The present invention relates to a positioning device and method for detecting light of fan shaped laser beam, as well as to a positioning system comprising the device and to a light emitting device emitting the fan shaped laser beam, which enable to find a spot of a laser beam easier and quicker. The positioning device comprises a detector for detecting light of a 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; and a position determining unit to obtain a first set of detection signals from the detector elements, determine a first time relation between the detection signals of the first set, and determine a positional relation between the detector and the propagation axis based on the first time relation.