . 2 0 0 0 ( d e g )
0 . 0 0 0 0 , 0 . 2 8 0 0 ( d e g )
0 . 2 0 0 0 , 0 . 2 0 0 0 ( d e g )
- 0 . 2 8 0 0 , 0 . 0 0 0 0 ( d e g )
0 . 0 0 0 0 , 0 . 0 0 0 0 ( d e g )
0 . 2 8 0 0 , 0 . 0 0 0 0 ( d e g )
- 0 . 2 0 0 0 , - 0 . 2 0 0 0 ( d e g )
0 . 0 0 0 0 , - 0 . 2 8 0 0 ( d e g )
0 . 2 0 0 0 , - 0 . 2 0 0 0 ( d e g )
1 . 0
0 . 9
0 . 8
0 . 7
0 . 6
0 . 5
0 . 4
0 . 3
0 . 2
0 . 1
0 . 0
0 2 4 6 8
R a d i u s F r o m C e n t r o i d i n µ m
G e o m e t r i c E n c i r c l e d E n e r g y
R i t c h e y C h r e t i e n w i t h f = 1 9 0 0 m m , D = 6 0 0 m m
2 1 .
0 4 .
2 0 1 3
W a v e l e n g t h : P o l y c h r o m a t i c
D a t a h a s b e e n s c a l e d b y d i f f r a c t i o n l i m i t .
S u r f a c e : I m a g e
D . S o l t a u
KIS
D i r k s R C _ 0 3 .
Z M X
C o n f i g u r a t i o n 1 o f 1
D . S o l t a u
KIS
D i r k s R C _ 0 3 .
Z M X
C o n f i g u r a t i o n 1 o f 1
-Might need a field corrector if larger
-needs baffling (daylight blindness)
Synoptic Network Workshop, Boulder 22.-24.4.2013

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Basic requirement: SNR
Image stabilization – if necessary – has large impact on the design
Diameter not determined by resolution arguments  telescope doesn‘t need to be diffraction limited
Evacuation should be considered (catadioptric system?)
Ritchey-Chretien promising. But false light counter measures necessary
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Synoptic Network Workshop, Boulder 22.-24.4.2013

Solar Spectral Irradiance from ASTM data in W/^m^2/nm 1,700 wavelength/nm 630,000 bandwidth/nm
Telescope aperture/m eff. focal length / m boxwidth FOV/arcsec
0,005
0,100
1,800
2000,000
Photon energy / J telescope area / m^2 input power/W output power w/o bandwidth e/W
Number of mirrors mirror reflectivity
Number of lenses windows lens transmission
0,000
0,900
4,000
0,900 telescope transmission image scale in arcsec/mm pixel scale in arcsec/pixel
FOV / mm
Power within bandwidth/W
Number of photons within bandwidth / arcsec^2 /s
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Extra transmission atmospheric transmission exposure time/s
Pixel size / mm
0,250
0,800
0,005
0,005
Quantum efficiency 0,700
Synoptic Network Workshop, Boulder 22.-24.4.2013
Number of photons within bandwidth / pixel /s
Number of photon electrons within bandwidth / pixel /s
Number of photoelectrons
SNR
3,15E-19
7,85E-03
8,59E+00
5,64E+00
6,56E-01
1,15E+02
5,73E-01
1,75E+01
8,76E-06
9,61E+06
3,15E+06
2,21E+06
1,10E+04
1,05E+02