SOT instrument overview
description
Transcript of SOT instrument overview
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SOT instrument overview
Kiyoshi Ichimoto
NAOJ
Hinode workshop, 2007.12.8-10, Beijing
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OTA: 50cm Gregorian Telescope
FPP:
HDM (Heat Dump Mirror)
M2
M1CLU (collimator Lens Unit)PMU (Polarizaiton Modulator Unit)Tip-tilt mirror
Optical Telescope Assembly (OTA), is a Gregorian telescope with 50 cm aperture, built by NAOJ/ISAS.Focal Plane Package (FPP), includes observation filters, spectrometer, and cameras , built by LMSAL/HAO/NASA.
Solar Optical Telescope SOT = OTA + FPP
1.5m
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SOT system overview
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OTA
OBU
FPP
SOT (Solar Optical Telescope):
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Key Features of SOT• Largest telescope ever built to observe the Sun from space
• Diffraction-limited images (0.2-0.3arcsec), achieved by 50-cm-diameter aperture
• Observation from space, free from the atmospheric seeing.• Continuous observation for 24 hours per day in ~8 months per y
ear, thanks to the sun-synchronous orbit of HINODE
• Stabilized image with the correlation tracker• 388-668nm range, including spectral lines and continuums usef
ul for studying photosphere and chromosphere• Optimized for high precession polarization measurements in sp
ectral lines, continuous modulation of Stokes IQUV in every 0.8sec.
• Provides accurate vector magnetic fields in the photosphere.
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Color Coding OTACommon OpticsCTNFIBFISP
Polarization Modulator
Folding Mirror
4096 x 2048 CCD
Polarizing BS
Birefringent FilterFilterwheel Field Mask
Field lens
Shutter
X2 Mag lens
Folding Mirror
Telecentric lenses
X3 Mag lens
Shutter
Field lens
Filterwheel
Litrow Mirror
Polarizing BS
Folding Mirrors
Slit
Preslit
Grating
Folding Mirror
Image Offset Prisms
Demag lens
50 x 50 CCD Secondary
Primary
CLU
Tip Tilt Mirror
Reimaging Lens
Beam Distributor
Dual 256 x 1024 CCD
Narrowband Filter InstrumentBroadband Filter Instrument
Spectoro-polarimeter
OTA
Correlation Tracker
HDM
Astigmatism corrector lens
Optical layout of SOT
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SOT Optical Telescope Assembly (OTA)
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Gregoriantelescope
Aperture area 500mm, 153434mm2
Linear central obscuration 0.344 ( = 172/500 )
HDM outer diameter 32.83mm (Maximum offset pointing angle)
Effective f-length at secondary focus
4527 25 mm
Effective F-ratio at secondary focus
9.055 0.05
Plate scale at secondary focus 21.95 m/arcsec
Field of view 360 x 200 arcsec
Exiting beam
Collimation Collimated in air
Angular magnification 16.667
Exit pupil size 30.0 mm
Exit pupil position 73.05 from tip-tilt mirror
Chromatic aberration Nearly zero (<35m 388—670nm)
Optical parameters of OTA
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Point Spread Function ( ideal )
500 mm
40 mm
172 mm
+Y
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5. OTA flight model integration
Target mirror
clinometer Vertical meter
Six axisstage
Reference flat
Telescope Up
M1
M2
OTA
InterferometerMiniFiz
Optical bench
Dummy OBU
Rotation mechanism
Alignment cube
OTA is integrated on a dedicated tower. Interferometoric measurement is performed with 60cm reference flat at the top of tower. OTA can be upside top and upside down to cancel gravity.
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Gravitational deformation of OTA optics Average of upside top and upside down gives the Zero-G WFE
~ /20 rms @633nm
Example of WFE map
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19.9 ~ 43.2 C
1.1 ~ 16.3 C
27.8 ~ 4.6 C
1.7 ~ 25.0 C
16.0 ~ 30.0 C
26.2 ~ 45.7 CHeater control
21.5 ~ 4.4 C
21.1 ~ 67.3 C
Heater control
Large T from the ground testing.
Large dT/dz.
Predicted OTA temperature in orbit
OTA Opto-thermal testing -- motivation
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Flat mirror reference
OTA alignment cubeLower shroud
Upper shroud
OTA
flat mirror
theodlite alignment cube.
Support
Tilt/shift stage
shroud
Reference mirror OTA pointing ax.
interferometer
Theodolite OTA center of FOV
Dummy OBU
Autocollimator OTA pointing ax.
