Dr. Charmayne E. Lonergan Profile

Dr. Charmayne E. Lonergan

at Pacific Northwest National Lab

SPIE Involvement:

Author

Publications (9)

Proceedings Article | 14 June 2023 Presentation + Paper

Using synthetic infrared spectra derived from n/k optical constants for standoff detection of chemical deposits

Charmayne Lonergan, Jeremy Erickson, Molly Rose Kelly-Gorham, Oliva Primera-Pedrozo, Michael Wilhelm, Brenda Forland, Kendall Hughey, Bruce Bernacki, Timothy Johnson, Tanya Myers

Proceedings Volume 12541, 1254109 (2023) https://doi.org/10.1117/12.2663579

KEYWORDS: Reflectivity, Aluminum, Statistical analysis, Film thickness, Infrared radiation, Standoff detection, Coating thickness, Solids, Reflection, Infrared detectors

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We report results from a recent field experiment to test the validity of using physics-based synthetic infrared spectra to serve as endmembers in a spectral database targeted at chemical deposits. Specifically, the optical constants n and k, (the real and imaginary part of the refractive index) were used to first model infrared reflectance spectra for different thicknesses of chemical layers (e.g. acetaminophen, methylphosphonic acid – MPA, etc.) on various conducting and insulating substrates such as aluminum, wood, and glass. In the experimental portion of the research, thin films of the solid and liquid analytes were deposited onto such substrates to form micron-thick layers of the analytes at different thicknesses: Standoff data from an imaging instrument were then recorded and analyzed to not only identify the different analytes, but also quantify the layer/deposit thickness. To gauge success, the detection results using the synthetic data were compared to the results from laboratory hemispherical reflectance (HRF) spectra that were collected for the same sample planchets measured in the field via standoff methods. Preliminary results indicate good agreement between the synthetic reference data as compared to the lab-measured HRF data in terms of their ability to quantitatively reduce longwave infrared data. Specifically, modeled IR spectra for acetaminophen on an aluminum planchet at various thicknesses (1, 2, 5, 10, 15, and 20 μm) were synthesized and compared with standoff field reflectance data as well as HRF laboratory reflectance spectra for two samples: a 5.2 μm- and 12.8 μm-thick layer of acetaminophen on aluminum. Using a first-order approximation, analysis of the field data estimates the thicknesses of the samples to be 2 and 10 μm for the two samples, respectively, while the HRF laboratory data yields thickness estimates of between 5-10 μm and 10 μm, respectively. Both yield reasonable estimates, with the uncertainty most likely due to factors yet to be accounted for in the synthetic spectra such as light scattering.

Proceedings Article | 14 June 2023 Presentation + Paper

Preparation and characterization methods of thin layer samples for standoff detection

Oliva Primera-Pedrozo, Jeremy Erickson, Charmayne Lonergan, Sarah Burton, Bruce Bernacki, Tanya Myers, Timothy Johnson

Proceedings Volume 12541, 125410Q (2023) https://doi.org/10.1117/12.2663444

KEYWORDS: Aluminum, Glasses, Solids, Chemical analysis, Reflectivity, Liquids, Coating thickness, Bioalcohols, Statistical analysis, Coating

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Proceedings Article | 30 May 2022 Presentation + Paper

Determining infrared optical constants for dolomite using single angle reflectance and spectroscopic ellipsometry

Charmayne Lonergan, Michael Yokosuk, Emmanuela Diaz, Timothy Johnson, Tanya Myers

Proceedings Volume 12116, 1211607 (2022) https://doi.org/10.1117/12.2618920

KEYWORDS: Reflectivity, Crystals, Infrared spectroscopy, Polishing, Surface finishing, Reflectance spectroscopy, Epoxies, Ellipsometry, Spectroscopic ellipsometry, Infrared radiation

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Proceedings Article | 12 April 2021 Presentation + Paper

Measuring accurate optical constants of uranium minerals for use in optical modeling of infrared spectra

T. Myers, B. DeVetter, D. Saunders, C. Lonergan, M. Yokosuk, B. Bernacki, A. Bautista, T. Johnson

Proceedings Volume 11749, 117490T (2021) https://doi.org/10.1117/12.2588321

KEYWORDS: Minerals, Thermal modeling, Infrared radiation, Uranium, Solid modeling, Particles, Data modeling, Solids, Scattering, Reflectivity

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Proceedings Article | 8 May 2018 Presentation + Paper

Advances in infrared GRIN: a review of novel materials towards components and devices

Kathleen Richardson, Myungkoo Kang, Laura Sisken, Anupama Yadav, Cesar Blanco, Michael Antia, Spencer Novak, Charmayne Smith, Andy Buff, Antoine Lepicard, Marc Dussauze, Casey Schwarz, Stephen Kuebler, Chris Grabill, Carlo Pantano, Theresa Mayer, Alexej Pogrebnyakov, Clara Rivero-Baleine, Andrew Kirk, Samantha Mensah, Megan Driggers, Juejun Hu, Pao-Tai Lin, Anuradha Agarwal, Cheng Li, Weiwei Deng

Proceedings Volume 10627, 106270A (2018) https://doi.org/10.1117/12.2304608

KEYWORDS: Glasses, Crystals, Refractive index, GRIN lenses, Infrared radiation, Chalcogenide glass, Ceramics, Heat treatments, Nanocomposites, Ions

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Proceedings Article | 17 May 2016 Paper

Engineering novel infrared glass ceramics for advanced optical solutions

K. Richardson, A. Buff, C. Smith, L. Sisken, J. David Musgraves, P. Wachtel, T. Mayer, A. Swisher, A. Pogrebnyakov, M. Kang, C. Pantano, D. Werner, A. Kirk, S. Aiken, C. Rivero-Baleine

Proceedings Volume 9822, 982205 (2016) https://doi.org/10.1117/12.2224239

KEYWORDS: Glasses, Optics manufacturing, Ceramics, Chalcogenide glass, Refractive index, Infrared radiation, GRIN lenses, Crystals, Heat treatments, Transmission electron microscopy

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Proceedings Article | 17 May 2016 Paper

Designing mid-wave infrared (MWIR) thermo-optic coefficient (dn/dT) in chalcogenide glasses

Benn Gleason, Laura Sisken, Charmayne Smith, Kathleen Richardson

Proceedings Volume 9822, 982207 (2016) https://doi.org/10.1117/12.2229056

KEYWORDS: Glasses, Chalcogenide glass, Thermography, Refractive index, Selenium, Infrared radiation, Thermal optics, Germanium, Mid-IR, Infrared imaging

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