Measuring transmission at the Christiansen wavelength for dynamic sand samples

Cobey L. McGinnis; Jesse A. Frantz; Jason D. Myers; Anthony R. Clabeau; Austin F. Moore; Kenneth J. Ewing; Matthew B Hart; Abbie T Watnik; Jasbinder S. Sanghera

doi:10.1117/12.3001651

8 March 2024 Measuring transmission at the Christiansen wavelength for dynamic sand samples

Cobey L. McGinnis, Jesse A. Frantz, Jason D. Myers, Anthony R. Clabeau, Austin F. Moore, Kenneth J. Ewing, Matthew B Hart, Abbie T Watnik, Jasbinder S. Sanghera

Author Affiliations +

Proceedings Volume 12882, Optical Components and Materials XXI; 1288203 (2024) https://doi.org/10.1117/12.3001651
Event: SPIE OPTO, 2024, San Francisco, California, United States

Abstract

Degraded visual environments (DVEs) are the result of a high concentration of obscurants in the air, and occur often during rotary wing aircraft landings. When the obscurants are comprised of sand this leads to a condition called “brownout.” Current DVE penetrating technology is severely limited by a weak return signal in severe brownout conditions. One method of overcoming this weak return signal is to use light tuned to the Christiansen wavelength, the wavelength at which the refractive index of the scatterer matches that of the surrounding medium, eliminating the scattering effect associated with the obscurant particles. We have previously shown a novel method for determining the optical constants of particulate samples using spectroscopic ellipsometry and determined that, for several different sand samples, the Christiansen wavelength is approximately 8 microns. We present data from falling sand of several different types using Fourier transform infrared (FTIR) spectroscopy showing a higher transmission percentage at the Christiansen wavelength. We explain features in this data using previous measurements of the optical properties of these sands.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Cobey L. McGinnis, Jesse A. Frantz, Jason D. Myers, Anthony R. Clabeau, Austin F. Moore, Kenneth J. Ewing, Matthew B Hart, Abbie T Watnik, and Jasbinder S. Sanghera "Measuring transmission at the Christiansen wavelength for dynamic sand samples", Proc. SPIE 12882, Optical Components and Materials XXI, 1288203 (8 March 2024); https://doi.org/10.1117/12.3001651

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