Design status of theSolar UV-Vis-IR Telescope

(SUVIT)

K.Ichimoto （Ｋｙｏｔｏ Ｕ.）,Y.Katsukawa , Y.Suematsu, H.Hara, S.Tsuneta (NAOJ),

T.Shimizu, K.Matsuzaki (JAXA)and Solar-C WG

Hinode-6, Solar-C Science Meeting, 13 Aug. 2012 in St Andrews

Rev. 2012.8.9

The task of SUVITMeasure the magnetic field and plasma motion at the locations (from phtosphere to uppermost chromosphere) where the magnetic actions are taking place, with the highest angular resolution and spectropolarimetricprecision ever achieved.

Toward the understanding of,,– origin of the sun’s dynamic atmosphere (= chrompshere and corona),– fundamental MHD processes (reconnection, wave, acceleration,etc.),– mechanism of explosive phenomena (flare, CME,,) .

The design policy of SUVITEmploy the advantage of the space to the utmost.(We should never ignore ground-based telescopes)

Advantages of space;- Continuous sun light 24h/day (geo-synchronous orbit)- Constant PSF High spatial resolution diffraction limited optics High precision polarimetry high throughput

- Infinite isoplanatic angle Large field of view large ‘etendue’ (acceptance angle)

- Accessibility to shorter wavelength Include MgII 280nm (TBD) wide wavelength coverage

- No scattered light from the sky (coronagraph)- Different view angle from the earth (synergy with ground)

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Important delta from SOT/Hinode

• Spatial resolution• Polarimetric sensitivity• New spectral lines for

chromospheric diagnosis• Cadence of magnetogram

wide coverage

Efficient 2D-spectropolarimetry& large telemetry

Larger telescope

Demand on HW

As SOT/Hinode, SUVIT will have Filtergraph (BFI, NFI) and Spectro-polarimeter (SP)

Design goal -1

Spatial resolutionSOT x 3 = dx = 0.05 ~ 0.1” = 35 ~ 70km- dx ~ photon mean free path in the photosphere

resolve the collapsed magnetic flux tubes- dx < thickness of line forming layer 3D structure in photosph.- 10 times higher sensitivity for flux/energy elements (Bll dx2, j2)- chromosphere unpredictable discovery

Requirement to the telescope Strehl > 0.8 @ 633nm

PSF @280 (Strehl ~ 0.34) recovered by post-processing

Need 1.2 - 1.5m telescopeSufficient spatial sampling is crucial! e.g. dx ~ 0.015”

Design goal -2

Field of view• Ubiquitous, elementary phenomena (spicule, flux elements,,) can

be captured by a few hour observing run with a small FOV （ 180” x 180”FG need dual modes; ‘high resolution mode’ and ‘wide FOV mode’!

60”x60”

Do you want a continuous observation for days with this FOV?

100”x100”

SUVIT FOV180”x180”

SOT 320”x160”

17.59=19507

Design goal -3

Wavelength coverage• Measure the magnetic field of chromosphere by Zeeman effect

extension to longer wavelength is inevitable• Observe chromospheric dynamics with a higher resolution and

contrast demand for shorter wavelength, i.e. MgII 280nm

Optics that accepts 280nm ～1100nm!

SUVIT candidate lines

Design goal -4

Polarimetric sensitivity• For chromospheric magnetic field -- 10-4 in CaII 854nm & HeI

1083nm • integration time w/ 1.5m telescope ~ 10sec for 0.2”x 0.2”pix

• For photospheric magnetic field -- 10-3 ~ 10-4

Need high throughput (= large aperture, high transmission),& fast readout of camera /data processing

CaII 8542A inversion testing(de la Cruz Rodriguez et al 2012)

simulation

= 10 -4

= 10 -3

Bz Bx By

Design goal -5

Time resolution (for spectro-polarimetory)• Time needed for scanning a spicule with a slit

– 5” /0.2” x 10sec = 250sec– Scanning speed ~ 14km/s too slow!

