Taking extrasolar planet imaging to a new level with vector vortex coronagraphy: the ERC/ARC VORTEX project

Taking extrasolar planet imaging to a new level with vector vortex coronagraphy:

the ERC/ARC VORTEX project

Olivier Absil

F.R.S.-FNRS Research Associate University of Liège

Let there be (no) light!

Marois et al. 2008

Konopacky et al. 2013

Which planets?

current imaging surveys VLT

Coronagraphy

4

Opaque mask Phase mask

The birth of a concept

• _{1997: phase mask (PM) for on-axis light cancellation}

• _{Four Quadrant PM  ZOG FQPM  Annular Groove PM}

• _{Advantages of the “AGPM” (first vortex coronagraph)} • _{Inner working angle ≈ 1 λ/D}

• _{Clear 360° discovery space}

• _{Achromatic thanks to ZOG design} • _{Easy to implement} 5 0 0 π π

The AGPM, an optical vortex

Manufacturing process

7 Preparation of the

diamond substrate

Moulding of the silicon stamp with PDMS

Plasma etching

Grating design/optimization

A long, iterative process 9 Design selecting optimal parameters Univ. of Liège Aluminum coating Univ. Uppsala E-beam master

Univ. Joensuu Nano-imprint + plasma etching Univ. Uppsala Tests + integration Univ. of Liège Laser writing master Univ. Uppsala A B: manufacturing C

1st step: N-band AGPMs

(λ=10µm)

10

November 2009 October 2010 February 2012

 Perfect profile of the central annular grooves  Improved roughness  reduced scattering

 _{N band:- IR background too high}

2nd step: L-band AGPMs

(λ=4µm)

December 2010 September 2012

4.7 µm

1.4 µm

 Close to optimal design

Setting up the bench

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Getting closer…

14 Aug-10Nov-10Feb-11Jun-11Sep-11Dec-11Apr-12 Jul-12 Oct-121

10 100 1000 P e ak r e je cti o n

Outstanding performance!

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NACO: science demonstration

Raw image Post-processed image

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NACO: sensitivity to planets

THE VORTEX PROJECT

Action de Recherche Concertée (ARC, ULg)

European Research Council Starting Grant (ERC StG)

The VORTEX project

• _{WP1: Exploitation of 1}st generation AGPMs

• _{Install, test and optimize AGPMs on world-class telescopes} • _{Perform the observations / analyze the data}

• _{Astrophysical interpretation}

• _{WP2: Development of 2}nd generation AGPMs

• _{Better L- and N-band AGPMs}

• _{Shorter wavelengths (K, H, … down to λ=1µm?)} • _{Beyond topological charge = 2}

• _{WP3: Test and validation of new ideas}

• _{Exploitation of photon orbital angular momentum (OAM)} • _{Post-vortex speckle cancellation techniques}

VORTEX project strategy 22 WP1 Exploitation WP2 Next generation WP3 New ideas PhD student #1 Postdoc #1 (2014) PhD students #2, #3 Postdocs #2, #3 PhD student #4 Postdoc #4 (2014) Highest gain

The VORTEX team

• _{Université de Liège}

• _{Coordinator: Olivier Absil}

• _{Academic: Jean Surdej (AEOS), Serge Habraken (Hololab),}

Marc van Droogenbroeck (INTELSIG)

• _{Postdoc: Christian Delacroix}

• _{PhD students: Brunella Carlomagno, Carlos Gomez,}

Aïssa Jolivet, Valentin Christiaens (U. Chile)

• _{Uppsala Universitet}

• _{Academic: Mikael Karlsson} • _{Postdoc: Pontus Forsberg} • _{PhD student: Ernesto Vargas}

• _{Collaborators}

• _{Dimitri Mawet (ESO), Denis Defrère (Arizona),}

Pierre-Antoine Absil (UCLouvain)

PHD PROJECT #1: SEARCH FOR PLANETS IN YOUNG DISKS

Valentin Christiaens (U. Chile / ULg) (+ 1 postdoc in 2014)

Combining ALMA with NACO

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Advantages of NACO/AGPM

• L-band = sweet spot for planet imaging

• Access to new parameter space  surveys

• _{Complementary to near-IR imagers}

 characterization

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β Pic with VLT/NACO at L band (no AGPM) VLT/NACO + AGPM-L

2003 2009 2013

L

New search region

Habitable zone

PHD PROJECT #2: OPTIMAL IMAGE PROCESSING

Carlos Gomez

Detection in speckle noise?

Angular differential imaging

• _{Principle: use field rotation}

• Stop field stabilization (e.g., derotator)

• Let sky rotate in front of telescope

• _{Keep quasi-static speckles fixed while planet moves}

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Principal Component Analysis

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Main goals of PhD project #2 • _{Build upon}

state-of-the-art • _{Advanced use of} Principal Component Analysis • _{Investigate new} approaches • _Background subtraction techniques • _{Machine learning /} dictionary learning 33

PHD PROJECT #3: DESIGN OF

2ND GENERATION AGPM

Brunella Carlomagno & Christian Delacroix (postdoc) (+ Ernesto Vargas & Pontus Forsberg @ Uppsala)

2nd generation mid-IR AGPMs • _{Improvement of the}

grating parameters • _Improved

anti-reflective solutions • _{Goal: meet the specs}

for E-ELT/METIS

• _{R > 1000 over full L, M} and N bands

AGPMs at shorter wavelengths

• _{Cover near-infrared window (1 – 2.5 µm)}

• _{More a technology challenge than a design issue}

• _{Goal 1: installation on VLT/SPHERE by 2016} • _{Goal 2: prepare for E-ELT}

• ₁st _{light infrared camera (MICADO)}

• _{Dedicated high contrast imaging camera (PCS)} • _{May require higher topological charges}

• _{Goal 3: space applications}

Higher topological charges l_p=2 l_p=3 l_p=4 1λ/D 2λ/D 3λ/D 4λ/D l_p=2 l =6 Guyon et al. 2006

“AGPMs” with various l_p

New challenges • _{Discretization of the} grating seems mandatory • _{Require new 2D} modeling tools • _{Pioneered by}

Technion (Israel) for mid-IR applications

• _{Adaptation to diamond}

not straightforward

PHD PROJECT #4: TESTING AGPM + NEW INSTRUMENTAL IDEAS

Aïssa Jolivet

(+ 1 postdoc, early 2014)

Coronagraphic test bench

• _{Develop in-house}

coronagraphic bench • _{Main goals}

• _{Test AGPMs designed} for the 1 – 4 µm range • _{Become independent} • _{Test new concepts and}

ideas

Orbital angular momentum

OAM: history

• _{Predicted by Poynting}

(1909)

• _{Observed by Allen et al.}

Effect of the AGPM

44

Biener et al. 2002; Mawet et al. 2005; Marucci et al. 2006

AGPM in convergent beam?

No OAM _{No OAM}

Photon sorting based on OAM

• _{Beam rotation  phase shif} • _{Separate OAMs with}

constructive and destructive interferences

• _{Isolate planetary signal!}