Light scattering

About: Light scattering is a research topic. Over the lifetime, 37721 publications have been published within this topic receiving 861581 citations.

Mie and Rayleigh modeling of visible-light scattering in neonatal skin

Abstract: Reduced-scattering coefficients of neonatal skin were deduced in the 450-750-nm range from integrating-sphere measurements of the total reflection and total transmission of 22 skin samples. The reduced-scattering coefficients increased linearly at each wavelength with gestational maturity. The distribution of diameters d and concentration ρ(A) of the skin-sample collagen fibers were measured in histological sections of nine neonatal skin samples of varying gestational ages. An algorithm that calculates Mie scattering by cylinders was used to model the scattering by the collagen fibers in the skin. The fraction of the reduced-scattering coefficient µ(s)' that was attributable to Mie scattering by collagen fibers, as deduced from wavelength-dependent analysis, increased with gestational age and approached that found for adult skin. An assignment of 1.017 for n(rel), the refractive index of the collagen fibers relative to that of the surrounding medium, allowed the values for Mie scattering by collagen fibers, as predicted by the model for each of the nine neonatal skin samples to match the values for Mie scattering by collagen fibers as expected from the measurements of µ(s)'. The Mie-scattering model predicted an increase in scattering with gestational age on the basis of changes in the collagen-fiber diameters, and this increase was proportional to that measured with the integrating-sphere method.

Thermoreversible Gelation of Aqueous Methylcellulose Solutions

Abstract: The thermoreversible gelation of methylcellulose in aqueous solution has been studied by static and dynamic light scattering (DLS), small-angle neutron scattering (SANS), and rheology. At 20 °C, dilute solution light scattering establishes the molecular weight, second virial coefficient, radius of gyration, and hydrodynamic radius of the polymer. Semidilute solutions exhibit two relaxation modes in DLS, one reflecting cooperative diffusion and the other attributable to pregel clusters. Rheological measurements in this regime also suggest a weak supermolecular association. The gelation of semidilute solutions proceeds in two stages with increasing temperature above 20 °C, consistent with previous reports. The first stage is attributable to clustering of chains, driven by hydrophobic association, and extends up to approximately 50 °C. This process is accompanied by an increase in the low-frequency dynamic elastic modulus, G‘, and an increase in both light and neutron scattered intensity. The DLS properties ...

Light scattering study of tissues

Abstract: Tissue optics is a rapidly expanding field of great interest to those involved in the development of optical medical technologies. In the present review both strongly (multiple) scattering tissues, such as skin, brain tissues, and vessel walls, and weakly scattering high-transparent tissues, such as eye tissues (cornea and lens), are discussed. For the former, radiation transport theory or Monte Carlo simulation are used to describe the propagation of light (laser beams). For weakly scattering ordered tissues, ensembles of close-packed Rayleigh or Mie scatterers are employed. Methods for solving the inverse problem of finding biotissue optical parameters are discussed. The propagation of photon-density diffusion waves in scattering and absorbing media is analyzed and the prospects of these waves for optical tomography are discussed. Polarization phenomena in both strongly and weakly scattering biotissues are discussed.

