Progress on 1.5m Aperture
Telescope and Instruments:
Solar UV, Visible and near IR
Telescope (SUVIT)
Y. Suematsu, Y. Katsukawa (NAOJ), K.
Ichimoto (Kyoto), T. Shimizu (ISAS)
and Solar‐C/Chromosphere sub‐WG
1Solar Optical Telescope
space

Ground ‐based

SOT Φ1.5 m (planned 1980)
resolve photon mean‐free‐path
scale in the photosphere
OSL Φ0.8 m （planned late1980s)
Spacelab 0.3 m
NST Φ1.6 m (2009～）
Hinode/SOT Φ0.5 m (2006～）
need more photons andGREGOR Φ1.5 m (2010?～）resolution!
Solar‐C/Plan‐B
ATST Φ4 m (2018?～）
Heritage of developments of Hinode/SOT and large-aperture ground based
telescope.
→ Technology is getting mature enough to build 1.5-m class space-borne
telescope.

2

Basic requirements to the instrument• Telescope aperture and length– 1.5mφ– Fit within the H-IIA nose fairing• Spatial resolution– 0.1" in UV– 0.16" in Vis/NIR (Diffraction limit of1.5mφ at 1μm )• FOV– ~200" x 200" to cover a medium size AR with 4kx4k detector• Wavelength coverage (250 – 1100 nm)– Shortest ~250 nm to observe Mg II h/k.
– Longest ~1100 nm to observe He I 10830.

• I/F between the telescope and the focal-plane instrument– Collimated beam with ~φ60mm exit pupil to relax the tolerance ofalignment.

3

Primary Mirror
Monolithic light-weight mirror for 1-1.5 m aperture arefeasible
・90% light-weighting: 100 – 150 kg (weight budget)
・Small gravity effect in horizontal configuration
WFE < 35 nm rms (optical performace)
coma < 4 nm rms (alignment)
Coating chamber can be accommodated with 1.5 m mirror

Structure model of the Sunrise 1-m
aperture primary4Telescope Structure
Hinode/SOT truss
structure of CFRP (CTE <0.1 ppm/K)

Thermal stability (△T=5deg) in focus
accommodate 1.5 m
aperture and 3 m M1-M2
length Gregorian.
5

Conceptual Design for SUVIT
Polarization
Modulator

Correlation Tracker

Tip‐Tilt
MirrorVisible‐IR Filtergraph(2D) Spectro‐Polarimeter

Polarization
Calibration Wheel
with through hole

Telescope Assembly

UV Filtergraph(2D) UV Spectrograph

UVVIR FPP
6

Positional Tolerance Study of φ1.5 m
GregorianM1-M2 (cm)f1 (cm)

300
280
246.6
231.467(F1/1.64) (F1/1.54)

250
208.467(F1/1.39)

220
185.167(F1/1.23)

OTA 150
116.9617(F1/2.34)

30.4184
0.0636(0.951)26.2470.0178(0.997)f2 (cm)45.7633
Defocus 1μ 0.0367
A20 (Strehl) (0.983)

41.7750.0415(0.980)35.99610.0508(0.968)

Defocus 3μ
A200.1245(0.832)0.1522(0.748)Decenter10μ -0.0359
A31(0.994)-0.0432(0.991)-0.0588(0.983)-0.0831(0.966)-0.0125(0.999)Decenter50μA31-0.216(0.791)-0.294(0.653)-0.4156(0.4267)-0.0625(0.98)

0.1379(0.910)0.01897(0.998)Tilt 10”B31

0.0908(0.960)0.0996(0.952)0.1161(0.936)

Tilt 50”B31

0.454(0.362)0.498(0.289)0.581(0.190)0.057(0.967)

0.0948(0.955)7Baseline Optical Parameters
SOT-OTA (SOLAR-B)

SUVIRT-OTA

Entrance pupil (mm)

500

1500

M1-M2 distance (mm)1500

2800 (<4500)

M1 outer diameter (mm) 560(SOLAR-C)

1580

clear aperture

509

1513

radius（focal）

2339.4 (1169.7)

4629.34 (2314.67)

conic const.

-0.9706-0.990927

M2 outer diameter (mm) 159

340

clear aperture

147

320.5

radius (focal)

524.94 (262.47)

835.494 (417.747)

conic const.

-0.3996-0.548155

HDM outer diameter
(mm)

32.83

48.37
8

Baseline Telescope Design

9Spot Diagram10Collimating Optics
Trade off study among
1. All reflective
2. Lens (SiO2, CaF2)
3. Composite lensCassegrain design
・Chromatic aberration
・Thermal stability in focus
All reflective option ispromising11

Spot diagram for Gregorian + 3‐
mirror collimator12

Heat dump path from M1 and M2 in case of Solar‐B OTA
To space
To sun‐shade &thermal shield tube
(ε =0.75)

Thermal input tosecondary mirror (2.3W)

Front apertureSun‐shade (CFRP)
Top ring
Top spider
Mirror support(Super invar)
Secondary mirror (ULE)
Heat dump mirror
Upper truss
Thermal shieldtube(CFRP)
Center section

Thermal input toprimary mirror (21W)

Optical bench unit

To cold plate (ε =0.75)

Primary mirror (ULE)

Radiation to cold plateMirror support(Super invar)
Cold plate (Aluminum)

13

Structure Model of φ1.5 m Telescope:
Scaled‐up model of OTA

Termal properties of surfaces are of end-of-life except for M1 and M2.

