The present disclosure relates to a positioning system including a positioning device and method for detecting light of fan shaped laser beam. The positioning device includes a detector for detecting light of the fan shaped laser beam rotating around a propagation axis with a direction of rotation and having two detector elements arranged in a known spatial relation for outputting a detection signal when irradiated. A position determining unit is used to obtain a first set of detection signals from the detector elements, to determine a first time relation between the detection signals of the first set, and to determine a positional relation between the detector and the propagation axis based on the first time relation.