Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.iki.rssi.ru/oct4/2007/ppt/03_07_Oleg_Korablev.pdf Äàòà èçìåíåíèÿ: Tue Dec 4 17:13:14 2007 Äàòà èíäåêñèðîâàíèÿ: Fri Dec 21 22:05:01 2007 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: m 11

ACOUSTO-OPTIC SPECTROSCOPY IN PLANETARY MISSIONS
O. Korablev , Y u. Kalinnikov , A. Kise lev , D. Be ly aev , A. Ste panov , I.I. V inogradov , A. Fe dorov a, A.V . Grigoriev Space Research Institute ( IK I) VN IIFT RI ( Inst. of Phys.-Che m. and Radiophys. Measurements) Physical Faculty of Moscow University J.L. Be rtaux , E. Dim are llis, J.P. Dubois, E. V illard, D. Neve jans, E. Nee fs, J.P. Bibring, M. Be rthe Service d'Aerono mie du CNRS Belgian Institute for Space Aerono my Institut d' Astrophysique Spatiale

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AOTF = Acousto-Optic Tunable Filter
A birefringent crystal: for example TeO2 (0.4-5.2 µm) Effectiveness 60-70% Maximal possible resolving power 1500-2000 (best resolution in wavenumbers ~3.5 cm-1) Aperture < 1 cm2, < 5-6º Spectral range 2 and more* RF ~ 10-200 MHz RF power : 0.3 W -3W Time to tune ~30 µs.
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Why AOTF in planetary missions?
very light, compact, and robust device with no moving parts easily controlled by changing RF fast and random tune RF=OFF no diffracted light signal to reject stray light possibility to filter images
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easy modulation of


M ARS EXPRESS PAYLOAD
ASPERA

SPICAM

PFS

MARSIS

OMEGA

HRSC

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Mars Express: SPICAM
Near-IR AOT F channel Electronic block

SP ICA M ­ versatile atmospheric spectrometer PI Jean Loup Bertaux, SA Verrieres le Buisson Cooperation: F rance, Belgium (mechanics), Russia (IR channel), USA

UV channel

Main ch ar acte ristics of SPICAM UV Near-IR 1000-1700 0.5-1.2 17.5 1.5 4.9 kg 30 Mbit/orbit 5

UV ch annel
Pa ra bo lo c m irr o r

Su n
40 x40

Spectral range, nm
Nadir

118-320 0.9 0.2x1 0.2

Spectral resolution, nm Angular resolution, mrad nadir occultations Mass Data vo lu me

M Slit Gr at in g CCD Im a ge int en sif ier
FOV di aph ragm
ü30

o ptc al fib er

IR channel
IR det ector

li ght tra p

Nad ir

AOTF

Te le scop e M


SPICAM Light / MEX

UV: 110-310 nm IR: 1-1.7 µ m AOT F spectrometer T wo pixels
spherical grating imaging spectromete r with slit mecha nism
6

+Z (nadir)


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IR channel of SPICAM : First Acousto Optic Tuneable Filter (AOTF) flown in civil space
Mass inferior to 1 kg (700 g, DC/DC and Solar entry not included) Spectral resolution specified as 3.5 cm-1 ( / ~1800) Capable of measuring H2O in Mars atmosphere similar to MAWD

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Wavelengths calibration and resolving power
=a(1+T)/f +b(1+ T) accuracy ~0.1 nm , ~10-5 K-1 1130 nm / =2200 1500 nm / =1750 Resolving power at least 1800 in the H2O region at 1.38 µm Sinc2 tails
1

1529.5 nm 1128.7 nm
0. 5

0 -2 .0 - 1.8 -1 .6 -1.4 - 1.2 -1.0 -0.8 -0.6 -0.4 -0 .2 0 . 0 0 .2 0. 4 0 .6 0. 8 1.0 1. 2 1.4 1. 6 1.8 2 .0

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Noise Equivalent Brightness and S/N
Detector 1
-1

NEB, W m -2µm -1sr

~50

S/N
~120 ~100 ~70

Wave le ngth, nm

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M ARS with SPICAM in Nadir
1.4 1.2

S P ICAM rel ati ve albedo m odel wi th Ea rth O3/200 mod el wi th Ea rth O3

Rela ti v e a lbedo

1.0 0.8 0.6 0.4 0.2 0.0

UV

MEX/ SPIC AM

IR

SPICAM ­ Ultra-Violet observations, orbit 8, 9 jan. 2004
200 220 240

w av elength ( nm)

