absorber coatings for mid-infrared astrophysics · observational cosmology lab, nasa goddard space...

ABSORBERCOATINGSFORMID-INFRAREDASTROPHYSICS

DAHLIABAKER1,EDWARDWOLLACK2 ,KARWAN ROSTEM2,3

1.COECOLLEGE,DEPARTMENTOFPHYSICS

2.OBSERVATIONALCOSMOLOGYLAB,NASAGODDARDSPACEFLIGHTCENTER

3.DEPARTMENTOFPHYSICSANDASTRONOMY,THEJOHNSHOPKINSUNIVERSITY

• PhysicsandMathematicMajor

• PhysicsClubandOutreach

• StudiedComputationalBiophysics,movingontoPlanetaryScienceresearch

ABOUTME

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BACKGROUND

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• HIRMES- HighResolutionMid-InfrarEd Spectrometer• Functioninginthe20-200micrometerrange

• Eliminate

• SOFIA– StratosphericObservatoryforInfraredAstronomy

APPROACH• Goals

• Createamaterialthatabsorbsstraylight• Lightweight,easyapplicable• Knowndielectricfunction

• Whatisthis?Describestheelectricresponsetoincidentradiation

• Diffusivelyreflectsratherthanspecularly reflects• Withstandcryogenictemperatures(µK)

• FirstStep- Characterizethematerials• Dielectricfunctions

• SecondStep- Matlab Model• Modeleachsamplelayerwithfounddielectricfunction

• ThirdStep- Manufacturing• Createsampleplates

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APPROACH

3MGlassMicrospheres~100micronsindiameter

Epotech 377HGraphene- LoadedEpoxysC(5):377(65):SiOx(30)

Aeroglaze Z306

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Specular Diffuse

SAMPLES

SampleLetter

ThicknessofEpoxy(µm) FinalLayerCount Composition(LayerOrder)

A 579 2 Epoxy,Z306B 644 3 Epoxy,Z306,K1C 449 3 Epoxy,K1,Z306D 505 4 Epoxy,K1,Z306,K1E 707 1 EpoxyF 494 2 Epoxy,K1

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DIELECTRICCHARACTERIZATION

Frequency (GHz) 22 26 30 34 38 42

Res

pons

e (d

B)

-40

-30

-20

-10

0

WR28.0 Sampleholder: K1 Microspheres

Average: S11 & S22Theory: S11, S22Average: S12 & S21Theory: S12, S21

Ø Frequencyresponsedatatakenwithamicrowavenetworkvectoranalyzer

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TransmissionthroughwaveguideReflectionfromsample

• Periodicstructureofreflectionshowsconstructiveanddestructiveinterference

• Showsthe“truedensity”asseenbyanincidentelectromagneticwave

• Lossisduetodielectricpropertiesofmicrospheres,scatteringduetogeometryisnotconsidered

THEMODEL

Material Thickness(µm) Dielectric(-)

Aluminum 500 1+1x108i

Epoxy377H 500 7.4+0.4i3MK1

Microspheres 100 1.1 +0.002i

Aeroglaze Z306 50 2.6+0.6i

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Responsevs.Wavelength

RESULTS

• Conclusions• Ourproposedmaterialcanbe

manufacturedatasmallscale• Modelpredictscorrectresponse• Drawback– modelcannotpredict

responsefromdiffusescatteringduetomicrospheres

• FurtherStudies• Measureoptical

frequency-dependentresponsewithaFourierTransformSpectrometer

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Transmittancevs.FrequencyforEpoxy

Reflectancevs.FrequencyforEpoxy

ACKNOWLEDGEMENTS

CoeCollegeAdvisors

SteveFeller Ugur Akgun Firdevs Duru MarioAffatigato

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ACKNOWLEDGEMENTS

AIP/SPS

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ACKNOWLEDGEMENTS

NASAandCollaboratorsIwouldliketogivespecialthankstotheObservational

CosmologyLabatNASAGoddardSpaceFlightCenterandmymentors

EdwardJ.Wollack Karwan Rostem

Fortheirsupportofmyproject:

• DaveChuss andRileyMcCarten,VillanovaUniversity

• PaulMirel,ObservationalCosmologyLab,NASAGSFC

• KyleJohnson,GeorgeWashingtonUniversity

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