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In order to provide a more thorough explanation of the light scattering characteristics of wake in real marine environments, this study examined the variations in light scattering characteristics of wake bubbles induced by organic matter films in real marine environments. Drawing on Mie’s scattering theory, the study simulated the scattering intensity distribution, scattering coefficient, scattering phase function, and polarization degree of clean bubbles, as well as organic bubbles enveloped in protein and lipid films, under varying wavelengths of incident light. The simulation findings reveal that the scattering coefficients of clean bubbles and the two types of organic bubbles enveloped in films fluctuate around 2.025, with the organic bubbles exhibiting significantly larger oscillation amplitudes than the clean bubbles. Notably, at a scattering angle of 180°, the scattering intensity and scattering phase function of organic bubbles experience a notable increase. These organic bubbles can amplify the amplitude of scattering coefficient oscillations and the intensity of backscattering. The simulation results offer theoretical and data support for wake detection in real marine environments and provide a practical foundation for research on marine pollution monitoring and water quality assessment.

This paper presents the results of measurements of the optical characteristics of aerosol particles using a solar photometer and nephelometer from 2016 to 2021 obtained at the atmospheric monitoring station in Peterhof (59.88° N, 29.83° E). The measurements are compared with the MERRA-2 reanalysis data. It is shown that interseasonal variability is observed in the region, characterized by low values of the Angstrom exponent in winter and high values in the warm season. The backscatter fraction has a similar—but less pronounced—seasonal cycle. The average value of the turbidity coefficient for the period is less than 0.10, which makes it possible to determine the observation station as a background one. Using the HYSPLIT model, the origin of air masses forming the atmospheric air state at the observation station is determined when the limiting values of the measured scattering coefficients (<10 and >70) and the Angstrom exponent (<1) are realized. Air masses coming from the northwest correspond to clean and humid air from the marine area and are manifested in the minimum values of the measured parameters. The maximum values of the scattering coefficient are associated with fine aerosol entering the atmosphere both from regional emissions sources (urban pollution from the territory of St. Petersburg) and as a result of transboundary transport from southwestern directions. [ABSTRACT FROM AUTHOR]

Knowledge of the optical properties of blood plays important role in medical diagnostics and therapeutic applications in laser medicine. In this paper, we present a very rapid and accurate artificial intelligent approach using Dragonfly Algorithm/Support Vector Machine models to estimate the optical properties of blood, specifically the absorption coefficient, and the scattering coefficient using key parameters such as wavelength (nm), hematocrit percentage (%), and saturation of oxygen (%), in building very highly accurate Dragonfly Algorithm-Support Vector Regression models (DA-SVR). 1000 training and testing sets were selected in the wavelength range of 250-1200 nm and the hematocrit of 0-100%. The performance of the proposed method is characterized by high accuracy indicated in the correlation coefficients (R) of 0.9994 and 0.9957 for absorption and scattering coefficients, respectively. In addition, the root mean squared error values (RMSE) of 0.972 and 2.9193, as well as low mean absolute error values (MAE) of 0.2173 and 0.2423, this result showed a strong match with the experimental data. The models can be used to accurately predict the absorption and scattering coefficients of blood, and provide a reliable reference for future studies on the optical properties of human blood. [ABSTRACT FROM AUTHOR]

We present a goniometer designed for capturing spectral and angular-resolved data from scattering and absorbing media. The experimental apparatus is complemented by a comprehensive Monte Carlo simulation, meticulously replicating the radiative transport processes within the instrument's optical components and simulating scattering and absorption across arbitrary volumes. Consequently, we were able to construct a precise digital replica, or "twin", of the experimental setup. This digital counterpart enabled us to tackle the inverse problem of deducing optical parameters such as absorption and scattering coefficients, along with the scattering anisotropy factor from measurements. We achieved this by fitting Monte Carlo simulations to our goniometric measurements using a Levenberg–Marquardt algorithm. Validation of our approach was performed using polystyrene particles, characterized by Mie scattering, supplemented by a theoretical analysis of algorithmic convergence. Ultimately, we demonstrate strong agreement between optical parameters derived using our novel methodology and those obtained via established measurement protocols. [ABSTRACT FROM AUTHOR]

Surface scattering greatly impacts and improves the acoustic quality of an auditorium, affecting properties such as the reverberation time, early decay time, definition, and sound strength. However, this aspect has not been sufficiently investigated to date. In this study, six completed auditoriums are taken as research samples and computer simulations are performed to analyze the variation patterns in the acoustic-quality parameters as functions of increments in the surface scattering coefficients. The results show that the reverberation time and early decay time change marginally (<5%) when the ceiling scattering coefficient increases from 0.01 to 0.99. When the sidewall scattering coefficient increases, the reverberation time and early decay time shorten, and the variation range expands (5–16.7%). In most cases, the definition and sound strength do not significantly change (<0.05 and 1.0 dB). A balcony on the auditorium sidewall can affect the reverberation time-change curve when the sidewall scattering coefficient changes. Changes in the ceiling and sidewall scattering coefficients affect the reflected sound-energy distribution along the time axis differently. Sidewall scattering has a significantly greater impact on the impulse response than ceiling scattering. The findings of this study provide theoretical guidance for the scattering design of the surface of theater auditoriums. [ABSTRACT FROM AUTHOR]

