INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Natural Guide Stars (NGS) only for Adaptive Optics (AO) on ELT

Ismaning - Feb 28th 2013 by R. Ragazzoni, C. Arcidiacono, M. Bergomi, M. Dima,

J. Farinato, D. Magrin, L. Marafatto, V. Viotto

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Why NGSs for AO on ELT...?• Because are cheaper than LGSs • Because lim mag of Pyramid WFS pushed

the limits of AO... • Because the patrol field of E-ELT is huge • Because the rays from LGSs will arrive

nevertheless from a similarly skewed angle • Because NGSs are less invasive then LGS • Because MCAO can be extended a little

into Global MCAO and making this true...

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Courtesy S. Esposito - Based upon real LBT data

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Courtesy S. Esposito - Based upon real LBT data

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Courtesy S. Esposito - Based upon real LBT data

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Courtesy S. Esposito - Based upon real LBT data

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Courtesy S. Esposito - Based upon real LBT data

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

40% =>16..17

Courtesy S. Esposito - Based upon real LBT data

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Field of View comparison

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Field of View comparison

10..30 arcsec isoplanatic patch

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Field of View comparison

2 arcmin MAD-like MCAO FoV

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Field of View comparison

10 arcmin patrol FoV of E-ELT

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Field of View• SCAO: 10..30 arcsec • MAD-like MCAO 2' • x 16..144 wrt SCAO • E-ELT patrol FoV 10' • x 25 wrt MAD • x 400..3600 wrt SCAO • ....and sky coverages goes linearly with for a

fixed number of stars (1 for SCAO, 2+ for MCAO likes...)

• Still using 3..5 stars makes a gain of ~100..1000

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Field of View• SCAO: 10..30 arcsec • MAD-like MCAO 2' • x 16..144 wrt SCAO • E-ELT patrol FoV 10' • x 25 wrt MAD • x 400..3600 wrt SCAO • ....and sky coverages goes linearly with for a

fixed number of stars (1 for SCAO, 2+ for MCAO likes...)

• Still using 3..5 stars makes a gain of ~100..1000

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

39 m

92 km

1.57 arcmin

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

α

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

39 m

92 km

1.57 arcmin

α

θmax∼ 2α + 1.57 arcmin

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

θ max (arcmin)

α (arcmin) 0.785

SCAO

3.14

3.571.57 5.57 7.57 9.5710

4.21

From M. Le Louarn - ELT AO LGSs simulations

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

θ max (arcmin)

α (arcmin) 0.785

SCAO

3.14

3.571.57 5.57 7.57 9.5710

4.21

From M. Le Louarn - ELT AO LGSs simulations

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

θ max (arcmin)

α (arcmin) 0.785

SCAO

3.14

3.571.57 5.57 7.57 9.5710

4.21

From M. Le Louarn - ELT AO LGSs simulations

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

θ max (arcmin)

α (arcmin) 0.785

SCAO

3.14

3.571.57 5.57 7.57 9.5710

4.21

From M. Le Louarn - ELT AO LGSs simulations

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

θ max (arcmin)

α (arcmin) 0.785

SCAO

3.14

3.571.57 5.57 7.57 9.5710

4.21

From M. Le Louarn - ELT AO LGSs simulations

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

0 km

8 km

Dtel = 8 m N. DMs = 2 N. actuators = 8 Field of View = 2 arcmin

( )∑∫ Φ=H

F

D dffR 2

ϕ

RMAD-8m = 0.0262

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

0 km

8 km

Dtel = 40 m N. DMs = 2 N. actuators = 80 Field of View = 2 arcmin

( )∑∫ Φ=H

F

D dffR 2

ϕ

RMAD-40m = 0.0239

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Dtel = 40 m N. DMs = 3 N. actuators = 80 Field of View = 2 arcmin

0 km

8 km

13 km

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

0 km

8 km

13 km

Dtel = 40 m N. DMs = 3 N. actuators = 80 Field of View = 2 arcmin N.VDMs = 0

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Ground VDM FoV = 5 arcmin VDMs FoV = 10 arcmin

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

0 km

Ground VDM FoV = 5 arcmin VDMs FoV = 10 arcmin

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Ground VDM FoV = 5 arcmin VDMs FoV = 10 arcmin

0 km

8.6 km

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Ground VDM FoV = 5 arcmin VDMs FoV = 10 arcmin

0 km

14.1 km

8.6 km

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Ground VDM FoV = 5 arcmin VDMs FoV = 10 arcmin

0 km

14.1 km

8.6 km7.4 km

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Ground VDM FoV = 5 arcmin VDMs FoV = 10 arcmin

0 km

14.1 km

8.6 km7.4 km

17.6 km

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Ground VDM FoV = 5 arcmin VDMs FoV = 10 arcmin

0 km

14.1 km

8.6 km7.4 km

17.6 km

11.5 km

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Ground VDM FoV = 5 arcmin VDMs FoV = 10 arcmin

0 km

14.1 km

8.6 km7.4 km

17.6 km

11.5 km

4.7 km

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Ground VDM FoV = 5 arcmin VDMs FoV = 10 arcmin

0 km

14.1 km

8.6 km7.4 km

17.6 km

11.5 km

4.7 km

2.8 km

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Ground VDM FoV = 5 arcmin VDMs FoV = 10 arcmin

0 km

14.1 km

8.6 km7.4 km

17.6 km

11.5 km

4.7 km

2.8 km

15.6 km

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Ground VDM FoV = 5 arcmin VDMs FoV = 10 arcmin

0 km

14.1 km

8.6 km7.4 km

17.6 km

11.5 km

4.7 km

2.8 km

15.6 km

9.9 km

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

SNR

N. Layers

• The more the considered layers, the more precise the turbulence reconstruction

• The more the reconstructed layers, the more the noise from single measurments

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Technology is at hands...• Locally closed loop WFSs makes Pyramids

working in (almost) closed loop • These devices (we called Very Linear VL-

WFSs) works around non zero • Concpetually is exactly the same problem

as MOAO • NGSs are less invasive in the scientific

focal plane

10arcmin FoV Science focal plane

Stars

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

We are evaluating pro and cons of several different optical designs … work in progress

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

MCAO on 2 arcmin at an 8m

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

MCAO on 10 arcmin at an 8m would not give advantages other then for GLAO...

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

MCAO on 10 arcmin (probably with 5+DMs) would works fine...

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

GMCAO on 10 arcmin compensating only the central 2 arcmin...!!!

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Conclusions• GMCAO can be used as back-up plan or... • ...as performance mitigator (cyrrus, LGS

failure...) and can coexists with LGSs. • Performance assessment expected by

AO4ELT3 in Florence late May

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Conclusions• GMCAO can be used as back-up plan or... • ...as performance mitigator (cyrrus, LGS

failure...) and can coexists with LGSs. • Performance assessment expected by

AO4ELT3 in Florence late May • We have got a GMT model so...

INAF – Astronomical Observatory of Padova Roberto Ragazzoni NGS only for AO on ELT

Conclusions• GMCAO can be used as back-up plan or... • ...as performance mitigator (cyrrus, LGS

failure...) and can coexists with LGSs. • Performance assessment expected by

AO4ELT3 in Florence late May • We have got a GMT model so...