scholarly journals Method for Quantitative Broadband Diffuse Optical Spectroscopy of Tumor-Like Inclusions

2020 ◽  
Vol 10 (4) ◽  
pp. 1419 ◽  
Author(s):  
Sandhya Vasudevan ◽  
Farnoush Forghani ◽  
Chris Campbell ◽  
Savannah Bedford ◽  
Thomas D. O’Sullivan
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Near Infrared ◽  
Continuous Wave ◽  
A Priori ◽  
Hybrid Technique ◽  
Scattering Spectra ◽  
Heterogeneous Tissue ◽  
The Mean ◽  
Homogeneous Background

A hybrid reflectance-based diffuse optical imaging (DOI) technique combining discrete wavelength frequency-domain (FD) near-infrared spectroscopy (NIRS) with broadband continuous wave NIRS measurements was developed to quantify the broadband optical properties of deep tumor-like inclusions. This method was developed to more accurately measure the broadband optical properties of human tumors using a compact handheld imaging probe and without requiring a priori spectral constraints. We simulated the reconstruction of absorption and scattering spectra (650–1000 nm) of human breast tumors in a homogeneous background at depths of 0 to 10 mm. The hybrid DOI technique demonstrated enhanced performance in reconstruction of optical absorption with a mean accuracy over all 71 wavelengths of 8.39% versus 32.26% for a 10 mm deep tumor with the topographic DOI method. The new hybrid technique was also tested and validated on two heterogeneous tissue-simulating phantoms with inclusion depths of 2, 7, and 9 mm. The mean optical absorption accuracy over all wavelengths was similarly improved up to 5x for the hybrid DOI method versus topographic DOI for the deepest inclusions.

scholarly journals Time-Resolved Reflectance Spectroscopy Applied to the Nondestructive Monitoring of the Internal Optical Properties in Apples

2001 ◽  
Vol 55 (10) ◽  
pp. 1368-1374 ◽  
Author(s):  
Rinaldo Cubeddu ◽  
Cosimo D'Andrea ◽  
Antonio Pifferi ◽  
Paola Taroni ◽  
Alessandro Torricelli ◽  
...  
Keyword(s):  
Optical Properties ◽  
Industrial Applications ◽  
Nondestructive Monitoring ◽  
Nondestructive Measurement ◽  
Time Resolved ◽  
Mean Values ◽  
Scattering Coefficients ◽  
Scattering Spectra ◽  
The Mean ◽  
Temporal Dispersion

Time-resolved reflectance has been used for the nondestructive measurement of optical properties in apples. The technique is based on the detection of the temporal dispersion of a short laser pulse injected into the probed medium. The time distribution of re-emitted photons interpreted with a solution of the diffusion equation yields the mean values of the absorption and reduced scattering coefficients of the medium. The proposed technique proved useful for the measurement of the absorption and scattering spectra of different varieties of apples, revealing the spectral shape of chlorophyll. No major variations were observed in the experimental data when the fruit was peeled, showing that the optical properties measured were those of the pulp. With this technique the change in chlorophyll absorption during storage and ripening could be followed. Finally, a compact prototype working at few selected wavelengths was designed and constructed, demonstrating potentialities of the technique for industrial applications.

scholarly journals Электронная структура и спектры оптического поглощения золотых фуллеренов Au-=SUB=-16-=/SUB=- и Au-=SUB=-20-=/SUB=-

2019 ◽  
Vol 61 (6) ◽  
pp. 1204
Author(s):  
Г.И. Миронов
Keyword(s):  
Optical Properties ◽  
Energy Spectrum ◽  
Optical Absorption ◽  
Near Infrared ◽  
Fourier Transforms ◽  
Green Functions ◽  
Optical Absorption Spectra ◽  
New Class ◽  
Infrared Spectral ◽  
Neighboring Site

AbstractThe electronic and optical properties of gold fullerenes are studied in the framework of the Hubbard model. The expressions of the Fourier transforms of anticommutator Green functions have been obtained for gold fullerenes Au_16 and Au_20, the poles of which determine the energy spectrum of the system under consideration. The calculations are performed for the thermodynamic means that characterize jumps of electrons from a nanosystem site to a neighboring site, the correlation functions demonstrating the possibility of existing two d electrons with oppositely oriented spin projections on the same site of the fullerenes consisting of gold atoms. The optical absorption spectra are presented. The optical absorption peaks of ions $${\text{Au}}_{{20}}^{ - }$$ and $${\text{Au}}_{{16}}^{ - }$$ correspond to a near-infrared spectral region, where the light absorption by blood or a soft tissue is vanishingly small; thus, these ions can be used as a new class of contrast improvements and phototherapeutic means for diagnostics and treatment of cancer.

scholarly journals Examining cerebral hemodynamics in a two-layer model of the human head using broadband near-infrared spectroscopy

2021 ◽  
Author(s):  
Olivia Pucci
Keyword(s):  
Optical Properties ◽  
Near Infrared ◽  
Continuous Wave ◽  
Lower Layer ◽  
Homogeneous Medium ◽  
Human Head ◽  
Cerebral Hemodynamics ◽  
Layer Model ◽  
Adult Human ◽  
Two Layer Model

The development of a continuous-wave method is presented, to quantify accurately the optical properties of a two-layer model of the human head using a broadband spectral approach. In particular, focus is put on the reconstruction of the absolute absorption and scattering properties of a two-layered phantom model of the human head with steady-state multi-distance measurements by performing differential fit analysis of the near-infrared (NIR) reflectance spectrum between 700 nm and 1000 nm. The two-layer model approximation was fitted to experimental broadband absorbance measurements obtained from two-layered phantoms with known optical properties. Results demonstrated that the suggested method was able to determine the optical properties of the lower layer with minimal error at specific source-detector distances. Preliminary results on the non-invasive measurement of the optical properties of the adult human brain in a two-layer approximation are presented. Finally, a mobile wireless NIR device is used to measure changes in the temporal characteristics of cerebral hemodynamic responses to functional brain activity, in particulaur the effect of smoking. Results suggest that assuming homogeneous medium for the adult human head severely underestimates the changes in cerebral hemodynamics. Hence, it is important to take surrounding layers into consideration when performing cerebral measurements using NIR spectroscopy.