We consider wave scattering from a system of highly contrasting resonators with time-modulated material parameters. In this setting, the wave equation reduces to a system of coupled Helmholtz equations that models the scattering problem. We consider the one-dimensional setting. In order to understand the energy of the system, we prove a novel higher-order discrete, capacitance matrix approximation of the subwavelength resonant quasi-frequencies. Further, we perform numerical experiments to support and illustrate our analytical results and show how periodically time-dependent material parameters affect the scattered wave field. [ABSTRACT FROM AUTHOR]

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To investigate the relationship between optical properties and soluble solids content (SSC) in different regions of Gong pear. The optical properties of the upper, middle and lower parts of Gong pear were measured by the single integrating sphere system in the range of 500–1100 nm. The differences of absorption coefficient ( μ a ) spectra and reduced scattering coefficient ( μ s ′ ) spectra in three regions of Gong pear were analyzed. The differences of μ a and μ s ′ at 670,710, 750, 800 and 980 nm were analyzed. Gong Pear SSC was positively correlated with μ a and μ s ′ in the range of 500–1050 nm.The local model of Gong pear SSC was established based on the μ a spectra and μ s ′ spectra in the upper, middle and lower regions respectively. And the partial least square regression (PLSR) model and support vector regression (SVR) model were established based on the mean μ a spectra, mean μ s ′ spectra and mean μ a + μ s ′ spectra after standard normal variables (SNV) pretreatment. The results showed that the optical properties of the upper, middle and lower sections of Gong pear were less different. Among all established SSC prediction models, the model based on the mean μ a spectra had the best prediction effect. Its correction coefficient of determination ( R c 2 ) and prediction coefficient of determination ( R P 2 ) were 0.894 and 0.837, and its correction root mean square error (RMSEC) and prediction root mean square error (RMSEP) were 0.305 and 0.429, respectively. The results showed that soluble solids content mainly affected the absorption characteristics of Gong pear, and the internal quality of Gong pear could be predicted better based on the absorption coefficient. [ABSTRACT FROM AUTHOR]

Continuous measurement of pressure is vital in many fields of industry, medicine, and science. Of particular interest is the ability to measure pressure in a noninvasive and contact-free manner. This work presents the potential of oblique incident reflectometry (OIR) to monitor variation in pressure via the reduced scattering parameter (μ s ′). Pressure deforms the geometry of the medium and causes distortion of its internal structure and the spatial distribution of optical properties. Light scattering is related to the morphology (size, density, distribution, etc.) and refractive index distributions of the medium, and applied pressure will influence directly these parameters. Therefore, we assume that pressure can be quantitatively assessed through monitoring the reduced scattering coefficient. For this purpose, the technique of OIR to evaluate the scattering parameter during pressure variations was utilized. OIR is a simple noninvasive and contact-free imaging technique able to quantify both absorption and scattering properties of a sample. In our setup, the medium is illuminated obliquely by a narrow laser beam, and the diffuse reflectance light is captured by a CCD camera. In offline processing, the shift (δ) of the diffuse light center from the incident point is mathematically analyzed and μ s ′ coefficient (μ s ′ ∼ δ − 1) is extracted. We present here confirmation of the validity of this assumption through results of a series of experiments performed on turbid liquid and artery occlusion of a human subject under different pressure levels. Thus, μ s ′ has the potential to serve as a good indicator for the monitoring of pressure. [ABSTRACT FROM AUTHOR]

SignificanceSpatial frequency domain imaging (SFDI) is a wide-field diffuse optical imaging technique for separately quantifying tissue reduced scattering (μs  '  ) and absorption (μa) coefficients at multiple wavelengths, providing wide potential utility for clinical applications such as burn wound characterization and cancer detection. However, measured μs  '   and μa can be confounded by absorption from melanin in patients with highly pigmented skin. This issue arises because epidermal melanin is highly absorbing for visible wavelengths and standard homogeneous light-tissue interaction models do not properly account for this complexity. Tristimulus colorimetry (which quantifies pigmentation using the L  *   "lightness" parameter) can provide a point of comparison between μa, μs  '  , and skin pigmentation.AimWe systematically compare SFDI and colorimetry parameters to quantify confounding effects of pigmentation on measured skin μs  '   and μa. We assess the correlation between SFDI and colorimetry parameters as a function of wavelength.Approachμs  '   and μa from the palm and ventral forearm were measured for 15 healthy subjects with a wide range of skin pigmentation levels (Fitzpatrick types I to VI) using a Reflect RS® (Modulim, Inc., Irvine, California) SFDI instrument (eight wavelengths, 471 to 851 nm). L  *   was measured using a Chroma Meter CR-400 (Konica Minolta Sensing, Inc., Tokyo). Linear correlation coefficients were calculated between L  *   and μs  '   and between L  *   and μa at all wavelengths.ResultsFor the ventral forearm, strong linear correlations between measured L  *   and μs  '   values were observed at shorter wavelengths (R  >  0.92 at ≤659  nm), where absorption from melanin confounded the measured μs  '  . These correlations were weaker for the palm (R

