Sub-diffraction limit three dimensional particle tracking velocimetry

Here we present an optical measurement technique and image analysis process capable of tracking particles in three dimensions with a single point of view. In addition to single view 3D-PTV, the optical system is capable of tracking individual particles even at particle-particle spacings that are closer then the diffraction limit of the base imaging system. The measurement system, termed Bessel Beam Microscopy (BBM), functions as an attachment for a microscope that fits between the microscope base and camera. The addition of the BBM attachment transforms the point spread function (PSF) of the microscope allowing two unique functions: single image superresolution imaging, and the extraction of three dimension location information of particles without calibration. The result is a fluid characterization tool with unique capabilities for velocimetry and characterization of the dynamics of dense fluid-particle suspensions