Particle counting in the presence of a dominant background by incoherent statistical optics

Extraction of the mean number of foreground particles that evolve in the presence of an arbitrary background population is achieved by means of a comparative measurement of incoherent scattered intensity fluctuations. Photon-counting experiments are conducted on test particles (latex spheres) that appear in a background population of polydisperse sand particles (Arizona fine, International Organization for Standardization standard 12103). Measurements show recovery of the test particle concentration with an error of less than 10%, despite the presence of the background population that contributes more than 90% of the scattered intensity.