1. 1 High-order coronagraphic phase diversity: demonstration of COFFEE on SPHERE. B.Paul 1,2, J-F Sauvage 1, L. Mugnier 1, K. Dohlen 2, D. Mouillet 3, T. Fusco 1,2, J.-L. Beuzit 3, M. Ferrari 2, M. N’Diaye 4 1 Onera, DOTA/HRA 2 Laboratoire d’Astrophysique de Marseille 3 Institut de Planétologie et d'Astrophysique de Grenoble 4 Space Telescope Science Institute 1

2. Outline  Context: high-contrast imaging  Principle of COFFEE  COFFEE's optimization & performance evaluation  Application to the SPHERE instrument 2

3. Context: XAO for high-contrast imaging High contrast needs for exoplanet imaging  Today:  Angular separations from 0.1 to arcsec (a few /D to 100 /D)  Contrast up to 10 6 - 10 7  Observation made from the ground (turbulence)  Tomorrow:  Angular separations below 0.1 arcsec  Contrast up to 10 9 - 10 10 (Earth like planets)  Ground / space observations 3 Limitation: Light residuals in final focal plane created by quasi-static aberrations (Non Common Path Aberrations) Solution : focal plane wavefront sensing with the scientific detector

4. 4 Upstream aberrations ( ϕ u ) i( ϕ u, ϕ d ) i( ϕ u + ϕ div, ϕ d ) Diversity phase ( ϕ div ) COFFEE : phase diversity using coronagraphic images (1/2) Coronagraphic imaging system  Coronagraphic focal plane mask  Downstream aberrations ( ϕ d ) + One image: not enough data Two images: OK Image formation model Coronagraphic phase diversity:  Uses only two images to estimate the aberrations upstream of the coronagraph  Rely on a coronagraphic image formation model: i c ( ϕ u, ϕ d ) = Model( ϕ u, ϕ d ) Pupil plane Detector

5. COFFEE : phase diversity using coronagraphic images (2/2) COFFEE: COronagraphic Focal-plane wave-Front Estimator for Exoplanet detection Estimation of aberrations upstream ( ϕ u ) and downstream ( ϕ d ) of the coronagraph by criterion J minimization « Maximum Likelihood »: Distance experimental images / computed images Regularization metrics: A priori information on the parameters J.-F. Sauvage, L. Mugnier, B. Paul et R. Villecroze, Coronagraphic phase diversity: a simple focal plane sensor for high-contrast imaging, Optics Letter, Dec. 2012 5 Definition of a maximum a posteriori criterion:

6. Aberration estimation: pixel map Estimation of high-order aberration Reduction of the aliasing error Aberration estimation: Zernike modes  Estimation of low-order aberrations only  Strong aliasing error Model : electric field propagation No model mismatch Can be adapted to any coronagraphic focal plane mask M (ALC, FQPM, VPM…) COFFEE's optimization (1/3)  Adaptation to any coronagraphic device 6  Estimation of high-order aberrations Model : perfect coronagraph model  Model mismatch  Application to the apodized Roddier & Roddier coronagraph only 100 parameters > 3.10 3 parameters SPIE 2012 AO4ELT3 2013 B. Paul, J.-F. Sauvage et L. M. Mugnier, Coronagraphic phase diversity: performance study and laboratory demonstration, A&A, April 2013

7. COFFEE's optimization (2/3) : performance evaluation Aberration estimation: simulation  Coronagraph: ALC (4,52 λ/D); Lyot Stop = 100%  WFE up = 50 nm ; WFE down = 20 nm (λ = 1589 nm, monochromatic images)  Incoming flux: 1e9 photons ; detector noise: σ e- = 1 e-; photon noise  No residual turbulence  up i foc i div ε rec = 1.71 nm RMS Simulation Estimation Image computation  up COFFEE: aberration estimation Image computation

8. Pseudo-closed loop: simulation  Coronagraph: ALC; Lyot Stop = 96%  WFE up = 50 nm ; WFE down = 20 nm (λ = 1589 nm, monochromatic images)  DM: 41x41 actuators  Incoming flux: 1e9 photons ; detector noise: σ e- = 1 e-; photon noise  No residual turbulence No compensation After NCPA compensation 8 COFFEE’s optimization(3/3) : NCPA compensation No compensation After NCPA compensation 10 -0 10 -3 10 -4 10 -1 10 -2 10 -5 10 -6 10 -7 Contrast

9. COFFEE : validation on SPHERE (1/5) Coronagraph : ALC (d M = 4.5 λ/D) Coronagraphic images : IRDIS Diversity phase : AO loop COFFEE : 9 Dead actuator 9 COFFEE Rec. images Calibration Point-Source, H band XAO system, 41 act, 1200Hz IRDIS imager, H2 band, ALC Stop Coronagraph ALC (incl. Apodizer) Exp. images

10. Defocus Astigmatism IRDIS Coronagraphic image computed by COFFEE Estimated aberration 10 COFFEE : validation on SPHERE (2/5) Low order aberration estimation : Zernike modes  Wavelength : 1589 nm  Coronagraph : APO1 / ALC2  Lyot Stop : Stop ALC (96% entrance pupil + 15% central obstruction) 10

11. 11 High order aberration estimation : poke  Wavelength : 1589 nm  Coronagraph : APO1 / ALC2  Lyot Stop : Stop ALC (96% entrance pupil + 15% central obstruction) COFFEE : validation on SPHERE (3/5) Introduced poke Estimated poke

12. 12 COFFEE : validation on SPHERE (4/5) Pseudo – closed loop process Closed loop on initial reference slopes Acquisition of two images i foc, i div Measurment of  u and  d COFFEE From  u, computation off correction slopes Modification of reference slopes  Wavelength : 1589 nm  Coronagraph : apodized Lyot coronagraph (d M = 4.5 λ/D)  Lyot Stop : Stop ALC (96% entrance pupil + 15% central obstruction)  Gain = 0.5

13. COFFEE : validation on SPHERE (5/5) First validation of the compensation process: 13 No compensation After NCPA compensation (5 iterations) Energy decrease Contrast : gain x2 – x5 Energy increase 10 -4 10 -5 10 -6 Contrast

14.  COFFEE’s optimization:  Estimation of a pixel-wise map  New imaging model: Adaptation to any coronagraphic mask M  Application to SPHERE :  Estimation of introduced aberration  First experimental validation of the compensation process Conclusion & Perspectives 14 COFFEE : application of the phase diversity to coronagraphic images Perspectives  COFFEE: full validation of iterative process on SPHERE  Combination with ZELDA for a SPHERE upgrade (K. Dohlen talk, Thu. 14h)  Ultimate extinction Creation of a dark hole on the detector Impact of a segmented mirror => refined cophasing

15. 15 …. Thanks for your attention !