OTA Opto-thermal testing -- configuration
WFE of OTA is measured in a dedicated vacuum chamber. Two shrouds control the OTA temperature as it is in orbit.
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D◎=32’35”
max.offset = 19.6’
SOT FOV
margin ~ 1.2’
Heat Dump Mirror at primary focus focus
Sun
Maximum offset of Hinode pointing = 19.6 arcmin
HDM outer diameter 32.83mm
Maximum offset pointing of SOT
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CLU (FM measurement)
M1 (FM sample)
CTM-TM (theoretical)
NFI wavelengths
BFI wavelengths
M2 (FM sample)
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FPP Mechanical Design
BFI/NFI CCD Radiator
BFI/NFI CCD Electronics
SP CCD Radiator
SP CCD Electronics
NFI Lyot Filter
CT CCD Electronics
SP Littrow MirrorSP Littrow Grating
SP Slit
BFI Filterwheel
BFI Shutter
NFI Shutter
BFI/NFI Beam Combiner
SP Slit Scanner
NFI Filterwheel
Beam Distributor
NFI FocalplaneMask
CT wedge wheel
SOT Focal Plane Package (FPP)
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HINODE SOT has four optical paths:
< aims >
1. Broadband Filter Imager (BFI) images with highest spatial resolution
2. Narrowband Filter Imager (NFI) wide FOV, high resol. mag./Dopp., chrom.
3. Spectro-Polarimeter (SP) precise photospheric magnetic fields
4. Correlation Tracker image stabilization
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BFI NFI SP CT
CCD format 4096 x 2048 112 x 1024 x 2 50 x 50
pixel scale (arcsec/pix) 0.054 0.08 0.16 0.22
328x164
~0.1
1~4
10~60s
0.1 ~ 0.5
maximum FOV (arcsec2)
(EWxNS)
218x109 328 (scan range)
x164 (slit length)
11x11
wavelength resolution (A) 3~10 0.02 5
number of wavelength in a data set
1 244 1
time resolution (typical) 5~30s 1min~3hr 580Hz
photometric aquracy (%) 0.5 ~ 0.1 ~0.5
Basic parameters of four optical paths:
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SOT broadband filters
Field of view 218" × 109" (full FOV)
CCD 4k × 2k pixel (full FOV), shared with the NFI
Spatial Sampling 0.0541 arcsec/pixel (full resolution)
Spectral coverage
Center (nm) Width (nm) Line of interest Purpose
388.35 0.7 CN I Magnetic network imaging
396.85 0.3 Ca II H Chromospheric heating
430.50 0.8 CH I Magnetic elements
450.45 0.4 Blue continuum Temperature
555.05 0.4 Green continuum Temperature
668.40 0.4 Red continuum Temperature
Exposure time 0.03 - 0.8 sec (typical)
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SOT narrowband filterField of view 328"×164" (unvignetted 264"×164")
CCD 4k×2k pixel (full FOV), shared with BFI
Spatial sampling 0.08 arcsec/pixel (full resolution)
Spectral resolution 0.009nm (90mÅ) at 630nm
Spectral windows (nm) and lines of interest
Center -range Lines geff Purpose
517.2 0.6 Mg I b 517.27 1.75 Dopplergrams and magnetograms
525.0 0.6 Fe 524.71 2.00 PhotosphericmagnetogramsFe I 525.02 3.00
Fe I 525.06 1.50
557.6 0.6 Fe I 557.61 0.00 Photospheric Dopplergrams
589.6 0.6 Na I D 589.6 1.33 Very weak fields (scattering polarization)Chromospheric fields
630.0 0.6 Fe I 630.15 1.67 Photospheric magnetograms
Fe I 630.25 2.50
Ti I 630.38 0.92 Umbral magnetograms
656.3 0.6 H I 656.28 ~1.3? Chromosphreic structure
Exposure time 0.1 - 1.6 sec (typical)
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SOT SP (Spectro-Polarimeter)
• Fe I 630.15nm and 630.25nm• Obtain spectra at 16 angular
positions of polarization modulator• 83min for 160" wide scan
Field of view along slit 164" (north-south direction)
Spatial scan range ±164"
Slit width 0.16"
Spectral coverage 630.08nm - 630.32nm
Spectral resolution 27mÅ / 21.53 mÅ sampling
Measurement of polarization
Stokes I,Q,U,V simultaneously with dual beams (orthogonal linear components)
Polarization signal to noise 103 (with normal mapping)
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EIS (360”x512”)
XRT(2048”x2048”)
E W
S
SOT:NFI/SP(328”x164”)
SOT: BFI(205”x102”)
N
Solar-B Fields of View
SOHO/EIT FeXII 195A
