computing euclid psfs - cosmostat · 2016-11-07 · computing euclid psfs • what is a typical psf...

ComputingEuclidPSFs• WhatisatypicalPSFforEuclidmission?• OpticalPSF

– Typicaldeviationfromthenominalopticaldesign– Spatially,temporallyandwavelengthdependent

• Detectorcharacteristics– Intra-pixelresponsefunction(IPQE)– Chargediffusion(detectorPSF)– Chargetransferinefficiency(CTI)– Brighter-fatter

• AOCS(attitudeandorbitalcontrolsystem)– Temporalvariationofthetelescopepointing

• CapturethePSFcomplexity:– Spatialvariations– Wavelengthvariation– Temporalvariation(medium– hourtolongscale– days/months)

October17th2016 EuclidPSFmeetingatOrmedesMerisiers 1

Korsch telescope,dichroicandinstruments


VIS

NISP

AirbusDefense&Space (CodeV)

• Amonte-carlo toleranced telescopemodelNo.69(95%ofthesystemswillhaveabetterWFErms) chosenbyAirbusDefenseandSpaceamongseveralmonte-carlomodelsmadewithCodeVraytracing– Manufacturingerror:alignment,tilt(parameters)– Remainingdeviationafterpolishing(2Dimages)– Afterlaunchvibration(parameters)– Afterthermalcooldown(2Dimages)– Alignmentandfocusreadjustment(compensator)


Airbus(CodeV)toCEA-IAP(Zemax)• ConversionfromCodeVmodelfiletoaZemax inputfile(SamuelRonayette)– Conversionusingthetoolseq2zmx.exeprovidedbyZemax– Checkandcorrectforerrorsoftheconversion.– Makeonlyone2DMSEimageforeachopticalsurfacebyinterpolating,addingandfittingpolynomials.

– InputtheMSEimagesinZemax.


M1asanexample

Anexampleof2Dresidualimagesafterpolynomialssurfacesubtraction


M1thermal4nmrms

M1mounting2nmrms

FOM1thermal1.6nmrms

ComputeaPSFinZemax

• Twomethods:FFTversusHuygens


WFMandFouriersolutionfromLanceMiller

(Oldmodelbutstillvalidforinternalcomparisons)

Huygenscomputationistooslow(tensofmn)!

WhyHuygens?• FFTinZemax cannotsimulate

anonorthogonal detectorplaneaccurately.

VISangleofchiefray is~10deg.


PSFfactorypipeline:fromPSFtoWFM• WhysimulateWFMinsteadofPSFs:

– WFMhavefinitesize– WFMareeasytoscaleinwavelength(VISachromatic)– WFMareeasiertointerpolate

• Pipelineschema:Gridproduction/gridinterpolation

ZEMAX WFMFinegrid

HF/BFdecomposition

Zernicke coeffsFinegrid

WFM-HFmapsFinegrid

ForpositionX,Yinterpolation

Zernicke coeffsAtX,Y

WFM-HFmapsAtX,Y

Fourier PSF

SLOW(Zemax licences)

SLOW(butmassiveParallelpossible)

OnLINUXcomputerfarms


PSFfactory:WFMgridspecs• HowgoodmustbetheWFMtogetPSFwithinrequirements(refisHuygens):• Thepupilmustbedetailedenoughtocontainallinformations.• Keyparameteristhesampling.Highestfrequencyarethespider sharpedges.• Analysis showthata4096x4096sampling isrequiredfora1e-5accuracyinellipt.• Ifedgesmoothingisappliedinthemask,asamplingof1028px isequallygood.• ZemaxSimulationwithoutobstruction tobefittedwithorthogonalpolynomials.

• HowgoodmustbethegridofWFMtogetPSFwithintherequirements:• ThegridmustsampletheFPAwellenoughtocapturethespatialvariations• Analysis showthatthePSFellfromWFMisstableto1e-4with3arcsec.• Interpolationwillbeneededtogodownto1e-5• Thefinalgridis700x800WFMoverthefullVISFPA

PSFstabilitywithin1e-4(2.7arsec) 3monthson2Zemax machines


PSFfactorypipeline:interpolation

WFMdecomposition:low/Highfrequencies• Lowfrequencies :Zernikepolynomials to56th order(800x800x56 table)• Highfrequencies :HFpixelmaps(pupil size):800x800maps:2.2TB.• Zernikefitsaredone inZEMAX,HFareWFMresidual afterZernikesubtraction.• Doneonlyonceforagrid.

WFMreconstruction:low/Highfrequencies• LowFreq :bilinearinterpolationofeachZernikecoefficient(4clothest gridpoints)• HighFreq :bilinear interpolationofeachpixeloftheHFmaps(4clothest)• Obscuration addedfollowingaanalyticmodelwiththeFPAposition• Doneforeachstar/galaxyposition• Pythoncode,easilytorunonclusters(30son1core/WFMmap)


PSFfactory:WFMtoPSF– affineDFT (L.Miller)

WFMtoPSFisaFouriertransform:WhynotFFT?• FFTlinks theimagesamplingtothepupil size(hugepaddingneeded)• FFTcannotcopewithnonorthogonaldetectorplane

LanceMiller developedaDFTcode(discret Fouriertransform):affineDFT• Usercanselectthepsf sampling• VerygoodaccuracycomparedtoHuygens(1e-5inellipticity)

Itisslow…100sona32coremachinefora512pxPSF.

