Imaging Science Ph.D. Defense: Charles Tabor
Ph.D. Dissertation Defense
Reflectance and Emittance Spectra of Intimately Mixed and Layered Mixed
Charles Tabor
Imaging Science Ph.D. Candidate
Chester F. Carlson Center for Imaging Science, RIT
Remote characterization of intimately mixed and layered media is a complicated, yet critical aspect of understanding the impacts of natural events and human activities. An improved model for predicting radialith thickness is proposed.
Abstract:
The remote characterization of intimately mixed and layered media is a complicated and yet critical aspect of understanding the impacts of natural events and human activities. Hapke developed two models that attempt to address these challenges in the context of reflectance spectroscopy. The Hapke mixing model predicts the spectra of intimate mixtures based upon end member spectra and known geophysical parameters, but has not been evaluated over a wide range of non-powder mixtures, which are common in littoral environments. The Hapke model for the diffusive reflectance of layered media can be used to predict the physical thickness of the radialith, but those predictions have not been validated. Laboratory experiments characterized the spectra of mixtures composed of silica, olivine and calcium carbonate mineral sands of varying grain sizes and mass fractions. The reflectance and emissivity of sample mixtures and their component end members were measured. The measured mixture spectra and model predicted mixture spectra were compared. Prior experiments have shown the Hapke mixing model to predict reflectance spectra for fine grain (< 90 μm) media within the bounds of experimental error. In these experiments using larger grain (100 - 1000 μm) size media, the predicted results fell outside the bounds of experimental error. In contrast, emissive spectra measurements of the same materials differed from linear mixing model predictions of spectral emissivity by less than 2%. Additional laboratory experiments assessed the optical thickness of deposited layers of olivine, silica and calcium carbonate mineral sands. Samples consisted of a substrate media upon which particle layers were built up over successive iterations of material deposition. Substrate detectability was assessed after each layer deposition to determine the point at which optical thickness substantially exceeded empirical observations and fell well outside the bounds of experimental error. An improved model for predicting radialith thickness is proposed.
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Those with interest in the topic.
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