Determination of the reduced scattering and absorption coefficients by spatially resolved reflectance and total reflectance measurements

2011 ◽  
Author(s):  
Florian Foschum ◽  
Marie-Theres Heine ◽  
Alwin Kienle
Keyword(s):  
Absorption Coefficients ◽  
Total Reflectance ◽  
Spatially Resolved ◽  
Reflectance Measurements

Simultaneous Determination of Absorption Coefficients for Skin and Muscle Tissues Using Spatially Resolved Measurements

2011 ◽  
Vol 222 ◽  
pp. 309-312 ◽  
Author(s):  
Hiroshi Suzuki ◽  
Masatsugu Niwayama ◽  
Toshitaka Yamakawa ◽  
Masaki Ohkubo ◽  
Ryotaro Kime ◽  
...  
Keyword(s):  
Near Infrared ◽  
Absorption Coefficients ◽  
Calculation Algorithm ◽  
Spatially Resolved ◽  
Muscle Tissues ◽  
In Vivo Tests ◽  
Deep Layers

We present a method for simultaneous measurement of optical absorption coefficients for skin (μas) and muscle (μam) tissues using spatially resolved near-infrared spectroscopy (SRS). A novel calculation algorithm was developed to determine the absorption coefficients of superficial and deep layers within a three-layered structure using Monte Carlo simulation. A method for measuring the skin and muscle absorption coefficients was proposed based on this algorithm. In vitro experiments with tissue-like phantom and in vivo tests were performed using the SRS system with four separate detectors. The results show that the absorption coefficients for both skin and muscle tissues were obtained accurately.

Quantitative Determination of the Scattering and Absorption Coefficients from Diffuse Reflectance and Transmittance Measurements: Application to Pharmaceutical Powders

1997 ◽  
Vol 51 (3) ◽  
pp. 309-317 ◽  
Author(s):  
T. Burger ◽  
J. Kuhn ◽  
R. Caps ◽  
J. Fricke
Keyword(s):  
Particle Size ◽  
Diffuse Reflectance ◽  
Pharmaceutical Powders ◽  
Separate Determination ◽  
Absorption Coefficients ◽  
Absorption Properties ◽  
Flux Approximation ◽  
Reflectance Measurements ◽  
Made In

A measurement and data evaluation technique for the separate determination of the scattering and absorption properties of loose pharmaceutical powders is described. The equation of radiative transfer for diffuse reflectance and transmittance is analytically solved by using a three-flux approximation. Combined transmittance and reflectance measurements then allow one to derive both the scattering and the absorption coefficients. The scattering and absorption coefficients provide more information about particle size, degree of agglomeration, and chemical composition of the samples in comparison to the usual determination of only the ratio of the coefficients from diffuse reflectance measurements on optically thick samples. Furthermore, the theory of diffuse reflectance of optically thick samples according to Kubelka and Munk is compared to the three-flux approximation. The influence of the particle size on the scattering and absorption coefficient is investigated, and it is shown that the assumption of a wavelength-independent scattering coefficient, though often made in reflectance spectroscopy, is not generally valid.

Clinical determination of tissue optical properties in vivo by spatially resolved reflectance measurements

2003 ◽  
Author(s):  
Tobias J. Beck ◽  
Wolfgang Beyer ◽  
Thomas Pongratz ◽  
Walter Stummer ◽  
Raphaela M. Waidelich ◽  
...  
Keyword(s):  
Optical Properties ◽  
Spatially Resolved ◽  
Tissue Optical Properties ◽  
Reflectance Measurements ◽  
Clinical Determination

Determination of visible near-IR absorption coefficients of mammalian fat using time- and spatially resolved diffuse reflectance and transmission spectroscopy

2005 ◽  
Vol 10 (5) ◽  
pp. 054004 ◽  
Author(s):  
R. L. P. van Veen ◽  
H. J. C. M. Sterenborg ◽  
A. Pifferi ◽  
A. Torricelli ◽  
E. Chikoidze ◽  
...  
Keyword(s):  
Diffuse Reflectance ◽  
Ir Absorption ◽  
Absorption Coefficients ◽  
Spatially Resolved ◽  
Near Ir ◽  
Transmission Spectroscopy

A simplified two layer model for light diffuse reflectance in thin skin fruits

2010 ◽  
Vol 6 (1) ◽  
pp. 35-72 ◽  
Author(s):  
António Brázio ◽  
Ana Cavaco ◽  
Rui Guerra
Keyword(s):  
Diffuse Reflectance ◽  
Incident Beam ◽  
Layer Model ◽  
Total Reflectance ◽  
Spatially Resolved ◽  
Thin Skin ◽  
Two Layer Model ◽  
Absolute Reflectance ◽  
Reflectance Measurements ◽  
Reflectance Profile

A simple model of light diffuse reflectance in thin skin fruits is presented. The model is based in a semi-infinite two-layer geometry (skin and flesh) and introduces simplifications due to the fact that the first layer is very thin. The flesh is described in terms of the usual reduced scattering and absorption coefficients µs′ and µa but the skin is modeled by simple reflection (R), absorption (A) and transmission (T) coefficients. The problem of diffuse reflectance is thus reduced to the problem of determining the four constants µs′, µa, R and T. It is shown that the problem can be solved by using absolute reflectance and spatially resolved reflectance measurements simultaneously. The coefficients µs′ and µa are determined by the usual fit of the diffuse reflectance profile (photons re-emitted from the flesh far from the incidence point) to the diffusion approximation. The coefficients R and T are determined by a second fit involving the total reflectance profile (photons reemitted both from skin and flesh), the incident beam profile and the diffuse reflectance profile calculated according to the previously determined values of µs′ and µa. The anisotropy of the light re-emitted by the fruit can also be roughly compared with the Lambertian expected behavior. In order to test the model we have followed a population of 22 ‘Rocha’ pears along a period of two weeks. We have then performed the population averages along the time and checked the plausibility of the values obtained for µs′, µa, R and T according to the expected fruit physiological changes along ripening. The results show that all parameters are physically acceptable and evolve in time according to the expected fruit ripening physiology.

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