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327.7” CCD of NFI / SPG scanning
Vignetting by tunable filter
183.2”
163.8”
Field stop at f2, ” x 197.4” or 7.93 x 4.33 mm2 @f2
HDM hole, 505” or 2.864mm @f1
16.8” or 0.37mm @f2
52.5” or 0.3mm @f1
0 %
20 %
40 %
CCD of BFI
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Schematics of the SOT polarimeter
Pupil image
HDM
Polarization modulator unit (PMU)
CTM-TM
OTA
M1M2
FG/NFI
SP
FG-CCD
SP-CCD left/right
SP- Polarization analyzer (beam splitter)
NFI- Polarization analyzer
Non-polarizing beam splitter
Collimator lens unit (CLU)
Tunable filter
Slit scan mirror
Mask wheelMech. shutter
Astigmatism corrector lens (ACL)
Reimaging lens
Slit
Blocking filter wheel
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Polarization modulatorWaveplate: Common for FG/SP (PMU) Continuous rotation, 1.6sec/rot Retardation: N+0.35@632nm and 517nm
Wavelength (nm)
Retardation (wave)
517.3 6.682
525.0 6.572
589.6 5.762
630.2 5.344
656.3 5.110
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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15PMU segment
Q
U
V
VmUmQmImI VUQI '
V
U
Q
I
WP:PL
Polarization modulation
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16-pos. continuous readout 4-pos. (example)
SP, NFI shutterlessMod. cycle = 0.8sec ε ~ 0.1%
Polarization sampling
NFI shutteredMod. cycle > 5sec ε ~ 0.5%
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NFI shutterless mode
Mask off outer parts of CCD by focal plane maskContinuous readout (10frame/sec) without operating the mechanical shutterOn-board demodulation and accumulation to achieve high S/N
16” x 163.8” 32” x 163.8” 64” x 163.8”128” x 163.8”164” x 163.8”328” x 163.8”
Size of focal plane maskFG CCD
1024 pix shift = 6.30msec
Transfer speed = 6.15sec/pix
6.30ms/1600ms*360*2 = 2.83 deg. azimuth rotation
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SOT observables
FG: - simple image - Dopplergram (2 wavelengths) - Stokes IV - Stokes IQUV - IVDG (2 wavelengths)
SP: - normal mode (0.16” step, 4.8s/slit) - fast mode (0.32” step, 3.2s/slit) - dynamic mode (0.16” step, 1.6s/slit) - deep mode (0.16” step, 9.6s/slit)
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Data rate( 4k*2k*100/2s ~ 1GB/sec)
Observation planning
10” 100” 1000” FOV
Time res.
1”0.1”Spatial res.
1sec
1min
Time span
1hr
1day
1week
10sec
1
# of wavelength (reliability)
Random noise(detection limit)
1min
1hr
1day
10min 4
2
64
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0.01%
0.1%
1%
0.2” 0.4”
SOT limit
SOT limit performance
~104 times larger than telemetry limit (0.3Mbps)
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10” 100” 1000” FOV
Time res.
1”0.1”Spatial res.
1sec
1min
Time span
1hr
1day
1week
10sec
1
# of wavelength (reliability)
Random noise(detection limit)
1min
1hr
1day
10min 4
2
64
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0.01%
0.1%
1%
0.2” 0.4”
Flux tube dynamics: local physical processenergy flow into corona
3D dynamics
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10” 100” 1000” FOV
Time res.
1”0.1”Spatial res.
1sec
1min
Time span
1hr
1day
1week
10sec
1
# of wavelength (reliability)
Random noise(detection limit)
1min
1hr
1day
10min 4
2
64
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0.01%
0.1%
1%
0.2” 0.4”
AR energetics: global energy storage
SOT/SPfull scan
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10” 100” 1000” FOV
Time res.
1”0.1”Spatial res.
1sec
1min
Time span
1hr
1day
1week
10sec
1
# of wavelength (reliability)
Random noise(detection limit)
1min
1hr
1day
10min 4
2
64
16
0.01%
0.1%
1%
0.2” 0.4”
Origin of mag.field:emerging flux/ internetworkflux disappearance
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SOT observation table
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Solar Optical Telescope on HINODE
2006.9.23
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