• To capture the chromospheric dynamic phenomena, 2D (Integrated Field Unit; IFU) spectroscopy is required

• For observations of photospheric B and chromospheric Doppler, a slit spectroscopy has advantage (higher throughput & resolution)

Require both slit and 2D spectro-polarimetry!

spectrograph

FOV of IFU spectro-polarimeter

slit

flare

wavelengthFilament

SUVITItem DescriptionTelescope Aplanatic Gregorian telescope: diameter of primary: ~1.5m

Focal Plane Instruments Broadband Filtergraph (BF), Narrowband Filtergraph (NF), Spectro-polarimeter (SP)

Wavelength coverage 280 nm (TBD) – 1100 nm

Spectral lines(spectro-polarimetry)

Chromosphere: He I 1083 nm, Ca II 854 nm Dynamics: Mg II 280nm (not baseline)Photosphere: Si I 1082.7 nm, Fe I 525 nm

Spectral lines(imaging)

Chromosphere: Mg II 280nm (TBD), Ca II 854nm, H I 656nm, Na I 589nm, Mg I 517nmPhotosphere: Fe I 525 nm, continuum (wavelength TBD)

Sampling scale Imaging: 0.015” (narrow field), 0.045” (wide field)Spectro-polarimetry: 0.07”

Spatial resolution (or imaging performance)

Imaging: 0.05” at 280nm (TBD), 0.09” at 525nm, 0.14” at 854nmSpectro-polarimetry: Slit scan: 0.14”, IFU: 0.14”(along slit)×0.18” (across slit)

Slit width Slit: 0.07”, IFU: effectively 0.18”

Spectral resolution Narrowband filtergram: ~50,000Spectro-polarimetry: 100,000 –210,000 (slit), ~96,000 (IFU)

Exposure time Intensity observations: 0.05 – 1 sec, Polarimetric observations: 1 – 20 sec

Polarimetric accuracy of chromospheric lines

1×10-4 (6×10-3) for 0.2” (0.1”) sampling and 20 (1) sec integration Sensitivity of Blong: 1–2 (10-20) G, of Btrans: ~100 (~300G) [Zeeman], 0.1–100 [Hanle] G

Filed of view Imaging: 61×61 arcsecs (narrow field), 184×184 arcsecs (wide field)Slit scanning polarimetry: 184×143 arcsecs2D spectro-polarimetry (IFU) : 10×10 arcsecs

SUVITItem Science requirements Science

backgroundsRelated hardware limitations

1.5m telescope aperture - High spatial resolution

SUVIT basic param’s (goal)SOT/Hinode SUVIT/Solar-C

BFI Wavelength 388 - 668nm (280) - 668nm

Spatial resolution 0.2” 0.05” - 0.11”

FOV 220” x 110” 61” x 61” (narrow)184” x 184” (wide)

NFI Wavelength 517 - 656 nm 517 - 854 nm

Spatial resolution ~0.3” ~0.1”

FOV 320” x 160” ~80” x 80” (narrow)~200” x 200” (wide)

SP Wavelength 630 nm (280), 525, 854, 1083 nm

Spatial sampling 0.16” 0.07” (slit)0.18” (IFU)

FOV 320” x 160” 184” x 143”(slit)~10” x 10” (IFU)

Sensitivity 10-3 10-3 - 10-4

Time resol. 180” x 140”(10-3) 10” x 10”

~6000 s340 s

~2600 s1 s 13

Current baseline designand

critical area

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SUVIT ongoing design work• Maximum usage of the Hinode heritage

– An axi-symmetric Gregorian telescope with 1.5m aperture

– Filtergraph (BFI, NFI) and Spectro-polarimeter (SP)– Common rotating waveplate as a pol. modulator– Image stabilizing system with a tip-tilt mirror– Heat dump mirror and 2nd field stop to minimize

the heat lord to FPP

• But, SUVIT’s new demands make it something different from the SOT/Hinode …

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16

1300

Pupilϕ60

200

SP package

FG package

200

1300

400

400

Optical layout (baseline)

TTMϕ89.2

PMUϕ60

CMU

BSϕ120.2

Reimg-lensϕ110.8

Scan mirrorϕ126.8

Folding mirrorϕ105.0

2FS

CT

IF unit

Entrance of FG packageϕ128

Beam size FOV 200”x200”(diagonal 282”)

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SP package

FG package

1300

Pupilϕ60

PMUϕ73.4

TTMϕ90.8

CLUϕ87

1300

748.6

748.6

389M3ϕ132

2FS

M3ϕ132

Folding mirrorϕ79

CLUϕ87

PMUϕ73.4

TTMϕ90.8

Reimg lensϕ63.4

Scan mirrorϕ79.4

Folding mirrorϕ70.2

CT

IF unit

Entrance of FG packageϕ92

Beam size FOV 200”x200”(diagonal 282”)

Optical layout (another option)

Layout of the spectrograph

720 mm

24 m

m

~120 mm

92 mm

~184 mm

36 mm

spectrum mask

Slit/IFU

detector

offset parabola

grating18

Relay lensx1.5 magnification

The spectrograph with F/7.8 covers 1.5xFWHM of exit beam from the IFU.Collect 80% of photon.

