Abstract: A method and device of detecting a scattering light beam for tools measuring scattering signals produced by the interaction of solid microparticles, such as a biological cells moving with a high-intensity, focused light beam, capable of reducing the influence of the cell movement with respect to the optical axis of the illuminating beam, and improving the quality of the signal characterized by the recognition of the individual particle or cell, specifically in fluid currents, such as those used in flow cytometry are disclosed.