The single-particle optical sensing (SPOS) using optical fiber intensity modulation sensors

The ability to accurately measure the particle size distribution (PSD) of particle suspensions and dispersions has proven to be crucial for ensuring the success of a wide process material and final products. We propose two optical fiber sensors that exploit light intensity modulation in optical fibers. One of them is constructed in a typical reflection-sensing configuration but it uses the backscattering effect on particles in suspension. The other one is based on intensity modulation of the transmitted light through optical fibers. In this case, the diffusing particle acts as a tiny lens deflecting the light away from incident beam. Furthermore, we have presented the theoretical framework concerning the light scattering on dielectric spheres (Mie scattering) and colloidal aggregates. The relevant experimental data are also shown in order to prove the sensors reliability.