PBS

Optical fiber IFU and slit Teledyne H2RG + SIDECAR ASIC, HgCdTe, 2k x 2k pixels, 18m/pixReadout 64 frames/sec

Choice of tunable filterLyot filter vs. Fabry Perot

Air spaceFoster etal 2009 Opt. Soc. America

LiNbO3Schuhle etal 2009(?)

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Tunable filter FPP/SOT

Diameter (D=1.5m, FOV=2’)~40mm ~200mm ~80mm

Oil chamber Mitigated by LCVR

Big, heavy!Stability of flat

FragileSlow tuningSmall FSR

Experiment for LCVR Lyot filter is ongoing in SUVIT J-team and LMSAL/HAO.(Michelson -- another possibility..?)

TA: Telescope Assy (MELCO)

FG: Filtergraph (NASA)

SP: Spectrograph (MELCO,TBD)

PMU CTAdj.

M2M1

BS

CT-Cam

SP-Cam

FG-Cam

CL

SP-E-box(MHI)

FG-E-box(NASA)

Scan-M Gratingslit FW

E-box HK,HTR

E-box

Baseline config 2012.8.2TF FW1&2

HK, HTR

HK,HTR

BS

focus

focus

IF unit(MELCO)

TA-E-box(MELCO)

PMU signal

S/C bus

CT command

( TBD )

controldata

Control,data

Control,status

( ESA? )

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SUVIT block diagram and possible task share

shutter

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Design goal and impact on the instrument

MgII 280nm- challenging optical design may force a compromised optical performance

in Vis.&IR- challenging coating may cause a less throughput, larger heat absorption,

polarization effects- need more serious study of contamination control

HeI 1083nm in SP- IR camera saturates in room temp. How to test the instrument on ground..

FOV 200” w/ 1.5m aperture- large beam size, big optical elements (~14cm lens & BS in baseline layout)

10-4 accuracy in 10sec - fast readout (2kx2k 64frame/s), fast data transfer & processing- 2D spectro-polarimetry lower Technical Readiness Level

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CollimatorCovering 280nm – 1100nm is a challenge..

3 mirror system(current baseline)

We need to allow a significant field curvature correction in FPP

Silica CaF2 Silica CaF2

Lens system with Silica+CaF2(athermal solution)

We need to allow a significant chromatic aberration correction in FPP

Scientific issues critical for SUVIT/Solar-C

• Scientific advantage and technical challenge for having MgII 280nm.

• FOV 184” x 184” necessary and sufficient?• Does Ca854nm/He1083nm spectro-polarimetory

(10”FOV, 0.2”pixel, dI/I~10-4 in 10s) really tell us .. – energy carried by waves to solve heating problem?– good boundary condition for field extrapolation?– direct evidence of magnetic reconnection?– origin of spicule, prominence, flare,,?

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Summary

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SUVIT’s design goal and current concept are presented. More works on scientific justifications and technical feasibility are needed..

Backup slides

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SOT lines

D1

6303

H

CaH

26

imaging

Spectro-polarimetory

D1

SUVIT lines

6303

H

CaK

HeI

CaII IR

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imaging

Spectro-polarimetry

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Polarization Calibration Unit (PCU), Collimating Mirror Unit (CMU), heat dump mirror (HDM), secondary field stop (2FS), polarization modulation unit (PMU), tip-tilt mirror (TTM)

Baseline Telescope Design

TTM

PMU

To FPP Out-of-field light

M1 structure and support

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Light waighted (~90%) Zerodure or ULE

Designed for minimum gravitational deformation when the mirror is in vertical.

