&lt;title&gt;Optical parameters of turbid materials and tissues as determined by laterally resolved reflectance measurements&lt;/title&gt;

Oelkrug, D.; Brun, Manfred; Hubner, Peter; Egelhaaf, Hans‐Joachim

doi:10.1117/12.260831

Cited by 4 publications

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“…1, which means that the reflected intensity is proportional to ρ −3 . This result is in accordance with Farrell et al 16 , whereas other authors 17,23 propose a final intensity slope proportional to ρ −2 .…”

Section: Theoretical Sectionsupporting

confidence: 92%

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Penetration of Light into Multiple Scattering Media: Model Calculations and Reflectance Experiments. Part II: The Radial Transfer

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In continuation of our contribution to "The Axial Transfer" (Appl. Spectr. 2012. 66(8): 934-943), this paper describes the distribution of localized incident radiation in multiple scattering layers of arbitrary thickness and analyzes the lateral intensity profiles of radiation leaving the sample from its illuminated and non-illuminated surfaces. The theoretical profiles are calculated with different approximations of the equation of transfer. We derive for both non-absorbing and absorbing layers simple analytical expressions and verify their accuracy and range of applicability by comparison with Monte Carlo simulations. Particular emphasis is given to the analysis of the radial absorption, an under-theorized and under-investigated feature that can help to identify weak or hidden absorbers. In addition, we contribute to the description of how the radial reflectance is affected by anisotropy or by error sources like multiple surface reflection for samples in glass cells or deflectance (sideway loss) of radiation in small samples. Finally, the theoretical results are compared with experimental data of radial reflectance for quasi non-absorbing and absorbing powder layers.

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Section: Theoretical Sectionsupporting

confidence: 92%

“…Thus, the reflectance analysis of packed substrates with typical scattering coefficients of σ = 10 2 −10 3 cm −1 requires resolution beyond the limits of fiber optics. The corresponding equipment has been developed for medium 22 and strongly 23 scattering materials.…”

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confidence: 99%

Penetration of Light into Multiple Scattering Media: Model Calculations and Reflectance Experiments. Part II: The Radial Transfer

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“…For many “real” samples thin layers cannot be prepared without significantly disturbing the physical properties of the bulk material. In those cases one can measure the radial reflectance profile d R /dρ = R '(ρ) upon “point” irradiation, the so-called point spread function (PSF), and calculate from these curves the optical parameters 19,28,32,37–41 or try to find a correlation of R '(ρ) with the desired depth profile d R /d z p . Figure 7 presents the correlation for a non-absorbing layer as intensity contour diagram.…”

Section: Resultsmentioning

confidence: 99%

“…From the integral reflectance R = N R / N 0 and the radial reflectance profile d R (ρ)/dρ one obtains finally σ eff and κ. 19,32…”

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Penetration of Light into Multiple Scattering Media: Model Calculations and Reflectance Experiments. Part I: The Axial Transfer

et al. 2012

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The article presents two general equations of radiation penetration into layers of diffuse reflectors. One of the equations describes the depth origins of reflection, the other the depth profiles of absorption. The equations are evaluated within the theory of radiative transfer applying various degrees of analytical approximations and Monte Carlo simulations. The data are presented for different scattering and absorption coefficients, arbitrary layer thicknesses, collimated and diffused irradiation, and anisotropic forward scattering. The calculated mean depths of reflection are always lower than the mean depths of absorption. For nearly non-absorbing layers, the mean depths of absorption are about one third of the physical layer thickness. In contrast, penetration saturates for strong absorbers at very low depth levels. From the simulated data, methods are derived for the determination of the penetration depth from reflectance and transmittance data of thin layers or from radially diffused reflectance profiles upon spot irradiation. The methods are experimentally verified for a series of metal oxide powders with particle sizes ranging from much smaller to much larger than the wavelength of irradiation and for microcrystalline cellulose stained with different concentrations of an organic dye.

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Handbook of Biophotonics

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The sections in this article are Introduction and Definitions Introduction Historical Aspects Definition of Quality: Product Functionality Quality Control Quality Assurance Management and Strategy PAT Initiative PAT Toolbox The Concept of Quality by Design ( Qb D ) ICH The Concept of a Design Space Implications for Other Branches of the Life Sciences General Remarks Biotechnology Food Industry Summary and Outlook Toolboxes for Process Control and Understanding Introduction: Causality Sampling Process Validation Role of Design of Experiments ( Do E ) Role of Failure Mode and Effects Analysis ( FMEA ) Measurement Technologies (How to Measure) Selection of the Appropriate Technique Working in Aqueous Systems Trace Analysis Qualification of a Spectrometer Data Analysis and Calibration (How to Process Data and How to Calibrate) Introduction Spectral Data Pretreatments and Data Cleaning Chemometrics Regression Analysis Process Control (How to Control a Process) Specific Problems Encountered in Industrial Process Analytics Moisture Measurements ( NIR , MW ) NIR Spectroscopy Microwave Resonance Technique ( MWR ) Process Analytics of Solids and Surfaces: Specular and Diffuse Reflectance Working in Multiple Scattering Systems: Separating Scatter from Absorbance Basics in the Measurement of Opaque Systems Separation of Scatter from Absorption Optical Penetration Depth Spectral Imaging and Multipoint Spectroscopy Survey Through Industrial Applications Selection of Applications Pharmaceutical Industry UV /Vis Spectroscopy NIR Spectroscopy Raman Spectroscopy Imaging Techniques Food and Agriculture UV /Vis Spectroscopy NIR Spectroscopy Raman Spectroscopy Imaging Techniques Polymers UV /Vis Spectroscopy NIR Spectroscopy Raman Spectroscopy Imaging Techniques Perspectives Technology Roadmap 2015+ Medical Applications and Tomographic Imaging Multi‐ Point‐Information Systems in Manufacturing Multimodal Spatially Resolved Spectroscopy Microreactor Control and Reaction Tomography

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<title>Optical parameters of turbid materials and tissues as determined by laterally resolved reflectance measurements</title>

Cited by 4 publications

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Penetration of Light into Multiple Scattering Media: Model Calculations and Reflectance Experiments. Part II: The Radial Transfer

Penetration of Light into Multiple Scattering Media: Model Calculations and Reflectance Experiments. Part II: The Radial Transfer

Penetration of Light into Multiple Scattering Media: Model Calculations and Reflectance Experiments. Part I: The Axial Transfer

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