sistemi adattivi per l’astronomia: concetti ed esempi
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Sistemi Adattivi per l’astronomia:Sistemi Adattivi per l’astronomia:concetti ed esempiconcetti ed esempi
S. Esposito, Osservatorio Astrofisico di Arcetri, INAF
Scuola Nazionale di tecnologie astromicheNapoli, 23-28 Settembre 2002
Sommario
Immagini da telescopi a terra e turbolenza atmosferica Concetti e parametri fondamentali dei sistemi ottici adattivi Astronomici
I sistemi adattivi di: CFHT/Gemini VLT TNG
Novità nel settore: Sistema adattivo di LBT La prossima tappa: Extremely Large Telescopes
AO system layout
Atmosfera turbolenta
Keck Telescope
Keck Telescope
)(
O
Obj. Intensitydistribution
Immagini da telescopi a terra
dPOI )()()(
Teoretical Point Spread function
/D
/D
)(P
)(I
Measured Intensity
La Modulation transfer function (MTF)
)f(P~
)f(O~
)f(I~
)f(P~
d
/df
MTF=
Overlap areaOverlap area
W = Funzione Pupilla1 r < D/20 r > D/2
D
r0/ D/
MTFs
La MTF teoricaLa MTF teorica
Optical Transfer function
rdrWdrW
)()(
Turbolenza I
Strati turbolenti
dT10T/P79dn 62
~1m/K/m~1m/K/m
telescopio
~20Km
Funzione di struttura della fase
350
212 rr88.6)r()r()r(D
Media statistica delle differenze quadratiche di fase fra due punti
Media statistica delle differenze quadratiche di fase fra due punti
Valori di r0 a 0.5 e 2.2 m
Acromaticità della perturbazione in mAcromaticità della perturbazione in m56
0 r
I polinomi di Zernike
i / j 2 3 4 5 6 7 8 9 102 0.449 0 0 0 0 0 0.0142 0 03 0 0.449 0 0 0 0.0142 0 0 04 0 0 0.0232 0 0 0 0 0 05 0 0 0 0.0232 0 0 0 0 06 0 0 0 0 0.0232 0 0 0 07 0 0.0142 0 0 0 0.00619 0 0 08 0.0142 0 0 0 0 0 0.00619 0 09 0 0 0 0 0 0 0 0.00619 0
10 0 0 0 0 0 0 0 0 0.00619Matrice di varianza-covarianza statistica
)(rie
2/
2/
Dr
Dr
0
W = Funzione Pupilla
Turbolenza II
r0/ D/
MTFs
MTF media in atmosferaTurbolenta
MTF media in atmosferaTurbolenta
Area di coerenzaD = r0
Area di coerenzaD = r0
d Effetto della correzione adattiva !Effetto della correzione adattiva !
)(5.0exp)()( 0 fDfTfMTF
Questioni fondamentali
Numero di punti di sampling del wf ? Massima sep. Oggetto scientifico stella di guida ?
Numero di punti di sampling del wf ? Massima sep. Oggetto scientifico stella di guida ?
Numero di gradi di libertà ? Numero di gradi di libertà ?
Tempi caratteristici di funzionamento ? Tempi caratteristici di funzionamento ?
Natt ~ (D/r0)^2Natt ~ (D/r0)^2
Nsamp ~ (D/r0)^2Nsamp ~ (D/r0)^2
Angolo Isoplanatico
~ r0 / h h
Angolo di decorrelazione:Angolo isoplanatico
Angolo di decorrelazione:Angolo isoplanatico
r0
Evoluzione temporale
v
2l
sec25
125 sec10 m
>> D/V >> D/VDtelescopio
0 ~ r0 / v0 ~ r0 / v
Focus Anisoplanatism
LGS
NGS
Tel. pupil
90 km
Strato di sodio10 km
Stelle di riferimento laser
Tilt Indetermination
LGS
Tel. pupil
Pos. reale
Pos. apparente
Strato turbolento
d
hr
Hhr /1
Loop di controllo
SR
CControlsystem
[Natt x Nsens]
Natt ~ (D/r0)^2Natt ~ (D/r0)^2
Nsens ~ 2 (D/r0)^2Nsens ~ 2 (D/r0)^2
•"Adaptive Optics for Astronomy”, Francois Roddier (ed.), Cambridge University Press, 1999 •"Adaptive Optics for Astronomical Telescopes", John W. Hardy, Oxford Books, 1998 •"Adaptive Optics for Astronomy", ed. Danielle M. Alloin & Jean-Marie Mariotti, Kluwer Academic Publishers, Dordrecht, 1994 •"Imaging Through Turbulence", Michael C. Roggemann & Byron Welsh, CRC Press, 1996 •"Principles of Adaptive Optics", Robert K. Tyson, Academic Press, 1997 •"Adaptive Optics for Atmospheric Compensation", James E. Pearson (ed.), SPIE Milestone Series, Volume MS 92 •“Introduction to Wavefront Sensors” (Tutorial Texts in Optical Engineering, Vol Tt18,) Joseph M. Geary, Society of Photo-optical Instrumentation Engineers, 1995 •Babcock, H. W. "Adaptive Optics Revisited." Science 249, 253-257, 1990. •Beckers, J. M. "Adaptive Optics for Astronomy: Principles, Performance, and Applications." Ann. Rev. Astron. Astrophys. 31, 13-62, 1993. •Hubin, N. and Noethe, L. "Active Optics, Adaptive Optics, and Laser Guide Stars." Science 262, 1390-1394, 1993. •Collins, G. P. "Making Stars to See Stars--DOD Adaptive Optics Work is Declassified." Physics Today 45, 17-21, Feb. 1992.
