Light Distribution, Optical Properties, and Cardiovascular Tissues

Author(s):  
Martin J. C. van Gemert ◽  
A. J. Welch ◽  
Steven L. Jacques ◽  
Wai-Fung Cheong ◽  
Willem M. Star
Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3039
Author(s):  
Ali Rizwan ◽  
Muhammad Saleem ◽  
Suhail H. Serbaya ◽  
Hemaid Alsulami ◽  
Aqsa Ghazal ◽  
...  

(1) Background: This study investigated the miscibility of carbon-based fillers within industrial scale polymers for the preparation of superior quality polymer composites. It focuses on finding the light distribution in gamma irradiated ultra-high molecular weight polyethylene (UHMWPE). (2) Methods: The Kubleka–Munk model (KMM) was used to extract the optical properties, i.e., absorption coefficients (μa) and scattering coefficients (μs). Samples amounting to 30 kGy and 100 kGy of irradiated (in the open air) UHMWPE from 630 nm to 800 nm were used for this purpose. Moreover, theoretical validation of experimental results was performed while using extracted optical properties as inputs for the Monte Carlo model of light transport (MCML) code. (3) Conclusions: The investigations revealed that there was a significant decrease in absorption and scattering coefficient (μa & μs) values with irradiation, and 30 kGy irradiated samples suffered more compared to 100 kGy irradiated samples. Furthermore, the simulation of light transport for 800 nm showed an increase in penetration depth for UHMWPE after gamma irradiation. The decrease in dimensionless transport albedo  μs(μa+μs) from 0.95 to 0.93 was considered responsible for this increase in photon absorption per unit area with irradiation. The report results are of particular importance when considering the light radiation (from 600 nm to 899 nm) for polyethylene modification and/or stabilization via enhancing the polyethylene chain mobility.


2014 ◽  
Vol 19 (7) ◽  
pp. 075001 ◽  
Author(s):  
Mehdi Azimipour ◽  
Ryan Baumgartner ◽  
Yuming Liu ◽  
Steven L. Jacques ◽  
Kevin Eliceiri ◽  
...  

2000 ◽  
Author(s):  
Cheng-Lun Tsai ◽  
Ming Chang ◽  
Jui-Hsiang Hsieh ◽  
Yi-Fong Yang ◽  
Yi-Sheong Chou

Author(s):  
BADRI NARAYAN MOHAPATRA ◽  
RASHMITA KUMARI MOHAPATRA

Successful integration of day lighting systems requires the ability to predict their performance for given climates. In this, a bottom-up approach is applied to evaluate the optical performance of a selection of day lighting systems. The evaluations are based on the optical properties of the included materials, and focuses on developing new optical characterization methods. The work on characterization techniques uses an integrating sphere method to characterize the transmittance of light scattering samples more accurately. The method's principle is to reduce the discrepancy in light distribution between the reference and the sample scans by using an entry port beam diffuser. For samples exhibiting distinct light scattering patterns, the benefits of improved uniformity outweigh the errors introduced by the diffusing material. The method is applicable to any integrating sphere instrument, and its simplicity makes it suitable for standard measurements.


2013 ◽  
Vol 739 ◽  
pp. 394-399 ◽  
Author(s):  
Shi Bao Li ◽  
Da Ming Wu ◽  
Ying Liu ◽  
Ya Jun Zhang ◽  
Jian Zhuang ◽  
...  

LED has characters of small size, long life and low power consumption, and it is environmental friendly. These advantages make LED have a huge market in the lighting industry. LED with the light distribution design can meet the requirements of the application under different circumstances. With the acknowledgement of the principles of light distribution design, based on optical engineering software LightTools, we study the light distribution design of LED back light module for direct-down illumination and LED shadowless lamp. After the secondary optics light distribution design of the LED light, its transmittance and uniformity has been noticeably improved. We depict different types of micro-structure on the surface of 3mm thickness PMMA diffuser, test and analysis the optical properties of the diffuser under different microstructure.


Author(s):  
K. Tsuno ◽  
T. Honda ◽  
Y. Harada ◽  
M. Naruse

Developement of computer technology provides much improvements on electron microscopy, such as simulation of images, reconstruction of images and automatic controll of microscopes (auto-focussing and auto-correction of astigmatism) and design of electron microscope lenses by using a finite element method (FEM). In this investigation, procedures for simulating the optical properties of objective lenses of HREM and the characteristics of the new lens for HREM at 200 kV are described.The process for designing the objective lens is divided into three stages. Stage 1 is the process for estimating the optical properties of the lens. Firstly, calculation by FEM is made for simulating the axial magnetic field distributions Bzc of the lens. Secondly, electron ray trajectory is numerically calculated by using Bzc. And lastly, using Bzc and ray trajectory, spherical and chromatic aberration coefficients Cs and Cc are numerically calculated. Above calculations are repeated by changing the shape of lens until! to find an optimum aberration coefficients.


Author(s):  
A. Strojnik ◽  
J.W. Scholl ◽  
V. Bevc

The electron accelerator, as inserted between the electron source (injector) and the imaging column of the HVEM, is usually a strong lens and should be optimized in order to ensure high brightness over a wide range of accelerating voltages and illuminating conditions. This is especially true in the case of the STEM where the brightness directly determines the highest resolution attainable. In the past, the optical behavior of accelerators was usually determined for a particular configuration. During the development of the accelerator for the Arizona 1 MEV STEM, systematic investigation was made of the major optical properties for a variety of electrode configurations, number of stages N, accelerating voltages, 1 and 10 MEV, and a range of injection voltages ϕ0 = 1, 3, 10, 30, 100, 300 kV).


Author(s):  
Marcos F. Maestre

Recently we have developed a form of polarization microscopy that forms images using optical properties that have previously been limited to macroscopic samples. This has given us a new window into the distribution of structure on a microscopic scale. We have coined the name differential polarization microscopy to identify the images obtained that are due to certain polarization dependent effects. Differential polarization microscopy has its origins in various spectroscopic techniques that have been used to study longer range structures in solution as well as solids. The differential scattering of circularly polarized light has been shown to be dependent on the long range chiral order, both theoretically and experimentally. The same theoretical approach was used to show that images due to differential scattering of circularly polarized light will give images dependent on chiral structures. With large helices (greater than the wavelength of light) the pitch and radius of the helix could be measured directly from these images.


Author(s):  
R. B. Queenan ◽  
P. K. Davies

Na ß“-alumina (Na1.67Mg67Al10.33O17) is a non-stoichiometric sodium aluminate which exhibits fast ionic conduction of the Na+ ions in two dimensions. The Na+ ions can be exchanged with a variety of mono-, di-, and trivalent cations. The resulting exchanged materials also show high ionic conductivities.Considerable interest in the Na+-Nd3+-ß“-aluminas has been generated as a result of the recent observation of lasing in the pulsed and cw modes. A recent TEM investigation on a 100% exchanged Nd ß“-alumina sample found evidence for the intergrowth of two different structure types. Microdiffraction revealed an ordered phase coexisting with an apparently disordered phase, in which the cations are completely randomized in two dimensions. If an order-disorder transition is present then the cooling rates would be expected to affect the microstructures of these materials which may in turn affect the optical properties. The purpose of this work was to investigate the affect of thermal treatments upon the micro-structural and optical properties of these materials.


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