simulations in the context of sphere exoplanet imaging workshop david mouillet
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Simulations in the context of SPHERE Exoplanet Imaging Workshop David Mouillet Lecture 27 Feb 2012. Numerous contributors in the simulation work for SPHERE: Kjetil Dohlen, Anthony Boccaletti, Arthur Vigan, Dino Mesa, Raffaele Gratton, Marcel Carbillet, …. SPHERE overall presentation. - PowerPoint PPT PresentationTRANSCRIPT
Simulations in the context of SPHERESimulations in the context of SPHERE
Exoplanet Imaging WorkshopExoplanet Imaging Workshop
David Mouillet David Mouillet Lecture 27 Feb 2012Lecture 27 Feb 2012
Numerous contributors in the simulation work for SPHERE: Kjetil Dohlen, Anthony Boccaletti, Numerous contributors in the simulation work for SPHERE: Kjetil Dohlen, Anthony Boccaletti,
Arthur Vigan, Dino Mesa, Raffaele Gratton, Marcel Carbillet, … Arthur Vigan, Dino Mesa, Raffaele Gratton, Marcel Carbillet, …
SPHERE overall presentationSPHERE overall presentation Many similarities wrt GPI Many similarities wrt GPI (see Lisa’s presentation) in terms (see Lisa’s presentation) in terms
of high level purposes, main components and challenges :of high level purposes, main components and challenges : High order AO, coronagraphs, multi-wavelength differential High order AO, coronagraphs, multi-wavelength differential
imaging, angular differential imaging, budget analysis up to 8-10 imaging, angular differential imaging, budget analysis up to 8-10 target magnitude, …target magnitude, …
With With some significant differencessome significant differences: : Focus: Nasmyth vs Cassegrain (flexures, telescope vs instrument Focus: Nasmyth vs Cassegrain (flexures, telescope vs instrument
WFE)WFE) Wavelength coverage:Wavelength coverage:
A VISIBLE imager with differential polarimetry: ZIMPOL. 500-900 nmA VISIBLE imager with differential polarimetry: ZIMPOL. 500-900 nm Wider NIR simultaneous coverage: 0.95 – 1.65 mic (IFS + diff imager IRDIS, or IFS Wider NIR simultaneous coverage: 0.95 – 1.65 mic (IFS + diff imager IRDIS, or IFS
only)only)
Variable / Differential WFE: Variable / Differential WFE: pupil de-rotator, 2 ADCs: some rotating surfaces (eventhough in a predictible pupil de-rotator, 2 ADCs: some rotating surfaces (eventhough in a predictible
manner)manner) No « CAL » system (NIR tilt/defocus sensor only)No « CAL » system (NIR tilt/defocus sensor only)
High frequency AO correction (41x41 act.)High stability : image / pupil controlVisible – NIR Refraction correctionFoV = 12.5’’40x40 SH-WFS in visible1.2 KHz, RON < 1e-
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/2D @ 0.6 µm, FoV = 3.5”
0.95 – 1.35/1.65 µm λ/2D @ 0.95 µm, Spectral resolution: R = 54 / 33FoV = 1.77”
0.95 – 2.32 µm; λ/2D @ 0.95 µm Differential imaging: 2 wavelengths, R~30, FoV = 12.5’’Long Slit spectro: R~50 & 400Differential polarizationNasmyth platform, static bench,
Temperature control, cleanliness control Active vibration control
Beam control (DM, TT, PTT, derotation)Pola controlCalibration
Concept overview
ImplementationImplementationCPICPI
IRDISIRDISIFSIFS
ZIMPOLZIMPOL
ITTMITTM
PTTMPTTM
DMDM
DTTPDTTP
DTTSDTTS
WFSWFS
De-rotatorDe-rotator
VIS ADCVIS ADCNIR ADCNIR ADC
Focus 1Focus 1
Focus 2Focus 2
Focus 3Focus 3
Focus 4Focus 4
NIR coronoNIR corono
VIS coronoVIS corono
HWP2HWP2
HWP1HWP1
Polar CalPolar Cal
IRDISIRDIS
IFSIFS
ZIMPOLZIMPOLCPICPI(structure, (structure,
damping damping
system..)system..)
Calibration Calibration
sourcessources
SPHERE in test environmentSPHERE in test environment
SPHERE small house…
Simulations: risks and Simulations: risks and difficultiesdifficulties
Variety of effects to be taken into account, various Variety of effects to be taken into account, various timescalestimescales
Needed accuracyNeeded accuracy Metric to consider ? Metric to consider ?
