The invention relates to a device to detect and/or characterize individual moving objects having very small dimensions which comprises a photo electric sensor having at least one light beam emitter and one light beam receiver in which the objects that are to be measured move through the optical path of the photo electric sensor, a first number of optical waveguides whose inputs are connected to the light beam emitter, the light beams emitted by the outputs of the optical waveguides forming the optical path of the photo electric sensor, a second number of optical waveguides whose inputs pick up the light beams emitted by the optical waveguides and whose outputs are connected to the light beam receiver, the outputs of the optical waveguides and the inputs of the optical waveguides being arranged in the form of a ring on a common plane, and an evaluation unit which is coupled to the light beam receiver and records the change in light intensity of the photo electric sensor produced by the objects passing through the optic path.