Abstract: The device permits a wide field of detection with high sensitivity and high locating precision. To this end, the device has a four-quadrant detector associated with a diaphragm formed by the central transparent zone of an opaque mask. The diaphragm preferably has a circular shape and no focusing lens. These elements are in parallel planes so that the line joining the centers of the diaphragm and the detector is perpendicular to these planes. The set is placed in a housing and is shielded by a transparent window. With a deviation measurement circuit that processes the detected signals, the assembly enables the computation of the angular offset of a pinpoint radiant source. With two elementary sensors of this type, it is possible to compute the spatial location of the source, for example a laser.