Impact on final contrast performance after data Impact on final contrast performance after data reductionreduction
Inter-dependency of various contributors to the Inter-dependency of various contributors to the budgetbudget
Risk: forget an important limitation source, system Risk: forget an important limitation source, system imperfectionimperfection
Risk: in the limit of very bright targets, including only Risk: in the limit of very bright targets, including only well understood defects (also considered in data well understood defects (also considered in data reduction): syndroma of infinite performancereduction): syndroma of infinite performance
separate limitation types: separate limitation types: « noise » contributors derived from « noise » contributors derived from mean image properties and system mean image properties and system properties: stellar halo, detector, properties: stellar halo, detector, background, FFbackground, FF
speckle calibration residualsspeckle calibration residuals
Simulation approachSimulation approach
Requirements for simulation Requirements for simulation ToolsTools
To estimate To estimate mean image profilemean image profile in various conditions in various conditions (AO correction conditions, coronagraphs, filters) (AO correction conditions, coronagraphs, filters) photon photon noise, FF noisenoise, FF noise……
To estimate To estimate sensitivity to WFE dependenciessensitivity to WFE dependencies, , in in particular as a function of wavelength (various sources of particular as a function of wavelength (various sources of chromatism), and time chromatism), and time system specificationssystem specifications
to estimate to estimate long-term speckle pattern evolutionlong-term speckle pattern evolutionDetailed AO loop simulation Detailed AO loop simulation system specification system specification on on stability, noise propagation, control laws, vibration filtering, stability, noise propagation, control laws, vibration filtering, impact of calib errorsimpact of calib errors
IFS internal behaviour IFS internal behaviour system specifications system specifications on cross-on cross-talk, samplings, detector calibration accuracy…talk, samplings, detector calibration accuracy…
Baseline diffraction codeBaseline diffraction code Baseline including: Baseline including:
Fraunhofer propagation through pupil and focal planesFraunhofer propagation through pupil and focal planes
AO-filtered turbulence residuals, based on analytical model: AO-filtered turbulence residuals, based on analytical model: simulation of n independent realization of residualssimulation of n independent realization of residuals
realistic optics wfe in terms of rms and DSPrealistic optics wfe in terms of rms and DSP
various coronagraph typesvarious coronagraph types
WFE: clear distinction between before/after coronagraph, time WFE: clear distinction between before/after coronagraph, time variable, chromaticityvariable, chromaticity
Limitations or effects treated on a case-by-case basisLimitations or effects treated on a case-by-case basis no out-of-pupil WFE in baseline. Fresnel effects only roughly no out-of-pupil WFE in baseline. Fresnel effects only roughly estimated for some of the most sensitive surfaces (PROPER code, estimated for some of the most sensitive surfaces (PROPER code, see J. Krist’s presentation)see J. Krist’s presentation)
Amplitude defects: few test cases but not treated exhaustivelyAmplitude defects: few test cases but not treated exhaustively
Chromatism not treated exhaustively: mainly residual tilt, defocus, Chromatism not treated exhaustively: mainly residual tilt, defocus, diff WFE for IRDIS dual band imagingdiff WFE for IRDIS dual band imaging
Difficulty to handle very different timescales from ms to hrDifficulty to handle very different timescales from ms to hr
Fulfilling the RequirementsFulfilling the Requirements
To estimate To estimate mean image profilemean image profile in various conditions in various conditions (AO correction conditions, coronagraphs, filters) (AO correction conditions, coronagraphs, filters) photon photon noise, FF noisenoise, FF noise……
To estimate To estimate sensitivity to WFE dependenciessensitivity to WFE dependencies, , in in particular as a function of wavelength (various sources of particular as a function of wavelength (various sources of chromatism), and time chromatism), and time system specificationssystem specifications
to estimate to estimate long-term speckle pattern evolutionlong-term speckle pattern evolutionDetailed AO loop simulation Detailed AO loop simulation system specification system specification on on stability, noise propagation, control laws, vibration filtering, stability, noise propagation, control laws, vibration filtering, impact of calib errorsimpact of calib errors
IFS internal behaviour IFS internal behaviour system specifications system specifications on cross-on cross-talk, samplings, detector calibration accuracy…talk, samplings, detector calibration accuracy…
Fulfilling the RequirementsFulfilling the Requirements
From x,y,From x,y,cubes to simulated detector images:cubes to simulated detector images:Including fraction on lenslets and downstream opticsIncluding fraction on lenslets and downstream optics
Possible detector and calibration defectsPossible detector and calibration defects
Time consuming: can often be restricted to a small part of the Time consuming: can often be restricted to a small part of the imageimage
On operational point of view: definite support to data reduction On operational point of view: definite support to data reduction testingtesting
On Signal/performance point of view:On Signal/performance point of view:Some tests about sensitivity to cross-talkSome tests about sensitivity to cross-talk
Analysis not so easy ; some coupling with image spatial structure, Analysis not so easy ; some coupling with image spatial structure, data extraction algo, and final impact depends also on the temporal data extraction algo, and final impact depends also on the temporal structure (in case of artifact, how wold they smooth down ?)structure (in case of artifact, how wold they smooth down ?)
