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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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