•"Adaptive Optics for Astronomy”, Francois Roddier (ed.), Cambridge University Press, 1999 •"Adaptive Optics for Astronomical Telescopes", John W. Hardy, Oxford Books, 1998 •"Adaptive Optics for Astronomy", ed. Danielle M. Alloin & Jean-Marie Mariotti, Kluwer Academic Publishers, Dordrecht, 1994 •"Imaging Through Turbulence", Michael C. Roggemann & Byron Welsh, CRC Press, 1996 •"Principles of Adaptive Optics", Robert K. Tyson, Academic Press, 1997 •"Adaptive Optics for Atmospheric Compensation", James E. Pearson (ed.), SPIE Milestone Series, Volume MS 92 •“Introduction to Wavefront Sensors” (Tutorial Texts in Optical Engineering, Vol Tt18,) Joseph M. Geary, Society of Photo-optical Instrumentation Engineers, 1995 •Babcock, H. W. "Adaptive Optics Revisited." Science 249, 253-257, 1990. •Beckers, J. M. "Adaptive Optics for Astronomy: Principles, Performance, and Applications." Ann. Rev. Astron. Astrophys. 31, 13-62, 1993. •Hubin, N. and Noethe, L. "Active Optics, Adaptive Optics, and Laser Guide Stars." Science 262, 1390-1394, 1993. •Collins, G. P. "Making Stars to See Stars--DOD Adaptive Optics Work is Declassified." Physics Today 45, 17-21, Feb. 1992.
Bibliografia
Pueo & Hokupaa: Curvature AO
Wavefront SensorCurvature 36 elements,
2 arcsec WFS FOV, 12 arcsec guide star patrol radius
Deformable Mirror36 element Bimorph
60mm pupilDM stroke sufficient for ~ 0.9arcsec seeing
Sampling Rate 1 kHz
Imager
University of Hawaii's QUIRC1-2.5 micron HgCdTe 1k2 HAWAII array,
19.7 milliarcsec/pixel~20 arcsec FOV
Def mirrors: bimorphGeometriadegli elettrodi
V proporzionale al laplaciano della sup. otticaNo. Di attuatori 13-85DM size 30-200 mmGeometria attuatori radialeVoltaggio 100 VFreq. Di risonanza 500 Hz
V proporzionale al laplaciano della sup. otticaNo. Di attuatori 13-85DM size 30-200 mmGeometria attuatori radialeVoltaggio 100 VFreq. Di risonanza 500 Hz
Deformazione del bimorfo
Curvature sensor: concept
lrfwl
lff
rIrI
rIrI/
)(
)( 2
21
21
2
subd
fl
f2/lf2/l
Esiste un valore minimo per l !Esiste un valore minimo per l !
