Broadband absorption and reduced scattering spectra of in-vivo skin can be noninvasively determined using δ-P_1 approximation based spectral analysis

Abstract

Previously, we revealed that a linear gradient line source illumination (LGLSI) geometry could work with advanced diffusion models to recover the sample optical properties at wavelengths where sample absorption and reduced scattering were comparable. In this study, we employed the LGLSI geometry with a broadband light source and utilized the spectral analysis to determine the broadband absorption and scattering spectra of turbid samples in the wavelength range from 650 to 1350 nm. The performance of the LGLSI δ-P 1 diffusion model based spectral analysis was evaluated using liquid phantoms, and it was found that the sample optical properties could be properly recovered even at wavelengths above 1000 nm where μ s ' to μ a ratios were in the range between 1 to 20. Finally, we will demonstrate the use of our system for recovering the 650 to 1350 nm absorption and scattering spectra of in-vivo human skin. We expect this system can be applied to study deep vessel dilation induced hemoglobin concentration variation and determine the water and lipid concentrations of in-vivo skin in clinical settings in the future.

Formation of refractory black carbon by SP2-induced charring of organic aerosol

“…The behavior exhibited by nigrosin under varying laser power suggests that nigrosin is charring, thereby producing the rBC detected by the SP2. Nigrosin possesses a broad absorption spectrum that spans into the near-IR, with an imaginary component of refractive index at 1064 nm estimated to be 0.07 based on Bluvshtein et al (2017) and Hung et al (2015). The proposed explanation for this behavior is that nigrosin molecules absorb 1064 nm laser light, heating the particle sufficiently that chemical reactions result in charring of a fraction of the nigrosin, with the formed rBC material continuing to heat in the SP2 laser until incandescence.…”

“…Aerosols were generated from deionized water-based stock solutions of nigrosin (Aldrich, 198285;NKbg74932; 4 mg/g) and carbon black (CAB-O-JETV R 200 pigment; Cabot Corp; 110 mg/g) using a constant output atomizer (TSI; model 3076) and dried inline in a diffusion drier (Topas; model DDU 570/H). Nigrosin, a water-soluble, polyaniline-based black dye is often used in studies of atmospheric aerosol absorption as it possesses a broad, featureless absorption spectrum in the visible and near-IR (Bluvshtein et al, 2017;Hung et al, 2015) and dries to make spherical particles (Lack et al, 2006). Carbon black was used as BC reference material for comparison with nigrosin.…”

Effect of skin color on optical properties and the implications for medical optical technologies: a review

“…[37][38][39][40][41]48 Published scattering data were available from 289 subjects for FST III-IV. 39,41,[44][45][46][47] Only two manuscripts described scattering data for FST V-VI from a total of seven recruits. 39,41 Variability between the published data within each FST group at given wavelength is huge with the average difference between the maximum and minimum reduced scattering coefficients across the measured wavelengths being 98%, 25%, and 31% for FST I-II, III-V, and V-VI, respectively.…”

“…At this depth, it is virtually impossible to focus the light with standard optics and without the use of wave-front correction or adaptive optics. [37][38][39][40][41][42][43]48 III-IV, 39,41,42,[44][45][46][47] and V-VI. 39,41,42 The results gathered from the published data and analyzed here suggest that beyond 600 nm the depth at which an image could potentially be formed increases with increasing wavelength and is greatest for FST I-II at 980 to 1000 nm being 1.37 mm, for FST III-IV at 1470 nm being 1.27 mm, and for FST V-VI at 940 nm being 0.83 mm.…”

Tissue Phantoms for Biomedical Applications in Raman Spectroscopy: A Review

“…The reduced scattering and absorption coefficients are based on experimental data of healthy human tissue at 830 nm for different skin layers, 25 brain, 26,27 breast, 28 cranial bone, 29 liver, 30 muscle, 31 stomach wall mucosa, 32 colon, 33 prostate, 34 skull, 26 and whole blood. 35 Optical properties of the scattering and absorbing media included in the plot were also derived from the literature for nigrosin, 36 TiO 2 , 37 milk, 38 Liposyn, 39 hemoglobin, 40 indocyanine green (ICG), 39 Intralipid, 41 and India ink. 42 The exact values used in the figure can be found in Supplementary Material (S1).…”