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

ELT’s

Euro 50

Optical diagram for MCAO

Telescope

DM1 DM2

Turb. Layers#1 #2

Atmosphere

WFS

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