Curvature sensor: optics
Pupil image
Pupil image
Oscillating membrane
2l
NAOS images
Thetis
Differential tracking
Composite image H-K20.6 arcsec diameterresolution 70 mas or 410 km~10 sec exposure time
NAOS images
Naos@VLT
VLT AdapterNAOS
CONICA
Cable Twist
NAOS at Paranal Nov. 2001
Naos optical layout
VLT Nasmyth focus
Inputparabola
Deformablemirror
CONICA Input focus
Outputparabola
WFS inputfocusTip-Til
mirror
Dichroic
Naos def. Mirror: 185 attuatori
V proporzionale allo spostamento della sup. otticaNo. Di attuatori 30 – 349Spaziatura attuatori 5-10 mmDM size 50-150 mmGeometria attuatori griglia quadrataVoltaggio 100 VFreq. di risonanza 500-1000 Hz
V proporzionale allo spostamento della sup. otticaNo. Di attuatori 30 – 349Spaziatura attuatori 5-10 mmDM size 50-150 mmGeometria attuatori griglia quadrataVoltaggio 100 VFreq. di risonanza 500-1000 Hz
Piezo-Stacked monolithic deformable mirrors
Shack-Hartmann sensor: concept
subap
Ax rxdrwsub
)(1
4321
4321
IIII
IIIIS subxsubx
sub2
x
S
NAOS WFS characteristic
Shack-Hartmann sensor: optics
Visible WFS Infrafred WFS
Wavelenght range 0.45-1.0 mm 0.8-2.5 mm
14x14 FOV
Mag. range
2.3 arcsec
0-13
5.15 arcsec
0-11
7x7 FOV
Mag. range
4.6 arcsec
13-19
5.15
11-15
Deetector 128x128 EEV CCD50
1024x1024 Rockwell hawaii
NAOS IR WFS
TNG
NICS@K band, FWHM 0.15
NICS ,K band, 35% SR
Marzo 2002Settembre 2001
Primo anello di diffrazione
TNG optical layoutSpeckle ModuleTip-Tilt moduleHO module PS, SHS
Speckle ModuleTip-Tilt moduleHO module PS, SHS
F/32 dal telescopio
Pyramid WFS: conceptm
odul
azio
ne
X
Y
x0
y0
R mod
w/x = R/F Sx w/x = R/F Sx
I1I2
I3 I4
Immagini pupille
Sx(x,y) = ([I1(x,y)+I4(x,y)] - [I2(x,y)+I3(x,y)])/Itot
Sy(x,y) = ([I1(x,y)+I2(x,y)] – [I3(x,y)+I4(x,y)])/Itot
Pyramid WFS: optics
Un raffronto........
w/x = R/F Sx
Slff
lw
2
2
min
subd
fl
xsub
Sd
xw
/
xsubSxw /w/x
PSCS
SH
Open loop
Ad oggi……………….• Curvature systems: modesto numero di gardi di libertà (dof)
– Canada France Hawaii Telescope: 13 dof, 14th mag– Univ. of Hawaii: 19 dof, 12th mag– San Pedro Martir (Baja CA): 19 dof – Subaru: 19 dof– Hokupaa on Gemini Telescope: 36 dof, 13-17th mag– Hokupaa 85 (under construction): 85 dof
• Shack-Hartmann systems: tendono ad avere più gradi di liberta ma richiedono stelle di rif. più brillanti.
– Lick: 61 dof, 13.5 mag– Palomar: 241 dof– Keck: 250 dof, 13.5 mag– ADONIS: 50 dof (?), 13 mag– VLT (ESO) NAOS• Pyramid Sensor - TNG: 97dof, mag ?
• Curvature systems: modesto numero di gardi di libertà (dof)– Canada France Hawaii Telescope: 13 dof, 14th mag– Univ. of Hawaii: 19 dof, 12th mag– San Pedro Martir (Baja CA): 19 dof – Subaru: 19 dof– Hokupaa on Gemini Telescope: 36 dof, 13-17th mag– Hokupaa 85 (under construction): 85 dof
• Shack-Hartmann systems: tendono ad avere più gradi di liberta ma richiedono stelle di rif. più brillanti.
– Lick: 61 dof, 13.5 mag– Palomar: 241 dof– Keck: 250 dof, 13.5 mag– ADONIS: 50 dof (?), 13 mag– VLT (ESO) NAOS• Pyramid Sensor - TNG: 97dof, mag ?