Atmospheric aerosols play a pivotal role in the earth-atmospheric system. Analyzing their optical properties, specifically absorption and scattering coefficients, is essential for comprehending the impact of aerosols on climate. When different optical properties of aerosols are individually measured using multiple devices, cumulative errors in the detection results inevitably occur. To address this challenge, based on photoacoustic spectroscopy (PAS) and integrating sphere (IS) scattering enhancement, a compact gas cell (PASIS-Cell) was developed. The PASIS-Cell comprises a dual-T-type photoacoustic cell (DTPAC) and an IS. IS is coupled with DTPAC through a transparent quartz tube, thereby enhancing the scattering signal without compromising the acoustic characteristics of DTPAC. Concurrently, DTPAC can realize high-performance photoacoustic detection of absorption signal. Experimental results demonstrate that PASIS-Cell can simultaneously invert atmospheric aerosol absorption and scattering coefficients, with a minimum detection limit of less than 1 Mm−1, showcasing its potential in the analysis of aerosol optical properties.

To determine the complex refractive indices of aerosol particles in the atmospheric boundary layer, simultaneous measurements of scattering coefficients at 450, 550, and 700 nm wavelengths, absorption coefficient at 565 nm, and aerosol particle number size distributions were performed during a voyage of the icebreaker Shirase from Tokyo to the offing of the Philippines over the northwestern Pacific in November 2010. Three sets of Ångström exponents were calculated using the three observed scattering coefficients. Using the observed number size distributions, three sets of Ångström exponents were reproduced by assuming their complex refractive indices. Appropriate complex refractive indices for aerosol particles in the atmospheric boundary layer can be obtained when the difference between the observed and reproduced Ångström exponents is minimal. Absorbing substances were assumed to be present in the fine particles. For polluted air masses, if the refractive index for aerosol particles was uniform regardless of the particle size, the estimated Ångström exponents were consistent with the observed values. The refractive index must be the normal dispersion, which increases with a decrease in wavelength. For pristine air masses, the refractive index was estimated to be higher for coarse particles than for fine particles. This could be explained by preferential condensation of organic compounds onto coarse particles, which is observed to alter the number size distribution over Chichi-jima of the Ogasawara Islands in the northwestern Pacific in August 2014 and February 2015. This study is the first to report that the increase in the refractive index of coarse particles is likely caused by the optical properties of volatile organic compounds and/or secondary organic aerosols condensed on coarse particles. [ABSTRACT FROM AUTHOR]

The results of the modernization of the mobile aerosol Raman lidar LOZA-A2 are presented. Lidar measures purely rotational Raman scattering signals simultaneously with measurements of the vibrational component of spontaneous Raman scattering of lidar signals. The technique for interpreting Raman lidar sensing data is considered. Data are obtained from simultaneous measurements of vibrational–rotational and purely rotational Raman scattering in atmospheric sensing over the Lake Baikal. The results are presented from retrieving the vertical profiles of the optical characteristics of the atmosphere at a wavelength of 532 nm using these data. [ABSTRACT FROM AUTHOR]

Accurate determination of the optical properties of biological tissues enables quantitative understanding of light propagation in these tissues for optical diagnosis and treatment applications. The absorption ( μ a ) and scattering ( μ s ) coefficients of biological tissues are inversely analyzed from their diffuse reflectance (R) and total transmittance (T), which are measured using a double integrating spheres (DIS) system. The inversion algorithms, for example, inverse adding doubling method and inverse Monte Carlo method, are sensitive to noise signals during the DIS measurements, resulting in reduced accuracy during determination. In this study, we propose an artificial neural network (ANN) to estimate μ a and μ s at a target wavelength from the R and T spectra measured via the DIS to reduce noise in the optical properties. Approximate models of the optical properties and Monte Carlo calculations that simulated the DIS measurements were used to generate spectral datasets comprising μ a , μ s , R and T. Measurement noise signals were added to R and T, and the ANN model was then trained using the noise-added datasets. Numerical results showed that the trained ANN model reduced the effects of noise in μ a and μ s estimation. Experimental verification indicated noise-reduced estimation from the R and T values measured by the DIS with a small number of scans on average, resulting in measurement time reduction. The results demonstrated the noise robustness of the proposed ANN-based method for optical properties determination and will contribute to shorter DIS measurement times, thus reducing changes in the optical properties due to desiccation of the samples. [ABSTRACT FROM AUTHOR]

