Abstract: An apparatus for measuring the light scattering properties of a sample in a liquid medium, wherein the liquid medium with the sample is illuminated by a laser beam in a measuring cell transversely to the direction of filling the liquid medium in the measuring cell or transversely to the flow direction of the liquid medium within the measuring cell, comprising a laser, a cylindrical measuring cell, a first inner aperture system, a second outer aperture system and at least two detectors, wherein the detectors are arranged outside of the second outer aperture system so that they collect the light scattered on the sample within set, different angle ranges, wherein the first inner aperture system and the second outer aperture system are formed and arranged circularly and concentrically around the axis of the measuring cell. Use of the apparatus and a method that makes use of the apparatus are also disclosed.