The overall field of the invention is that of systems for detecting the posture of a moving object in space. The device according to the invention comprises: a fixed electrooptical device comprising a point emission source, a telecentric lens comprising a projection lens, a reception lens and a semireflective optical element and a photosensitive matrix-type sensor, the point emission source being arranged at the common focal point of the projection lens and of the reception lens by reflection or transmission through the semireflective optical element, and; an assembly comprising at least three corner cube retroreflectors which are arranged on the moving object. The main application of this device is the detection of the orientation of an aircraft pilot helmet.