Surface scattering greatly impacts and improves the acoustic quality of an auditorium, affecting properties such as the reverberation time, early decay time, definition, and sound strength. However, this aspect has not been sufficiently investigated to date. In this study, six completed auditoriums are taken as research samples and computer simulations are performed to analyze the variation patterns in the acoustic-quality parameters as functions of increments in the surface scattering coefficients. The results show that the reverberation time and early decay time change marginally (

We present a goniometer designed for capturing spectral and angular-resolved data from scattering and absorbing media. The experimental apparatus is complemented by a comprehensive Monte Carlo simulation, meticulously replicating the radiative transport processes within the instrument’s optical components and simulating scattering and absorption across arbitrary volumes. Consequently, we were able to construct a precise digital replica, or “twin”, of the experimental setup. This digital counterpart enabled us to tackle the inverse problem of deducing optical parameters such as absorption and scattering coefficients, along with the scattering anisotropy factor from measurements. We achieved this by fitting Monte Carlo simulations to our goniometric measurements using a Levenberg–Marquardt algorithm. Validation of our approach was performed using polystyrene particles, characterized by Mie scattering, supplemented by a theoretical analysis of algorithmic convergence. Ultimately, we demonstrate strong agreement between optical parameters derived using our novel methodology and those obtained via established measurement protocols.

Accurate determination of the optical properties of biological tissues enables quantitative understanding of light propagation in these tissues for optical diagnosis and treatment applications. The absorption ([Formula: see text]) and scattering ([Formula: see text]) coefficients of biological tissues are inversely analyzed from their diffuse reflectance (R) and total transmittance (T), which are measured using a double integrating spheres (DIS) system. The inversion algorithms, for example, inverse adding doubling method and inverse Monte Carlo method, are sensitive to noise signals during the DIS measurements, resulting in reduced accuracy during determination. In this study, we propose an artificial neural network (ANN) to estimate [Formula: see text] and [Formula: see text] at a target wavelength from the R and T spectra measured via the DIS to reduce noise in the optical properties. Approximate models of the optical properties and Monte Carlo calculations that simulated the DIS measurements were used to generate spectral datasets comprising [Formula: see text], [Formula: see text], R and T. Measurement noise signals were added to R and T, and the ANN model was then trained using the noise-added datasets. Numerical results showed that the trained ANN model reduced the effects of noise in [Formula: see text] and [Formula: see text] estimation. Experimental verification indicated noise-reduced estimation from the R and T values measured by the DIS with a small number of scans on average, resulting in measurement time reduction. The results demonstrated the noise robustness of the proposed ANN-based method for optical properties determination and will contribute to shorter DIS measurement times, thus reducing changes in the optical properties due to desiccation of the samples.

Manipulating the wavefront of coherent light incident on scattering media to enhance the imaging depth, sensitivity, and resolution is a common technique in biomedical applications. Local phase variations cause changes in the interference and can be used to create a focus inside or behind a scattering medium. We use wavefront shaping (WFS) to force constructive interference at an arbitrary location. The amount of light transmitted into a given region strongly depends on the scattering and absorption characteristics. These are described by their respective coefficients μ s and μ a and the scattering phase function. Controlling the scattering and absorption coefficients, we study the behavior of wavefront shaping and the achievable intensity enhancement behind volume scattering media with well-defined optical properties. The phantoms designed in this publication are made of epoxy resin. Into these epoxy matrices, specific amounts of scattering and absorbing particles, such as titanium dioxide pigments and molecular dyes, are mixed. The mixture obtained is filled into 3D-printed frames of various thicknesses. After a precise fabrication procedure, an integrating sphere-based setup characterizes the phantoms experimentally. It detects the total hemispherical transmission and reflection. Further theoretical characterization is performed with a newly developed hybrid P N method. This method senses the flux of light into a particular angular range at the lower boundary of a slab. The calculations are performed without suffering from ringing and fulfill the exact boundary conditions there. A decoupled two-path detection system allows for fast optimization as well as sensitive detection. The measurements yield results that agree well with the theoretically expected behavior. [ABSTRACT FROM AUTHOR]

Ellipsometrically obtained spectral dependences of ordinary αxy and extra-ordinary αz extinction/attenuation coefficients within the spectral range λ = 300…980 nm of uniaxially anisotropic polytetrafluoroethylene (PTFE) films were analyzed. We considered the capabilities and specific features of the graphical representation technique for determining the contribution of Rayleigh scattering and Urbach absorption to light attenuation in the spectral range beyond fundamental absorption. It has been shown that the graphical approach enables to estimate these contributions qualitatively, semi-quantitatively or quantitatively, depending on the situation. The conclusions made using the analysis of graphical representation are confirmed by numerical solution of the inverse problem via simulation of the αxy (λ), αz (λ) experimental dependences within the framework of a best-fit procedure. Being based on both of these approaches, we have ascertained that, in the as-prepared PTFE films, the so-called anomalous light scattering (ALS) with the spectral dependence of scattering coefficient αs ≈ as λ–p (p > 4) takes place. Transformation of scattering from ALS to the Rayleigh one with p ≅ 4 due to annealing is accompanied by an increase of Urbach (subband) absorption. Both of these factors cause narrowing the dynamic range of extinction coefficient values. Both scattering and absorption coefficients are higher for the component of light polarized along the normal to the substrate as compared to the component polarized in parallel to it. The relationship between observed behavior of the scattering and absorption coefficients and the film structure has been discussed. [ABSTRACT FROM AUTHOR]