Telescope frame structure and I/F to S/C

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Tangential support of M2 to prevent the defocus caused by a thermal effect (lesson learned from Hinode OTA)

Obs Mg II h&k G-band Na I D H I Hα Ca II IR He Iwavelength 280nm 430nm 589nm 656nm 854nm 1083nm

Aｌ＋MgF2

Ag

Highly enhanced Ag(SAGEM)

Coating

An issue remains that non-uniformity of coating over the large mirror gives non-negligible WFE degradation with wavelengths. also polarization..

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Accommodating Slit and IFU

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Idea -1

Idea -2

24.6 mm

25 mm 25 mm

8 8

18.5 mm

~35 mm

~66 mm

F/23.6 F/7.83

F/23.6 F/7.83

F/23.6 F/7.83

18.5 mm

14.5 14.5

Switching mechanism4 slits / 4 IFU slits

No mechanism1 slit + 3 IFU slits

Parameters of the spectrographSlit BiFOIS image slicer

Focal length L 720 mm 720 mm

F-ratio F 23.57(f=1414.4 for 0.07”/12µm)

7.83

Footprint diameter D=L/F 31 mm(Diffraction λ/s x L = 65mm @ 1083 nm)

92 mm

Grating size W 31 x 62 mm 92 x 184 mm

Groove density (1/σ) 110 /mm 110 /mm

Order m 15 @ He I 1083 nm19 @ Ca II 854 nm31 @ Fe I 525 nm

15 @ He I 1083 nm19 @ Ca II 854 nm31 @Fe I 525 nm

Spatial sampling 0.07” / 12 µm(FOV 143”x143” with 2Kx2K)

0.18” /30 µm(FOV 11”x11” with 64x64)

Pixel size (at the spectrum mask) p 12 µm(12 x 1.5 mag = 18µm)

12 µm(12 x 1.5 mag = 18 µm)

Slit width s 12 µm 30 µm

Spectrum resolution (detector sampling)λ/Δλ = 2L tanβ/p

2.4×105 2.4×105

Spectrum resolution (slit width)λ/Δλ = 2L tanβ/s

2.4×105 9.6×104

Spectrum resolution (grating size)λ/δλ = m N = m W/σ

1.0×105 @ 1083 nm1.3×105 @ 854 nm2.1×105 @ 525 nm

(for W=62 mm)

3.0×105 @ 1083 nm3.8×105 @ 854 nm6.3x105 @ 525 nm(for W=184 mm) 33

Pointing stabilitySolar-C requires 2 – 3 times higher pointing stability than Hinode

Critical area

Contamination control;SOT throughput (real) SOT contamination model

We do not understand exactly the cause of degradation of SOT throughtput. Need further experiments for Solar-C!

FG: Filtergraph (NASA)

SP: Spectrograph (MELCO)BS

CT-Cam

SP-Cam

FG-Cam

SP-E-box(MHI)

FG-E-box(NASA)

Scan-M Gratingslit FW

E-box HK,HTR

E-box

SUVIT block diagram and possible task share

TF FW1&2

HK, HTR

TA: Telescope Assy (MELCO)

PMU CTAdj.

M2M1

CL

HK,HTR

BS

focus

focus

IF unit (MELCO)

TA-E-box(MELCO)

S/C bus

( TBD )

PMU signalCT com

controldata

Control,data

Control,status

( ESA? )

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Another config 2012.8.2shutter

Image slicer (fiber ribbon)

• Fiber ribbon developed by Collimated Holes (Inc., CHI) with H. Lin (Hawaii Univ.)

• Size of the elemental fiber 10µm x 40µm.• Material: Bolosilicate Glass• Polarization maintaining (to be verified)

37

input arrayoutput array

Detector (candidate): H2RG

38

Teledyne Co.H2RG FPA, SIDECAR ASIC, HgCdTe, 2k x 2k pixels, 18m/pix

Space qualified(TRL-6 for H2RG, TRL-9 for SIDECAR)

Readout 64 frames/sec, (WP 1 sec/rot)

Critical areas;- very fast data transfer and demodulation- possible saturation at room temp.

Photometric accuracy vs. spatial scale

1000 100 1 0.1Spatial scale (arcsec)

10-2

10-3

10-4

Pola

rimet

ricse

nsiti

vity

10

SDO/HMI

Hinode/SOT

ATST, EST

Solar-CSUVIT

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