A point to be precised in very good performance regime (other A point to be precised in very good performance regime (other aspects well handled) and/or if problem in terms of IFS internal aspects well handled) and/or if problem in terms of IFS internal calibration and signal extractioncalibration and signal extraction
IFS internal behaviour IFS internal behaviour IFS internal behaviour IFS internal behaviour
Fulfilling the RequirementsFulfilling the Requirements
End-2-end simulation from incoming turbulent WFE, through End-2-end simulation from incoming turbulent WFE, through AO signal at each iteration and AO residual estimatesAO signal at each iteration and AO residual estimates
Time consuming: Time consuming: Used for AO loop system analysis and specificationsUsed for AO loop system analysis and specifications
Used to validate simpler analytical tools (based on DSP filtering)Used to validate simpler analytical tools (based on DSP filtering)
NOT used for numerous overall instrument image estimatesNOT used for numerous overall instrument image estimates
Good feedback from tests: Good feedback from tests: good agreement between end-2-end simus and actual loop behaviour. good agreement between end-2-end simus and actual loop behaviour.
Validation of analytical toolValidation of analytical tool
Pending confirmation concerning lowest flux Pending confirmation concerning lowest flux
AO loop detailed study AO loop detailed study AO loop detailed study AO loop detailed study
Fulfilling the RequirementsFulfilling the Requirements
Simple use of diffraction code, low sensitivity to exact WFE Simple use of diffraction code, low sensitivity to exact WFE values. Main dependencies: values. Main dependencies:
AO correction qualityAO correction quality
CoronagraphCoronagraph
Mean wavelength. (+ also, spectral width if speckle constrast is Mean wavelength. (+ also, spectral width if speckle constrast is concerned)concerned)
combined use with analytical formulae for extrapolation to combined use with analytical formulae for extrapolation to numerous astrophysical cases (star type, distance, numerous astrophysical cases (star type, distance, magnitude, total integraton time, individual detector magnitude, total integraton time, individual detector integration time…) and comparison of various noise sources integration time…) and comparison of various noise sources
Mean Images Mean Images Mean Images Mean Images
Fulfilling the RequirementsFulfilling the Requirements
Strong support to system specifications, with numerous and Strong support to system specifications, with numerous and coupled system parameters, also depending on signal coupled system parameters, also depending on signal extraction: need for an underlying very schematic approach extraction: need for an underlying very schematic approach for differential imaging: whatever the exact signal extraction for differential imaging: whatever the exact signal extraction algo, we want to minimize algo, we want to minimize
The chromaticity of speckle pattern obtained simultaneouslyThe chromaticity of speckle pattern obtained simultaneously
The image variability over time, with specific attention to two timescales:The image variability over time, with specific attention to two timescales:Minutes : time for companion differential imaging with field rotation (or polarimetric/filter Minutes : time for companion differential imaging with field rotation (or polarimetric/filter switches)switches)
Hour: typical type for deep integration, potential re-calibration of the systemHour: typical type for deep integration, potential re-calibration of the system
Numerous tests made with just simple differences between Numerous tests made with just simple differences between two distinct images: two distinct images:
Not representative to final perfNot representative to final perf
But good estimate to pvarious parameter sensitivityBut good estimate to pvarious parameter sensitivity
Use of baseline diffraction code, in various conditions; Note: Use of baseline diffraction code, in various conditions; Note: AO residuals not critical here. AO residuals not critical here.
Sensitivity to WFE dependencies Sensitivity to WFE dependencies Sensitivity to WFE dependencies Sensitivity to WFE dependencies
Fulfilling the RequirementsFulfilling the Requirements
Support and typical example for various ADI data reduction: 4 hr Support and typical example for various ADI data reduction: 4 hr continuous observation, crossing meridian, sampled with 144 continuous observation, crossing meridian, sampled with 144 mean images (1 every 100 s). mean images (1 every 100 s).