260

280

300

320

Absorption by gas



1

v ve rtical o ptical

W ater vapour band

CO2

thick ne ss o f abso rptio n, varie s stro ngly w ith wave le ngth

Sca tter ing by surfa ce w ith albedo A

SPICAM ­ near Infra-red observations, orb it 8, 9 jan. 2004

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Modes of operation
IR channel = 2 detectors ( polarization) Spectra acquisition in 1, 2 or 3 "windows" + dots set (starting frequency, points, step) max points = 3984, max acquisition time = 24s) normally points = 664-1328, acquisition time = 2-4s

three w indow s + dots se t 1 2 3 dots

single w indow: "full spe ctrum "

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Calibrated SPICAM IR data
25 Channel 0 Channel 1

Radiance, W/m2/ster/micron

20

15

10

Orbit 30 Ls 335.7 Lon 61 Lat -46 LT 13:35 SZA 41

H2O

CO CO
2

2

5 1000 1100 1200

wavelength, nm

1300

1400

1500

1600

14

1700


O2a1

g

T he oxygen O2a1 g emission line at 1.27 µm is produced by UV dissoc iatio n of ozone

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O2a1

g

T he oxygen O2a1 g emission line at 1.27 µm is produced by UV dissoc iatio n of ozone
20 spe ctra ave rage d

solar line

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Seasonal map of O2 emission by SPICAM

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Seasonal map of Ozone by SPICAM

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H2O seasonal distribution on MARS SPICAM vs TES

SPICAM MY27

TES MY26
Scale 0 to 50 pr. µm
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H2O seasonal distribution on MARS SPICAM vs TES

SPICAM MY27

TES MY26
Scale 0 to 50 pr. µm
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THE SPICAV-SOIR INS TRUME NT

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VE X P AYLO AD

VE X Payload : 7 instru ments MAG : magneto meter VIRT IS : i maging spectro meter PFS : Fourier spectrometer VMC : monitoring ca mera VER A : radio science ASPER A : space plas ma SPIC AV : U V/ IR spectro meter

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SPICAV/SOIR
SPICAV-UV
Spare of SPICAM- UV Made in France

SPICAV-IR (AOTF)
Modified from SPICAM- IR Made in Russia

SOIR (with AOTF)
Completely new instrument built in two years High spectral resolution: echelle grating+AOTF Built in Belgium with Russian AOTF

DPU: electronic block
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SO IR AO TF

SPICAV- IR AOTF

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SOIR : SPECTRO METE R SCHE ME (1)

Front end optics (1) AOT F entrance optic reduces ü incoming light bea m to match acceptance aperture of AOT F (2) diaphragm confines FOV to avoid parasitic light effects (3) AOT F order sorting filter (4) AOT F exit optics images bea m on spectro meter slit

Spectrometer part (5) spectrometer slit entrance aperture of spectro (6) collimating lens collimates to parallel bea m (7) echelle grating disperses light Detector part (8) camera lens images spectru m to detector (9) detector 25


Echelle-spectrometer The principle of separation of diffraction orders
divide wavelength domain in small parts observe sequentially or at random echelle : higher resolution and dispersion echelle : orders overlap order sorting


n AOTF bandpass

n+1

6 order n+2 5 3 1 Detector
pixels

4 order n+1 2 order n

0

Diffraction angle

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SOIR : OPTICAL DES IGN (3)
Diffraction angle+1.09960 rad

choice of design parameters guarantees quasi-continuous coverage in mid IR allows a wavelength to be associated to every pixel Figure red lines represent grating diffraction angles (orders 101 till 194) numbers are diffraction order nu mber black traces are overlapping parts

0.010 0.005 176 172 168

1800.000 -0.005 -0.010 2.50

2.55

2.60 Wavelength, um

2.65

2.70

Diffraction angle+1.09960 rad

0.010 0.005 124 0.000 -0.005 -0.010 3.60 3.65 3.70 Wavelength, um 3.75 120

Diffraction angle+1.09960 rad

blue intervals correspond to AOT F bandpass (20 cm-1) resulting in (nearly perfect) order sorting full vertical scale gives the angular width of a 320 pixel detector

0.010 0.005 112 0.000 -0.005 -0.010 4.00 4.05 4.10 4.15 Wavelength, um 4.20 4.25 108 104

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4.30


SOIR

Solar Occultation InfraRed
430, 0 99 , 9
° e 63 bl as mm 4g / t i ng Gra

295, 6

G

37, 3

E liptical mirror l

63, 1° 60 ,2 °
De t ec to r 2 56 pix 4 2x 80 0u m
0 12,0

70 , 0

f =3 50

220,00
L i gh t t ra p

S2 M3 f =2
50x800 um
6

R 3 50

M5

M4

f=2 6

50x 50 um

Det LR .

