可視赤外観測装置開発ワークショップ2020 12/1-2

低散乱軸外し望遠鏡の高コントラスト観測と近赤外高分散分光器ESPRIT開発の現状*坂野井健1, 鍵谷将人1, 神原歩1, 笠羽康正1,中川広務1, 小原隆博1, 岡野章一1, 市川隆1
平原靖大2, 栗田光樹夫3, J. Kuhn4,S. Berdygina5, M. Emilio6

1東北大学・理, 2名古屋大学・環境, 3京都大理

4米・ハワイ大学, 5ドイツ・ケーペンハウワー研
6ブラジル・ポンタグロッサ大1

Introduction: Aim and targets
Jupiter Io torus

Why is high-contrast observation with high-resolution
spectroscopy necessary?
→ To detect faint emission surrounding a bright object

Saturn Enceladusイオ
エンケラドスエウロパ

ü Emissions of volcanic-origin gases fromsatellites of Jupiter and Saturne.g., Io, Europa, Enceladusü Exosphere and escaping neutrals and ionse.g., Martian and Venusian exosphereü Exoplanetary atmosphere
Mars HDO/H2O mapMars/Venus

Exoplanets2

High-contrast performance by the PLANETS telescope
B. PLANETS（Φ1.8m)

Low-scattering system with an
off-axis 1.8m primary＋
Adoptive optics by a deformablesecondary mirror to compensate
atmospheric turbulence＋
Coronagraphy
High-contrast observation

C. PLANETS（Φ1.8m)+ Coronagraph

A conventional

Intensity

A. Conventional
telescope(Φ3.6m)

B PLANETSC PLANETS+ CoronagraphDistance from main object surface

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Key technologies of the PLANETS telescopeü Low-scattering and high-contrast
optical system
ü Coronagraphy
ü Adoptive optics
ü High-resolution spectroscopy invisible to mid-infrared range
ü Fiber imaging/spectroscopyü Monitoring capability
ü Flexibility for TOO

PLAENTS makes possible to observe faintemission near the bright main body (whichis fainter by 10-5 to 10-7 than the main body)with sufficient SNR.

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Specification of PLANETS• Gregorian focus (50-100kg)- Fiber bundle (Vis. NIR)
- Hollow cone fiber (MIR)
FOV(TBR): 6 arc min (Gregorian)
1 arc min (def. limted image) ）• (Nasmyth or Coude focus)- Cryogenic near and mid-infrared
Echelle spectrometers- Guest instrument
M1: parabola, 1.86m
4.333m fl
M2: ellipse, 12cm
0.26m fl5

1.85m primary mirror
Ohara Clearceram Z-HS

Φ＝1850mm, t=100mm

Melting(Dec. 2010)

Shipping to Los Angels(May 2011)

Rough polishing at Harris/EXELIS(July 2012)
Arrived in Maui (June 2017)10.9µm P-V
1.51µm RMS
Now at Tohoku Univ., Japan (Jan. 2020)6

Primary mirror: current status

AJan. 2020 Transferred from Hawaii to Tohoku Univ.
Feb. 2020 Metal adopters for the mirror support wereglued in the backside(A,B)
Feb. 2020- Now developing the mirror support withwhiffle-tree system（C, D, E）•We adopted the whiffle-tree support system andwarping harnesses that is similar to TMT and 3.8m Kyoto
Seimei telescope.
Whiffle-tree mirror support

CE

Gluing metal adoptersBD

Final polishing of primary mirror•••

Dec. 2020 -Collaboration with Nagoya Univ. Kyoto
Univ., and Logist-Laboratory (AstroAerospace)
Polishing by a robot arm
Metrology by 3-point drag probe

By the only robot-arm, polishing andmeasuring are executed on large and freeform optics(including flat and convex shapes).
・Dragging 3-point probe method
・Data stitching algorithm
・Flow of data processing
・Sample resultmirror〜2 m8

Metrology and polishing by robot arm
Achieved RMS<10nm for the secondary mirror of Seimei(Φ1m)
We require RMS<20nm for PLANETS primary mirror (Φ1.8m)

Measuring

Data stitching

Dec. 2020 Stitchingand Evaluation
Evaluation

PLANETS 1.8m case

Correcting polish

Proposed scanning paths across the PALENTS M1

Telescope mountMarch 2020 -ü Reuse of the technical demonstration model of the3.8m Seimei telescope stored at Nagoya University
ü Lightweight and robust pedestal
ü Some parts (R-guides, encoder, servo motor, etc.)
and upper truss are newly procured.
ü Fabrication has been started, and will becompleted within a year.
Now at Tohoku Univ.

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Observation targets suitable forhigh-contrast capability of PLANETS• Volcano on Jupiter’s satellite Io and Europa[Collaboration with Hisaki/Juno/JUICE]• Martian ionosphere/exosphere and escaping gases[Collaboration with MAVEN/MMX/MACO]• Mercury Na, Ca, K atmosphere [Collaboration withBeppi Colombo/Mio]• Exoplanetary atmosphere• Active small bodies like comets and asteroids

What are the required time and spatialresolutions?
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Observation simulation• Black: diffraction limit• Orange: required （20 nm for 10- cmscale, 6 nm for 1-cm scale),• Light blue：best case

RMS variation(nm)Four cases in polished mirror roughness• Micro-roughness < 4 nm （best case <2 nm ）Spatial scale on the main mirror（cyc/m)

S/NMars

CaseA
CaseB
CaseC
CaseD

EuropaS/N12Instruments
Instrument

Spec.

Fiber : Visible Imager and Spectrograph withCoronagraphy (Vispec)

0.4-0.9µm, FOV~1’ / R~70,000

Fiber : Mid-IR laser heterodyne spectrometer (MILAHI) 7-11µm, R ~ 106-7
polarimetry (DoLP ~ 10-5~6)

Gregorian: DiPOL-2 (Polarization imager) (KIS)

B, V, R

Nas: NIR Echelle spectrograph (ESPRIT)

1-4µm, R ~ 20,000

Nas: Mid-IR GIGMICS (Nagoya U.)

7-12µm, R ~ 40,000

13e.g., Near-infrared Ecelle spectrograph(ESPRIT)[on-going]

Slit

Detector; Raytheon InSb 256x256 array
Imaging and Echelle spectrographλ/Δλ; 20,000
Wavelength range: 1 – 4 µm
Temp.: 30K (detector) 90K(radiation shield)

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First light in Japan

2021 -

Fortunately, our Iitate observatory (37.6oN, 2-hour
drive from Sendai) is suitable to enclose thetelescope structure and carry out the first lightdetection of stars.

Roll-off roof building in the Iitate observatory

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Future plan at Haleakala•••

2021(TBR) -Haleakala High-Altitude Observatory, Maui, Hawaii(3040m,GLAT=20º 42.5ʼ N, GLON=203º 44.5ʼ W)
Got permission (CDUP) for the renovation of Chicago building,
University of Hawaii.
In addition, alternative (and cheaper) renovation of old Ashra
house is now under discussion.

Ashra house
T60

Chicago building

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