Use of diffraction code including various timescales and Use of diffraction code including various timescales and variability effects: variability effects:
Approximative representation of turbulence residuals (not sampling AO loop Approximative representation of turbulence residuals (not sampling AO loop iterations): average of 100 independent realization, statistics not fully iterations): average of 100 independent realization, statistics not fully converged but correlated on successive images. converged but correlated on successive images.
Predictible WFE evolution: rotating surfaces, ADC residuals associated to Predictible WFE evolution: rotating surfaces, ADC residuals associated to airmassairmass
Slow random effects: Slow random effects: Turbulence non-stationarity: seeing, windspeedTurbulence non-stationarity: seeing, windspeed
Thermal drifts effects on centering, defocusThermal drifts effects on centering, defocus
Production of x,y,l,t cubes (limited to small number of Production of x,y,l,t cubes (limited to small number of wavelengths up to now…)wavelengths up to now…)
Long-term speckle pattern evolution Long-term speckle pattern evolution Long-term speckle pattern evolution Long-term speckle pattern evolution
Fulfilling the RequirementsFulfilling the RequirementsLong-term speckle pattern evolution Long-term speckle pattern evolution Long-term speckle pattern evolution Long-term speckle pattern evolution
eg: DEC = -45° from Paranal, HA = -2 -> +2 hreg: DEC = -45° from Paranal, HA = -2 -> +2 hrAirmass and Field rotation rateAirmass and Field rotation rate Evolution of pre-coro WFE varEvolution of pre-coro WFE var
Evolution of pre-coro variability between Evolution of pre-coro variability between
successive imagessuccessive images
PSD of difference between WFE: 0 -1PSD of difference between WFE: 0 -1 PSD of difference between WFE: 0 -71PSD of difference between WFE: 0 -71
Fulfilling the RequirementsFulfilling the RequirementsLong-term speckle pattern evolution Long-term speckle pattern evolution Long-term speckle pattern evolution Long-term speckle pattern evolution
eg: DEC = -45° from Paranal, HA = -2 -> +2 hreg: DEC = -45° from Paranal, HA = -2 -> +2 hr turbulenceturbulence
r0r0
Wind speedWind speed
Variable de-centeringVariable de-centering
Fulfilling the RequirementsFulfilling the RequirementsLong-term speckle pattern evolution Long-term speckle pattern evolution Long-term speckle pattern evolution Long-term speckle pattern evolution
Lessons learntLessons learnt
We have We have the ability to simulate many effects the ability to simulate many effects eventhough some eventhough some care/effort may be involved, and possibly some simplifying tricks (for care/effort may be involved, and possibly some simplifying tricks (for computation time saving)computation time saving)
Eg from very short ot long timescalesEg from very short ot long timescales
Fresnel effects on numerous surfacesFresnel effects on numerous surfaces
Detailed effects internal to IFS…Detailed effects internal to IFS…
A major challenge for system/performance analysis = the A major challenge for system/performance analysis = the number number of parameters involved of parameters involved and combination to signal extraction and combination to signal extraction approachapproach
Strong relation to system/signal: an a priori analysis of defects is needed first Strong relation to system/signal: an a priori analysis of defects is needed first qualitatively => simulations provide the quantitative answerqualitatively => simulations provide the quantitative answer
Single parameter sensitivity analysis in context of a given system paradigm = Single parameter sensitivity analysis in context of a given system paradigm = more robust than multi-parameter investigationmore robust than multi-parameter investigation
Conclusions for a given system may not be extrapolated to another systemConclusions for a given system may not be extrapolated to another system
Major risk for performance prediction = missing significant Major risk for performance prediction = missing significant contributor ?? contributor ??
Risk itemsRisk items risk probably reasonable up to contrast 10 risk probably reasonable up to contrast 10 6-76-7
timescales around minutes at very fine levels (eventhough the timescales around minutes at very fine levels (eventhough the system is specified for this)system is specified for this)
vibrations, turbulence non-stationarityvibrations, turbulence non-stationarity
rotating surfaces, + ADC correctionrotating surfaces, + ADC correction
thermal drifts, slow loops residualsthermal drifts, slow loops residuals
ultimate performance for WFE calibration ? ultimate performance for WFE calibration ? (current assumptions for (current assumptions for simus=quite conservative): simus=quite conservative): margin for improvement and upgradesmargin for improvement and upgrades
Amplitude/Fresnel/chromatic effects, crosstalk effects for Amplitude/Fresnel/chromatic effects, crosstalk effects for contrasts >~10 contrasts >~10 77
Fine detector calibration residuals ?Fine detector calibration residuals ?
+ the unexpected !+ the unexpected !