A cargo rollout stop includes a base, and a guide head pivotally mounted to the base. From a parallel light beam produced by a light source partial light beams having positive and negative diffraction angles are produced using a beam splitter in the form of a diffraction grating. Each brush segment includes a plurality of bristles having free ends extending away from the belt body, and neighboring brush segments are disposed proximate to one another to define a continuous density of the free ends about the length of the endless brush belt. The examinationanalysis may include a correlator for correlating received pulses with themselves or samples previously obtained.