Sensing device for detecting moisture on a transparent glass pane

The arrangement has at least one radiation transmitter (31) and at least one radiation receiver (32) in a housing (10,20), a refractive radiation guidance arrangement (21,22) that couples radiation from the transmitter into the screen and feeds part of the radiation to the receiver depending on the wetting of the screen. A reflective radiation guide arrangement feeds radiation not directly captured by the refractive arrangement to it indirectly.