Technical Prospect for
280nm Observations withSUVIT
Y. Suematsu (NAOJ)

Glass and Coating Material
Big jump in designing optics from 388-1100 nm to280-1100 nm band, because
transmitting material in UV (< 350 nm) is limited.
Glass: Silica, CaF2, (LiF)reimaging lensfor SP
TTM
BSCMU

2FS
M3

FG package

reimaging lensfor FG
SP package
TTM

BSSP package

foldingmirror

reimaging lensfor SP

FG package
M3
2FS

BSCMU
TTM

Collimator Unit in Telescope Assembly
388-1100 nm

280-1100 nm

22:51:44

S-BSM2, S-LHA64, S-BAH27

Silica, CaF2SilicaNonachromatic
combination

PCaF2N

positive power
df/dT < 0Athermal, Apochromatic

SilicaCaF2NP

Achromatic
combination

positive power
df/dT > 0Athermal but not achromatic (△f～50mm)
25.00

GE1323_ATcol35_Ti

M5
Φ84mm
２FS

M4
Φ72mm

FULL SCALE

Highly aspherical mirrors, fieldcurvature with Gregorian
Exit pupil
Φ56.4mm

M6
Φ96mm
M3 to M4 680mm

Clear perture
φ79.6mm

M4 to Exp 347mm

MM17-Jul-12

Mirror CoatingObs

wavelength

Mg II h&k
280nm

G-band430nm

Na I D H I Hα589nm 656nm

Highly enhanced Ag(SAGEM)Ag

Ca II IR
854nm

He I
1083nmAｌ＋MgF2

An issue remains that non-uniformityof coating over the large mirror gives
non-negligible WFE degradation withwavelengths.

5Design of AR Coating
For 350 nm – 10830 nm

280nm

For 280 nm – 10830 nm ?

Design of Beam Splitter Coating

Reflection

Transmission

Filtergraph280nm Broadband Imager, FG Design by LMSAL

Beam selector(lores/hires)
Filterwheels(4 pos. ea.)

Field lensRe-imaging lenswide-field path

ShutterFilterwheel(5 pos.)SOLC

Field lensRe-imaging lens high-res pathBeam selector(lores/hires)

Pupil /aperturestop

Lyot (split intotwo halves)
Re-scaling lens for NB wide-fieldpath (high-res path goes directly toLyot)

Shutter

Re-imaging lens NB pathInterference filter for 280 nm band

Central wavelength: 279.9nm±0.05nm

FWHM: 1nm

Transmission： >10% (TBD)

IRIS Solc Filter• Filter design strategy– Solc filters have multiple orders, or peaks, separated by the Free Spectral Range (FSR). Using asingle filter, can place one peak at the Mg II K-line core (λ0 = 2796 Å) and the next peak at the+1 order (λ0 + FSR = 2830Å).
– Design plate thickness to achieve FSR = 34 Å.
– Design number of plates to achieve FWHM < 4 Å.
– Design plate angles to control sidelobe amplitudes.
– Choose orders using an upstream 2-cavity interference filter which has a FWHM given byapproximately FSR/2 (~15 Å). Such filters are easily manufactured.

SUVIT Meeting, 12 Dec 2012

T. Tarbell, LMSAL

Filtergraph4-slit configuration for a slit and IFU
Slittrue slit
slit-1Spectrum mask

Detectorfrom IFU
slit-2slit-3

Window-1 Window-2 Window-3 Window-4

slit-4

Width30 μm

spectraspectraspectraspectrafrom slit-1 from slit-2 from slit-3 from slit-4

window

Width12 μm

mask
3.07 mm1.53 mm

6.14 mm

12µm x 2048 = 24.6mm

3.07 mm

Two orthogonal polarization states
separated by PBS.

12µm x 2048 = 24.6mm
18µm x 2048 = 36.9mm

Evaluation points

13

Spectral Bands for SP
Spectral window corresponding
to 220pix on the detector

He I 1083.0 nm

Fe I 525.0 nm

OptionMg II 280 nm

Ca II 854.2 nm

OrderSampling# of pixels

Wavelength range

He I 1083.0 nm

1545.2 mÅ

220 pixels

1082.50 – 1083.49 nm (0.99 nm)

Ca II 854.2 nm

1935.6 mÅ

220 pixels

853.72 – 854.50 nm (0.78 nm)

Fe I 525.0 nm

3121.9 mÅ

220 pixels

524.65 – 525.13 nm (0.48 nm)

11.7 mÅ

220 pixels

279.43 – 280.69 nm (0.26 nm)

Mg II 280 nm

14Three Cameras

15

Fiber IFU
F/23.6

Fiber IFU

14.5

18.5 mm14.5

F/7.8318.5 mm

10μm ｘ 30μm
Not transmit 280 nm

45 slicers (30μm each)
1.35mmx1.58mm
8.1”x9.5”
Metal, Micro rough 1 nm rms
before coating

Mirror slicer
Slice image withIFU
thin mirror

Micro image
slicer (30μm）
Pseudo-pupil
mirror arrayTo
collimatorof SP

Re-arranged
sliced images

Pseudo- Pupil Mirror Array （3x7 only）

For SOLAR-C SP
57.6 arcsec

R
Pick-upmirrorCMicroimageslicerL

Pseudopupil mirror

Re-arranged

R C L
Normalslit

Wavelength dependence of image quality
Strehl ratio = exp[-(2π rms-WFE/λ)2]

Post-fact
imagerestoration?

Severe Contamination Control Necessary
request much sever contamination control thanHinode caseSummary
To realize 280 nm observations (scientifically useful)・Many issues to be solved exist in coatings
・2D Spectroscopy
is not possible with Filtergraph(only broadband imager)
needs dedicated spectrograph for 280 nm bandwith high speed slit scan and/or mirror IFU