Dr. Amanda J. White Profile

Dr. Amanda J. White

Area of Expertise:

Polarimetry

Websites:

Personal Website

Publications (7)

Proceedings Article | 29 August 2022 Presentation + Paper

Understanding polarization accuracy: the effect of mirror coating non-uniformity on instrument polarization

Amanda J. White, David M. Harrington

Proceedings Volume 12188, 121881R (2022) https://doi.org/10.1117/12.2630684

KEYWORDS: Metrology, Modeling and simulation, Coating, Mirrors, Polarization, Dielectric polarization, Telescopes, Polarimetry

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Proceedings Article | 26 August 2022 Poster

Modeling the polarization behavior of multi-layered mirror coatings for system-level polarization predictions of DKIST

Amanda J. White, David M. Harrington

Proceedings Volume 12188, 121884U (2022) https://doi.org/10.1117/12.2630710

KEYWORDS: Polarization, Mirrors, Optical coatings, Software development, Polarimetry, Data modeling, Calculus, Telescopes, Solar telescopes, Refractive index

SPIE Journal Paper | 28 December 2021 Open Access

Polarization modeling and predictions for DKIST, part 9: flux distribution with FIDO

David Harrington, Friedrich Wöger, Amanda White, Stacey Sueoka

JATIS, Vol. 7, Issue 04, 048005, (December 2021) https://doi.org/10.1117/12.10.1117/1.JATIS.7.4.048005

KEYWORDS: Coating, Polarization, Mirrors, Reflection, Reflectivity, Cameras, Metrology, Calibration, Aluminum, Ellipsometry

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SPIE Journal Paper | 2 August 2021 Open Access

Polarization modeling and predictions for DKIST, part 8: calibration polarizer spatial variation impacts

David Harrington, Tom Schad, Stacey Sueoka, Amanda White

JATIS, Vol. 7, Issue 03, 038002, (August 2021) https://doi.org/10.1117/12.10.1117/1.JATIS.7.3.038002

KEYWORDS: Polarizers, Calibration, Polarization, Modulation, Wave plates, Sapphire, Optical calibration, Telescopes, Metrology, Adaptive optics

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SPIE Journal Paper | 30 March 2021 Open Access

Polarization modeling and predictions for Daniel K. Inouye Solar Telescope, part 7: preliminary NCSP system calibration and model fitting

David Harrington, Stacey Sueoka, Amanda White, Arthur Eigenbrot, Tom Schad

JATIS, Vol. 7, Issue 01, 018004, (March 2021) https://doi.org/10.1117/12.10.1117/1.JATIS.7.1.018004

KEYWORDS: Mirrors, Polarizers, Polarization, Modulation, Wave plates, Calibration, Metrology, Systems modeling, Coating, Solar telescopes

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SPIE Journal Paper | 9 July 2020 Open Access

Polarization modeling and predictions for Daniel K. Inouye Solar Telescope, part 6: fringe mitigation with polycarbonate modulators and optical contact calibration retarders

David Harrington, Sarah Jaeggli, Tom Schad, Amanda White, Stacey Sueoka

JATIS, Vol. 6, Issue 03, 038001, (July 2020) https://doi.org/10.1117/12.10.1117/1.JATIS.6.3.038001

KEYWORDS: Crystals, Wave plates, Calibration, Modulators, Polarization, Solar telescopes, Quartz, Coating, Interfaces

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SPIE Journal Paper | 3 June 2019 Open Access

Polarization modeling and predictions for Daniel K. Inouye Solar Telescope part 5: impacts of enhanced mirror and dichroic coatings on system polarization calibration

David Harrington, Stacey Sueoka, Amanda White

JATIS, Vol. 5, Issue 03, 038001, (June 2019) https://doi.org/10.1117/12.10.1117/1.JATIS.5.3.038001

KEYWORDS: Mirrors, Optical coatings, Reflectivity, Silver, Polarization, Systems modeling, Refractive index, Data modeling, Solar telescopes, Calibration

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The Daniel K. Inouye Solar Telescope (DKIST) is designed to deliver accurate spectropolarimetric calibrations across a wide wavelength range and large field of view for solar disk, limb, and coronal observations. DKIST instruments deliver spectral resolving powers of up to 300,000 in multiple cameras of multiple instruments sampling nanometer scale bandpasses. We require detailed knowledge of optical coatings on all optics to ensure that we can predict and calibrate the polarization behavior of the system. Optical coatings can be metals protected by many dielectric layers or several-micron-thick dichroics. Strong spectral gradients up to 60 deg retardance per nanometer wavelength and several percent diattenuation per nanometer wavelength are observed in such coatings. Often, optical coatings are not specified with spectral gradient targets for polarimetry in combination with both average- and spectral threshold-type specifications. DKIST has a suite of interchangeable dichroic beam splitters using up to 96 layers. We apply the Berreman formalism in open-source Python scripts to derive coating polarization behavior. We present high spectral resolution examples on dichroics where transmission can drop 10% with associated polarization changes over a 1-nm spectral bandpass in both mirrors and dichroics. We worked with a vendor to design dichroic coatings with relatively benign polarization properties that pass spectral gradient requirements and polarization requirements in addition to reflectivity. We now have the ability to fit multilayer coating designs which allow us to predict system-level polarization properties of mirrors, antireflection coatings, and dichroics at arbitrary incidence angles, high spectral resolving power, and on curved surfaces through optical modeling software packages. Performance predictions for polarization at large astronomical telescopes require significant metrology efforts on individual optical components combined with system-level modeling efforts. We show our custom-built laboratory spectropolarimeter and metrology efforts on protected metal mirrors, antireflection coatings, and dichroic mirror samples.

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