A type-II C2N/α-Te van der Waals heterojunction with improved optical properties by external perturbation

2019 ◽  
Vol 21 (39) ◽  
pp. 21753-21760 ◽  
Author(s):  
Zhuang Ma ◽  
Yusheng Wang ◽  
Yuting Wei ◽  
Chong Li ◽  
Xiuwen Zhang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Broad Spectrum ◽  
Near Infrared ◽  
External Perturbation ◽  
Band Alignment ◽  
Type Ii ◽  
Unique Type ◽  
Spectrum Width ◽  
Tunable Band Gap

The C2N/α-Te vdW heterojunction possessed a unique type-II band alignment, tunable band gap, improved optical absorption strength, and broad spectrum width (ultraviolet to near-infrared).

scholarly journals Examining cerebral hemodynamics in a two-layer model of the human head using broadband near-infrared spectroscopy

2021 ◽  
Author(s):  
Olivia Pucci
Keyword(s):  
Optical Properties ◽  
Near Infrared ◽  
Continuous Wave ◽  
Lower Layer ◽  
Homogeneous Medium ◽  
Human Head ◽  
Cerebral Hemodynamics ◽  
Layer Model ◽  
Adult Human ◽  
Two Layer Model

The development of a continuous-wave method is presented, to quantify accurately the optical properties of a two-layer model of the human head using a broadband spectral approach. In particular, focus is put on the reconstruction of the absolute absorption and scattering properties of a two-layered phantom model of the human head with steady-state multi-distance measurements by performing differential fit analysis of the near-infrared (NIR) reflectance spectrum between 700 nm and 1000 nm. The two-layer model approximation was fitted to experimental broadband absorbance measurements obtained from two-layered phantoms with known optical properties. Results demonstrated that the suggested method was able to determine the optical properties of the lower layer with minimal error at specific source-detector distances. Preliminary results on the non-invasive measurement of the optical properties of the adult human brain in a two-layer approximation are presented. Finally, a mobile wireless NIR device is used to measure changes in the temporal characteristics of cerebral hemodynamic responses to functional brain activity, in particulaur the effect of smoking. Results suggest that assuming homogeneous medium for the adult human head severely underestimates the changes in cerebral hemodynamics. Hence, it is important to take surrounding layers into consideration when performing cerebral measurements using NIR spectroscopy.

Near-Infrared Diode Laser Based Spectroscopic Detection of Ammonia: A Comparative Study of Photoacoustic and Direct Optical Absorption Methods

2002 ◽  
Vol 56 (6) ◽  
pp. 715-719 ◽  
Author(s):  
Zoltán Bozóki ◽  
Árpád Mohácsi ◽  
Gábor Szabó ◽  
Zsolt Bor ◽  
Miklós Erdélyi ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Room Temperature ◽  
Near Infrared ◽  
Continuous Wave ◽  
Fast Response ◽  
Minimum Detectable Concentration ◽  
Mode Of Operation ◽  
Detectable Concentration ◽  
Ammonia Detection ◽  
Ppm Level

A photoacoustic spectroscopic (PAS) and a direct optical absorption spectroscopic (OAS) gas sensor, both using continuous-wave room-temperature diode lasers operating at 1531.8 nm, were compared on the basis of ammonia detection. Excellent linear correlation between the detector signals of the two systems was found. Although the physical properties and the mode of operation of both sensors were significantly different, their performances were found to be remarkably similar, with a sub-ppm level minimum detectable concentration of ammonia and a fast response time in the range of a few minutes.

scholarly journals Non-Invasive Measurement Of Tissue Chromophore Concentrations And Cerebral Blood Flow Using Broad-Band Continuous Wave Near Infrared Spectroscopy

2021 ◽  
Author(s):  
Hadi Zabihi-Yeganeh
Keyword(s):  
Blood Flow ◽  
Optical Properties ◽  
Cerebral Blood Flow ◽  
Infrared Spectroscopy ◽  
Indocyanine Green ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Continuous Wave ◽  
Broad Band ◽  
Optical Properties Of Tissue

We present a broad-band, continuous wave spectral approach to quantify the baseline optical properties of tissue, in particular the absolute absorption and scattering properties and changes in the concentrations of chromophores, which can assist to quantify the regional blood flow from dynamic contrast-enhanced near-infrared spectroscopy data. Experiments were conducted on phantoms and piglets. The baseline optical properties of tissue were determined by performing a multi-parameter wavelength-dependent differential data fit of the near infrared reflectance spectrum between 680 nm and 970 nm of a photon diffusion equation solution for a semi-infinite homogeneous medium. These baseline optical properties of the piglet head tissue were used to quantify the temporal dynamics of the concentration of the intravenously administered contrast agent Indocyanine Green in the piglet brain. The temporal traces of the Indocyanine Green concentration measured by our method were used to estimate the cerebral blood flow using a bolus tracking technique.

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