The Kubelka-Munk function is simple but it ignores the film's thickness, so its applications are greatly limited. Though the exact relationship between the Kubelka-Munk function and the thickness can be derived from a differential model, it is too complex to be practically used. Here a modification is suggested by taking the thickness effect and the temperature effect into account, and the validity is widely enlarged. The modified Kubelka-Munk theory can be used as a colormatching model for colorful fabrics. If the porosity of the film is considered, a fractal modification with two-scale fractal derivative has to be adopted. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) irradiation causes 90% of photodamage to skin and long-term exposure to UV irradiation is the largest threat to skin health. To study the mechanism of UV-induced photodamage and the repair of sunburnt skin, the key problem to solve is how to non-destructively and continuously evaluate UV-induced photodamage to skin. In this study, a method to quantitatively analyze the structural and tissue optical parameters of artificial skin (AS) using optical coherence tomography (OCT) was proposed as a way to non-destructively and continuously evaluate the effect of photodamage. AS surface roughness was achieved based on the characteristic peaks of the intensity signal of the OCT images, and this was the basis for quantifying AS cuticle thickness using Dijkstra's algorithm. Local texture features within the AS were obtained through the gray-level co-occurrence matrix method. A modified depth-resolved algorithm was used to quantify the 3D scattering coefficient distribution within AS based on a single-scattering model. A multiparameter assessment of AS photodamage was carried out, and the results were compared with the MTT experiment results and H&E staining. The results of the UV photodamage experiments showed that the cuticle of the photodamaged model was thicker (56.5%) and had greater surface roughness (14.4%) compared with the normal cultured AS. The angular second moment was greater and the correlation was smaller, which was in agreement with the results of the H&E staining microscopy. The angular second moment and correlation showed a good linear relationship with the UV irradiation dose, illustrating the potential of OCT in measuring internal structural damage. The tissue scattering coefficient of AS correlated well with the MTT results, which can be used to quantify the damage to the bioactivity. The experimental results also demonstrate the anti-photodamage efficacy of the vitamin C factor. Quantitative analysis of structural and tissue optical parameters of AS by OCT enables the non-destructive and continuous detection of AS photodamage in multiple dimensions. [ABSTRACT FROM AUTHOR]

For most of nanostructured glasses (NGs) (phase-separated glasses and glass-ceramics), the light scattering coefficient (turbidity) is described by a power function of the inverse wavelength with an exponent which differs appreciably from the Rayleigh value 4 and is called the scattering exponent. The knowledge of the scattering exponent of a material is important from both fundamental and practical points of view. Previously, we developed three rather complex methods to determine the scattering exponent. Here, we present a novel simple express method for its estimation. In the method, the measured optical density for only one sample is used, the refractive index of the material is not required, and the dispersion of refractive index is assumed to be insignificant. The method is based on the differentiation of the measured optical density with respect to the wavelength. The scattering exponent values obtained by the new method for NGs of different types are in good agreement with those found by the traditional methods. The new method is found to be applicable even to NGs with high dispersion of refractive index. Thus, the new method does not require the data on the refractive index dispersion and can be applied without restrictions. [ABSTRACT FROM AUTHOR]

Apple bruises are a common defect that diminishes fruits' economic value. Therefore, an effective method for detecting fruit bruises is crucial. Nondestructive testing methods, such as near-infrared and hyperspectral imaging typically use tissue absorption properties, disregarding scattering as noise even if fruit tissues are highly scattering media. This study created a spatial frequency domain imaging system to identify early apple bruises by focusing on scattering properties. The optical parameters of bruised and nonbruised apple tissues were determined using a new inversion method proposed in this paper. Comparative analysis shows that the alternating current (AC) component is more effective in detecting early bruises than the direct current (DC) component. The ratio of the AC to DC components in structured-light images helped in identifying bruises. Suspicious points are identified using Difference of Gaussians images and Hough circle detection, where these points correspond to potential locations of bruises. Subsequently, subimages were extracted and a classification algorithm was used to evaluate the presence of bruises within those subimages. The classification accuracies of decision trees, linear discriminant analysis, K-nearest neighbors, and support vector machines (SVM) are 94.56 %, 98.12 %, 97.75 %, and 99.81 %, respectively. Ultimately, SVM combined with a localization algorithm achieved a classification accuracy of 98.78 % for apples and accurately identified the locations of all bruises. The results demonstrate that the proposed method achieves remarkable detection accuracy, providing a new approach for detecting apple bruises. • A new matrix method with high accuracy for optical parameter inversion was proposed. • Optical parameter lookup tables were generated to improve the efficiency of SFDI. • Comparison of optical parameters in bruised and non-bruised apples was carried out. • A method for early bruise localization was developed with an accuracy of 98.78 %. [ABSTRACT FROM AUTHOR]