Image transfer through a scattering medium

Abstract: 1 Introduction.- 1.1 A Brief History.- 1.2 Structure of the Book.- 1.3 Notes on Terminology.- 2 Radiation Field and Scattering Medium Characteristics.- 2.1 Radiation Field.- 2.2 Optical Parameters of a Volume Element.- 2.3 Radiation Transfer Equation.- 2.4 Similarity Principle and Modeling.- 2.5 Corollaries of the Optical Reciprocity Theorem.- 3 Light Scattering in Semi-Infinite Media and Plane Layers Illuminated by Infinitely Extended Plane Sources.- 3.1 Basic Equations.- 3.2 Asymptotic Regime in Deep Layers.- 3.2.1 Asymptotic Attenuation Coefficient and Angular Radiance Distribution.- 3.2.2 The Light Field in Absolute Units.- 3.3 Reflection from a Semi-Infinite Medium.- 3.3.1 Nonabsorbing Media.- 3.3.2 Weakly Absorbing Media.- 3.3.3 Absorbing Media with Strongly Anisotropic Scattering.- 3.4 Reflection and Transmission by Layers of Finite Thickness.- 3.5 Reflection and Transmission by Optically Thick Scattering Layers.- 3.5.1 Nonabsorbing Media.- 3.5.2 Weakly Absorbing Media.- 3.5.3 Absorbing Media with Strongly Anisotropic Scattering.- 3.6 Approximate Indicatrix Model Solutions.- 3.6.1 Forward Peak Truncation. Similar Media.- 3.6.2 Transport Approximation.- 3.6.3 Quasi-Single Scattering Approximation.- 3.6.4 Small-Angle Solution Iteration.- 3.6.5 Sobolev Approximation. Conservative Scattering.- 3.7 Two-Stream Approximation.- 3.7.1 Irradiance Coefficients. Boundary Conditions.- 3.7.2 Four-Parameter Variant of the Two-Stream Approximation.- 3.7.3 Two-Parameter Variant of the Two-Stream Approximation.- 4 Radiation Transfer in Scattering Media Illuminated by Localized Sources.- 4.1 Transfer Equation for a Narrow Beam. Spatial Radiance and Irradiance Distribution Moments.- 4.2 Local and Asymptotic Properties of Transfer Equation Solutions.- 4.3 The Diffusion Equation.- 4.3.1 Derivation of the Diffusion Equation.- 4.3.2 Solution of the Diffusion Equation for an Isotropic Point Source.- 4.3.3 Radial Irradiance Distribution from a Monodirectional Point Source.- 4.4 Small-Angle Approximation.- 4.4.1 Various Approaches.- 4.4.2 Transfer Equation in the Small-Angle Approximation.- 4.4.3 Solution of the Small-Angle Transfer Equation.- 4.4.4 Irradiance and Radiance of a Medium Illuminated by an Infinitely Extended Source.- 4.4.5 The Spread Function and its Moments.- 4.4.6 Light Flux.- 4.4.7 Radiation Fields in Scattering Media with Fluctuating Optical Parameters.- 4.4.8 The Merits and Weaknesses of the Small-Angle Approximation.- 4.5 Small-Angle Diffusion Approximation.- 4.5.1 Transfer Equation in the Small-Angle Diffusion Approximation.- 4.5.2 Light Fields Generated by an Infinitely Wide Source.- 4.5.3 Characteristics of Light Fields Produced by Narrow Beams.- 4.5.4 Oblique Medium Illumination.- 4.5.5 Light Fields in Media with Depth-Dependent Optical Characteristics.- 4.5.6 The Scope of the Small-Angle and Small-Angle Diffusion Approximations.- 4.5.7 Modified Small-Angle Diffusion Approximation.- 4.6 Notes on Multiple Backscattering.- 4.7 Generalized Multiple Scattering Theory Parameters and Applicability of Approximate Solutions.- 4.8 Nonstationary Radiation Field from Localized Pulsed Sources.- 4.8.1 The Nonstationary Transfer Equation.- 4.8.2 Pulse Propagation in Optically Thick Media.- 4.8.3 Pulse Reflection from a Semi-Infinite Scattering Medium.- 4.8.4 Forward Pulse Spread in a Strongly Anisotropic Scattering Medium.- 4.8.5 Mean Time and Variance of Photon Paths.- 5 Elements of Vision Theory.- 5.1 Image Quality Characteristics.- 5.1.1 Contrast and Signal-to-Noise Ratio.- 5.1.2 Threshold Contrast.- 5.1.3 General Image Quality Criterion.- 5.1.4 Threshold Signal-to-Noise Ratio.- 5.1.5 Signal-to-Noise Ratio in a Medium with Fluctuating Optical Parameters.- 5.2 Image Transfer Characteristics.- 5.2.1 Point Spread Function. Optical Transfer Function.- 5.2.2 Aspect Invariance of a System.- 5.2.3 Image Recording Techniques.- 5.2.4 Aspect Invariance Applicability.- 5.2.5 PSF and OTF Measurements.- 5.3 Active Vision Systems.- 5.3.1 Basic Relations.- 5.3.2 Classification of Vision System.- 5.3.3 Comparison of Vision Systems.- 5.3.4 Systems with Scattered Light Suppression.- 5.4 Visual Perception. Real Object Detection and Discrimination Range.- 5.4.1 The Johnson Criteria.