To detect the relative position of bodies, surfaces or the like, especially those on machines, there is an optoelectronic sensor. The latter reacts to incident light, for example, monochromatic laser light. The available receiving surface is however comparatively small for low-cost or pixel-oriented sensors. By making available a diffuser and a projecting objective lens in front of an optoelectronic sensor the usable receiving surface for incident light can be greatly increased. The diffuser or also the projecting objective lens can additionally be designed as a color filter and can be used to reduce the effects of outside light. A process is provided with which an especially accurate determination of the median point of the laser light spot incident on the target (optoelectronic sensor) can be achieved.