  As part of a consortium between academic and industry, this PhD work
investigates the interest and capabilities of organic photo-sensors (OPS) for
the optical characterization of suspensions and two-phase flows. The principle
of new optical particle sizing instruments is proposed to characterize particle
systems confined in a cylinder glass (standard configuration for Process
Analytical Technologies). To evaluate and optimize the performance of these
systems, a Monte-Carlo model has been specifically developed. This model
accounts for the numerous parameters of the system: laser beam profile,
mirrors, lenses, sample cell, particle medium properties (concentration, mean &
standard deviation, refractive indices), OPS shape and positions, etc. Light
scattering by particles is treated either by using Lorenz-Mie theory, Debye, or
a hybrid model (that takes into account the geometrical and physical
contributions). For diluted media (single scattering), particle size analysis
is based on the inversion of scattering diagrams obtained over a wide angular
range or near optical singularities (rainbow, critical scattering,
diffraction). For dense media (multiple scattering), the solutions foreseen are
based on the analysis of the backscattering spotlight characteristics.
