This thesis deals with optical aerosol measurements employing sampling filters.
The primary objective is to assess the quantity of airborne particles by scrutinizing
alterations in light transmission through the sampling filter, onto which
these particles adhere. It’s essential to recognize that optical measurements are
profoundly influenced by various factors, including the optical and geometrical
properties of the particles, the sampling filter, the light source, and the light
detector.
The variations in transmittance primarily result from the absorption and scattering
of particles deposited on the filter. Consequently, measuring particles with
sampling filters presents a formidable challenge due to the potential for numerous
phenomena that may distort the interpretation of measurement outcomes. Notably,
we emphasize the impact of particle loading and the influence of multiple
scattering. Fortunately, both of these detrimental effects can be mitigated by
implementing algorithms that correct measurement results, either with fixed or
time-dependent correction parameters.
In this study, we employ the stochastic Monte Carlo simulation method within
the PyXOpto simulation environment to illustrate the intricate relationship between
optical parameters (e.g., absorption coefficient, scattering coefficient, scattering
phase function, and refractive index) and reflectance and transmittance
measurements. Specifically, we present the outcomes of simulations conducted
to assess reflectance measurements using optical fibers. Notably, we observe a
significant dependence of measured reflectance on the thickness of the deposited
layer of absorbing particles and their associated absorption coefficient. On the
other hand, the dependence of reflectance on the scattering phase function is
negligible.
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