Patent ID: 8013995

Claim:
A method for determining size and composition of a particulate matter in a fume flow produced by a combustion process, the method comprising: projecting a polarized laser light beam through the fume flow in a projection direction transversal to a fume conveying direction gathering the scattered light from the fume flow in a sideward scattering direction and in at least one forward scattering direction with respect to the projection direction; separating, for each of said scattering directions, the gathered light into two polarized light components on the planes parallel and orthogonal to the scattering direction; measuring, for each of said scattering directions, the light intensity of each of the corresponding polarized light components; calculating, for each of said scattering directions, a respective scattered light polarization ratio as a function of the light intensities of the polarized light components measured for the scattering direction; and determining the size of the particulate matter and the unburnt carbon percentage in the particulate matter as a function of the scattered light polarization ratios determined for said scattering directions.