Upload
lyquynh
View
215
Download
3
Embed Size (px)
Citation preview
3.18 10 m
– 37 –
4.�Relay�Optics�from�Nasmyth�to�Heterodyne�Receivers�[6]-�3�cryostats����6�recievers�installed-�Observation�modes����9�ways�we�will�be����able�to�choose-�Switching�receivers����using�a�mechanism�as����shown�in�Fig.�4�lower,����with�2�wire�grids,�a�plane����mirror,�and�void�space
2.�Optical�Design�(to�Nasmyth)-�Ritchey-Chrétien�system����two�hyperboloid�mirrors�(PM,�SM)�����and�correcting�mirror�(TM)-�Wide�Field-of-View����F/6,�1�degree�at�1.5�THz�(Nasmyth)
NRO�UM�2014�
Overview�of�Antarctica�10�m�THz�Telescope�OpticsH.�Imada1,�T.�Tsuzuki2,�T.�Nitta2,�M.�Nagai1,�M.�Seta1,�K.�Asakura1,�Y.�Onodera1,�M.�Sugaya1,�Y.�Sekimoto2,�N.�Nakai1,�N.�Kuno1,
S.�Kitamoto1,�K.�Kobayashi1(��1University�of�Tsukuba,�2NAOJ)
����We�have�a�plan�to�construct�a�10-m�THz�telescope�in�Antarctica�and�show�an�overview�briefly.�Meteorological�and�optical�environments�in�Antarctica,�opti-cal�systems�of�our�telescope�are�shown.�Ritchey-Chrétien�system�and�free-form�mirrors�are�adopted�to�aquire�a�wide�field-of-view.�To�study�feasibility�to�manufacture,�we�have�made�a�brief�error�budget�and�investigated�whether�to�satisfy�it�with�regard�to�primary�mirror�panels�and�relay�optics�mirrors.
1.�Science�goal��There�are�many�galaxies�called�SMGs�that�cannot�be�observed�at�vis-ible�light,�but�can�only�be�observed�at�sub-mm.�SMGs�and�more�distant�galaxies�are�expected�to�be�most�luminous�in�THz�band.�Developing�a�THz�telescope�(400�GHz�-�1.5�THz)�with�wide�field-of-view,�it�allows�us�to�survey�a�whole�sky�and�to�detect�a�number�of�unknown�galaxies.
3.�Relay�Optics�from�Nasmyth�to�Radio�Camera�[5]-�Convert�F/6�to�F/1����four�free-form�mirrors�and�one����alumina�lens-�Wide�Field-of-View����F/1,�1�degree�at�850�GHz�(at�detectors)
references[1]�H.�Okita,�Ph.D.�dissertation,�Tohoku�University,�Feb.�2014.�[2]�Data�provided�by�H.�Okita,�NAOJ.�[3]�S.�Takahashi,�et�al.,��JARE�Data�Reports.�Meteorology,�vol.�36,�pp.�1–416,�Mar.�2004.�[4]�S.�Ishii,�et�al.,�Polar�Science,�Vol.�3,�pp.�213–221,�August�2010.�[5]�Tsuzuki�et�al.,�Journal�of�Astronomical�Telescope�Instruments,�and�Systems,�2014�(submitted).�[6]M.�Sugaya,�Master's�thesis,�University�of�Tsukuba,�Feb.�2014.�[7]�Y.�Onodera,�Master's�thesis,�University�of�Tsukuba,�Feb.�2014.�[8]�K.�Asakura,�Bachelor's�thesis,�University�of�Tsukuba,�Feb.�2014.
5.�brief�error�budget��Wavefront�errors�for�radio�camera�are�roughly�assigned�as�shown�in�Table�1�(see�also�Fig.�2�and�3).�Thermal�and�gravitational�deformation�for�PM�panels�are�permitted�at�most�~�8�um.�4.5�um�for�relay�optics�requires�deviation�oftemperature�less�than1�℃.
6.�Deformation�of�PM�panels����PM�is�composed�of�90�Al�panels�[7].�Optimizing�thickness�of�panels,�and�positions�and�widths�of�ribs,�wavefront�errors�will�be�less�than�12.6�um.�The�details�are�as�follows:����gravitational�deformation�3.8�um����thermal�deformation��������3.4�um����thermal�gradient��������������5.6�um�→�rss�7.6�umother�componets:����manufacturing�errors�������2.9�um����misalignment�������������������9.6�um�→�rss�12.6�um
7.�Two�receiver�cabins�thermal�design-�Specifications�for�two�cabins�(radio�camera�and�heterodyne�receivers)
Conclusion We show environments in Antarctica, the optical systems of our tel-escope, and feasibility to manufacture partly. It seems to be possible to manufacture at present but very difficult, we guess. After this, we will investigate mirrors not evaluated here and supporting structures.