Butitispossibletorunitoncomputerfarms(unlikeZemax)

October17th2016 EuclidPSFmeetingatOrmedesMerisiers

PSFfactory:wavelengthinterpolation(L.Miller)• SimulatethePSFforacoloredobject• Thebandpass isVERYlarge:450um.Factorof2from!• Bruteforce:slicetheSEDoftheobjectinnslices, compute

thenPSF,applyweightandstack.• Numberifslicesrequiredtoconvergeonellipticity (1e-5)is

around100slices(100affineDFT runsperobject!!).

• Onesolution:interpolation• DifficulttointerpolatethePSF(varyingsize,noboundaries)• GotoFourierspace,interpolate,weight,stack,backtoreal

space.• Only20PSFsareneededtointerpolateto100with1e-5

accuracy.

affineDFT 20PSFs

Fourier

100fftPSF

ColoredPSF

Fourier- 1

Interpolation

weight,stack

1fftPSF

SolarPSFMonowl PSFFromPerdereau andBoucaud


Othercontributions:DetectorPSF

DetectorPSF(NiemiandKitching):• Chargesspreadinthesubstrateinneighbouringpixel• NotBrighter– Fatter(butdetPSF(flux)containssome)• Simulatedasa2DGaussianconvolution (analytical /empirical

formulaefrommeasurements)• Dependsoncolorandflux• FWHM:around8um– 0.6px – 0.06arcsec


Othercontributions:AOCSPSF

AOCSPSF(Astrium data):• ThePSF ismodified bythepointingmovementsofthespacecraft.• Thalessent100realizationoftimeseries(700s, onpoint/s)• Method:

– Convertpointings anglestoFPApositions– Fit2Dgaussians parametersovertheFPApositions– 5th orderpolynomial fit(betterthan1e-6)

• Finalsigmaaround0.11px• NotconstantovertheFPA(smallvariation)

(becauseoftherotationaroundthepointingaxis)

Somevalidationtest:ECinternal


WFMreconstructionatgridpoint:• Checkthatthedecomposition /reconstructiondoesnotalterthePSF.• ComputetheWFMatagridpositionusingthepipeline(LF/BF)• ComparewiththeoriginalPSF• Smallresidualtilt(doesnotaffectthePSFshapebuttheposition)• Underinvestigation.

WFMinterpolation:• InterpolateaWFM/PSFaroundapointofthegrid• ComparewiththecentralWFM/PSF• Verygoodaccuracy(below1e-5finalvariation)• Realinterpolationisonsmallerscale->evenbetterresults. • UsegreenWFMtointerpolateat

theredPSF position• CompareredtointerpolatedPSF


Somemorevalidationtest:Perdereau /Boucaud

PSFstatistics:• 40x40grid,mono-wl• Ellipticity,FWHM,EE,

positions• VariationsovertheFPA

AnissueregardingthevariationsofthepositionsofthereconstructedPSFswasfound.WeinvestigateifitisthesameproblemthantheresidualtiltofthePSFsreconstruction


ComparisonwithAstrium PSFs

PSFsfromAstrium :• PSFsat9referencegridpositions(F1toF9).• Monochromatic(800nm)• Highfrequencymapsincluded• FromtheoriginalCodeV opticalmodel

ComparewithourPSFs(ZEMAX)• Wefindsomedescrepancies webelievecomefromtheHF

transcriptionfromCodeV toZEMAX• Firstissueidentified:indexationofZernicke polynomialsin

ZEMAX(with/withoutgridsag)• Otherissuesarebeinganalysed now.

• WebelievethatwecapturedtheLowFreq correctly.(TBC)• ProgressinbeingmadeontheHFcontribution.

Productsuptonow(opticalPSFs)


Sensibilityanalysis :• WFMwithlowandhighfrequencyMSE• PSFsgeneratedbyvaryingeachopticalelement position/angle• Monochromatic(800nm)• LanceMillerWFMmodeling

Phasediversity:• Onlylowfrequencymechanical surfaceerror(MSE)• PSFsandwavefrontswithdefocus(21M2offsets:-200to200um)• 9positions+8aroundonecorner• UsedforWFMreconstruction

PSFstatisticalanalysis :• WFMwithlowandhighfrequencyMSE• 40*40positions,LF+HF,solarSED

PSFsforOU-SHE(F.Courbin)• OnlyZernikepolynomialscomponentofWFM• 12000PSFs(x4forthedithers)• LFonly• Firstditherisreadytobereleased(opticalPSFonly)

Zernicke polynomial:• CompletegridofZernikepolynomials


Todo list…Production:• PSFsforOU-SHE(remaining3dithers)

– AddAOCSanddetectorcontributions

Modelvalidation:• SolvetheissueswiththeHFdiscrepancywithAstrium PSFs• WriteafullreportonthePSFfactorytestsandvalidation• Adddichroiccontribution

• MigratethecodetotheSDCsECinfrastructure

computing euclid psfs - cosmostat · 2016-11-07 · computing euclid psfs • what is a typical psf...

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