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Anthony Boccaletti Observatoire de Paris LESIA. Several instruments dedicated to Exoplanet detection and characterization with High Contrast Imaging since.

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Presentation on theme: "Anthony Boccaletti Observatoire de Paris LESIA. Several instruments dedicated to Exoplanet detection and characterization with High Contrast Imaging since."— Presentation transcript:

1 Anthony Boccaletti Observatoire de Paris LESIA

2 Several instruments dedicated to Exoplanet detection and characterization with High Contrast Imaging since 2001 For this decade : SPHERE and GPI : 2011/12 JWST-MIRI: 2015 For the future (> ): ELT / EPICS Space coronagraphs : ACCESS, PECO, SPICES …. => need for simulation tools adapted to the instruments and to the observing cases

3 Effectsissuessolutions Stellar diffraction- photon flux - photon noise coronagraphy Wavefront errors (dynamic and static) - speckle noise - photon noise wavefront sensing and correction Residual aberrations (mostly static) - un-seen - un-corrected speckle calibration differential imaging Issues or noises related to Image formation (so to the source itself)

4 Background : sky, thermal emission of instrument/telescope, zodiacal light, exozodi Detector related : Flat Field, readout noise, remanance, … Many others that we don't even thought about !!! simulator coronagraphy Wavefront aberrations Differential imaging Background Detectors artifacts Targets characteristics

5 Assess the performance for a science case Evaluate the limitations : which source of noise, or which issues are relevant ? Put some constraints on the instrument design Optimize the design itself (instrumental choices) And then => reassess the performance

6 plan focal + diaphragme pupille détecteur pupille FFT FFT -1 FFT + masque Plan A Plan B Plan C Plan D

7 si Plan A: Plan B: Plan C:Plan D:

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9 High frequency AO correction (41x41 act.) High stability : image / pupil control Visible – NIR Refraction correction FoV = 12.5’’ 40x40 SH-WFS in visible 1.2 KHz, RON < 1e- High frequency AO correction (41x41 act.) High stability : image / pupil control Visible – NIR Refraction correction FoV = 12.5’’ 40x40 SH-WFS in visible 1.2 KHz, RON < 1e- Pupil apodisation, Focal masks: Lyot, A4Q, ALC. IR-TT sensor for fine entering Pupil apodisation, Focal masks: Lyot, A4Q, ALC. IR-TT sensor for fine entering Coronagraphic imaging: Dual polarimetry, direct BB + NB. λ = 0.5 – 0.9 µm, λ 0.6 µm, FoV = 3.5” Coronagraphic imaging: Dual polarimetry, direct BB + NB. λ = 0.5 – 0.9 µm, λ 0.6 µm, FoV = 3.5” 0.95 – 1.35/1.65 µm λ 0.95 µm, Spectral resolution: R = 54 / 33 FoV = 1.77” 0.95 – 1.35/1.65 µm λ 0.95 µm, Spectral resolution: R = 54 / 33 FoV = 1.77” 0.95 – 2.32 µm; λ 0.95 µm Differential imaging: 2 wavelengths, R~30, FoV = 12.5’’ Long Slit spectro: R~50 & 400 Differential polarization 0.95 – 2.32 µm; λ 0.95 µm Differential imaging: 2 wavelengths, R~30, FoV = 12.5’’ Long Slit spectro: R~50 & 400 Differential polarization Nasmyth platform, static bench, Temperature control, cleanliness control Active vibration control Nasmyth platform, static bench, Temperature control, cleanliness control Active vibration control Beam control (DM, TT, PTT, derotation) Pola control Calibration Beam control (DM, TT, PTT, derotation) Pola control Calibration

10 - characterization of Giant Planets and Brown Dwarves : contrast of / ’’ - instrumentation :- exAO - coronography Calibration of the residual speckle pattern is needed contrast ~

11 plan focal + diaphragme pupille détecteur différentiel pupille FFT FFT -1 FFT + masque Plan A Plan B Plan C Plan D

12 - single subtraction : obj(  ) – obj(  ) - spectral obj(  ) – ref(  )- temporal (reference star or filters swapping) - double subtraction : [obj(  ) – obj(  )] – [ref(  ) – ref(  )] telescopeAOcoronagraph filter 2 filter 1 detector data are rescaled and normalized in intensity calibration of common aberrations (dynamic & static) calibration of differential aberrations (static)

13 pupil plane 1 focal plane 2 focal plane 1 (coro. mask) pupil plane 2 (Lyot stop) - phase & amplitude screen, (atmospheric): , , star, ref - instrumental jitter - telescope aberrations - aberrations: telescope -> dichroïc - aberrations: dichroic -> corono - common aberrations corono -> detector - differential aberrations corono -> detector ( ,  ) - flux normalisation: star, ref, planets ( ,  ) - background - RON - flat field ( , , star, ref) - corono (4Q, achro 4Q, Lyot, apo Lyot): chromatism - pupil shear: ( , , star, ref) - pointing: ( , , star, ref) - Lyot stop shear (star, ref) FFT FFT -1 FFT - single subtraction - double subtraction - detectivity plot AO filtering phase diversity filtering

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18 Sampling of the pupil : good sampling needed to reproduce pupil shape Make use of grey approx. Sampling of the image PSF size = N / D = lambda/D (N: array size, D: pupil diameter) PSF chromaticity Modify pupil size but keep the array constant => change the actual shape of the pupil Modify array size but keep the pupil constant Uses of FFT with IDL Shift the center to coordinates [0,0] Aliasing: make sure N is at least 2xD

19 Image normalization: use an off-axis object far from the center (not affected by the mask) but account for the throughput Wavefront errors: Define the Power Spectrum Density of aberrations with power law and cut-off frequencies WFE screen = random screen X sqrt (PSD)

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21 2 codes : 1 for image formation and 1 for contrast curves Image formation – Make pupil – generate common aberrations + differential temporal aberrations upstream – Build complex amplitude in pupil – Build PSF complex amplitude – Make coronagraphic image for on-axis and off-axis objects – Save results Contrast curves – Read results – Normalize – Resample 1 to 0 – Calculate various subtraction – Plot contrast curves

22 Image formation – Start with circular pupil then use the routine sph_pupil to produce VLT pupil in grey level. – Generate diaphragm (under/over-sized) – Define bands: H2 H3 filters of SPHERE = & microns – upstream aberrations : use the provided VLT_wfe.fits Add a 4nm defocus on the reference target – Define a loop on filter and scale array size accordingly – Calculate complex amplitude in pupil : sph_amp_complex.pro – Build PSFs with sph_psf.pro – Introduce differential aberrations with sph_wfdiff.pro – Build coronagraphic images with sph_corono.pro – Take intensities – Rescale the arrays to 1kx1k with sph_taille.pro – Produce off-axis planets with sph_planet.pro – Save results

23 Contrast curves: – Read results of image formation – Resample to camera pixels (shannon at 0.95mic) make use of sph_rescale.pro – Resample of image at 1 to 0 (again sph_rescale.pro ) – Calculate subtractions: obj( 0)-ref( 0) obj( 0)-obj( 1) [obj( 0)-obj( 1)] – [ref( 0)-ref( 1)] – Azimuthal contours with sph_profil1d.pro – Plot averaged contour for psf and corono image and 5sig level for subtractions

24 And play with the parameters …. D = 8m / 160 pix N = linear actuators Relative offset (star/ref) = 0.5 mas Differential aberrations = 10nm Planet separations = 0.1", 0.5", 1"

25 Reference to : – CAOS + SPHERE Software package (public) – PROPER by John Krist (public) – PESCA for ELT (not public)


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