The directional reception of extremely weak light signals without diverting a portion of the signal light into separate detectors for the purpose of obtaining an alignment signal is caused by the arrangement of several detector means (X, Y) which, when unmodulated light is superimposed on them, generate electrical output variables (x1, x2, y1, y2) which, after they have been added in a network (I), result in an information signal which, when it is linked by multiplication with several difference signals (x, y) formed in the network (I), converts them into narrow-band signals, which reproduce an alignment error.