A door sensor system (90) for detecting a target object (56) in and/or near a door comprising a door opening (96), and at least one movable door element (76, 76-1, 76-2, 76-3, 76-4), the system comprising at least one light scanner device (10) which is capable of measuring optically the distance to a target to make such a measurement over a given scan angle at regular intervals by deflecting the light with moving mirrors, and which generates at least one vertical plane of detection.