14

Solar‐C Solar Synchronous Polar
Orbit same as Hinode15

Temperatures for Polar Orbit

16

Solar‐C Geosynchronous Orbit

17Temperatures for Geosynchronous Orbit

18

Sensitivity study with radiator area
modification
1) Mod-1 Expand radiator area at
Shield Tube

2) Mod-2 Enhance conduction at
HDM inner spider
AlBe (210W/mK) x 3 spiders↓AlBe (210W/mK) x 6 spiders

3) Mod-3 Expand HDM cylinder

19

MirrorCoatingIssue
Hinode/OTA: M1 and M2 have a protected Ag coat （solar light absorption α～6.5%) which is not suitable for UV observation (not capable of reflecting UVlight shorter than 360 nm).
A typical coating for UV is Al+MgF2. However, The coating has a large α of ～12% and overall reflectivity in visible and IR is Lower than the Ag coating.
→ The development of UV-reflective and low solar absorption coating isunder study.

20Degraded (EOL) Reflectivity forAl+MgF2 Coating
Assume that the solar absorption α incease by 0.05 inthe end of life (EOL).

21Predicted temperatures for optics
T (degC)

Polarorbit

M161
surface

Geosync. orbit

Polar orbit Polar orbit
with Mod‐1 withMdd‐1 andMod‐2

Polar orbit
with Mod‐
1 and Md‐
2 andMod‐3

Polarorbit+Mod‐1
α+0.05@M1&M2

Geosync+Mod‐1
α+0.05@
M1&M2

49

52

52

80

70

M2
‐2 ～ ‐7 ‐24Surface‐12 ～‐8 ‐12 ～‐8 ‐12 ～‐7 0～4‐17～‐16103～
104

77～78 60～61 63～
64

51

24 ‐ 27

29HDM
109～
surface 111

100

CLU

22‐24 24 ‐ 27

34 ‐ 3752

24 ‐ 26

41

22

Heat dump path from M1 necessary
To space
To sun‐shade &thermal shield tube(ε =0.75)

Front apertureSun‐shade (CFRP)
Top ring
Top spider
Mirror support(Super invar)
Heat dump mirror
Upper truss
Secondarymirror (ULE)
Thermal shieldtube(CFRP)
Center section
Optical bench unit

To cold plate (ε =0.75)
Radiation to cold plate

Mirror support(Super invar)
Primary mirror (ULE)
Cold plate (Aluminum)23Off‐axis GregorianPro・no central obscuration, lower scattered light, higher contrast
images・more freedom in designing HDM at primary focus, direction ofreflected light and cooling method
Con・largerer intrumental polarization (may be calibrated withcontinuum and sunspot obs.)
・harder to fabricate and validate M1 and M2 mirrors
alignment・higher non axi‐symmetric structural and thermal deformation oftelescope24Off‐Axis Gregorian
2800mmThe same optical parameters except for off-centered M1
Plane HDM

1200mm25

Preliminary choices of spectrum lines(most deluxe configuration)
Instrument

Spectrum line

wavelength Purpose

Vis/UV broadband imager

UV continuum~250nm

High res. Img of photospehre

Mg II h/k

280nm

High res img of chromosphere

CN band

388nm

Granules and magnetic elements

G-band430nm

Granules and magnetic elements

Mg Ib2512nm

Low chromosphere V and B

Fe I

525nm

Photosphere B

Na ID1 (D2)589nm

Low chromosphere V and B
High photosphereHα656nmHigh chromosphere V

Ca II IRT

854nm

High chromosphere T, V and B

Mg II h/k

280nm

High chromosphere T and V

Ca II IRT

854nm

High chromosphere T, V and B

He I

1083nmHigh chromosphere V and B

Vis/NIR narrowband imager+He D3

UV/Vis/NIR spectrometer+Ca II IRT weaker line

26Block diagram of the optical configuration
UV/Vis/NIR spectrometer

Telescopep. modulator

spectrometer

Detector

Vis/NIR narrowband imager
narrow-band filter

Detector

Vis/UV broadband imager
broad-band filter

Detector

27

Pixel size and FOV of the instruments
FOV
UV-VisBroad
NIR
band
telescope

Pixelsize

Expos Note.
ure

164" x 0.04" < 1sec • 2.5 pix sampling164"
of 0.1" res.
• 4Kx4K detector
Narrow 246" x 0.06" < 1sec • 2.5 pix samplingband246"of 0.16" res.
• 4Kx4K detector• 2.5 pix sampling
Spectro 246" x 0.06" 1sec
meter246"(S/N~ of 0.16" res.
1600) • 4K pix along slit
0.12" 10sec(S/N~104)28