Elect ronics S1
60 x 1000 um
f = 17 5

M2
To the Sun 25x 25

Pa bolicmirror ra

M1

Fig ure 3. Layout o f t he hig h-reso lut io n so lar o ccult at io n sp ect ro met er. M1 (of f -axis p arab . f =175) ­ ent rance t elesco p e; S 1 ­ f ield d iap hrag m; A OTF; M2, M3, M4 (f =26) ­ A OTF co ll im at o r; lig ht t rap ; LR d et ect o r; S 2 ­ HR sp ect ro met er slit ; M5 (of f -ax. p arab ., f =350) ­ HR sp ect ro met er co llimat o r; G ­ HR sp ect ro met er grat ing; HR det ect o r.

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SOIR : SPECTRO METE R SCHE ME (2)
compacting e xercise

(3) AOT F (7) echelle grating

(9) folded detector optics (10) detector assembly placed upright

(8) folding mirror (6) collimating and ca mera lens merged into one off-axis parabolic mirror

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SPICAV ON VE X

SOIR : 2.2 - 4.3 µ m R=25000

UV : 110 - 310 n m IR : 0.7 - 1.7 µ m shutter
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SOIR/VEX summary
Features
resolving power R=25000 in spectral range 2.354.2 µm relatively compact design (~5 kg) no moving parts (except cryocooler) Spectral range with "methane on Mars" potential

Limitations
Solar occultation operations Only a small portion of spectrum at a time
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SOIR : AOTF

Working principle · interaction light beam and acoustic wave s mall wavelength do main trans mitted · acoustic RF wave injected via transducer (001-direction) · transmitted wavelength = electronically tunable · non-polarized light bea m in 2 diffracted bea ms out with different polari zation small angle between diffracted and undiffracted · inclined output facet correction for angular shift caused by Bragg diffraction and polarization rotation refolding of diffracted beam collinear with inco ming bea m 32


SOIR : AOTF

IN

OUT

RF IN

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SOIR: in-flight calibration of AOTF bandwidth (orbit 142)
Vie w fro m the top

AOTF functions at different wav enumbers and different points of acoustic field

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HDO detection by SOIR solar occultation

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VENUS H2O and HDO at 3 orbits, 75° N at terminator (solar occultation)

Bulk atmosphere
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SPICAV AOTF

Serious modification from MARS EXPRESS version Extended spectral range (0.7-1.7 µm)
2 actuators on the AOTF New detectors (Si-InGaAs sandwich detectors)

Increased sensitivity
New registration electronics
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SPICAV AOTF: QM

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AOTFs operating in flight
Parameter SPICAM-IR (direct filtration) 1-1.65µm 0.5-1.2 nm 3.5 cm-1 ~3 W SPICAV-IR (direct filtration) SOIR (selection of orders)

Spectral range Spectral resolution RF power

0.7-1.05µm 2.2-4.4 µm 1.05-1.65µm 0.4-1.6 nm 5-8 cm-1 ~3 W ~20 nm 22 cm-1 <1W
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AOTF in preparation
MICROMEGA for EXOMARS 2013
operational temperature range ­150° ...+40° storage temperature range ­200° ... +40° Spectral range 0.8-4 µm (new version 0.8-2.6 µm) Spectral resolution 10-15 nm

SOIR-Terre
A high-resolut ion spectrometer for the Earth atmosphere: monitoring of green-house gases (CO2, CH4 with O2 reference) Spectral range 0.7-1.7 µm Spectral resolution ~35 nm
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MICROMEGA AOTF illumination system

ãIV A-M/I optical conce pt (J-P.Bibring e t al.)

out put

Light s our c e diaphr agm 2.5 mm Wor ki ng Plane 0.5- 3m m fr om lamp ac ceptanc e angle ~ 10°

F=20,00 Blac k c oating (li ght trap) T otal inter nal r efl ec ted "0" order beam

F=20,00

Ac oustic wave abs orber

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