Sistemi Adattivi per l’astronomia:Sistemi Adattivi per l’astronomia:concetti ed esempi IIconcetti ed esempi II
S. Esposito, Osservatorio Astrofisico di Arcetri, INAF
Scuola Nazionale di tecnologie astromicheNapoli, 23-28 Settembre 2002
Sommario
Immagini da telescopi a terra e turbolenza atmosferica Concetti e parametri fondamentali dei sistemi ottici adattivi Astronomici
I sistemi adattivi di: CFHT/Gemini VLT TNG
Novità nel settore: Sistema adattivo di LBT La prossima tappa: Extremely Large Telescopes
System Overview & Location
LGS
AGW
NGS
LUCIFER window
LUCIFER
System Key features
Adaptive Secondary mirror: LBT672 [4839-85], A. Riccardi
Pyramid wavefront Sensor (PS)
Improves AO channel transmission ~ 40% (WFS)Actuators pitch ~ 28cm ~ ro @ 0.75 m, (0.8” seeing V Band)effective correction down to sensing wavelenght
Improves AO channel transmission ~ 40% (WFS)Actuators pitch ~ 28cm ~ ro @ 0.75 m, (0.8” seeing V Band)effective correction down to sensing wavelenght
Better performance WRT Shack-Hartmann > 1 mag Pupil sampling adjustable using on-chip binning, LBT 30x30,15x15,10x10...
Better performance WRT Shack-Hartmann > 1 mag Pupil sampling adjustable using on-chip binning, LBT 30x30,15x15,10x10...
Moveable WFSAllows use of small refractive optics, 32mm Ø max.Reference star acquisition on a 3x2 arcmin FOVSmall AOS opto-mechanics 320x400 mm (20 kg) Reduces costs, flexures, turbulence.....
Allows use of small refractive optics, 32mm Ø max.Reference star acquisition on a 3x2 arcmin FOVSmall AOS opto-mechanics 320x400 mm (20 kg) Reduces costs, flexures, turbulence.....
WFS Opto -Mechanical design
(1) Fixed telecentric lens, 80mm ø
2 arcmin FOV, (3x2 arcmin) (2) Refocusing triplet, 32mm ø(5) Fast steering mirror: ± 0.8” (PI)(6) Pupil Rotator
(8) Refractive pyramid, 2.5” FOV ø
(9) Camera triplet, 10mm ø (10) Pyramid sensor CCD(12) Technical/acquisition camera max FOV 30 arcsec
Two WFS optical path:Pyramid sensor optical path: blue, 500mm, [0.6-0.9 m]Tech./Acquisition camera: red
F/15 LBT beam reflected on LUCIFER 15° window
400mm
320m
m
Four on-board motorizedparts (3),(4),(6),(9)
ADC (4)
Secondario adattivo: Concetto
WFS
Sci. Camera
DM
Coll.
TTMBS
Secondarioconvenzionale
Secondarioadattivo
Sci. Camera
WFS
•Minori superficicalde
•K band: riduzionetempo esposizionedi 2-2.6 volte
•Attuatori elettro-magnetici: ampiostroke (LBT>100m)Correttore di TT ewind buffeting
Secondario adattivo per LBT
2x8.4m specchi primari
Ogni AdSec:672 attuatori911mm diam.
Da MMT336 a LBT672
LBT: Gregoriano672 attuatori
911mm
MMT: Cassegrain336 attuatori
642mm
Schema di LBT676
Esapodo
Flangia di interfaccia esupporto strutturale
3 scatole di elettr.raffreddate
Esapodo fissoCold-plate e
supporto per att.
Leve astaticheRef-plate di Zerodur
(spessore 50mm)
Shell deformabiledi Zerodur (spessore 1.6mm)
(MMT336) shell asferica
Attuatori e sensori capacitivi
Magneti
642mm diam.2mm spessore
(12mm diam.)
