High resolution particle sizing using the combination of time-of-flight and light-scattering measurements

To achieve a high precision of sizing of particles in flow we investigated the combination of light scattering and time-of-flight (TOF) measurements using two laser beams different in wavelength and spot size. Light-scattering vs TOF size measurements done on polysterene beads (0.481–5 μm) demonstrate convincingly the multivalue nature of light-scattering data as predicted by Lorenz–Mie theory. Using the size information by TOF measurements the angular regions for high resolution sizing by light-scattering measurements are predictable and could be selected during the experiment. Measurements done on a mixture of spheres and biological cells (thymocyte nuclei, fixed lymphocytes) show that combining TOF and light-scattering dual-parameter measurements allow excellent discrimination and sizing of cells.