- 5.4.2 Object Detection Range.- 5.4.3 Object Discrimination Range.- 5.5 Television and Location Target Detection Systems.- 5.5.1 Location in a Given Direction (Laser Echo-Ranging).- 5.5.2 Image Forming Location.- 5.6 Basic Characteristics of the Eye and Other Photodetectors.- 5.6.1 The Human Eye as a Radiation Receiver.- 5.6.2 Photographic and Photoelectric Recording.- 5.6.3 Notes on Infrared Imaging.- 6 Optical Transfer Function of a Scattering Medium.- 6.1 OTF of a Homogeneous Layer.- 6.1.1 OTF within the Small-Angle Approximation.- 6.1.2 The Small-Angle Diffusion Approximation.- 6.1.3 The Diffusion Approximation.- 6.1.4 MTF Dependence on Optical Medium Parameters.- 6.1.5 Scattering Layer MTF under Pulsed Source Illumination.- 6.2 OTF of an Inhomogeneous Layer.- 6.2.1 The Small-Angle Approximation.- 6.2.2 OTF of an Inhomogeneous Strongly Scattering Layer.- 6.2.3 MTF Dependence on the Scattering Layer Position along the Observation Path.- 6.2.4 Stochastic Medium MTF.- 6.3 Scattering Layer OTF along an Oblique Path. Phase Transfer Function.- 6.4 Nonlinear Distortions in Thick Scattering Layers.- 6.5 Object Image Contrast.- 6.5.1 Small Object Contrast.- 6.5.2 Contrast in the Johnson Striped Test Object.- 6.5.3 Finite Object Contrast as a Function of the Scattering Layer Position along the Observation Path.- 6.6 The Function ? in Object Detection and Discrimination.- 7 Image Transfer in Coherent Light.- 7.1 Coherent-Holography Imaging Through a Scattering Medium.- 7.1.1 Time-Averaged Holography.- 7.1.2 Limited Time Coherence (LTC) Method.- 7.1.3 Reference-Free Image Plane Holography (RFIPH).- 7.2 Comparison of Holographic and Incoherent Vision Systems.- 7.2.1 Mutual Coherence Function as Related to Radiance.- 7.2.2 Quality Characteristics of Rough Object Images in Reference Wave Holography.- 7.2.3 Contrast and Signal-to-Noise Ratio in Time-Averaged Holography and the Limited Time Coherence Technique.- 7.2.4 Contrast and Signal-to-Noise Ratio as Functions of the Averaging Time and Optical Parameters of a Scattering Medium.- 8 Viewing in Atmosphere.- 8.1 Optical Parameters of the Atmosphere.- 8.1.1 Cloudless Atmosphere.- 8.1.2 Cloud and Fog.- 8.2 Light Source Visibility.- 8.3 Object Visibility in Sunlight.- 8.3.1 Meteorological Visibility Range.- 8.3.2 Visibility Range in Clouds.- 8.4 Vision Characteristics in Cloud and Fog.- 8.4.1 OTF and Single-to-Noise Ratio.- 8.4.2 Cloud Microstructure Effect on the OTF and SNR.- 8.4.3 Estimation of Cloud OTF from Microstructure Data.- 8.5 Viewing Through Stochastic Clouds.- 8.5.1 Viewing System OTF and Signal Power Fluctuations.- 8.5.2 Irradiance and Radiation Flux Fluctuation Variances.- 8.5.3 Signal-to-Noise Ratio.- 9 Underwater Vision and Location in Sea Water.- 9.1 Optical Properties of Sea Water.- 9.1.1 Experimental Data.- 9.1.2 Simple Model of Optical Sea Water Characteristics.- 9.2 Object Visibility in Sea Water.- 9.2.1 Light Source Visibility.- 9.2.2 Range of Visibility of a Sunlit Object at Ocean Depth.- 9.2.3 Sekky's Disc Depth of Visibility.- 9.3 Underwater Television.- 9.3.1 Underwater TV Systems.- 9.3.2 MTF and Valid Signal and Noise Energy in Underwater Vision Systems.- 9.3.3 Limiting Ranges of Underwater Vision.- 9.4 Image Transfer Through a Rough Sea Surface.- 9.4.1 Rough Sea Surface Model.- 9.4.2 Image Transfer Characteristics.- 9.5 The Range of Optical Pulsed Location in Sea Water.- 10 Image Quality Problems in Photographic Layers and Luminescent Screens.- 10.1 Optical Parameters of a Photographic Layer.- 10.1.1 Undeveloped Layer.- 10.1.2 Exposed Developed Layer.- 10.2 Modulation Transfer Function of Photographic Materials.- 10.2.1 Optical and Photographic Modulation Transfer Functions.- 10.2.2 Empirical and Approximate MTF Formulas.- 10.2.3 MTF Dependence on the Optical and Emulsion Parameters of Photographic Materials.- 10.3 Optical Parameters of a Luminescent Screen.- 10.4 Modulation Transfer Function of Luminescent Screens.- 10.4.1 Nonscattering Luminescent Screens.- 10.4.2 Screens Weakly Absorbing Exciting Radiation.- 10.4.3 Screens Strongly Absorbing Exciting Radiation.- 10.4.4 Modulation Transfer Function of Cathode-Ray Screens.- 10.4.5 Influence of Technological Screen Parameters on MTF.- List of Symbols and Abbreviations.- References.