0
1
2
3
4
5
6
7
8
9
-90 -80 -70 -60 -50 -40 -30 -20 -10 0
perc
ent
temperature [deg.]
winterGaussiansummer
all season
(a) (b) (c)
(d) (e) (f)
2.�Dome�Fuji�Station��Dome�Fuji�Station�is�located�about�1000�km�inland�(a)�and�at�an�alti-tude�of�about�3800�m.�An�annual�mean�temperature�is�about�-54�de-grees�Celsius�and�a�minimum�is�about�-80�℃.�Wind�is�calm�(b).�Dome�Fuji�Station�is�one�of�the�most�adquate�site�to�observe�sub-mm�and�THz�wave�(f).
ave. 5.8 m/sat 10 m high
0.3�m
9.5 m
12.0 m15.8 m
0.0 m
at 220 GHz at 220 GHz
(a)�Location�of�Dome�Fuji�Station.�(b)�Wind�speed�histogram.�(c)�Monthly�mean�temperature�[1].�red:�at�0.3�m�high,�blue:�at�9.5�m�high,�green:�at�12.0�m�high,�black:�15.8�m�high,�and�back:�at�0.0�m.�(d)�Mean�temperature�gradient�between�15.8�m�and�12.0�m�against�that�be-tween�9.5�m�and�0.3�m.�The�feature�encircled�appears�when�the�temperature�at�0.3�m�is�less�than�-55�℃.�[2]�(e)�Temperature�histogram.�red�cross:�May�to�Sep.,�blue:�Oct.�to�Apr.,�magenta:�all�season,�and�green:�Gaussian�fitting�for�winter�with�a�mean�of�-65�℃�and�a�deviation�of�5�℃.�[3]�(f)�Optical�depth�at�220�GHz.�[4]
Strehl�ratio�map Spot�diagram
Fig.�2����Layout�of�optical�design.�Primary�mirror�(PM)�and�Secondary�mirror�(SM)�are�hyperboloid.�Tertiary�mirror�(TM)�is�equipped�on�EL�axis�and�switches�from�one�focus�to�the�other.
Strehl�ratio�map Spot�diagram0.0
0.8
1.0
Fig.�3����Layout�of�the�relay�optics�to�the�radio�camera.�It�is�composed�of�four�free-form�mirrors�and�an�alumina�lens.�The�mirros�and�lens�are�optimaize�at�850�GHz�[5].
lens
RadioCameraCabin:4.8m(W),4.0m(H),3.0m(D)HeterodyneCabin:3.4m(W),2.0m(H),2.1m(D)
Receiver Room
Compressor Room
Air Circulation
ReceiverRadioWave
Compres-sor
Optical System RadioWave
Exhaust
TakeColdAir
CABIN
Fineadjustment oftemperatureusingheater
Width
Height
Steel: Insulation: Steel0.1mm:tobecalculate:0.1mm0.5mm: 99mm :0.5mm
InsulatingWall
CameraHeterodyne
53W/(mK)
Emissivity0.35
0.028W/(mK)
Sheet1
ページ 1
Cabin�temp. 0�℃�in�all�seasonsto�reduce�a�thermal�flow�into�receivers,�
to�run�instruments�normally
Temp.�deviation ±�1�℃ to�reduce�mirror�deformation
Source�of�heat exhaust�heat�of�instruments to�save�energy
Air�flowing�into�cabins
hot�exhaust�from�instruments�mixed�with�outside�cold�air
Structure�of�walltwo�sheets�of�steel�and�a�Styrofoam�insulation
See�Fig.�6
-�Thermal�model����Table�3,�Fig.�6,�and�7�show�thermal�models�considered.�3�cases�are�demonstrated:1)�radio�camera�cabin����in�summer�[8],2)�radio�camera�cabin����in�winter�[8],3)�heterodyne�receiver����cabin�in�winter�[6].
Fig.�6��Structure�of�insu-lating�wall
Table�2��Specification
Table�3��Parameters
Fig.�7�(above)��Schematic�illustration�of�re-ceiver�cabins.�Hot�exhaust,�mainly�from�com-pressor,�is�used�to�keep�the�inside�tempera-ture�at�about�0�℃.�Fig.�8�(right)��Thermal�flow�through�the�insu-lating�wall.�The�upper�part�represents�the�case�of�1),�the�middle�the�case�of�2),�the�lower�the�case�of�3).
