Terahertz scattering by dense media

Kaushik, Mayank; Ng, Brian W.-H.; Fischer, Bernd; Abbott, Derek

doi:10.1063/1.4720078

Cited by 12 publications

(8 citation statements)

References 13 publications

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“…Therefore, we assumed that the mismatch between the THz absorbance and mass values in kidney are due to the structure and chemical composition. The several tens of micron size capsules with urine act as scatterers in the THz frequency and increased the THz absorbance of kidney [22,23]. …”

Section: Analysis Methodsmentioning

confidence: 99%

Measuring water contents in animal organ tissues using terahertz spectroscopic imaging

Lee

Jeoung

Kim

et al. 2018

Biomed. Opt. Express

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Abstract:We investigated the water contents in several organ tissues such as the liver, spleen, kidney, and brain tissue of rats using the terahertz spectroscopic imaging technique. The water contents of the tissues were determined by using a simple equation containing the absorption coefficients of fresh and lyophilized tissues and water. We compared the measured water contents with the difference in mass of tissues before and after lyophilization. All results showed a good match except for the kidney, which has several Bowman's capsules. Pepper, and V. P. Wallace, "In vivo study of human skin using pulsed terahertz radiation," Phys.

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Section: Analysis Methodsmentioning

confidence: 99%

Measuring water contents in animal organ tissues using terahertz spectroscopic imaging

Lee

Jeoung

Kim

et al. 2018

Biomed. Opt. Express

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“…Therefore, estimating the scattering contribution in the extinction coefficient of materials with characteristic absorption signatures requires more advanced computational approaches. Moreover, previous studies have mainly focused on estimating the scattering loss in the ballistic regime 29,30,[32][33][34][35][36] , and the effects of volume scattering on diffuse THz fields have not been investigated. Here, we present a robust computational approach based on the wavelet multiresolution analysis (MRA) of the THz extinction spectra along with the kurtosis and skewness of the spectral images, presented as a new spectroscopy concept dubbed the bimodality spectrum, to reliably identify the characteristic resonant frequencies using the scattered THz waves in both ballistic and diffusive regimes.…”

Section: Scattering Mitigation Through Wavelets and Bimodality Spectral Analysismentioning

confidence: 99%

“…They either ignore the diffused THz waves 29,30 or employ them only by averaging with the ballistic forward-scattered fields 31 . For example, the effect of volume scattering in pressed pellets of materials were studied using forward-scattered THz electric-field transmission measurements 29,30,[32][33][34][35][36] . However, utilization of only diffusely-scattered waves critical in studying hostile and uncooperative samples, or in detection geometries without access to the narrow cone of the forward-scattered beams, has not been investigated.…”

Section: Introductionmentioning

confidence: 99%

Diffuse Terahertz Spectroscopy in Turbid Media Using a Wavelet-Based Bimodality Spectral Analysis

Khani

Osman

Arbab

2021

Preprint

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Current terahertz (THz) spectroscopy techniques only use the coherent light beam for spectral imaging. In the presence of electromagnetic scattering, however, the scattering-mitigated incoherent beams allow for flexible emitter-detector geometries, which enable applications such as seeing through turbid media. Despite this potential, THz spectroscopy using diffuse waves has not been demonstrated. The main obstacles are the very poor signal to noise ratios of the diffused fields and the resonance-like spectral artifacts due to multiple Mie scattering events that obscure the material absorption signatures. In this work, we demonstrate diffuse THz spectroscopy of a heterogeneous sample through turbid media using a novel technique based on the wavelet multiresolution analysis and the bimodality coefficient spectrum, which we define here for the first time using the skewness and kurtosis of the spectral images. The proposed method yields broadband and simultaneous material characterization at detection angles as high as 90o with respect to the incident beam. We determined the accuracy of the wavelet-based diffuse spectroscopy at oblique detection angles, by evaluating the area under the Receiver Operating Characteristic (ROC) curves, to be higher than 95%. This technique is agnostic to any a priori information on the spectral signatures of the sample materials or the characteristics of the scattering medium, and can be expanded for other broadband spectroscopic modalities.

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“…Действительно, влияние шероховатости границы раздела сред с хорошей степенью точности устраняется домножением измеренного спектра коэффициента отражения на exp 2σ 2 ω 2 /c 2 . Отметим, что совершенно аналогичное аналитическое выражение можно получить и для коэффициента пропускания [19,20], а также для слоистых сред с шероховатыми границами раздела слоев и объемным рассеянием. Практически для этого спектр коэффициента отражения следует умножить на фактор exp 2σ 2 ef ω 2 /c 2 , в котором эффективное сечение рассеяния σ ef можно подобрать из условия проявления наиболее резких спектральных контуров.…”

Section: результаты расчетовunclassified