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An EUV Imaging Detector of Space
Solar Telescope
Qian Song, Binxun Ye, Zhaowang Zhao
National Astronomical Observatories, China
Chinese Academy of Sciences
SWD 2005, Taormina, Jun,19-26
Introduction of SST
The Space Solar Telescope,
the first space astronomy program in China
SWD 2005, Taormina, Jun,19-26
Satellite
Solar synchronous circular orbit
Orbit height: 735 km
Inclination:
98.3°
Period:
99.3 min
Attitude:
accuracy ±6", stability ±3"/s
Weight:
2 ton
Lifetime:
3 years
Launch:
LM-4B
SWD 2005, Taormina, Jun,19-26
Payloads
•
•
•
•
•
SWD 2005, Taormina, Jun,19-26
MOT
EUT
HWT
WBS
SIR
Main optical telescop, MOT
with a 2-D polarizing spectrograph, working in 8 channels simultaneously
Resolution
0.1‘
FOV
2.8'×1.5‘
Polarization
Accu.
2×10 –4
SWD 2005, Taormina, Jun,19-26
Payloads
•HWT:
a Hα and white light telescope, whole sun viewing
resolution 1 , FOV 0.7°×0.7°
•
WBS: a wide band spectrometer,
investigating high energy flare process on  -ray, hard & soft x-ray
•
SIR: solar and interplanetary radiospectrometer, 1-60GHz
nonthermal electron populations
SWD 2005, Taormina, Jun,19-26
EUT
Based on the EUVSAT proposal. Consists of four normal
incidence telescopes mounted in a vacuum vessel, which
should overlap, be well aligned and synchronized with each
other and with the images of the MOT.
Field of view
7’×7’
Resolution
0.8”
Wave length 12.8, 17.1, 19.5, 30.4 nm (subject to change)
Focal length
7.04 m
Distance between Mirrors
1.4 m
Primary Mirror
120 mm
Secondary mirror
48 mm
SWD 2005, Taormina, Jun,19-26
EUT structure
SWD 2005, Taormina, Jun,19-26
EUT Detector: requirements




To achieve highest sensitivity, a combination of a phosphor
screen, an image intensifier and a CCD is proposed. This
not only improves the sensitivity for low intensity scenes,
but as a bonus it provides an electronic shutter as well, one
with no moving part.
2048×2048 format
At least 12 bit dynamic range between CCD readout noise
and full well capacity
Spacial resolution should match the telescope’s, 0.8”, or
27.3μ, 36.6 lp/mm
SWD 2005, Taormina, Jun,19-26
EUT Detector: Structure

In order to achieve
high sensitivity, an
image intensifier is
used
A phosphor
screen is
needed to converse
EUV photons to visible.
 A CCD
imager is to
be used with format
changing optics (fiber
optic taper)
SWD 2005, Taormina, Jun,19-26
Phosphor’s response on EUV
4.00E-009
3.50E-009
3.00E-009
Current (A)
2.50E-009
2.00E-009
1.50E-009
1.00E-009
5.00E-010
0.00E+000
50
100
150
200
Wavelength (Angstrom)
SWD 2005, Taormina, Jun,19-26
250
300
Phosphor’s output against input
270
170
17.1nm
l9.5nm
260
160
150
240
230
140
220
130
210
200
120
190
110
180
170
100
60
70
80
90
100
Current of Accumulate Circle (mA)
SWD 2005, Taormina, Jun,19-26
110
19.5nm's Current (pA)
17.1nm's Current (pA)
250

MCP image intensifier, resolution 57 Lp/mm,
gain 8900 cd /m2 /Lx, equivalent background
irradiance 0.16 µLx

Optic taper: resolution >102Lp/mm
SWD 2005, Taormina, Jun,19-26
The front end of the detector
SWD 2005, Taormina, Jun,19-26
The outlook and inside of the detector
荧光屏
像增强器
光锥
CCD
SWD 2005, Taormina, Jun,19-26
5s dark: MCP contribution 800DN
SWD 2005, Taormina, Jun,19-26
Test on BSRF
SWD 2005, Taormina, Jun,19-26
The image of the 17.1nm beam of BSRF
SWD 2005, Taormina, Jun,19-26
Resolution test on 17.1nm
9µ
13µ
23µ
19µ
SWD 2005, Taormina, Jun,19-26
The intensity distribution of the 19μ grid
17500
19 miron grid
CCD Readout (DN)
17000
16500
16000
15500
15000
14500
1140
1144
1148
1152
1156
1160
1164
Pixel No.
SWD 2005, Taormina, Jun,19-26
1168
1172
1176
1180
Response of the detector on 17.1nm & 19.5nm
2.00E+010
1.80E+010
G: measurements on 17.1nm
Linear Fit of DATA171_G
1.80E+010
H: measurements on 195nm
Linear Fit of DATA195_H
1.60E+010
-
-
1.60E+010
R: 21 e /photon
R: 18 e /photon
Readout electrons
Readout electrons
1.40E+010
1.40E+010
1.20E+010
1.00E+010
8.00E+009
1.20E+010
1.00E+010
8.00E+009
6.00E+009
6.00E+009
4.00E+009
4.00E+009
3
4
5
6
7
8
9
10
11
12
3
5
6
7
8
Incident photon number (10 photons)
Incident photon number (10 photons)
17.1nm, 18e/photon
4
8
8
19.5nm, 21e/photon
SWD 2005, Taormina, Jun,19-26
9
10
Possible Solution

Better phosphor screen, MCP, fiber optic taper

Open MCP with CrI or KBr-coated photon cathode+CCD

EUV L3 CCD
Suggestions and comments are very
precious for us
SWD 2005, Taormina, Jun,19-26
SWD 2005, Taormina, Jun,19-26