Basic requirements on TF (preliminaily)- Wavelength range- band width (FWHM)- Strehl- FOV- free spectral range- tuning range- tuning speed- tuning resolution- repeatability- uniformity
wavelengthtransmission- stability
wavelengthtransmission (flat)- Parastic light- Ghost-TBD (a possibility 5000 – 8700A)~100mA (50~70mA)>0.9~200 arcsec w/φ1.5m (TBR)>5A+/- 5A<50ms<5mA<2mA
5mA (TBD)
5%5mA /day
1% /day<2%<1%29

Choice of tunable filter
Lyot filter

vs.

Fabry Perot

Need Bubble-free design!
All elements can be attached withindex matching oil?.
30

Lyot filter

Fabry Perot

F (Speed of incident beam)

F~ 40

F ~ 200 (air space) ~ 90(LiNb)

Necessary diameter of filter(D=1m, FOV=3’)~40mm~180mm, ~80mm

Transmission~ 5%~ 70%

Simultaneous 2-polarization

impossible

possible

Simultaneous multi wavelen(in principle possible)

impossible

Structure

ComplexHigh accuracyOil

NecessaryFreeControl device

Rot. waveplate or liquid
crystalPiezo or LiNb

Past experience

SOT/Hinode

LASCO C1/SoHO

Concern- Contact of opt. elem.s - Mount and control for highaccuracy surfaces(avoiding bubble)(thermal/mech. stress)- Mounting calcites- Endurance of coaring- Outgas- Stability of inhomogeneity- Calcite availability- (cm, Telecentric)
Lmin = image size =- F*D*(W/60/180*π) = 0.0003*F*D*W

Filter diameter,
D: aperture, cm、 W: FOV, arcmin、 F: F‐ratio31

Need of 2-dimensional spectroscopy• Rapid motion of chromospheric materials are
ubiquitously seen associated with eruptions, jets, andwave propagation.
• There are several options under investigation to achieve
the 2D spectroscopy in SOLAR-C.
– Double pass spectrograph• Slot spectroscopy with medium wavelength
dispersion– Tunable filter-type instruments with rapid wavelengthtuning• Fabry-Perot or Lyot
– Integral field spectroscopy• Fiber-optics bundle or image slicer
32

Broadband imager layout• Similar design with the HINODE broadband filter imager (BFI).
• The rotating shutter is located near the focal plane• 0.04"/12μm pix, 4Kx4K→ f ~ 2470mm (F/41)→ FOV 164"
pupil

reimaging lens

field lensfilter wheel

6049

90700

relay lens

shutter

1650

detector

28800

1110

33

Spectrograph layout• Littrow spectrograph design similar with the10830/8542
HINODE spectropolarimeter (SP)detector• Multiple detectors for observing multiple
p. analyzer
spectrum lines
blocking filter• 0.06"/12μm pix, 4K (along slit)
2800 detector→ f ~ 1650mm (F/28)
blocking filter→ FOV 246"
pupilreimaging lensoffsetparabolaslit

p. modulator
7060

90230

grating

700

1650

blaze angle

56°

groove80lines/mm

1650

λ

Order

dispersion

2800A

737.0mÅ/12μm

8542A

2421mÅ/12μm

10830

1927mÅ/12μm

34

Narrowband imager layout• Telecentric configuration to have uniform wavelength over FOV.
• Large F (F>150) at the Fabry-Perot etalon.
• The shutter is located near the exiting-pupil.
• 0.06"/12μm pix, 4Kx4K→ f ~1650mm (F/28)→ FOV 246"
pupil reimaging lens

700

90

detector
relay lens

FP721320

telecen lens

telecen lensfilter wheel

p. modulator

60

field lens

shutterp. analyzer

220

720

1000

1000

1500

500

35

Strawman layout of the focal-plane package

500

~3000

1000

1650

500

Broadband imager
~1400

800

1000

~2500

Spectrograph

Narrowband imager

36

Items to be further studied•

Priority of the spectrum lines (wavelength coverage)– Either spectrograph or filtergraph for each line•

Telescope thermal design– Radiator configuration for cooling M1– Development of UV-reflective and low solar absorption coating– Axi-symmetric vs. off-axis design•Configuration of the narrowband filtergraph– Fabry-Perot or Lyot (telecentric or collimated)• Configuration of the spectrograph– Multi-slit (or image slicer) or IFU (integral field unit) spectrographto achieve high time res.
– Multi-wavelength simultaneous obs. or multi-wavelength obs byswitching filters (and tilting a grating).
• Availability of large format detectors– IR detector for He I 10830– UV enhanced detector for Mg II h/k37