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 pr esence of an arbitrary background population is achieved by means of a comp arative measurement of incoherent scattered intensity fluctuations. Photon- counting experiments are conducted on test particles (latex spheres) that a ppear in a background population of polydisperse sand particles (Arizona fi ne, International Organization for Standardization standard 12103). Measure ments show recovery of the test particle concentration with an error of les s than 10%, despite the presence of the background population that contribu tes more than 90% of the scattered intensity. (C) 2000 Optical Society of A merica OCIS codes: 290.5850, 120.5820, 030.6600, 030.5260.