Study of the dynamics of transformation of point defects in phosphosilicate fibres by the induced refraction index
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A method for studying the dynamics of transformation of defects in optical fibres, exposed to UV radiation, by the dose dependence of the induced refractive index is proposed. The processes of transformation of defects in a low-loss phosphosilicate fibre, loaded with molecular hydrogen, irradiated at the 193-nm wavelength are investigated using this method. It is assumed that such a fibre has at least two types of defects, responsible for the induction of the refractive index.Refractive index provides fundamental insights into the electronic structure of materials. At high pressure, however, the determination of refractive index and its wavelength dispersion is challenging, which limits our understanding of how physical properties of even simple materials, such as MgO, evolve with pressure. Here, we report on the measurement of room-temperature refractive index of MgO up to ∼140 GPa. The refractive index of MgO at 600 nm decreases by ∼2.4% from ∼1.737 at 1 atm to ∼1.696 (±0.017) at ∼140 GPa. Despite the index at 600 nm is essentially pressure independent, the absolute wavelength dispersion of the refractive index at 550–870 nm decreases by ∼28% from ∼0.015 at 1 atm to ∼0.011 (±8.04 × 10−4) at ∼103 GPa. Single-effective-oscillator analysis of our refractive index data suggests that the bandgap of MgO increases by ∼1.1 eV from 7.4 eV at 1 atm to ∼8.5 (±0.6) eV at ∼103 GPa.
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Refractive index variations of film materials are measured using a spectral micro-reflectometer, the Tencor® TF-1. The principles of thickness and refractive index determination are discussed. An effective medium model of film materials is applied to calculating refractive indices and their wavelength dependence. Refractive indices for typical poly-crystalline silicon are given. Compositional and structural inhomogeneities cause refractive index variations. Neglecting these index variations leads to misinterpretation of film thickness measurements.
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Because the refractive index of hemoglobin in the visible range is sensitive to the hemoglobin concentration, optical investigations of hemoglobin are important for medical diagnostics and treatment. Direct measurements of the refractive index are, however, challenging; few such measurements have previously been reported, especially in a wide wavelength range. We directly measured the refractive index of human deoxygenated and oxygenated hemoglobin for nine wavelengths between 400 and 700 nm for the hemoglobin concentrations up to 140 g l−1. This paper analyzes the results and suggests a set of model functions to calculate the refractive index depending on the concentration. At all wavelengths, the measured values of the refractive index depended on the concentration linearly. Analyzing the slope of the lines, we determined the specific refraction increments, derived a set of model functions for the refractive index depending on the concentration, and compared our results with those available in the literature. Based on the model functions, we further calculated the refractive index at the physiological concentration within the erythrocytes of 320 g l−1. The results can be used to calculate the refractive index in the visible range for arbitrary concentrations provided that the refractive indices depend on the concentration linearly.
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Deoxygenated Hemoglobin
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An experimental procedure is described making it possible to determine from one diffusion experiment both the diffusion coefficient D and the dependence of the refractive index on concentrations ∂μ/∂c for many wavelengths of light. The results from the measurements of D and ∂μ/∂c at 6 wavelengths (6328Å, 5145Å, 4965Å, 4880Å, 4765Å and 4579Å) for LiNO3, NaNO3, KNO3, RbNO3, and CsNO3 in water are presented.
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The index of refraction for D2O at common wavelengths was measured for several temperatures at atmospheric pressure. While heavy water's refractive index was precisely measured decades ago using the transition lines of elements, those wavelengths are seldom used now that inexpensive lasers provide a range of available wavelengths. We review those measurements, note some inconsistencies between research groups, and fit the best of the literature data to a simple equation that allows an easy calculation for the refractive index of D2O with an accuracy of ± 0.0002 at any visible wavelength and between (278 and 359) K. To verify the equation, we then compare the calculated refractive index to our measured values for three He–Ne laser wavelengths (543.5, 594.1, and 632.8) nm over a temperature range from (288 to 338) K and find good agreement.
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Ten glasses of PbO-ZnO-P 2 O 5 system have been prepared. The experimental values of refractive index of these glasses were compared with the theoretical ones calculated using (i) Lorentz-Lorenz equation, (ii) Virtual Crystal Approximation (VCA), and (iii) Effective Medium Theory (EMT). It is shown that the refractive index determined by EMT and VCA follows the experimental values of refractive index quite well and these methods can be used for prediction of the refractive index values in PbO-ZnO-P 2 O 5 system glasses. It is also supposed that the nonlinear refractive index value could reach the value n 2 [esu] 5.4×10 - 1 2 for glasses with the linear refractive index n > 1. 8.
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A three-wavelength method based on Cauchy or Sellmeier formulas is proposed for simultaneous determination of the thickness and refractive index without using approximate expansions of the refraction index over the wavelength. The method is also applicable for the simultaneous determination of other optical characteristics together with the refractive index. To test the applicability of the proposed method, the refractive index and thickness of ultrathin polysulfone film were obtained in the surface plasmon resonance experiment.
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A method is described for determining the thickness and refractive index of barium stearate double layers. Films prepared by the method of Blodgett, but using a different piston oil, were found to have a thickness of 45.7A and an ordinary refractive index of 1.508.
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Barium
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High-refractive-index polymer
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Abstract A technique is described for determining the density of polyolefin film from refractive index measurements. The procedure involves the measurement of the refractive indexes ( n x , n y , and n z ) along the three major axes of a film sample and conversion of the arithmetic average refractive index to a density value. The refractive index data are also used to calculate the per cent crystallinity and birefringence in the film.
Polyolefin
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Optical density
Refractometer
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X-ray optics
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Prism
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