Based on the particle spectrum of floating dust, with the analysis of the scattering efficiency factor and scattering coefficient of floating dust particle size by Mie scattering theory; Monte Carlo method was used to simulate and analyze the effect of floating dust particle size and concentration on UV communication in floating dust weather. Finally, an experimental device was built to test and analyze the effects of particle size and concentration on UV communication performance in different floating dust weather, the results of which were then contrasted with the simulation ones. The results show that: 1) the scattering efficiency factor and extinction efficiency factor of floating dust particles show an oscillatory attenuation trend, and the oscillation finally converges near 2.07 and 1.14 with the increase of scale parameters, respectively. 2) When the floating dust concentration is constant, the path loss of UV communication decreases first and then increases with the increase of particle size, and the radius of the minimum is 1.0~1.5 μm. 3) During short distance communication in dusty weather, the path loss decreases with the increase of dust concentration and increases with the increase of communication distance and transceiver elevation.

The study investigates the dynamics of the Russian scientific journals input stream based on the results of article classification, according to the State Rubricator of Scientific and Technical Information in the VINITI RAS Database. The authors aim to trace the changes in the information provision of the codes of the subject field Chemistry, chemical technology, and the chemical industry. The research procedure presented includes the methods of calculating the indicators that allow to automate the assessment of journals thematic profiles—the similarity and scattering coefficients. The proposed methodology facilitates the identification of trends in the thematic profiles of serial publications, i.e., growth or degradation of their headings, thus contributing to the optimization of the information center documents input stream. [ABSTRACT FROM AUTHOR]

MieLab software was used to perform calculations of the scattering of electromagnetic radiation by single or multilayered spheres. The scattering efficiency results allowed the calculation of scattering coefficients SMie, which were then used to compare the scattering performance of different materials and composites. Furthermore, the simulation results were compared to experimental results obtained from testing real paint films using the Kubelka–Munk treatment for TiO2-only systems (SCoat). It was found that SMie follows the same profile as SCoat in response to the change in pigment volume concentration. The MieLab simulations were also applied to two composite configurations, hollow sphere nanoparticles or mesoporous silica nanoparticles attached to a TiO2 pigmentary size particle. The results showed that neither of these configurations is a viable solution for increasing scattering efficiency of TiO2 in the range of typical PVCs. [ABSTRACT FROM AUTHOR]

Manipulating the wavefront of coherent light incident on scattering media to enhance the imaging depth, sensitivity, and resolution is a common technique in biomedical applications. Local phase variations cause changes in the interference and can be used to create a focus inside or behind a scattering medium. We use wavefront shaping (WFS) to force constructive interference at an arbitrary location. The amount of light transmitted into a given region strongly depends on the scattering and absorption characteristics. These are described by their respective coefficients μs and μa and the scattering phase function. Controlling the scattering and absorption coefficients, we study the behavior of wavefront shaping and the achievable intensity enhancement behind volume scattering media with well-defined optical properties. The phantoms designed in this publication are made of epoxy resin. Into these epoxy matrices, specific amounts of scattering and absorbing particles, such as titanium dioxide pigments and molecular dyes, are mixed. The mixture obtained is filled into 3D-printed frames of various thicknesses. After a precise fabrication procedure, an integrating sphere-based setup characterizes the phantoms experimentally. It detects the total hemispherical transmission and reflection. Further theoretical characterization is performed with a newly developed hybrid PN method. This method senses the flux of light into a particular angular range at the lower boundary of a slab. The calculations are performed without suffering from ringing and fulfill the exact boundary conditions there. A decoupled two-path detection system allows for fast optimization as well as sensitive detection. The measurements yield results that agree well with the theoretically expected behavior.

In the cosmetics industry, fine particles suspended or dispersed in a medium are widely used. Optical properties of the medium can be an indicator for evaluating the performance of cosmetic product, such as the ultraviolet protection capacity of sunscreens and also its appearance. However, the relationship between the optical properties and the appearance of the product has not been clarified. In this study, dispersions of fine particles with titanium dioxide or zinc oxide were used as scattering medium to clarify the relation between their scattering properties and changes in visual perception. For visual perception, sensory tests with human panelists were performed using a custom-designed apparatus to inspect the samples and evaluate the two visual sensory quantities, "glossiness" and "translucency". The sensory test employed Thurston's one-pair comparison method, and a total of 18 panelists were asked to evaluate the samples. The sensory tests showed that the translucency became stronger as the scattering coefficient decreased. On the other hand, only the samples in the group with the highest scattering coefficient showed a slightly low glossiness. In contrast, the other samples showed little difference in glossiness due to the difference in scattering coefficients. The results of this study indicate that the appearance of cosmetics products can be influenced by controlling the scattering properties of the medium. [ABSTRACT FROM AUTHOR]