Armature sens. Capacit. (ref.plate)
Elettronica per LBT672
Communication Board (1x backplane)
DSP control Board (14x backplane)
Reference Signal Generator Board (1x backplane)
Communication Board (1x backplane)
DSP control Board (14x backplane)
Reference Signal Generator Board (1x backplane)
Communication Board (1x backplane)
DSP control Board (14x backplane)
Reference Signal Generator Board (1x backplane)
Communication Board (1x backplane)
DSP control Board (14x backplane)
Reference Signal Generator Board (1x backplane)
Communication Board (1x backplane)
DSP control Board (14x backplane)
Reference Signal Generator Board (1x backplane)
Communication Board (1x backplane)
DSP control Board (14x backplane)
Reference Signal Generator Board (1x backplane)
Liquid cooled crates, each comprehending 2 backplanes (3x)
Distribution boards
Actuators
Gap
Specchio sottileSegnale di riferimento
Alimentazione
± 48V, 35 A
Comunicaz.Real-time2.9 Gbit/s
Connessione in dasy chain
DSP control Board (14x backplane)
DSP control Board (14x backplane)
Coil
3 scatole di elettronica raffreddate2 crate per scatola84 schede DSP custom4 DSP/scheda - 8 attuatori/scheda32-bit floating-point 180Mmac/s(MMT: 16-bit integer 40Mmac/s)
Gigabit Ethernet SwitchFibra comunicazione diagnosticaAll’AOsupervisor 400Mbit/s
Potenza di calcolo totale:60 Gmac/s (32bit fp)Ricostruttore real-time a bordo WFS: 30x30 => 34-47s (z-m)Trasferimento slopes: 20s
Prestazioni
r0=15cm@500nm MMT LBT
Diametro 641 mm 911 mm
N attuatori 336 672
Fitting error 72 nm 64 nm
Efficienza att. 0.5 N/W1/2 0.5 N/W1/2
Potenza nell’att. 0.41 W/act 0.19 W/act
Potenza nei crate 4.7 W/act 3.8 W/act
Comun. Real-time 160 Mbit/s 2.9 Gbit/s
Comun. Diagnost. No dedicated 400 Mbit/s
DSP 40 Mmac/s (int) 160 Mmac/s
System performance simulations IParameter Simulation values
Atmospheric parameters Two layers with wind velocity 15 m/sFried parameter 15cm @500nm => 0.67 arcsecTurbulence outer scale 40m
Guide StarSpectral type K5, V-magnitude in range 9.85—17.5
LBT TelescopeDiameter 8.25mObstruction ratio 0.11
Pyramid WFS
WF sampling: 10x10, 15x15, 30x30 (obtained using on chip binning)Exposure time: in range 1 – 10msRON from 3.5 to 8.4 e- according to frame rate (SciMeasure camera specs)Tilt mod.: ±1 ±2 (30x30sub), ±3 (15x15sub), ±4,±5,±6 (10x10sub) /D
System Transmission 0.9^3 * 0.7 * CCD QE = 0.4, (CCD average QE = 0.8 @ [600—900 nm])
Wavefront reconstructor: LBT672 mirror modes
36, 44, 55 and 66 modes @ 10x10 conf.78, 105 and 136 modes @ 15x15 conf.231, 351 and 496 modes @ 30x30 conf
Time filtering Pure integrator with gain = 0.5
Sistem performance simulations II
SR 0.2, mR = 14.3, 15.5, 16.7
Max SRs: 87,93,96
30x30
15x15
10x10
On-Axis SR 20 %Max off-axis 30 arcsec
SR 0.2, mR = 15.5 (SH), 16.7(PS)
Sky Coverage (b=20,l=180)
J band H band K band
Pyramid (PS) 11 33 83
Shack-Hartmann 6 18 47
Current situation & schedule
SciMeasure Analytical Systems, Inc.
4X HIGH SPEED COMMUNICATION MODULES
ETHERNET COMMUNICATION TIMING REFERENCE TX
TIMING REFERENCE RX
BACKPLANE SLOT CONNECTORS
SERDESETHERNETCONTROLLER
RS232
BOTTOM HEAT SINK
WFS HO
J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J2001 2002 2003 2004
Adaptive Secondaryact design
Inst
alla
tion
LBT672
Shi
ppin
g
Adaptive Secondary
Wavefront sensor
System Software
CCD60
Test tower
act design
procurement P36' test
Inst
alla
tionClosed loop
P45+WFS+RTR
LBT672
inst&test
inst.
P45 test
Design phase
OptoMecc Procur.
assemb.
and testMMTtest
Tower
CL WFS
+LBT672
Shi
ppin
g
Debugging
FASTI controller design and test LLLCCD Final controller test BI L3CCD
RT softwareDiagnostic Design phase 1 Design phase 2
Coding phase 2Coding phase 1
DR
P45+PWFS+RTR lab test: 4Q 2002 -1Q 2003P45+PWFS+RTR lab test: 4Q 2002 -1Q 2003
AO system parts acquisition: Oct/Nov 2002AO system parts acquisition: Oct/Nov 2002
AO system HW cost: 600K USD (two units)Manpower: 10 person / year (two years)People involved: ~ 8-10 people
AO system HW cost: 600K USD (two units)Manpower: 10 person / year (two years)People involved: ~ 8-10 people
LBT672+PWFS tower test: 4Q 2003 -1Q 2004LBT672+PWFS tower test: 4Q 2003 -1Q 2004
ELT’s
Tecnologia dei secondari adattivi per ELTs
Optical diagram for MCAO
Telescope
DM1 DM2
Turb. Layers#1 #2
Atmosphere
WFS
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