-�Results�(Fig.�8)����*�Radio�camera�cabin:�30�mm�insulation�can�keep�the�inside�temper-������ature�0�℃�in�winter.�Thus�the�thickness�of�50mm�is�adopted.�A�������maximum�of�surplus�internal�heating�is�7.2�kW�in�summer,�and�������1200�m3/h�cold�air�is�needed�to�mix�the�hot�exhaust�with.����*�Heterodyne�receiver�cabin:�A�maximum�of�surplus�internal�heating�������is�1.7�kW�in�winter,�and�115�m3/h�cold�air�is�needed.�100�mm�insu-������lation�can�keep�the�inside�temperature�0�℃�in�winter.����*�The�solar�radiation�changes�quickly.�There�is�a�difference�of�0.2�kW�������between�heat�flows�from�the�rooms�with�the�solar�radiation�and�������without�it.�60�kJ�are�required�to�change�the�room�temperature�by������1�℃.�Thus�timescale�is�about�300�sec.�(=�60�kJ/0.2�kW).
Sheet1
ページ 1
Radio�camera�cabin Heterodyne�receiver�cabin
parameters�to�be�calculated
thickness�of�insulator,�tempera-ture�of�two�sheets�of�steel
fixed�parameters
cabin�temp.
outside�temp.
wind�speed
insulator
conductivity
thichness
emissivity
snow
temp.
solar�radiation
amount�of�heat�from�instruments
temperature�of�outside�steel
-20�℃�(summer),�-80�℃�(winter)
0�℃�(all�seasons)
-60�℃�(winter)
1�m/s�(summer),�5�m/s�(winter) natural�convection
12�kW�(summer),�0�kW�(winter) 0�kW�(winter)
8.1�kW 2.3�kW
0.028�W/m/K
53�W/m/K
0.1�mm 0.5�mm
0.35
0.2not�to�be�considered
99�mm-
3.12 6 9 2
EM1
Nasmyth
3.14 2
Fig.�4��Heterodyne�receiver�cabin�[6].�(left)�Schematic�illustration.�There�are�two�ellipti-cal�mirrors�after�the�Nasmyth�focus.�(right)�Layout�of�the�relay�optics�to�Heterodyne�receivers.�(lower)�A�rotatble�mechanism�to�switch�over�to�another�receiver.
EM2 cryostat
INSIDE OUTSIDEINSULATINGWALL
RoomTemp.:0Wind:0m/s
RadioCameraSummer
Midnight Sun
OutsideTemp.:-20Wind:1m/s
OutsideTemp.:-80Wind:5m/s
OutsideTemp.:-60Wind:0m/s
0.13kW:Convection
Convection:3.6kW
3.6kW:Radiation
1.1kW:Radiation
0.45kW:Radiation
Conduc-tion
12kW:Solar radiation
9.1kW:Convection
2.5kW:sssssssConvection
Convection:0.74kW
0.58kW
3.6kW
0.74kWInternal
Heating:8.1kW
RadioCameraWinter
Polar Night
HeterodyneWinter
Polar Night
InternalHeating:8.1kW
InternalHeating:2.3kW Conduc
-tion
Conduc-tion
RoomTemp.:0Wind:1m/s
RoomTemp.:0Wind:1m/s -16.3-0.3
-1.5
0.0
-79.7
-59.2
0.58kW
a Assumingthistemperatureissameasroomtemperature.
℃
3mirrors-polynomial-20130914_50deg_almina_nonflat_131022_2_3_jump_last2_display.zmxコンフィグレーション 1 / 1
3D レイアウト
8
Nasmythfocus
1000�mm
M1
M2M3
M4
Sheet1
ページ 1
PM���������SM���������TM�������M1-M4������lens���������WEStrehlratio
12.6�um���5.8�um����3.2�um����4.5�um����4.5�um��17.4�um������0.7
Table 1 Wavefront errors (WE) at 1.5 THz
5.45: 1 2
5.46: 2
90
5.47:2
5.46
5.3.4
30m
m1.05
µm
1.9µm
30m
m19.23
kg4
kg
20m
m1.13
µm
40µm
,50
µm
10m
m1
kg90
90kg
30m
mB
5.5×10
4m
m2
4.5×10
4m
m2
915.47: 2 5.46
5.3.4
30 mm 1.05 µmµm 30 mm 19.23 kg
4 kg
20 mm1.13 µm 40 µm, 50 µm
10 mm1 kg 90 90 kg
30 mmB 5.5×104 mm2
4.5×104 mm2
91
0.0
5.0unit:�um
Fig.5�(upper)�Structure�of�ribs.�(lower)�Gravitational�deformation.