Mr. Devin M. Lewis Profile

Devin M. Lewis

SPIE Involvement:

Author

Area of Expertise:

Vacuum systems , Thin film evaporation , LiF

Publications (5)

Proceedings Article | 26 August 2024 Presentation + Paper

Stability of XeF2 passivated Al plus LiF as possible coating for HWO

Devin Lewis, Tanner Rydalch, David Allred, Luis Rodriguez de Marcos, Manuel Quijada, Javier del Hoyo, Mateo Batkis

Proceedings Volume 13100, 131000K (2024) https://doi.org/10.1117/12.3018471

KEYWORDS: Aluminum, Reflectivity, Laser induced fluorescence, Humidity, X-ray photoelectron spectroscopy, Atomic force microscopy, Relative humidity, Coating, Semiconducting wafers, Mirrors

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Proceedings Article | 21 August 2024 Paper

Enhanced far ultra-violet optical properties of physical vapor deposited aluminum mirrors through fluorination

Manuel Quijada, Javier Del Hoyo, Luis Rodriguez de Marcos, Edward Wollack, Mateo Batkis, Devin Lewis, Tanner Rydalch, David Allred

Proceedings Volume 13093, 1309340 (2024) https://doi.org/10.1117/12.3021592

KEYWORDS: Aluminum, Reflectivity, Silicon, Mirrors, Laser induced fluorescence, Far ultraviolet, Semiconducting wafers, Zerodur, Vacuum chambers, Relative humidity

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Astronomical instrumentation for measurements in the Far Ultraviolet (FUV, 90−200 nm) have historically considered aluminum (Al) thin film mirrors due to this material high reflectance over this wavelength range. However, the native aluminum oxide layer that forms on Al upon exposure to the atmosphere is strongly absorbing in this wavelength range, requiring that the films be protected with a dielectric that inhibits oxidation. Typically, magnesium fluoride (MgF₂) or lithium fluoride (LiF) coatings are used as protective layers, but each has shortcomings. For example, MgF₂ has an absorption cutoff at 115 nm that reduces performance below this wavelength, which is a critical part of the FUV spectrum for observational astrophysics. The use of LiF as a protection for Al provides a lower absorption cutoff at 100 nm, but it is hygroscopic and thus susceptible to degradation in humid conditions. Our team at GSFC has developed a new reactive Physical Vapor Deposition (rPVD) process that consists of a fluorination process with XeF₂ gas combined with our traditional PVD process. We have found that this new rPVD process produces Al+XeF₂+LiF (XeLiF) and Al+XeF₂+MgF₂ (XeMgF₂) mirror coatings with unprecedented reflectance. In addition, the rPVD process seems to produce much more environmentally stable coatings (when compared to the conventional process without the XeF₂ fluorination). We report on IR/Vis/UV reflectance of XeLiF and XeMgF₂ mirrors. The surface roughness as well as the FUV reflectance measured over a period of 8 months for a XeLiF sample with a relatively thin (≃ 30 nm) Al layer are also reported. We have also been investigating the compatibility of this rPVD coating process for potential efficiency enhancements of Si-based gratings. Since it is known that the XeF₂ vapor is a strong Si etchant, we are investigating if the native SiO₂ layer on Si is sufficient to protect the groove profile of E-beam-ruled Si gratings from degradation. Preliminary results indicate that the native SiO₂ layer is an effective barrier against etching of Si by XeF₂.

Proceedings Article | 3 October 2023 Presentation + Paper

Addressing calibration of high-harmonic generation sources used for studying magnetism

Taylor Buckway, Aaron Redd, Devin Lewis, Eric Gullikson, Joshua Vawdrey, Karine Chesnel, David Allred, Richard Sandberg

Proceedings Volume 12694, 1269404 (2023) https://doi.org/10.1117/12.2692397

KEYWORDS: Iron, Magnetism, Extreme ultraviolet, Calibration, Spectral calibration, Gold, High harmonic generation, X-rays

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Proceedings Article | 29 August 2022 Poster + Presentation + Paper

Stability of lithium fluoride thin films as a function of humidity and temperature

Tanner D. Rydalch, Devin M. Lewis, David D. Allred

Proceedings Volume 12188, 121884M (2022) https://doi.org/10.1117/12.2630514

KEYWORDS: Atomic force microscopy, Humidity, Aluminum, Thin films, Lithium, Silicon, Surface roughness, Mirrors

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Proceedings Article | 15 December 2020 Poster + Paper

Illuminating the degradation of lithium fluoride mirror coatings in humid environments

Devin Lewis, Caleb Michael Plewe, Alexandra Gallion Stapley, Joshua Vawdrey, R. Steven Turley, David Allred

Proceedings Volume 11451, 1145141 (2020) https://doi.org/10.1117/12.2576258

KEYWORDS: Laser induced fluorescence, Mirrors, Lithium, Scanning electron microscopy, Humidity, Thin films, Aluminum, Temperature metrology, Spectroscopy, Spectroscopic ellipsometry

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