Complex refractive index of non-spherical particles in the vis-NIR region - application to Bacillus Subtilis spores

A method is presented for the estimation of optical constants in the ultraviolet-visible-near-infrared (UVVis-NIR) region of nonspherical particles in a suspension at concentrations where multiple scattering issignificant. The optical constants are obtained by an inversion technique using the adding-doubling method to solve the radiative transfer equation in combination with the single scattering theories for modelling scattering by nonspherical particles. Two methods for describing scattering by single scatteringare considered: the T-matrix method and the approximate but computationally simpler Rayleigh-Gans-Debye (RGD) approximation. The method is then applied to obtain the optical constants of Bacillussubtilis spores in the wavelength region 400-1200 nm. It is found that the optical constants obtained using the RGD approximation matches those obtained using the T-matrix method to within experimental error

Optical properties of apple skin and flesh in the wavelength range from 350 to 2200 nm

Optical measurement of fruit quality is challenging due to the presence of a skin around the fruit flesh and the multiple scattering by the structured tissues. To gain insight in the light-tissue interaction, the optical properties of apple skin and flesh tissue are estimated in the 350-2200nm range for three cultivars. For this purpose, single integrating sphere measurements are combined with inverse adding- doubling. The observed absorption coefficient spectra are dominated by water in the near infrared and by pigments and chlorophyll in the visible region, whose concentrations are much higher in skin tissue. The scattering coefficient spectra show the monotonic decrease with increasing wavelength typical for biological tissues with skin tissue being approximately three times more scattering than flesh tissue. Comparison to the values from time-resolved spectroscopy reported in literature showed comparable profiles for the optical properties, but overestimation of the absorption coefficient values, due to light losses

Joyero engastador

Se presenta el diseño didáctico de la especialidad en joyería así como los bloques modulares, módulos instruccionales, objetivos, requisitos, operaciones y contenidos.The didactic design of the specialty in jewelry is presented as well as the modular blocks, instructional modules, objectives, requirements, operations and contents.Armado por moldeo -- Cadenerìa manual -- Engaste al grano -- Proceso de la cera perdida -- Armado especial -- Gestion empresarialna182 página

Estimation of optical constants of particles in suspension from multiple-scattered light

This thesis presents a method to extract complex refractive index (optical constants), m(A) = n(A) + ik(A) in the ultra-violet, visible and near-infrared wavelength regions, of particles in suspensions at concentrations where multiple scattering is significant. Optical constants can provide important information required for process and quality control of suspensions of particles, slurries, and biological suspensions. Moreover, accurate values of n(A) and k(A) are required to estimate particle size and size distribution using light scattering methods. The optical constants are obtained by inverting measurements of total diffuse reflectance and transmittance. The inversion method is based on solving the Radiative Transfer Equation (RTE), using the adding-doubling method, to account for multiple scattering along with single scattering theories to describe single-particle scattering characteristics. The method was initially implemented to estimate the optical constants of spherical particles in the UV-Vis-NIR region using the exact Mie theory for describing single scattering and taking polydispersity into account. This was applied to polystyrene and poly(methylmethacrylate) suspensions. The effect of particle size and concentration on the estimated optical constants were investigated. The inversion of multiple-scattered light measurements to extract optical constants is computationally intensive. Different approximations for computing the optical properties (absorption and scattering cross-section, anisotropic factor, and phase function) so as to significantly accelerate the calculations without introducing large inaccuracies were investigated. A comparison between the inverse method and the Kramers-Kronig relations, which extracted n(A) from known values of k(A), was also performed. In practice, we have to deal with systems of non-spherical particles as biological suspensions. An extension of the method to extract the optical constants that takes into account particle shape using the Rayleigh-Gans-Debye approximation and the T-Matrix method for non-spherical particles was implemented. This method was applied to a suspension ofBacillus subtilis spores to obtain the optical constants in the UV-Vis-NIR region.EThOS - Electronic Theses Online ServiceGBUnited Kingdo