POPS is a light-weight optical particle counter (GAO et al., 2013). Its working principle is based on the detection of the forward scattered light of individual particles. It uses a 405-nm laser and a photomultiplier tube detector. It measures particles in the size range from 0.1 to3.3 μmin diameter, with unit efficiency. POPS collection angle range is 38°-142°.
Spherical-shaped particles (Mie scattering) are considered and measurements are set for a refractive index equal to 1.615+0.001i (PSL spheres -given by the manufacturer). Further input is needed on how to correct its refractive index for dust particles.