In this article, we propose a new approach utilizing diffuse optical tomography (DOT) to monitoring the changes in tissues' optical properties and temperature in high-intensity focused ultrasound (HIFU) therapy. By correlating the tissue reduced scattering coefficient ( μ s ' ) reconstructed by DOT and the temperature measured by a thermocouple, the quantitative relationship between μ s ' and temperature in HIFU treatment was explored. The experiments were conducted using porcine and chicken breast muscle tissues during HIFU; the temperature of each tissue sample was recorded using a thermocouple. To incorporate the temperature dependency of tissue optical properties, both polynomial and exponential models were utilized to fit the experimental data. The results show that the change of μ s ' during HIFU treatment could be detected in real-time using DOT and that this change of μ s ' is quantitatively correlated with tissue temperature. Furthermore, while the tissue-type-dependent relationship between μ s ' and temperature is non-linear in nature, it is stable and repeatable. Therefore, our approach has the potential to be used to predict temperature of tissue during HIFU treatment. [ABSTRACT FROM AUTHOR]

Due to the dyeing process, learning samples used for color prediction of pre-colored fiber blends should be re-prepared once the batches of the fiber change. The preparation of the sample is time-consuming and leads to manpower and material waste. The two-constant Kubelka-Munk theory is selected in this article to investigate the feasibility to minimize and optimize the learning samples for the theory since it has the highest prediction accuracy and moderate learning sample size requirement among all the color prediction models. Results show that two samples, namely, a masstone obtained by 100% pre-colored fiber and a tint mixed by 40% pre-colored fiber and 60% white fiber, are enough to determine the absorption and scattering coefficients of a pre-colored fiber. In addition, the optimal sample for the single-constant Kubelka-Munk theory is also explored. [ABSTRACT FROM AUTHOR]

The natural occurrences of haze, mist and fog obscures the optically captured outdoor scenes. The essential parameters of the atmospheric scattering model for dehazing are air-light (which depends on atmospheric light) and transmission map. Inaccurate estimation of these parameters leads to halo-artifacts, color distortions, etc. The performance of the available single-image dehazing models is limited by the color shifts caused due to the offset of light sources. The proposed work estimates the atmospheric light component by considering the lowest entropy from the quad-decomposed image as the haze opaque regions in the scene considered has low entropy. The transmission map is estimated by computing the scattering parameter, further refined with the holistic edges to calculate haze at different densities. A regression model is trained with the haze relevant features such as hue disparity, contrast, and darkness to compute the scattering coefficient rigorously. This improves the color shifts and visibility of the degraded outdoor scenes and mitigates the imbalances in the haze density concentrations in the scenes. The current model is evaluated using reference-based and non-reference based metrics to emphasize its perceptibility on hazy images when blended with pure light and non-achromatic light. The evaluations on real-hazy images signify that the true colors are well preserved, and the degree of visibility is improved compared to the state-of-the-art models. [ABSTRACT FROM AUTHOR]

Next generation in-to-out-of body biomedical applications have adopted optical wireless communications (OWCs). However, by delving into the published literature, a gap is recognized in modeling the in-to-out-of channel, since most published contributions neglect the particularities of different types of tissues. In this paper, we present a novel pathloss and scattering models for in-to-out-of OWC links. Specifically, we derive extract analytical expressions that accurately describe the absorption of the five main tissues' constituents, namely fat, water, melanin, and oxygenated and de-oxygenated blood. Moreover, we formulate a model for the calculation of the absorption coefficient of any generic biological tissue. Next, by incorporating the impact of scattering in the aforementioned model, we formulate the complete pathloss model. The developed model is verified by means of comparisons between the estimated pathloss and experimental measurements from independent research works. Finally, we illustrate the accuracy of the proposed model in estimating the optical properties of any generic tissue based on its constitution. The extracted channel model is expected to enable link budget analysis, performance analysis, and theoretical framework development, which will boost the design of optimized communication protocols for a plethora of biomedical applications. [ABSTRACT FROM AUTHOR]

We proposed a diffuse imaging approach for universal noninvasive blood glucose measurements based on visible light, which can predict the blood glucose concentration without personal calibration. The proposed approach used a CCD to obtain diffuse images from human index finger pulp. The denoising autoencoder algorithm adopted effectively extracted the scattering information highly related to blood glucose concentration from the diffuse images, and the gradient boosting regression algorithm enabled an accurate calculation of blood glucose concentration without prior personalized calibration. In vivo experimental results showed that the proposed approach had a mean absolute error of 19.44 mg/dl, with all the predicted results observed within the clinically acceptable region (Region A: 78.9%) in the Clarke error grid analysis. Compared to other blood glucose concentration measurement methods of scattering coefficient, this new method does not require individual calibration, therefore it is easier to implement and popularize, which is critical for the noninvasive monitoring of blood glucose concentration.

