In particular, rain sensor to be used in the automobile

A rain sensor (10), in particular for a motor vehicle, is shown, having at least one transmitter (20) emitting radiation in the operating state, and at least one receiver (22) at least partially sensitive to the radiation from the transmitter (20), and a substantially flat light-conducting body (14) that is capable of being coupled nearly parallel to a surface of a wettable window pane (12) of the motor vehicle, and comprising structures (18a, 18b) for directing and catching the radiation from the transmitter (20), whereby the structures (18a) for directing the radiation are different from the structures (18b) for catching the radiation, and they have radiation-concentrating properties.