title: Superimposed noninterfering probes to extend the capabilities of phase Doppler anemometry.
abstract: We propose using multiple superimposed noninterfering probes (SNIPs) of the same wavelength but different beam angles to extend the capabilities of phase Doppler anemometry. When a particle is moving in a SNIP the Doppler signals that are produced exhibit multiple Doppler frequencies and phase shifts. The resolution of the measurements of particle size (i.e., by fringe spacing and Doppler frequency) increases with beam angle. Then, with the solution proposed, even with only two detectors several measurements of size can be obtained for the same particle with increasing resolution if we consider higher frequencies in the signal. Several optical solutions to produce SNIPs as well as a signal-processing algorithm to treat the multiple-frequency Doppler signals are proposed. Experimental validations of the sizing of spherical and cylindrical particles demonstrate the applicability of this technique for particle measurement. We believe that this new technique can be of great interest when high resolution of size, velocity, and even refractive index is required.
authors.affiliation: Institut Universitaire des Systèmes Thermiques Industriels, Unité Mixte de Recherche No. 6595. Centre National de la Recherche Scientifique, Université de Procence, Technopĵle de Château-Gombert, Marseille, France. Fabrice.Onofri@polytech.univ-mrs.fr
authors.forename: Fabrice
authors.initials: F
authors.lastname: Onofri
authors.forename: Anne
authors.initials: A
authors.lastname: Lenoble
authors.forename: Stefan
authors.initials: S
authors.lastname: Radev