Ultraviolet (UV) irradiation causes 90% of photodamage to skin and long-term exposure to UV irradiation is the largest threat to skin health. To study the mechanism of UV-induced photodamage and the repair of sunburnt skin, the key problem to solve is how to non-destructively and continuously evaluate UV-induced photodamage to skin. In this study, a method to quantitatively analyze the structural and tissue optical parameters of artificial skin (AS) using optical coherence tomography (OCT) was proposed as a way to non-destructively and continuously evaluate the effect of photodamage. AS surface roughness was achieved based on the characteristic peaks of the intensity signal of the OCT images, and this was the basis for quantifying AS cuticle thickness using Dijkstra’s algorithm. Local texture features within the AS were obtained through the gray-level co-occurrence matrix method. A modified depth-resolved algorithm was used to quantify the 3D scattering coefficient distribution within AS based on a single-scattering model. A multiparameter assessment of AS photodamage was carried out, and the results were compared with the MTT experiment results and H&E staining. The results of the UV photodamage experiments showed that the cuticle of the photodamaged model was thicker (56.5%) and had greater surface roughness (14.4%) compared with the normal cultured AS. The angular second moment was greater and the correlation was smaller, which was in agreement with the results of the H&E staining microscopy. The angular second moment and correlation showed a good linear relationship with the UV irradiation dose, illustrating the potential of OCT in measuring internal structural damage. The tissue scattering coefficient of AS correlated well with the MTT results, which can be used to quantify the damage to the bioactivity. The experimental results also demonstrate the anti-photodamage efficacy of the vitamin C factor. Quantitative analysis of structural and tissue optical parameters of AS by OCT enables the non-destructive and continuous detection of AS photodamage in multiple dimensions.

Based on the particle spectrum of floating dust, with the analysis of the scattering efficiency factor and scattering coefficient of floating dust particle size by Mie scattering theory; Monte Carlo method was used to simulate and analyze the effect of floating dust particle size and concentration on UV communication in floating dust weather. Finally, an experimental device was built to test and analyze the effects of particle size and concentration on UV communication performance in different floating dust weather, the results of which were then contrasted with the simulation ones. The results show that: 1)the scattering efficiency factor and extinction efficiency factor of floating dust particles show an oscillatory attenuation trend, and the oscillation finally converges near 2.07 and 1.14 with the increase of scale parameters, respectively. 2)When the floating dust concentration is constant, the path loss of UV communication decreases first and then increases with the increase of particle size, and the radius of the minimum is 1.0～1.5 μm. 3)During short distance communication in dusty weather, the path loss decreases with the increase of dust concentration and increases with the increase of communication distance and transceiver elevation. [ABSTRACT FROM AUTHOR]

We present a review of short-wave infrared (SWIR, defined here as ∼1000 to 2000 nm) spectroscopy and imaging techniques for biological tissue optical property characterization. Studies indicate notable SWIR absorption features of tissue constituents including water (near 1150, 1450, and 1900 nm), lipids (near 1040, 1200, 1400, and 1700 nm), and collagen (near 1200 and 1500 nm) that are much more prominent than corresponding features observed in the visible and near-infrared (VIS-NIR, defined here as ∼400 to 1000 nm). Furthermore, the wavelength dependence of the scattering coefficient has been observed to follow a power-law decay from the VIS-NIR to the SWIR region. Thus, the magnitude of tissue scattering is lower at SWIR wavelengths than that observed at VIS or NIR wavelengths, potentially enabling increased penetration depth of incident light at SWIR wavelengths that are not highly absorbed by the aforementioned chromophores. These aspects of SWIR suggest that the tissue spectroscopy and imaging in this range of wavelengths have the potential to provide enhanced sensitivity (relative to VIS-NIR measurements) to chromophores such as water and lipids, thereby helping to characterize changes in the concentrations of these chromophores due to conditions such as atherosclerotic plaque, breast cancer, and burns.

• Development of a 1/2-scale phantom using computational tomography (CT) data from a peritoneal carcinomatosis patient. • One of the strategies to ensure uniform light delivery in photodynamic therapy (PDT) involves controlling the concentration of scattering media. • Through the measurement of scattered light fluence and the calculation of the uniformity index, we determined the optimal concentration of scattering media for PDT. Photodynamic therapy (PDT), which exerts its effects through the coexistence of light, photosensitizer, and oxygen, has emerged as a promising clinical therapeutic tool for cancer treatment. An even distribution of light energy is a prerequisite for the safe and effective treatment of peritoneal carcinomatosis. To overcome unpredictable light delivery to the irregular surface, we used light dosimetry of a peritoneal cavity filled with light scattering media. For this study, we made a 3d-printed phantom based on the CT (Computed Tomography) data of a peritoneal carcinomatosis patient. Four isotropic probes were placed inside the peritoneal cavity by creating holes to measure the scattered light in the peritoneal space. Four irradiating catheters were located in four designated spaces. In this measurement, we found the optimal concentration of scattering media for PDT is 0.15% Winuf. This phantom model and our research strategy will guide the implementation of irradiation for safe and effective PDT of peritoneal carcinomatosis. [ABSTRACT FROM AUTHOR]